ИСТИНА

Typical structural defects are studied theoretically in the course of O -> Al -> O atomic depositions on the basic Si(110) surface. The defects are determined by analyses of the band gap states and projected densities of the s- and p-states after the deposition aimed to form a Si(110)/SiOX/AlOY/g-Al2O3 slab. The extent of Si(110) passivation after each deposition step is studied by scanning the band structure calculated using Density Functional Theory with periodic boundary conditions. Our modeling reproduces most features of the use of trimethylaluminium or any other organic ligand as Al precursor along O2 plasma assisted atomic layer deposition (PA ALD) when the organic ligands are completely oxidized so that their participation can be neglected in the deposition as already shown experimentally. The final oxidation step corresponds to the junction of a slab of -Al2O3 fragment deposited over Si(110), whose super cell (SC) parameters have been selected to lead to the minimum mismatch. Different examples of either non-satisfactory or accurate junction of the oxidized Si(110) slab and g-Al2O3 fragment (under two different forms) are discussed aiming to develop a route for understanding the dominant defect types at the interface. Such theoretical work should be the first step for the elaboration of computational tools for the passivation of silicon with amorphous oxides. The latter are mainly formed at the experimental conditions of the PA ALD depositions. A list of formed typical defects at the Si(110)/SiOX/AlOY/g-Al2O3 boundary is presented and characterized by the projected density of states and respective band structure around the band gap. One of the results of the study is the formation of boehmite-like chains with higher Al coordination (NAl = 6) without Al-Si bonds at the Si(110) surface. These chains can be the precursor for the transition from amorphous to crystalline Al2O3 along the following annealing.