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Semiconductors: Basics to Applications-2
Dr. Anurag Srivastava Associate Professor, ABV-IIITM, Gwalior
Email: [email protected] | [email protected]
Web: http://tiiciiitm.com/profanurag/ Office: Room-110, First Floor, E-Block, IIITM Campus
Si, Ge and GaAs
• Silicon (Si) as a semiconductor is preferred by the industry over Germanium (Ge) and Gallium Arsenide (GaAs), even though the Ge and GaAs semiconductors offer better electron mobility than Si.
• This can be explained in terms of the following… – Leakage current (IO).
– Peak Inverse Voltage (PIV).
– Energy Band Gap (EG).
– Abundance.
PN Junction Diode
PN Junction Diode… Band Diagram
The band diagram shown above is for zero applied bias voltage. In Forward bias, the shift between the conduction band edges as well as valence band edges decreases. While the opposite is true for Reverse bias.
PN Junction Diode… I-V curve
Applications: • Switch • Voltage Variable Capacitor
Tunnel Diode
Tunnel Diode… I-V curve
Applications: • High speed Switch • High Frequency Oscillator
Zener Diode
Applications: • Voltage Regulator
Schottky Diode… Band Diagram
Schottky Diode… I-V Characterisitcs
Features: • Very less recovery time. • Less Threshold Voltage.
• In Reverse Bias, More leakage flows in the schottky diode than the PN-junction diode, due to thinner depletion region.
Applications: • High Speed Switch
Bipolar Junction Transistor (BJT)
Emitter Base Collector
Width Moderate Low High
Doping High Low Moderate
Bipolar Junction Transistor (BJT)…
Junction 1 Junction 2 Region of Operation Application
FB FB Saturation ON-Switch
RB RB Cutoff OFF-Switch
FB RB Active Amplifier
RB FB Inverse Active Attenuator
FB = Forward Bias, RB = Reverse Bias.
• Uses Photo-Voltaic Effect and converts sunlight into electrical energy.
• Discovered by Chapin in 1954.
• Solar energy is green and renewable energy.
• Solar Cells are used to power Satellites, Space Station, and for several Household and commercial applications.
Solar Cell
