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Present article deals with the theoretical and experimental investigation of optical properties of Bi/Si(001) interfaces in a wide spectral range (1-4 eV). Theoretical excitation spectra of vicinal Si(001) surface, Bi/Si(001)-0.5 monolayer and Bi/Si(001)-1 monolayer interfaces are calculated by time-dependent density functional theory with the hybrid Becke and Lee, Yang and Parr pseudopotential. Calculations and experimental studies of the absorption spectrum of the samples revealed the blue shift of the optical absorption edge with increasing of the bismuth covering degree. Features of the experimentally obtained reflectance anisotropy spectra (RAS) and surface differential reflectance spectra (SDRS) concerned with changing of the silicon surface reconstruction from 2 × 1 to 1 × 1 with the increasing of the bismuth covering degree from 0.5 to 1 monolayer. It is shown that the correlation between the theoretically calculated and experimental data makes it possible to identify the electronic transitions in the surface region.

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Our study deals with the structure of thin nanosilicon films having the thicknesses less than 100 nm. It is measured using multi-angular and spectral ellipsometry methods. Modelling of angular dependences of the ellipsometric parameters shows a significant dependence of both structure and composition of the nanosilicon films upon their thickness. In particular, the volume fraction of voids increases with decreasing thickness of the film. The effect of SiO x shell of the nanocrystals on the optical properties of our films can be neglected. When the thickness of the nanocrystalline layer is less than 50 nm, the compositions of this layer and the surface-roughness layer become practically identical.

Дослiджено вплив хрому на змiну оптичних характеристик iнтерфейсiв Cr/Si(001) за їх окислення. На основi експериментально вимiряних значень елiпсометричних параметрiв ρ i ∆ розраховано оптичну провiднiсть iнтерфейсiв, пов'язану з мiжзонними переходами, в iнтервалi вiд 1 до 4.5 еВ. Виявлено, що окислення суттєво впливає на оптичну провiднiсть плiвок хрому товщиною до 2 нм.Ключовi слова: елiпсометричнi параметри, оптична провiднiсть, окислення.