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Lyudmila V. Goncharova, Sergey Dedyulin, Mitch Brocklebank Department of Physics and Astronomy,

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.

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Lyudmila V. Goncharova, Sergey Dedyulin, Mitch Brocklebank Department of Physics and Astronomy,

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  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 RBS Chamber ERD Chamber Duoplasmatron Source High Energy Magnet Injector Magnet Tandetron Accelerator MEIS Chamber Implant Chamber Sputter Source Group IV Molecular Beam Epitaxy System Group III,V Molecular Beam Epitaxy System

  3. H+ Energy [keV] Angle 2D MEIS Data 100keV H+, SiO2/poly-Si/ZrO2/Ge(100) 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 Photoluminescence (PL) Life-time decay hn2 hn1 Ion beam implantation Tx, N2 Rutherford Backscat. (RBS) Elastic Recoil Detection (ERDA) Raman X-ray Photoemission Spec. SRIM* *Stopping and Range of Ions in Matter, www.srim.org/

  8. Growth and Analysis of Si QD • RT Implantation Si- or Ge+ 90keV 5x1016 -1x1017ions/cm2 • 120min @11000C (Si) or 9000C (Ge) in furnace, 60 min @5000C 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 QDPhotoluminescense 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 Tx, N2 Ion beam implantation E.G. Barbagiovanni, et al., NIMB272 (2012) 74–77

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

  12. Moiré fringes become visible from the overlap of the crystal planes of Ge QD and the sapphire matrix Cross-sectional TEM micrographs • 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) 114317

  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 RBSvsMEIS Normalized ion yield:

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

  17. ME-ERD V+ V- V- V+ MEIS 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 Only charged particles are detected by TEA  use incident beam ions without negative ion fractions and detect negative H- recoils 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. H- Si+ ME-ERD for H-Si(001) Incident beam: 500keV Si+ Incident angle = 45o Recoil Angle = 75o (TEA centre) Dose = 0.5mC 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

  21. H- Si+ H- Yield as a function of Si+ dose • Irradiated area need to be refreshed! Without shifting irradiation area • YH(I=0) = 984  ~ 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

  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 H- Si+ Incident beam: 500keV Si+ Incident angle = 45o Dose = 0.5mC 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

  26. Thank you!

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