Ab initio molecular dynamics of Al irradiation-induced processes during Al2O3 growth

Al bombardment induced structural changes in α-Al2O3 (R-3c) and γ-Al2O3 (Fd-3m) were studied using ab initio molecular dynamics. Diffusion and irradiation damage occur for both polymorphs in the kinetic energy range from 3.5 to 40 eV. However, for γ-Al2O3(001) subplantation of impinging Al causes significantly larger irradiation damage and hence larger mobility as compared to α-Al2O3. Consequently, fast diffusion along γ-Al2O3(001) gives rise to preferential α-Al2O3(0001) growth, which is consistent with published structure evolution experiments.