Electronic Structure and Substructure of Epitaxial Tin Nanolayers on Silicon According to Synchrotron Studies

The specificity of the local atomic surrounding, the physicochemical state, and the electronic structure of five tin monolayers on a thin buffer layer of silicon formed epitaxially, and their transformation as a result of thermal annealing are studied in situ in the presented work. Using radiation from three synchrotron sources high-resolution surface-sensitive experimental methods, X-ray absorption near edge structure spectroscopy and X-ray photoelectron spectroscopy, were used as well as computer modeling. The possibility of oxygen atoms diffusion from tin to a buffer layer of silicon during storage of structures in laboratory conditions is shown. It is shown that during the formation of Sn/Si epitaxial nanolayers there are no interatomic interactions at the heterogeneous boundaries of the structure up to the possible formation of a tin-silicon solid solution and as a result no noticeable distortions of the electronic spectrum. However, high-temperature ultrahigh vacuum annealing causes a phase rearrangement of the surface layers of such a structure accompanied by the redistribution of oxygen atoms from tin atoms to silicon of the epitaxial buffer with the formation of the thin layer of SiO. Within the thin tin-silicon transition layer of the studied structures and along its boundaries a complex bonds can be formed between tin, oxygen, and carbon atoms.