/ RBS and RBS / NR to determine the depth profile of atoms in the - - PowerPoint PPT Presentation

. 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

kE E

1

2 2 1 2 1 2 1 2 2 1 1

sin cos

M M M

M M k

2 2 2

2 2 2 2 1 1 2 1

V M V M V M

) cos( ) cos(

2 2 1 1 1

V M V M V M

• )

sin( ) sin(

2 2 1 1

V M V M

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

elements Depth [1*10

15 Atoms/cm 2]

C O Al In

• Graph1. The profile depth.

1000 1500 2000 2500 1000 2000

In Al experiment [counts] simulated [counts] energy [keV]

simulated experimental

=60

1000 1500 2000 2000

experimental [counts] In simulated [counts] energy [keV]

simulated experimental

Al

=30

2 4 6 8 10

Eα= 2028 keV ϴ=170o

500 1000 1500 1000 2000 3000 experimental [counts] simulated [counts] energy [keV]

simulated experimental

Sisurface Sisubstrate Nsurface

30

500 1000 1500 2000 500 1000 1500 2000 experimental [counts]

simulated experimental

simulated [counts]

energy [keV]

Sisurface Sisubstrate Nsurface 500 1000 1500 2000 2500 250 500 750 1000 1250 energy [keV]

experimental [counts]

simulated [counts]

Sn Al

simulated experimental

500 1000 1500 2000 2500

500 1000 1500 2000 2500 3000

Sn Al

experimental [counts]

simulated [counts] energy [keV]

simulated experimental

Spectrum: Agata Barańska Spectrum: Dimitar Stoychev

Eα= 2028 keV ϴ=170o Eα= 2028 keV ϴ=170o

ERD

2 2 1 2 1 2 1 2 2 1 1

sin cos

M M M

M M k

Simple model of scattering process

sample Detector RBS Detector ERD

1000 2000 3000 5000 10000 15000

experimental [counts] energy [keV] experimental simulated 400 600 800 20 40 60

simulated experimental

yield [counts] Energy [keV]

H Energy= 2297[keV] =30

• 1000

2000 3000 4000 5000 0,0 0,1 0,2 0,3 Concentartion [%] Thickness 1x10

15 [atoms/cm 2]

Bi

sample St922 EHe

1000 2000 3000 4000 5 10 15 Concentartion [%] Thickness 1x10

15 [atoms/cm 2]

H

sample St922 EHe

600 800 15000 30000 Yield [counts]

Energy [keV] simulated experimental

sample 223

The depth distribution of elements in the MOS structure

2000 4000 2 4 6 8 Concentration [%] Thickness [1x10

15 [atoms/cm 2]

H

sample 223

2000 4000 6000 2 4 6 Concentration [%] Thickness [1x10

N

sample 223

2000 4000 6000 10 20 30 40 50 60 Concentration [%] Thickness [1x10

sample 223

2000 4000 6000 10 20 30 40 50 60 Concentration [%] Thickness [1x10

Al

sample 223

2000 4000 6000 20 40 60 80 100 Concentration [%] Thickness [1x10

sample 223

Spectrum: Dagmara Bentryn

2000 4000 5 10 concenration [%] Thickness [atoms 1x10

B

500 1000 1500 2000 4000 6000 OSiO2 SiSiO2 Experimental Yield [counts] Energy [keV]

experimental simulated

SiSiO2

EHe

=135

• =75
• 400

450 500 550 600 650 700 750 100 200 300 400 500 yield [counts] Energy [keV] Hydrogen

Spectrum: Agata Barańska

RBS/NR

.

2 1 2 2 1 2 2 1 2 2 1 2 2 2 2 1

sin 1 sin 1 cos ) ( sin 2 M M M M E e Z Z 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

100 200 300 400 500 20 40 60 Concentration [%] Thickness [1x10

15[atoms/cm 2]

O Fe Co Ag

sample St404

1000 1500 1000 2000 3000

simulated energy (keV) Sisurface Sisubstrate Osurface E=3030keV 30

• 170
• 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 