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Physics Education bull October minus December 2009 297
PHYSICS THROUGH TEACHIG LAB XVIII
An Inexpensive PC Based Hall Effect Set Up
AMIT GARG REENA SHARMA VISHAL DHINGRA Department of Electronics
Acharya Narendra Dev College University of Delhi Govindpuri Kalkaji New Delhi 110019 India
Email amit_andcyahoocoin
ABSTRACT
We have developed a fully automatic inexpensive PC based Hall Effect setup The present development uses data acquisition using parallel port of the computer with the software written in Visual Basic Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results All parameters can be calculated using the software developed The aim of the development is to motivate students to the use of computers in science experimentationeducation
Keywords Computer interfacing parallel port automatic Hall Effect data acquisition PC based experiments
298 Physics Education bull October minus December 2009
Introduction The historical roots of the modern Hall Effect go back to the previous century before the physicists knew the laws of quantum mechanics In 1879 Edwin H Hall a graduate student at Johns Hopkins University discovered that when a magnetic field was applied perpendicularly to a thin metal sheet that was conducting current a small electrical voltage appeared that was perpendicular to both the sheet and the magnetic field The observed voltage is proportional to the strength of the applied field This effect was named the Hall Effect in his honor The Hall voltage and Hall resistance (the ratio of the Hall voltage to the current) are now commonly used in physics laboratories to measure the strengths of magnetic fields as well as charge densities in semiconductors and metals
The main purpose of Hall Effect experiment at the first year of undergraduate level in the Modern PhysicsElectronics Lab is to study the classical Hall Effect in n and p type semiconductor germanium samples as well as to understand how using the Hall Effect measurements one could determine the concentration the type and the mobility of the electric charge carriers in semiconductor samples Additionally it makes students know that the Hall Effect is an extremely important tool for measuring magnetic fields The Hall probes or Hall sensors are very convenient for numerous applications and several billion Hall Effect devices in keyboards and sensor products are now in use for measuring moderate magnetic fields with the accuracy better than 1 Besides being such an important tool recent discoveries of quantized Hall Effect and fractional quantum Hall Effect have opened new areas of active research123
Looking at the importance of this effect and in order to give impetus to the idea of increased use of computers in the science laboratories this is one of the series of experiments planned
to be made completely computer based This will not only make students realize the power of computers in science experimentseducation but also give them the taste to convert various science experiments into PC based experiments This fully automatic low cost PC based Hall Effect45 will make students appreciate the art of data acquisition using computers and computer software This exercise will motivate a lot of students to develop new computer based interfacing modules for different science experiments
This set up eliminates the use of any readymade commercially available costly instruments required for performing the Hall Effect experiment such as Digital Gaussmeter Hall-Effect Set Up containing a current source for providing current to the sample or readout for the Hall voltage etc The total cost of the components used in this set up is less than $15 The computer software has been developed using Visual Basic 6067
Hall Effect
It is often necessary to determine whether a material is n-type or p-type Measurement of the conductivity of a specimen will not give this information since it cannot distinguish between positive hole and electron conduction The Hall Effect can be utilized to distinguish between the two types of carrier and it also allows the density of the charge carriers to be determined In conjunction with a measurement of conductivity the mobility of the carriers can be found
EH Hall discovered that when a current was passed through a slab of material in the presence of a transverse magnetic field a small potential difference was established in a direction perpendicular to both the current flow and the magnetic field Figure 1 shows the current flowing in the positive x direction with the flux density B in the positive z direction and the potential difference appearing in the y
direction Probes may be attached to faces 1 and 2 and the potential difference may be measured
The Hall Effect may be explained by reference to Figure 2 which shows the front face of the slab only Assuming that the
material is an n-type semiconductor the current flow consists almost entirely of electrons moving from right to left This corresponds to the direction of conventional current from left to right
y
Physics Education bull October minus December 2009 299
Figure 1 Illustration of the Hall Effect If v is the velocity of electrons at right
angles to the magnetic field there is a downward force on each electron of magnitude Bqv This causes the electron current to be deflected in a downwards direction and causes a negative charge to accumulate on the bottom face of the slab (face 1) A potential difference is therefore established from top to bottom of the specimen with the bottom face negative8
The Hall coefficient Rh is defined as in equation (1) by
Rh = minus1nq = 1pq (1)
where n and p are the concentration of electrons and holes in the semiconductor sample respectively and q is the charge of an electron
By measuring the conductivity one can also calculate the mobility micro of the sample which is given as in equation (2)
micro = σRh (2)
where σ is the conductivity of the semiconductor sample and Rh is the Hall coefficient
I
Direction of conventional current flow
Probe
Probe attached to
face 2
attached to face 1
B
xz
Experimental Setup Hardware
Figure 3(3a 3b 3c) shows the systems hardware The detailed schematic of various
hardware blocks is as shown in Figure 3 and 4(4a 4b 4c) Functioning of the various blocks has been discussed as under
300 Physics Education bull October minus December 2009
Figure 2 Motion of electrons in an n-type semiconductor (Hall Effect) 1 Current to Voltage Converter The
function of current to voltage converter910 is to convert the input Hall current to the sample into voltage so as to be read by ADC9 The gain of this converter has been set such that the equivalent voltage does not exceed the maximum value of 5 volts for the maximum current of 18 mA The output of this converter being negative while ADC can read positive voltage therefore an inverter is connected at the output of this converter The output of this inverter is then fed to the ADC Channel 1 where it is converted into its
corresponding digital value and read by the PC Parallel Port
x
qε
Bqv
- - - - - - - -
Face 2 y
Face 1
2 Hall Sensor The Hall Sensor (IF 6) is used for magnetic field measurements This is a very cheap and easily available Hall sensor The Hall sensitivity of this sample at 10 mA is 03983 mVKGauss The output of this sensor is connected to ADC Channel 4 so as to be read by the PC
3 Differential Amplifier The Differential Amplifier amplifies the Hall Voltage obtained from the sample by a factor of
Physics Education bull October minus December 2009 301
10 The gain factor of 10 ensures A) The voltages generated are within the safe limits even at the maximum Hall Current B) It enhances the ADC resolution from 20 mV to 2mV
However as the Hall voltage generated can be negative or positive depending on the type of sample under consideration to ensure the working of the system being designed for any sample type the Hall voltage is inverted using an op-amp based inverter Hence both the positive and negative values of the amplified Hall voltage are available simultaneously at the switching circuit with the differential amplifier output giving the true amplified Hall voltage
4 Switching Circuit For a particular sample under consideration either the true Hall voltage or its inverted counterpart is read by the computer However if the negative voltage at the analog input of ADC is larger than -03 volts it starts malfunctioning Hence a switching circuit is designed which only sends a positive value of amplified Hall voltage to Channel 0 of ADC if the sample is p type or to Channel 3 if it is n type The other channel receives a zero voltage at the same time
5 Voltage Limiter with Buffer The Voltage Limiter Circuit along with buffer circuitry is used to sense whether the sample is p or n type When the sample is p type the output of this circuitry is zero and when the sample is n type the output is High (4-5 Volts) The computer reads this output from pin no 11 of parallel port to sense the sample type
6 Analog to Digital Converter (ADC) The ADC Section converts the analog Hall voltage Hall current Magnetic Field Sensor Output into their corresponding
digital values and sends the converted values to the PC when and where needed
The computer sends an SOC pulse to the ADC and the Channel Address (A0-A2) to select a particular channel for conversion As soon as the ADC receives the SOC pulse it converts the analog data on the desired channel and places the data on the Digital Address Bus (D0-D7) On successful conversion ADC enables the EOC pin high which enables the Output Enable (OE) and the data is ready to be read by the computer
7 Current Source A simple current source can be made using an operational amplifier as shown in Figure 4(c) In the present setup we have used two constant current sources
8 Current Source for Hall sensor This is a current source up to 15 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 1 KΩ and a 10 KΩ potentiometer
9 Current Source for Hall Sample This uses a current source up to 150 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 100 ohm and a 100 KΩ potentiometer
Software
The software developed by us is a graphical user interface11 with main functional provisions mentioned as under Calibrate From the start up screen calibration of the sample is mandatory to the user before proceeding to the start of experiment The other options of the startup screen remains deactivated until the user completes the calibration process As part of the calibration
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
298 Physics Education bull October minus December 2009
Introduction The historical roots of the modern Hall Effect go back to the previous century before the physicists knew the laws of quantum mechanics In 1879 Edwin H Hall a graduate student at Johns Hopkins University discovered that when a magnetic field was applied perpendicularly to a thin metal sheet that was conducting current a small electrical voltage appeared that was perpendicular to both the sheet and the magnetic field The observed voltage is proportional to the strength of the applied field This effect was named the Hall Effect in his honor The Hall voltage and Hall resistance (the ratio of the Hall voltage to the current) are now commonly used in physics laboratories to measure the strengths of magnetic fields as well as charge densities in semiconductors and metals
The main purpose of Hall Effect experiment at the first year of undergraduate level in the Modern PhysicsElectronics Lab is to study the classical Hall Effect in n and p type semiconductor germanium samples as well as to understand how using the Hall Effect measurements one could determine the concentration the type and the mobility of the electric charge carriers in semiconductor samples Additionally it makes students know that the Hall Effect is an extremely important tool for measuring magnetic fields The Hall probes or Hall sensors are very convenient for numerous applications and several billion Hall Effect devices in keyboards and sensor products are now in use for measuring moderate magnetic fields with the accuracy better than 1 Besides being such an important tool recent discoveries of quantized Hall Effect and fractional quantum Hall Effect have opened new areas of active research123
Looking at the importance of this effect and in order to give impetus to the idea of increased use of computers in the science laboratories this is one of the series of experiments planned
to be made completely computer based This will not only make students realize the power of computers in science experimentseducation but also give them the taste to convert various science experiments into PC based experiments This fully automatic low cost PC based Hall Effect45 will make students appreciate the art of data acquisition using computers and computer software This exercise will motivate a lot of students to develop new computer based interfacing modules for different science experiments
This set up eliminates the use of any readymade commercially available costly instruments required for performing the Hall Effect experiment such as Digital Gaussmeter Hall-Effect Set Up containing a current source for providing current to the sample or readout for the Hall voltage etc The total cost of the components used in this set up is less than $15 The computer software has been developed using Visual Basic 6067
Hall Effect
It is often necessary to determine whether a material is n-type or p-type Measurement of the conductivity of a specimen will not give this information since it cannot distinguish between positive hole and electron conduction The Hall Effect can be utilized to distinguish between the two types of carrier and it also allows the density of the charge carriers to be determined In conjunction with a measurement of conductivity the mobility of the carriers can be found
EH Hall discovered that when a current was passed through a slab of material in the presence of a transverse magnetic field a small potential difference was established in a direction perpendicular to both the current flow and the magnetic field Figure 1 shows the current flowing in the positive x direction with the flux density B in the positive z direction and the potential difference appearing in the y
direction Probes may be attached to faces 1 and 2 and the potential difference may be measured
The Hall Effect may be explained by reference to Figure 2 which shows the front face of the slab only Assuming that the
material is an n-type semiconductor the current flow consists almost entirely of electrons moving from right to left This corresponds to the direction of conventional current from left to right
y
Physics Education bull October minus December 2009 299
Figure 1 Illustration of the Hall Effect If v is the velocity of electrons at right
angles to the magnetic field there is a downward force on each electron of magnitude Bqv This causes the electron current to be deflected in a downwards direction and causes a negative charge to accumulate on the bottom face of the slab (face 1) A potential difference is therefore established from top to bottom of the specimen with the bottom face negative8
The Hall coefficient Rh is defined as in equation (1) by
Rh = minus1nq = 1pq (1)
where n and p are the concentration of electrons and holes in the semiconductor sample respectively and q is the charge of an electron
By measuring the conductivity one can also calculate the mobility micro of the sample which is given as in equation (2)
micro = σRh (2)
where σ is the conductivity of the semiconductor sample and Rh is the Hall coefficient
I
Direction of conventional current flow
Probe
Probe attached to
face 2
attached to face 1
B
xz
Experimental Setup Hardware
Figure 3(3a 3b 3c) shows the systems hardware The detailed schematic of various
hardware blocks is as shown in Figure 3 and 4(4a 4b 4c) Functioning of the various blocks has been discussed as under
300 Physics Education bull October minus December 2009
Figure 2 Motion of electrons in an n-type semiconductor (Hall Effect) 1 Current to Voltage Converter The
function of current to voltage converter910 is to convert the input Hall current to the sample into voltage so as to be read by ADC9 The gain of this converter has been set such that the equivalent voltage does not exceed the maximum value of 5 volts for the maximum current of 18 mA The output of this converter being negative while ADC can read positive voltage therefore an inverter is connected at the output of this converter The output of this inverter is then fed to the ADC Channel 1 where it is converted into its
corresponding digital value and read by the PC Parallel Port
x
qε
Bqv
- - - - - - - -
Face 2 y
Face 1
2 Hall Sensor The Hall Sensor (IF 6) is used for magnetic field measurements This is a very cheap and easily available Hall sensor The Hall sensitivity of this sample at 10 mA is 03983 mVKGauss The output of this sensor is connected to ADC Channel 4 so as to be read by the PC
3 Differential Amplifier The Differential Amplifier amplifies the Hall Voltage obtained from the sample by a factor of
Physics Education bull October minus December 2009 301
10 The gain factor of 10 ensures A) The voltages generated are within the safe limits even at the maximum Hall Current B) It enhances the ADC resolution from 20 mV to 2mV
However as the Hall voltage generated can be negative or positive depending on the type of sample under consideration to ensure the working of the system being designed for any sample type the Hall voltage is inverted using an op-amp based inverter Hence both the positive and negative values of the amplified Hall voltage are available simultaneously at the switching circuit with the differential amplifier output giving the true amplified Hall voltage
4 Switching Circuit For a particular sample under consideration either the true Hall voltage or its inverted counterpart is read by the computer However if the negative voltage at the analog input of ADC is larger than -03 volts it starts malfunctioning Hence a switching circuit is designed which only sends a positive value of amplified Hall voltage to Channel 0 of ADC if the sample is p type or to Channel 3 if it is n type The other channel receives a zero voltage at the same time
5 Voltage Limiter with Buffer The Voltage Limiter Circuit along with buffer circuitry is used to sense whether the sample is p or n type When the sample is p type the output of this circuitry is zero and when the sample is n type the output is High (4-5 Volts) The computer reads this output from pin no 11 of parallel port to sense the sample type
6 Analog to Digital Converter (ADC) The ADC Section converts the analog Hall voltage Hall current Magnetic Field Sensor Output into their corresponding
digital values and sends the converted values to the PC when and where needed
The computer sends an SOC pulse to the ADC and the Channel Address (A0-A2) to select a particular channel for conversion As soon as the ADC receives the SOC pulse it converts the analog data on the desired channel and places the data on the Digital Address Bus (D0-D7) On successful conversion ADC enables the EOC pin high which enables the Output Enable (OE) and the data is ready to be read by the computer
7 Current Source A simple current source can be made using an operational amplifier as shown in Figure 4(c) In the present setup we have used two constant current sources
8 Current Source for Hall sensor This is a current source up to 15 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 1 KΩ and a 10 KΩ potentiometer
9 Current Source for Hall Sample This uses a current source up to 150 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 100 ohm and a 100 KΩ potentiometer
Software
The software developed by us is a graphical user interface11 with main functional provisions mentioned as under Calibrate From the start up screen calibration of the sample is mandatory to the user before proceeding to the start of experiment The other options of the startup screen remains deactivated until the user completes the calibration process As part of the calibration
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
direction Probes may be attached to faces 1 and 2 and the potential difference may be measured
The Hall Effect may be explained by reference to Figure 2 which shows the front face of the slab only Assuming that the
material is an n-type semiconductor the current flow consists almost entirely of electrons moving from right to left This corresponds to the direction of conventional current from left to right
y
Physics Education bull October minus December 2009 299
Figure 1 Illustration of the Hall Effect If v is the velocity of electrons at right
angles to the magnetic field there is a downward force on each electron of magnitude Bqv This causes the electron current to be deflected in a downwards direction and causes a negative charge to accumulate on the bottom face of the slab (face 1) A potential difference is therefore established from top to bottom of the specimen with the bottom face negative8
The Hall coefficient Rh is defined as in equation (1) by
Rh = minus1nq = 1pq (1)
where n and p are the concentration of electrons and holes in the semiconductor sample respectively and q is the charge of an electron
By measuring the conductivity one can also calculate the mobility micro of the sample which is given as in equation (2)
micro = σRh (2)
where σ is the conductivity of the semiconductor sample and Rh is the Hall coefficient
I
Direction of conventional current flow
Probe
Probe attached to
face 2
attached to face 1
B
xz
Experimental Setup Hardware
Figure 3(3a 3b 3c) shows the systems hardware The detailed schematic of various
hardware blocks is as shown in Figure 3 and 4(4a 4b 4c) Functioning of the various blocks has been discussed as under
300 Physics Education bull October minus December 2009
Figure 2 Motion of electrons in an n-type semiconductor (Hall Effect) 1 Current to Voltage Converter The
function of current to voltage converter910 is to convert the input Hall current to the sample into voltage so as to be read by ADC9 The gain of this converter has been set such that the equivalent voltage does not exceed the maximum value of 5 volts for the maximum current of 18 mA The output of this converter being negative while ADC can read positive voltage therefore an inverter is connected at the output of this converter The output of this inverter is then fed to the ADC Channel 1 where it is converted into its
corresponding digital value and read by the PC Parallel Port
x
qε
Bqv
- - - - - - - -
Face 2 y
Face 1
2 Hall Sensor The Hall Sensor (IF 6) is used for magnetic field measurements This is a very cheap and easily available Hall sensor The Hall sensitivity of this sample at 10 mA is 03983 mVKGauss The output of this sensor is connected to ADC Channel 4 so as to be read by the PC
3 Differential Amplifier The Differential Amplifier amplifies the Hall Voltage obtained from the sample by a factor of
Physics Education bull October minus December 2009 301
10 The gain factor of 10 ensures A) The voltages generated are within the safe limits even at the maximum Hall Current B) It enhances the ADC resolution from 20 mV to 2mV
However as the Hall voltage generated can be negative or positive depending on the type of sample under consideration to ensure the working of the system being designed for any sample type the Hall voltage is inverted using an op-amp based inverter Hence both the positive and negative values of the amplified Hall voltage are available simultaneously at the switching circuit with the differential amplifier output giving the true amplified Hall voltage
4 Switching Circuit For a particular sample under consideration either the true Hall voltage or its inverted counterpart is read by the computer However if the negative voltage at the analog input of ADC is larger than -03 volts it starts malfunctioning Hence a switching circuit is designed which only sends a positive value of amplified Hall voltage to Channel 0 of ADC if the sample is p type or to Channel 3 if it is n type The other channel receives a zero voltage at the same time
5 Voltage Limiter with Buffer The Voltage Limiter Circuit along with buffer circuitry is used to sense whether the sample is p or n type When the sample is p type the output of this circuitry is zero and when the sample is n type the output is High (4-5 Volts) The computer reads this output from pin no 11 of parallel port to sense the sample type
6 Analog to Digital Converter (ADC) The ADC Section converts the analog Hall voltage Hall current Magnetic Field Sensor Output into their corresponding
digital values and sends the converted values to the PC when and where needed
The computer sends an SOC pulse to the ADC and the Channel Address (A0-A2) to select a particular channel for conversion As soon as the ADC receives the SOC pulse it converts the analog data on the desired channel and places the data on the Digital Address Bus (D0-D7) On successful conversion ADC enables the EOC pin high which enables the Output Enable (OE) and the data is ready to be read by the computer
7 Current Source A simple current source can be made using an operational amplifier as shown in Figure 4(c) In the present setup we have used two constant current sources
8 Current Source for Hall sensor This is a current source up to 15 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 1 KΩ and a 10 KΩ potentiometer
9 Current Source for Hall Sample This uses a current source up to 150 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 100 ohm and a 100 KΩ potentiometer
Software
The software developed by us is a graphical user interface11 with main functional provisions mentioned as under Calibrate From the start up screen calibration of the sample is mandatory to the user before proceeding to the start of experiment The other options of the startup screen remains deactivated until the user completes the calibration process As part of the calibration
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Experimental Setup Hardware
Figure 3(3a 3b 3c) shows the systems hardware The detailed schematic of various
hardware blocks is as shown in Figure 3 and 4(4a 4b 4c) Functioning of the various blocks has been discussed as under
300 Physics Education bull October minus December 2009
Figure 2 Motion of electrons in an n-type semiconductor (Hall Effect) 1 Current to Voltage Converter The
function of current to voltage converter910 is to convert the input Hall current to the sample into voltage so as to be read by ADC9 The gain of this converter has been set such that the equivalent voltage does not exceed the maximum value of 5 volts for the maximum current of 18 mA The output of this converter being negative while ADC can read positive voltage therefore an inverter is connected at the output of this converter The output of this inverter is then fed to the ADC Channel 1 where it is converted into its
corresponding digital value and read by the PC Parallel Port
x
qε
Bqv
- - - - - - - -
Face 2 y
Face 1
2 Hall Sensor The Hall Sensor (IF 6) is used for magnetic field measurements This is a very cheap and easily available Hall sensor The Hall sensitivity of this sample at 10 mA is 03983 mVKGauss The output of this sensor is connected to ADC Channel 4 so as to be read by the PC
3 Differential Amplifier The Differential Amplifier amplifies the Hall Voltage obtained from the sample by a factor of
Physics Education bull October minus December 2009 301
10 The gain factor of 10 ensures A) The voltages generated are within the safe limits even at the maximum Hall Current B) It enhances the ADC resolution from 20 mV to 2mV
However as the Hall voltage generated can be negative or positive depending on the type of sample under consideration to ensure the working of the system being designed for any sample type the Hall voltage is inverted using an op-amp based inverter Hence both the positive and negative values of the amplified Hall voltage are available simultaneously at the switching circuit with the differential amplifier output giving the true amplified Hall voltage
4 Switching Circuit For a particular sample under consideration either the true Hall voltage or its inverted counterpart is read by the computer However if the negative voltage at the analog input of ADC is larger than -03 volts it starts malfunctioning Hence a switching circuit is designed which only sends a positive value of amplified Hall voltage to Channel 0 of ADC if the sample is p type or to Channel 3 if it is n type The other channel receives a zero voltage at the same time
5 Voltage Limiter with Buffer The Voltage Limiter Circuit along with buffer circuitry is used to sense whether the sample is p or n type When the sample is p type the output of this circuitry is zero and when the sample is n type the output is High (4-5 Volts) The computer reads this output from pin no 11 of parallel port to sense the sample type
6 Analog to Digital Converter (ADC) The ADC Section converts the analog Hall voltage Hall current Magnetic Field Sensor Output into their corresponding
digital values and sends the converted values to the PC when and where needed
The computer sends an SOC pulse to the ADC and the Channel Address (A0-A2) to select a particular channel for conversion As soon as the ADC receives the SOC pulse it converts the analog data on the desired channel and places the data on the Digital Address Bus (D0-D7) On successful conversion ADC enables the EOC pin high which enables the Output Enable (OE) and the data is ready to be read by the computer
7 Current Source A simple current source can be made using an operational amplifier as shown in Figure 4(c) In the present setup we have used two constant current sources
8 Current Source for Hall sensor This is a current source up to 15 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 1 KΩ and a 10 KΩ potentiometer
9 Current Source for Hall Sample This uses a current source up to 150 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 100 ohm and a 100 KΩ potentiometer
Software
The software developed by us is a graphical user interface11 with main functional provisions mentioned as under Calibrate From the start up screen calibration of the sample is mandatory to the user before proceeding to the start of experiment The other options of the startup screen remains deactivated until the user completes the calibration process As part of the calibration
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Physics Education bull October minus December 2009 301
10 The gain factor of 10 ensures A) The voltages generated are within the safe limits even at the maximum Hall Current B) It enhances the ADC resolution from 20 mV to 2mV
However as the Hall voltage generated can be negative or positive depending on the type of sample under consideration to ensure the working of the system being designed for any sample type the Hall voltage is inverted using an op-amp based inverter Hence both the positive and negative values of the amplified Hall voltage are available simultaneously at the switching circuit with the differential amplifier output giving the true amplified Hall voltage
4 Switching Circuit For a particular sample under consideration either the true Hall voltage or its inverted counterpart is read by the computer However if the negative voltage at the analog input of ADC is larger than -03 volts it starts malfunctioning Hence a switching circuit is designed which only sends a positive value of amplified Hall voltage to Channel 0 of ADC if the sample is p type or to Channel 3 if it is n type The other channel receives a zero voltage at the same time
5 Voltage Limiter with Buffer The Voltage Limiter Circuit along with buffer circuitry is used to sense whether the sample is p or n type When the sample is p type the output of this circuitry is zero and when the sample is n type the output is High (4-5 Volts) The computer reads this output from pin no 11 of parallel port to sense the sample type
6 Analog to Digital Converter (ADC) The ADC Section converts the analog Hall voltage Hall current Magnetic Field Sensor Output into their corresponding
digital values and sends the converted values to the PC when and where needed
The computer sends an SOC pulse to the ADC and the Channel Address (A0-A2) to select a particular channel for conversion As soon as the ADC receives the SOC pulse it converts the analog data on the desired channel and places the data on the Digital Address Bus (D0-D7) On successful conversion ADC enables the EOC pin high which enables the Output Enable (OE) and the data is ready to be read by the computer
7 Current Source A simple current source can be made using an operational amplifier as shown in Figure 4(c) In the present setup we have used two constant current sources
8 Current Source for Hall sensor This is a current source up to 15 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 1 KΩ and a 10 KΩ potentiometer
9 Current Source for Hall Sample This uses a current source up to 150 mA This has been made using a constant voltage source of 15 volts with a fixed series combination of resistance of 100 ohm and a 100 KΩ potentiometer
Software
The software developed by us is a graphical user interface11 with main functional provisions mentioned as under Calibrate From the start up screen calibration of the sample is mandatory to the user before proceeding to the start of experiment The other options of the startup screen remains deactivated until the user completes the calibration process As part of the calibration
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Figure 3 Complete Hardware Section 3(a) Basic Hardware Blocks process user is asked to enter the sample parameters such as thickness and resistivity of the semiconductor sample under consideration Then the user is asked to place the sample in the magnetic field and the software reads the Hall voltage It then asks the user to place the sample in next direction Comparing the results of the two placements software finalizes the
sample type and the sample placement direction to proceed with the experiment
After completing the calibration process Start Experiment option in the software is activated
Save It provides the user the option to save the experimental observations and results at the desired location in a data file
302 Physics Education bull October minus December 2009
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Figure 3(b) ADC connections Mode Selection The software provides the user option to perform the experiment in two modes (i) Hall Voltage vs Hall Current at a constant magnetic field (ii) Hall Voltage Vs Magnetic Field at a constant current The constant parameter is read in real time through the software before a set of readings are taken for a particular mode User can take as many
numbers of sets for a given mode The user can switch between the two modes without restarting the software The real time observations taken for a given mode apart from being saved in the file are simultaneously displayed on the screen for user reference
Physics Education bull October minus December 2009 303
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Figure 3(c) ADC connections to the parallel port of PC
Figure 4(a) Schematic of current to voltage converter with inverter
304 Physics Education bull October minus December 2009
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Figure 4 (b) Schematics of differential amplifier op-amp based inverter switching circuit voltage limiter and buffer
Figure 4(c) Schematic of constant current source
Physics Education bull October minus December 2009 305
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
306 Physics Education bull October minus December 2009
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Physics Education bull October minus December 2009 307
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
308 Physics Education bull October minus December 2009
Analysis After the observations are acquired user can proceed with the analysis of the data The analysis section displays two sets of graphs representing the two modes separately Each set of graph can represent multiple sets of data for the given mode In the graph drawing section basic point representation module has been taken from wwwencoreconsulting comau12 However the second order curve fitting software module to join these points has been developed by us and integrated with the main software module Along with the graphs the slope Hall coefficient carrier concentration and mobility values are displayed for each set of readings When all the data sets have been plotted the results thus obtained are written to the file Print Report The user may then print the graphs and the data results from the file in the Print Report Section of the software This section is also capable of printing theory for the experiment and the results from any earlier data file ExitRestart The user may then restart with the next experiment from this section or may exit the software
Features of the system
The various key features of the hardware and the software are as follows
HARDWARE
1 Components used are easily available and cheap
2 Hardware interface works on all Windows 98XP2000NT and compatible versions with high reliability and reproducibility of results
3 The system can read Hall Voltage with a resolution of 2 mV
SOFTWARE
1 SAMPLE DETERMINATION minus One can determine whether the test sample is n-type or p-type
2 CALIBRATION UNIT ndash It makes the system independent of a set sample The user can enter data for different test samples Through the provisions in the Calibration Unit user can separately place the sample in Magnetic Field before performing the experiment to ensure correct results It also provides an option for changing incorrect sample parameters during calibration without going to the start up screen
3 Capability of performing and analyzing data for different settings of magnetic field and Hall Current are possible at one go
4 All data sets for a single mode are plotted on one graph irrespective of the order in which they have been taken besides displaying separate graphs for the two modes
5 Results are displayed along with the graphs on same screen for better comparison of different sets of data under study
6 Software generates a self explanatory report file for each experiment A single file contains data for all the different modes and sets for which experiment has been performed After the analysis the results are also added to the file for later use The user can take a print out of the current report or any other previous reports The detailed theory and procedure for the experiment can also be printed for the reference purpose
7 After performing a complete experiment user may start up again with the next experiment by clicking lsquoRestartrsquo in the Print Report Screen
8 All slope calculations are based on second order curve fitting
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
Physics Education bull October minus December 2009 309
Results
A comparison of experimental observations (manual as well as computer controlled mode) taken with the standard parameters for
germanium semiconductor sample as provided by the supplier is as shown in table 1 and table 2 The results are in agreement with the standard values
Table 1
Experimentally Obtained Values SNo Set No
Parameter Standard Value
Manual Mode Computer Controlled Mode
1 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
351205 cm3coulomb 177 1014 cm-3
351205 cm2voltsec
3543983 cm3coulomb 176 1014 cm-3 3543983 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
33000 cm3coulomb 19 1014 cm-3 3300 cm2voltsec 05 mm 10 ohm-cm
349903 cm3coulomb 178 1014 cm-3
349903 cm2voltsec
3459543 cm3coulomb 181 1014 cm-3 345954 cm2voltsec
2 1 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
378007 cm3coulomb 165 1014 cm-3
189003 cm2voltsec
3806114 cm3coulomb 164 1014 cm-3 190306 cm2voltsec
2 Hall Coefficient Carrier Density Mobility Thickness Resistivity
36000 cm3coulomb 173 1014 cm-3 1800 cm2voltsec 042 mm 20 ohm-cm
369048 cm3coulomb 169 1014 cm-3
184524 cm2voltsec
3720238 cm3coulomb 168 1014 cm-3 186012 cm2voltsec
Table 2
SNo Magnetic field as measured by a calibrated gaussmeter
Experimentally obtained values
1 256 KGauss 246 KGauss 2 311 KGauss 296 KGauss 3 396 KGauss 377 KGauss 4 433 KGauss 412 KGauss 5 426 KGauss 407 KGauss
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
310 Physics Education bull October minus December 2009
Conclusions
The present set up meets the following objectives 1 One can determine the semiconductor
sample type 2 One can determine Hall coefficient carrier
concentration and mobility of the sample 3 Through the Hall probe one can measure
and display in real time the strength of magnetic fields in which the Hall sample is placed making it as a real time gaussmeter
4 It must be emphasized that the aim has been to produce a cheap and relatively simple introduction to instrumentationdata acquisition for students of first-year undergraduate courses in science The system gives a feel to the students how to interfaceintegrate any physics experiment generating set of analog voltages into a computer-driven experiment
Acknowledgements
Authors are thankful to all the faculty members of the Electronics Department and Dr Arijit Chowdhuri of Physics Department for useful discussions at different stages of the project Authors are also thankful to all the support staff of the department for their continuous help Authors acknowledge the website wwwencoreconsultingcomau for providing the basic point drawing graph module which was integrated to our own developed software
References 1 Ahmed Houari ldquoUseful pedagogical
applications of the classical Hall Effectrdquo Nov 2007 Physics Education 42(6) pp 603-606
2 Ahmed Houari ldquoDetermination of Avogadrorsquos number via the Hall Effectrdquo March 2007 Physics Education 42(2) pp 198-200
3 JP Eisenstein ldquoThe quantum Hall Effectrdquo Feb 1993 AmJPhys 61(2) pp 179-183
4 wwwbeyondlogicorg 5 wwwlvrcomparporthtm 6 MSDN Library - January 2001 7 Visual Basic 60 by Mohammed Azam 8 Dennis Le Croissette Transistors PHI 9 wwwnationalcom 10 Ramakant Gayakwad Op-Amps and Linear
Integrated Circuits Pearson Education 11 httpelectronics-andcgroupblogspotcom
200908 software-developed-for-study-of-Hallhtml
12 wwwencoreconsultingcomau
