1. Medium energy ion scattering and elastic recoil detection analysis for processes in thin films and monolayers
Lyudmila V. Goncharova,
Sergey Dedyulin, Mitch Brocklebank
Department of Physics and Astronomy,
Western University ,
London, Ontario, Canada
Collaborators: P. J. Simpson (UWO), J. Botton (McMaster U.), D. Londheer (NRC)

2. 1.7 MeV Tandetron Accelerator Facility at UWO
Duoplasmatron Source
Sputter Source
Injector Magnet
Tandetron Accelerator
High Energy Magnet
RBS Chamber
ERD Chamber
MEIS Chamber
Implant Chamber
Group III,V Molecular Beam
Epitaxy System
Group IV Molecular Beam

3. Energy distribution for one angle
2D MEIS Data
100keV H+, SiO2/poly-Si/ZrO2/Ge(100)
H+ Energy [keV]
Angle
Energy distribution for one angle
Angular distribution for one element
Energy distributions:
mass (isotope) specific
quantitative (2% accuracy)
depth sensitive (at the sub-nm scale)

4. Outline Motivation Medium Energy Ion Scattering (MEIS)
- Nucleation and growth in Si and Ge quantum systems
Medium Energy Elastic Recoil Detection (ME-ERD)
- H-terminated Si(001)
- H in HfSiOx ultra-thin films /Si(001)
Conclusions and future directions

5. For the Age of Photonics…
Continued developments in
miniaturization,
speed and complexity
Wiring bottleneck
Need to merge electronics and photonics
III-V compounds dominate optoelectronics
Hybrid technologies are being used
OEICs and OICs incorporating Si/Ge detectors, modulators and waveguides now functional
D.J. Paul, Semicond. Sci. Tech. 19, R75 (2009)

6. Overcoming the indirect band gap
Alloying Ge with Si and/or C
Stress
Brillouin zone folding
Rare earth and transition metal impurity centres
Quantum confinement
Wells (1-D)
Wires (2-D)
Dots (3-D)
Band gap engineering

7. Experimental Approach
Life-time decay
Photoluminescence (PL)
hn1
hn2
Ion beam implantation
Tx, N2
Rutherford Backscat. (RBS)
Elastic Recoil Detection (ERDA)
Raman
X-ray Photoemission Spec.
*Stopping and Range of Ions in Matter,
SRIM*

8. Growth and Analysis of Si QD
RT Implantation Si- or Ge+ 90keV 5x x1017ions/cm2
(Si) or 9000C (Ge)
in furnace, 60 in N2/H2 gas
Early stage of formation governed
by diffusion
Eventually Ostwald ripening
Link between defects in the SiO2 and formation of Si-QDs*

9. Ge QD Photoluminescense in Ge quantum systems
Ge QD PL has two components:
blue-green PL at ~2 eV (590 nm) independent of NC size
near infrared PL size dependent, compatible with a QC effect
Larger exciton radius (24 nm) compared with Si (~4nm) causes larger confinement effect in Ge QD
Very challenging to fabricate a defect-free stable Ge QD!!!
N.L. Rowell, et al., JES 156, H913 (2009)

10. Ge in Al2O3(0001): crystallization and ordering
Ion beam implantation
Tx, N2
Ge is moving up slow diffusion rate of the alumina matrix atoms at < Tmelt, significant crysllinity
E.G. Barbagiovanni, et al., NIMB 272 (2012) 74–77

11. XPS Shift of Ge peak towards the surface (RBS)
Al2O3(0001)
GexO
disordered Al2O3
Tx>1100oC N2
Al2O3(0001)
Ge-QD
Ar sputtering prior to XPS analysis:
Ge layer is 3-5nm deep
Shift of Ge peak towards the surface (RBS)
GeOx peaks in XPS  Ge loss via GeO desorption

12. Cross-sectional TEM micrographs
Moiré fringes become visible from the overlap of the crystal planes of Ge QD and the sapphire matrix
Contrast arising from stress fields and end of range implantation damage

13. Ge QD in Al2O3(0001): MEIS vs HRTEM
Slow diffusion rate of the alumina matrix atoms at < Tmelt
Ge blocking minimum can be related to the stereographic projection of the sapphire crystal and corresponds to the [111] scattering plane:
(1104) Al2O3 // (111)Ge and [211] Al2O3 // [112] Ge
I.D. Sharp, Q. Xu, D.O.Y, et al., JAP 100 (2006)

14. Outline Motivation Medium Energy Ion Scattering (MEIS)
- Nucleation and growth in SI and Ge quantum systems
Medium Energy Elastic Recoil Detection (ME-ERD)
- H-terminated Si(001)
- H in HfSiOx ultra-thin films /Si(001)
Conclusions and future directions

15. Quantification in MEIS
Scattering potential
Cross section
Neutralization
RBS vs MEIS
Normalized ion yield:
f+ changes as a function of energy and angle…

16. Missing element from the picture… hydrogen!
Heavy Elements by MEIS or RBS
“Classical” ERD
Incident energy = 1.6MeV He+
Incident angle = 75o
Recoil Angle = 30o
Al-mylar (range foil)
~150nm SiONH/Si(001)
Detector
Light elements (He+ or H+) a
Light Elements by Elastic Recoil Detection
Detector
He+
H+, He+ 

17. TEA detector for negative ions
Crucial points for detecting H ion recoils directly are:
To increase the recoil cross-section
To reduce (to suppress) the background originating mainly from elastically scattered incident ions
To reduce recoil energy V- V+
ME-ERD
Only charged particles are detected by TEA
 use incident beam ions without negative ion fractions and detect negative H- recoils V- V+
MEIS X+
H+,H, H-

18. Selection of Incident Ions
Potential candidates: B, N, Ne, Na, Mg, Al, Si, P…
Limitations:
- possibility to produce these ions beam
- high beam current
- only H- are detected (fraction can be small)
W.N. Lennard, et al. NIMB 179 (1981) 413

19. ME-ERD for H-Si(001) Incident beam: 500keV Si+ H- Incident angle = 45o
Recoil Angle = 75o (TEA centre)
Dose = 0.5mC
Si+ H-
Although the fraction of Si- ions is small, it is not negligible!

20. ME-ERD for H-Si(001) H- Si(001) vs H-Si(111)
H- Si(001): assuming dihydride model  1.38x1015 /cm2
Sensitivity to H: 8x1013 H/cm2
Assuming that the normalized yield is 3500

21. H- Yield as a function of Si+ dose
Irradiated area need to be refreshed!
Si+ H-
Without shifting irradiation area
Compare with the sputter rates
YH(I=0) =  ~ 30% of H is lost after 0.1mC
Data shown below is without correction of H loss from the surface

22. ME-ERD for H-Si(001) H- Si(001) vs H-Si(111)
H- Si(001): assuming dihydride model  1.38x1015 /cm2
Estimate of sensitivity to H: 8×1013 H/cm2
Extrapolated sensitivity to H: 1×1013 H/cm2
Assuming that the normalized yield is 3500

23. Angular dependence Best conditions at EH=2-5keV and angle = 70-80o
observe angular dependence of H- fraction
No H peaks at angles above 80o
Low sensitivity at angles < 60o
J.B. Marion, F.C. Young, NRA Tables, 1968.
K. Mitsuhara et al., NIMB 276 (2012) 56-67

24. ME-ERD for Hf silicate films
Incident beam: 500keV Si+
Incident angle = 45o
Dose = 0.5mC
Sample
Tdep, C
#cycles
Thickness, nm
In-situ RTA
1367
200 16
3.6
1351
300 19
UHV, 800oC, 30 sec
1355
350 21
3.4
1376 60 24

25. Summary: Towards “Complete ME-IBA”
We were able to detect hydrogen using ME-ERD using Si(N) incident beams with no modification in TEA
Medium Energy Elastic Recoil Spectroscopy with incident Si, N ions gives complimentary information on hydrogen content
Hi-Si(001): we observe angular dependence of H- fraction
The H- fraction is expected to increase with decreasing energy of the recoils (incident energy)
Damage effects are significant  surface needs to be refreshed under the beam
Uniform lateral distribution is assumed
Accurate background fit is necessary to get quantitative fitting
We were also able to detect residual hydrogen presence in Hf silicate thin films grown by atomic layer deposition with better resolution than “classical” ERD

26. Thank you!