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Multiscale Approach for the Analysis of Channeling Profile Measurements of Ion Implantation Damage

Multiscale Approach for the Analysis of Channeling Profile Measurements of Ion Implantation Damage. G. Hobler, G. Otto, D. Kovac L. Palmetshofer 1 , K. Mayerhofer², K. Piplits² 1 Inst. Semiconductor and Solid State Physics, Univ. Linz ² Inst. Chem. Technol. and Analytics, TU Vienna.

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Multiscale Approach for the Analysis of Channeling Profile Measurements of Ion Implantation Damage

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  1. Multiscale Approach for the Analysis of Channeling Profile Measurements of Ion Implantation Damage G. Hobler, G. Otto, D. KovacL. Palmetshofer1,K. Mayerhofer², K. Piplits² 1 Inst. Semiconductor and Solid State Physics, Univ. Linz² Inst. Chem. Technol. and Analytics, TU Vienna Institute of Solid-State Electronics

  2. Damage Models in BC Simulations • Traditional model: • defect positions: generated statistically • atom positions: random interstitial model • dynamic annealing: „recombination factor“ • Proposed model: • defect positions: trace each defect during the whole simulation • atom positions: take from ab-initio simulations • dynamic annealing: kinetic lattice Monte Carlo simulation (kLMC) after each collision cascade

  3. Overview • Introduction • BC-kLMC approach • Application to channeling profile measurement (CPM) experiments

  4. Damage Measurements Channeling profile RBS

  5. Channeling Implantations • Fit dose dependence of channeling implantation profiles  recombination factor frec=0.125 Nsat=41021cm-2 (G.Hobler et al., J. Vac. Sci. Technol B14 (1) 272, 1996)

  6. Channeling Profile Measurements • Measure pre-existing crystal damage with a low-dose channeling implant (M. Giles et al., MRS Symp. Proc. 469, 253, 1997)

  7. The Role of Dynamic Annealing in Si • Temperaturedependence of implant damage: (J.E. Westmoreland et al., Appl. Phys. Lett. 15, 308, 1969)

  8. The Role of Dynamic Annealing in Si • Dose-rate dependence of implant damage: 70µA/cm² 0.14µA/cm² T=300K (O.W. Holland et al., Rad. Eff. 90, 127, 1985)

  9. Overview • Introduction • BC-kLMC approach • Application to channeling profile measurement (CPM) experiments

  10. Coupled BC-kLMC Approach • Traditional approach: • BUT: type and amount of defects influence BC trajectories (dechanneling) point defects BC loop over cascades 1 cascade kLMC point defects + clusters

  11. Coupled BC-kLMC Approach • Proposed new approach: defects atom positions for each defect loop over cascades BC old defects + new point defects kLMC point defects + clusters

  12. Details of kLMC • Each defect is associated with one or more lattice sites • Defects: Vn, In (n=1,2,3,...) • Events: • Diffusion hops (I, V) • Reactions of defects located within capture radius Vn+V  Vn+1 Vn+I  Vn-1 In+I In+1 In+V In-1 • Parameters: • DV=310-13 cm²/s DI=6.3510-17 cm²/s • (Capture radii)

  13. Details of kLMC • „Old“ defects: restricted to column(periodic boundaryconditions) • „New“ defects: anywhere • Interaction between „new“ and „old“ defects: Using periodicity of „old“ defects

  14. Details of BC • Read defects from kLMC (columnar domain) • Use periodicity to generate defects around projectile • Atom positions from ab-initio calculations (VASP) • defect structure • strain around defect • All defects composed of individual I and V (currently)

  15. Overview • Introduction • BC-kLMC approach • Application to channeling profile measurement (CPM) experiments

  16. CPM Experiments • Damage implant: N, 30 keV, 31014 cm-², 10° tilt • CPM implant: B, 30 keV, 1013 cm-2, 0° tilt (110)-Si shield

  17. CPM Experiments • Results:

  18. CPM Simulation Results • Simulation results without strain:

  19. CPM Simulation Results • Strain from vacancies:

  20. CPM Simulation Results • Strain from interstitials:

  21. What is wrong? • Defects: Vn, In (n=1,2,3,...) • Events: • Diffusion hops (I, V) • Reactions of defects located within capture radius Vn+V  Vn+1 Vn+I  Vn-1 In+I In+1 In+V In-1 • Parameters: • DV=310-13 cm²/s DI=6.3510-17 cm²/s • (Capture radii) • Lack of amorphous pockets?

  22. What is wrong? • Defects: Vn, In (n=1,2,3,...) • Events: • Diffusion hops (I, V) • Reactions of defects located within capture radius Vn+V  Vn+1 Vn+I  Vn-1 In+I In+1 In+V In-1 • Parameters: • DV=310-13 cm²/s DI=6.3510-17 cm²/s • (Capture radii) • Lack of amorphous pockets? NO • Approximate treatment of I-Clusters?

  23. I3 I2 I I4a I4b What is wrong? • I-Clusters: • Similar study on RBS-C: Efficiency of I2, I3, I4 within 40% of split-110 interstitial (G. Lulli et al., Phys. Rev. B69, 165216, 2004)

  24. What is wrong? • Defects: Vn, In (n=1,2,3,...) • Events: • Diffusion hops (I, V) • Reactions of defects located within capture radius Vn+V  Vn+1 Vn+I  Vn-1 In+I In+1 In+V In-1 • Parameters: • DV=310-13 cm²/s DI=6.3510-17 cm²/s • (Capture radii) • Lack of amorphous pockets? NO • Approximate treatment of I-Clusters? Probably not • Attraction of I+Vn, V+Inand/or Repulsion of I+In, V+Vn

  25. Conclusions • New approach for implant damage simulations • coupled BC and kLMC • atom positions from ab-initio • Consistent simulation of both defect generation and analysis • Simulations yield too much damage  need to use • interaction radii to favor recombination and/or • reaction barriers to impede clustering

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