1. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Martin Oberkofler, M. Reinelt, S. Lindig, M. Racinski, Ch. Linsmeier Max-Planck-Institut für Plasmaphysik, Garching b. München, Germany Hydrogen retention mechanisms in Beryllium

2. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Outline Motivation Experiment a)Thermal Desorption Studies Implantation Energy Dependence Fluence Dependence b)Morphology Studies Fluence Dependence Surface Orientation Dependence Conclusions and Outlook ITER cross section

3. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Motivation Simplify the system: 1.Well defined clean surface 2.Single vs. polycrystal 3.Ion energy influence Retention mechanisms Retention mechanisms Simplify the system: 1.Well defined clean surface 2.Single vs. polycrystal 3.Ion energy influence Retention mechanisms Retention mechanisms Large scatter in experimental data due to unclear influence of Surface impurity layer Surface impurity layer Crystallinity Crystallinity Intrinsic and ion induced traps Intrinsic and ion induced traps Large scatter in experimental data due to unclear influence of Surface impurity layer Surface impurity layer Crystallinity Crystallinity Intrinsic and ion induced traps Intrinsic and ion induced traps

4. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Nature of retention mechanisms Experiment: ARTOSS TPD Temperature Programmed Desorption TPD Temperature Programmed Desorption Sequential release of D Model with energy barriers for Detrapping Diffusion Recombination Sequential release of D Model with energy barriers for Detrapping Diffusion Recombination D ion implantation in situ... (10 -11 mbar) Ar sputter cleaning+ annealing XPS: Control of surface Ar sputter cleaning+ annealing XPS: Control of surface Ex situ morphology investigations (SEM, EBSD, AFM)

5. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation 3 mm Implantation spot on a-C:H layer

6. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation 0.6 at%

7. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation 0.6 at%

8. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation 0.6 at%

9. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation 0.6 at% 0.3 at%

10. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile Implantation depth profiles calculated with SDTrim.SP = initial trap and D depth profile 0.6 at% 0.3 at% Single crystal (11-20) Fluence = 2.7·10 19 D/m 2 Flux = 10 19 D/(m 2 s) Implanted area = 4 mm 2 Heating ramp = 0.73 K/s Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV Input for best fit TMAP7 calculations: Depth profiles from SDTrim.SP calculations Experimental diffusion coefficient [E. Abramov 1990, J.Nucl.Mater] Activation energy for detrapping: 1.9 eV [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Low Fluence Implantation

11. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Thermal Desorption Studies: Low Fluence Implantation Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Include trap mobility

12. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Thermal Desorption Studies: Low Fluence Implantation Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Include trap mobility

13. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Thermal Desorption Studies: Low Fluence Implantation Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Include trap mobility

14. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Thermal Desorption Studies: Low Fluence Implantation Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: Detrapped deuterium leaves mobile trap behind input for TMAP7: Detrapping with frequency factor 10 13 Trapping with frequency factor 10 10 Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Assumption: The traps are single vacancies calculate diffusion barrieres by ab initio (A. Allouche) take as input for newly developed lattice kinetic Monte Carlo code (M. Reinelt) Include trap mobility

15. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Be(11-20) [M.Reinelt 2007, Phys.Scripta] Thermal Desorption Studies: Fluence Dependence

16. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler polycrystalline BeBe(11-20) [M.Reinelt 2007, Phys.Scripta] [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Fluence Dependence

17. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler polycrystalline BeBe(11-20) Same threshold fluence of 1.2·10 21 D/m 2 for the appearance of the low temperature desorption stage in both specimens point defects saturate trapping in structurally modified regions, e.g. amorphous hydride (A. Allouche) Fluences above 10 22 D/m 2 low temperature peak dominant Same threshold fluence of 1.2·10 21 D/m 2 for the appearance of the low temperature desorption stage in both specimens point defects saturate trapping in structurally modified regions, e.g. amorphous hydride (A. Allouche) Fluences above 10 22 D/m 2 low temperature peak dominant [M.Reinelt 2007, Phys.Scripta] [M.Oberkofler 2009, Phys.Scripta] Thermal Desorption Studies: Fluence Dependence

18. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler cyclically annealed (>1000K) Be single crystal similar morphology after cyclic implantation ( 1000K) cyclically annealed (>1000K) Be single crystal similar morphology after cyclic implantation ( 1000K) Morphology studies: Low Fluence Implantation

19. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler No implantation Only annealing No implantation Only annealing Morphology Studies: Fluence Dependence

20. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler No implantation Only annealing No implantation Only annealing Implanted region Medium fluence and annealing Implanted region Medium fluence and annealing Morphology Studies: Fluence Dependence

21. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler No implantation Only annealing No implantation Only annealing Implanted region Medium fluence and annealing Implanted region Medium fluence and annealing Beam spot center High fluence and annealing Beam spot center High fluence and annealing Morphology Studies: Fluence Dependence

22. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE) Morphology Studies: Grain Orientation Dependence

23. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE)SEM (EBSD) Morphology Studies: Grain Orientation Dependence

24. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE)SEM (EBSD) Morphology Studies: Grain Orientation Dependence

25. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE)SEM (EBSD) Morphology Studies: Grain Orientation Dependence 1 μm AFM Δh = 380 nm AFM 1 μm Δh = 330 nm

26. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE)SEM (EBSD) Morphology Studies: Grain Orientation Dependence 1 μm AFM Δh = 380 nm AFM 1 μm Δh = 330 nm Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No

27. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 50 μm SEM (SE)SEM (EBSD) Morphology Studies: Grain Orientation Dependence 1 μm AFM Δh = 380 nm AFM 1 μm Δh = 330 nm Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No Anisotropic diffusion of D and self interstitials? Ab initio calculations Yes (A. Allouche) Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No Anisotropic diffusion of D and self interstitials? Ab initio calculations Yes (A. Allouche)

28. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler SEM (SE)SEM (EBSD) Surface orientation dependent morphology evolution and therefore trap evolution Effect on retention? Future experiments with differently oriented single crystal, e.g. (0001) Surface orientation dependent morphology evolution and therefore trap evolution Effect on retention? Future experiments with differently oriented single crystal, e.g. (0001) Morphology Studies: Grain Orientation Dependence 50 μm Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No Anisotropic diffusion of H and self interstitials? Ab initio calculations Yes (A. Allouche) Surface orientation dependent sputtering? Cumulative D fluence ~ 4.3·10 22 m 2 yield = 0.05 < 20 nm Be sputtered No Anisotropic diffusion of H and self interstitials? Ab initio calculations Yes (A. Allouche)

29. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Conclusions Deuterium Retention in Ion Implanted Beryllium Far below the threshold of 1.2·10 21 D/m 2 Assumption of trapping at the stopping site consistent with observed shifts Include material evolution during annealing to reproduce peak shape Near but below the threshold (discussed at last SEWG meeting) Second kind of trap with constant density up to depth varying with energy No ion induced modifications consistent annealing of point defects Above the threshold Low temperature desorption stage independent of crystallinity trapping in structurally modified regions Surface orientation dependent roughening due to anisotropic diffusion Deuterium Retention in Ion Implanted Beryllium Far below the threshold of 1.2·10 21 D/m 2 Assumption of trapping at the stopping site consistent with observed shifts Include material evolution during annealing to reproduce peak shape Near but below the threshold (discussed at last SEWG meeting) Second kind of trap with constant density up to depth varying with energy No ion induced modifications consistent annealing of point defects Above the threshold Low temperature desorption stage independent of crystallinity trapping in structurally modified regions Surface orientation dependent roughening due to anisotropic diffusion

30. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Outlook Deuterium Retention in Ion Implanted Beryllium Further desorption experiments Release in the low temperature stage expected to be predominant at higher fluences Quantitative comparison of the retention in polycrystalline and single crystalline beryllium (various surface orientations) Different ramps: characterize diffusion process Implantation Depth Profiles Experimental assessment with in situ nuclear reaction analysis Towards Mixed Materials Oxygen Retention after implantation into a thick BeO layer vs clean Be Carbon Retention mixed beryllium-carbon materials created by in situ vapour deposition or implantation of carbon on clean Be Deuterium Retention in Ion Implanted Beryllium Further desorption experiments Release in the low temperature stage expected to be predominant at higher fluences Quantitative comparison of the retention in polycrystalline and single crystalline beryllium (various surface orientations) Different ramps: characterize diffusion process Implantation Depth Profiles Experimental assessment with in situ nuclear reaction analysis Towards Mixed Materials Oxygen Retention after implantation into a thick BeO layer vs clean Be Carbon Retention mixed beryllium-carbon materials created by in situ vapour deposition or implantation of carbon on clean Be

31. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler end of presentation

32. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Variation of 1-2 ORDERS OF MAGNITUDE ! Variation of 1-2 ORDERS OF MAGNITUDE ! Motivation [R. A. Anderl 1999, J.Nucl.Mat.]

33. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Variation of system wide frequency factor Variation of system wide frequency factor Fitting with TMAP7

34. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler polycrystalline Be Fluence in maximum = 2.0·10 21 D/m 2 Be(11-20) Fluence = 7.6·10 20 D/m 2 [M.Oberkofler 2009, NIMB] Greater shift of the maximum desorption temperature explained by implantation engergy - dependent depth profile and amount of traps Analogous shifts do appear on polycrystalline Be Greater shift of the maximum desorption temperature explained by implantation engergy - dependent depth profile and amount of traps Analogous shifts do appear on polycrystalline Be Thermal Desorption Studies: Fluence Dependence

35. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Implantation and Frenkel defect profiles Simulation with TMAP7 Model with 2 E act for detrapping: D stopped at the end of the collision cascade depth profile from SDTrim.SP D trapped in defect clusters constant density up to a depth estimated from the tail of the Frenkel pair profile (higher number of such traps for higher implantation energies!!) Simulation with TMAP7 Model with 2 E act for detrapping: D stopped at the end of the collision cascade depth profile from SDTrim.SP D trapped in defect clusters constant density up to a depth estimated from the tail of the Frenkel pair profile (higher number of such traps for higher implantation energies!!) assumed density of surviving defect clusters: ~1at.% activation energy for diffusion of vacancies from DFT : 0.72 eV mobile at RT?

36. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Sind die Vacancies bei RT beweglich? – eine Abschätzung L 2 = 6 D(T) t … mittl. quadratische Diffusionslänge für random walk D(T) = g a 2 v 0 exp(-ΔG/k B T) … Diffusivität durch Sprünge auf Gitter (z.B. bcc) D 0 g ~ 1… Symmetriefaktor a = 0.23nm… Gitterabstand (aus Bulk-Dichte) v 0 = 10 13 … Frequenzfaktor (Gitterschwingungen) ΔG = ΔH – T ΔS… Gibbssche Enthalpie ΔH = ΔE… Migrations - Enthalpie oder Aktivierungsenergie ΔS ~ k B … Migrations - Entropie L 2 ~ (50nm) 2 … Weg zur Oberfläche T = 0K… selbe Näherung wie in DFT t = 18min ΔE = 0.72eV… Aktivierungsenergie aus DFT Fehler durch T = 0 K: 1. RT ΔS ~ 0.026eV t = 7min 2. Gitterschwingungen senken ΔE auf ein ΔE eff ab (MD!) Zeit zwischen Implantation und TPD-Messung: 20 Minuten bis zu einigen Stunden die Vacancies dürften in diesem Kontext mobil sein [Nicoitd 1968, J.Nucl.Mat.]

37. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Shift in maximum release temperature pc vs sc D 2 TPD from implanted Be Proposed plausible assumptions: - increased amount of traps in the sc - possibly at greater depths Proposed reasons: 1.diffusion of mobile traps to grain boundaries the pc 2.diffusion of moblie traps further into the bulk in the sc Additional mechanism leading to an increased number of traps (vacancies) in the single crystal: diffusional anisotropy difference (DAD) between vacancies and interstitials [C.H. Woo 2000, J.Nucl.Mat.]

38. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler TPD: Increasing fluence Structural modifications Sample saturation Threshold

39. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Parallel to basal plane 0.004 eV Normal to basal plane0.039 eV Direction of movement Vacancy in Be Be self interstitial Modelling with DFT [A. Allouche] ConfigurationActivation energy of movement (NEB) isotropic0.72 eV DAD of self interstitials and vacancies in Be sc with (11-20) surface orientation more vacancies available for trapping compare to TPD from implanted (0001) -surface lower release temperature ?

40. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Anisotropic diffusion of D in Be Parallel to basal plane 0.192 eV Normal to basal plane0.715 eV Direction of movement H interstitial Modelling with DFT [A. Allouche] ConfigurationActivation energy of movement (NEB) Enhanced diffusivity along basal planes in the perfect crystal higher release temperature for (0001) surface orientation? Effective diffusivity through the defective lattice governed by retrapping no influence of anisotropic H diffusion on the predicted shift in release temperatures between the (11-20)- and the (0001)-crystal

41. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Modeling of H-Be: Concept Dynamic modeling: TMAP7, LKMC Dedicated experiments Static modeling: DFT (Cooperation with A. Allouche) Status of modeling requirements: 1.Multi-scale approach 2.Dynamics of Be defects AND impurities (H) 3.Phase formations and chemical reactions (Be hydrides) 4.Anisotropy of many transport processes (Be is not hcp) Full 3D problem ! Status of modeling requirements: 1.Multi-scale approach 2.Dynamics of Be defects AND impurities (H) 3.Phase formations and chemical reactions (Be hydrides) 4.Anisotropy of many transport processes (Be is not hcp) Full 3D problem ! 1D codes such as TMAP7 are not sufficient. 3D Lattice based Kinetic Monte Carlo code (LKMC) developed. 1D codes such as TMAP7 are not sufficient. 3D Lattice based Kinetic Monte Carlo code (LKMC) developed.

42. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Modeling of H-Be: Test of LKMC Benchmarking: * Isotropic cubic primitive lattice * Diffusion limited ΔE = 1 eV * No trapping * No recombination Sample size: 100 x 10 x 10 nm 3 Benchmarking: * Isotropic cubic primitive lattice * Diffusion limited ΔE = 1 eV * No trapping * No recombination Sample size: 100 x 10 x 10 nm 3 Dynamic modeling: TMAP7 + LKMC Dedicated experiments Static modeling: DFT (Cooperation with A. Allouche) Simulation of TPD spectra in principle possible with LKMC !

43. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Modeling of H-Be: TMAP7 + Experiments Experiment: * 1keV Deuterium * Fluence: 2.55e19 D/m 2 * Implantation into (11-20) SC Be TMAP7 Model: * Isotropic 1D model * Detrapping barrier: 1.9 eV Experiment: * 1keV Deuterium * Fluence: 2.55e19 D/m 2 * Implantation into (11-20) SC Be TMAP7 Model: * Isotropic 1D model * Detrapping barrier: 1.9 eV Dynamic modeling: TMAP7 Dedicated experiments Static modeling: DFT (Cooperation with A. Allouche) Peak simulated by TMAP7 is much too broad.

44. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Modeling of H-Be: LKMC + Experiments Experiment: * 1keV Deuterium * Fluence: 2.55e19 D/m 2 * Implantation into (11-20) SC Be LKMC model: * Anisotropic diffusivity (DFT) * Migration and annihilation of traps at the surface Detrapping barrier: 2.1 eV Experiment: * 1keV Deuterium * Fluence: 2.55e19 D/m 2 * Implantation into (11-20) SC Be LKMC model: * Anisotropic diffusivity (DFT) * Migration and annihilation of traps at the surface Detrapping barrier: 2.1 eV Dynamic modeling: LKMC Dedicated experiments Static modeling: DFT (Cooperation with A. Allouche) LKMC simulation reproduces the peak shape ! 1) Exp falsch (3kV) 2) Stratistik noch zu schlecht Kommt noch

45. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler Modelling of H-Be: Status Dynamic modeling: LKMC Dedicated experiments Static modeling: DFT (Cooperation with A. Allouche) Full dynamic and DFT based 3D model: Trap = Monovacancy * Anisotropic diffusivity * Migration and annihilation of traps at the surface * Up to 8 H per trap Trapping barrier: 0.40 – 1.37 eV Detrapping barrier: 1.32 – 0.80 eV Full dynamic and DFT based 3D model: Trap = Monovacancy * Anisotropic diffusivity * Migration and annihilation of traps at the surface * Up to 8 H per trap Trapping barrier: 0.40 – 1.37 eV Detrapping barrier: 1.32 – 0.80 eV ? ?

46. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler 500 nm Orientation–dependent morphology SEMAFM Depht of the holes: up to 100nm

47. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler EBSD: Kikuchi bands Orientation of crystallite:

48. SEWG Mixed Materials Culham 2009-07-07 M. Oberkofler D trapping in Be: Schematic energy diagram [E S = -0.10 eV] Atomic D ΔH 0 [ΔE ads = 0.87 eV] Molecular D 2 [½ ΔH (D 2 ) = -2.278 eV] Surface Mobile state [E diff = 0.29 eV] Activation energies obtained from modeling of TPD spectra (TMAP7) Temperature [K] Desorption rate [a.u.] E act = 1.25 eV 1.33 eV E act = 1.9 eV, 2.1 eV (simple model, depends on depth profile) Ion-induced defects Supersaturated states ΔH relative to atomic D M. Reinelt, PhD thesis (2007), NJP (2009)