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. The use of nuclear methods RBS, ERD / RBS and RBS / NR to determine the
depth profile of atoms in the subsurface layers of the solid state
Agata Barańska University of Adam Mickiewicz, Poznań, Poland Dagmara Bentryn Nicolaus Copernicus University, Toruń, Poland Dimitar Stoychev University of Plovdiv „Paisii Hillndarski”, Bulgaria
Frank Laboratory of Neutron Physics Supervisor: Mirosław Kulik UMCS Lublin Poland
Table of contents
1. Physical basics of nuclear methods 2. Experiment and method of the study 2. RBS-Rutherford Backscattering 3. ERD-Elastic Recoil Detection 4. NR-Nuclear Reaction 5. Conclusion
Physical basics of nuclear methods
Hans Geiger
Ernest Rutherford
Series of experiments (Geiger-Marsden)conducted between 1908 and 1913 led to the discovery of nucleus.
Ernest Marsden
Experiment and experimental apparatus EG5 – van der Graaf accelerator
Ion source
Dome- collects an electrostatic charge
Experimental apparatus(scheme)
1. Ion beam 2. Magnetic lenses and screen forming ion beam 3. Holder 4. Sample 5. Screen 6. Detector 7. Multichannel analizator 8. Computer
RBS • Elastic collision between particle with the eneregy
Eo and stationary nucleus, • mirror surface • constant atomic density in layer • Rapid change of the density between two
neigbouring layers (assumption)
Scheme of elastic collision
Simple model of scattering process
kEE 01
2
21
2
1
2
1
2
211 sincos
MMM MM
k
222
2
22
2
11
2
01 VMVMVM)cos()cos( 22111 VMVMVM o
0)sin()sin( 2211 VMVM
Energy of scattered projectile
Conservation of kineti energy Conservation of momenetum
Kinematical factor
Yield
Y = σ(Ө, E) D Nt dΩ
D- total numer of incydent ions Nt – concentration of atoms in the layer σ(Ө, E)- cross-section dΩ- solid angle
0
2
4
6
ele
me
nts
Depth [1*1015
Atoms/cm2]
C
O
Al
In
Graph1. The profile depth.
1000 1500 2000 25000
1000
2000
In
Al
ex
pe
rim
en
t [c
ou
nts
]
sim
ula
ted
[c
ou
nts
]
energy [keV]
simulated
experimental
=60
1000 1500 2000
0
2000
ex
perim
en
tal
[co
un
ts]
In
sim
ula
ted
[co
un
ts]
energy [keV]
simulated
experimental
Al =30
0 2 4 6 8 10
Eα= 2028 keV ϴ=170o
500 1000 15000
1000
2000
3000
ex
pe
rim
en
tal
[co
un
ts]
sim
ula
ted
[c
ou
nts
]
energy [keV]
simulated
experimental
Sisurface
Sisubstrate
Nsurface
30
500 1000 1500 20000
500
1000
1500
2000
ex
pe
rim
en
tal
[co
un
ts]
simulated
experimental
sim
ula
ted
[c
ou
nts
]
energy [keV]
Sisurface
Sisubstrate
Nsurface
500 1000 1500 2000 25000
250
500
750
1000
1250
energy [keV]e
xp
eri
me
nta
l [c
ou
nts
]
sim
ula
ted
[c
ou
nts
]
Sn
Al
simulated
experimental
500 1000 1500 2000 25000
500
1000
1500
2000
2500
3000
Sn
Al
ex
pe
rim
en
tal
[co
un
ts]
sim
ula
ted
[c
ou
nts
]
energy [keV]
simulated
experimental
Spectrum: Agata Barańska
Spectrum: Dimitar Stoychev
Eα= 2028 keV ϴ=170o
Eα= 2028 keV ϴ=170o
ERD
2
21
2
1
2
1
2
211 sincos
MMM MM
k
Simple model of scattering process
sample
Detector RBS
Detector ERD
1000 2000 3000
0
5000
10000
15000
2000 2100 2200 2300 2400 2500
0
20
40
60
80
100
120
140
expe
rimen
tal [
coun
ts]
energy [keV]
Bie
xp
eri
me
nta
l [c
ou
nts
]
energy [keV]
experimental
simulated
400 600 800
0
20
40
60
simulated
experimental
yie
ld [
co
un
ts]
Energy [keV]
H
Energy= 2297[keV]
=30o
0 1000 2000 3000 4000 5000
0,0
0,1
0,2
0,3
Co
ncen
tarti
on
[%
]
Thickness 1x1015
[atoms/cm2]
Bi
sample St922
EHe
+=2297 keV
0 1000 2000 3000 4000
0
5
10
15
Co
ncen
tarti
on
[%
]
Thickness 1x1015
[atoms/cm2]
H
sample St922
EHe
+=2297 keV
600 8000
15000
30000
Yie
ld [
co
un
ts]
Energy [keV]
simulated
experimentalsample 223
The depth distribution of elements in the MOS structure
0 2000 40000
2
4
6
8
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
H
sample 223
0 2000 4000 6000
0
2
4
6
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
N
sample 223
0 2000 4000 6000
0
10
20
30
40
50
60
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
O
sample 223
0 2000 4000 6000
0
10
20
30
40
50
60
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
Al
sample 223
0 2000 4000 6000
0
20
40
60
80
100
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
Si
sample 223
Spectrum: Dagmara Bentryn
0 2000 40000
5
10
co
nc
en
rati
on
[%
]
Thickness [atoms 1x1015
/cm2]
B
500 1000 15000
2000
4000
6000
OSiO
2
SiSiO
2
Ex
pe
rim
en
tal
Yie
ld [
co
un
ts]
Energy [keV]
experimental
simulated
SiSiO
2
EHe
+=2297 keV
=135o
=75o
400 450 500 550 600 650 700 7500
100
200
300
400
500
yie
ld [
co
un
ts]
Energy [keV]
Hydrogen
Spectrum: Agata Barańska
RBS/NR .
21
2
2
1
2
21
2
2
1
2
2
2
21
sin1
sin1cos
)(sin2
MM
MM
E
eZZ
d
d
Yield depends on: • number of incident particles • atomic density of elements in the target • cross-section • solid angle
Simple model of scattering process
0 100 200 300 400 500
0
20
40
60
Co
ncen
tra
tio
n [
%]
Thickness [1x1015
[atoms/cm2]
O
Fe
Co
Ag
sample St404
1000 1500
0
1000
2000
3000sim
ula
ted
energy (keV)
Sisurface
Sisubstrate
Osurface
E=3030keV
30o
170o
Spectra: Dagmara Bentryn
Spectrum: Agata Barańska
Conclusions Application of the classical description
The ability to identify impurities and their
distributions
Layer thickness
Thank you for your attention
