DFT Modeling of Plasma-Assisted Atomic Layer Deposition for Si(110) Passivation: Formation of Boehmite-Like Chains as γ-Al2O3 Precursors

One accelerated computational route to elaborate a Si(110)/γ-Al₂O₃ interface model passivated via plasma-assisted atomic layer deposition is proposed. The final oxidation step corresponds to a junction of a slab with a γ-Al₂O₃ fragment after two O → Al or three O → Al → O atomic deposition steps over a basic Si(110) surface. The sizes of both Si(110)/γ-Al₂O₃ components were selected to lead to a minimal mismatch while atomic coordinates were optimized using DFT with periodic boundary conditions. The extent of Si(110) passivation after each deposition step was studied by analyzing the geometry of the atoms (to detect the under-coordinated defects) and by assigning the band structure and projected densities of the s- and p-states (to detect structural defects, with distorted bond lengths and angles). The formation of boehmite-like chains with higher (octahedral) Al coordination without Al–Si bonds in the Si(110)/SiO_X/AlO_Y interface is particularly discussed. Examples of models with a passivated interface (using or not the junction with γ-Al₂O₃ fragment) were obtained together with a list of typical defects.