Golinej R. Features of the energy spectrum of the low-dimensional silicon structures with a developed surface

The thesis is devoted to the study the features of the energy spectrum of the low-dimensional silicon structures (porous or nanocrystalline silicon) as well as to the study of electronic properties of the crystalline silicon - porous silicon interface. The study has been carried out by modulation electroreflectance spectroscopy technique. It is established that the positively charged defects in the silicon oxide film cause the enrichment of the subsurface layers of the crystalline silicon situated immediately under the coat of the porous layer, with electrons and that an internal electric field develops on the interface between the crystalline silicon and the porous layer. A band model of the inversion of the conductivity type of the crystalline silicon as a function of the effective surface area and the thickness of the silicon oxide layer has been constructed. The study proves the existence of a number of direct transitions with frequencies in 1.7 eV, 2.0 eV, 2.35 eV, 2.6 eV and 2.9 eV regions of theenergy spectrum of the porous or nanocrystalline silicon. These direct transitions are explained as the transitions between the bands of the surface states and the conduction band.