Svezhentsova K. Features of formation and property stain etched nanocrystalline silicon

The dissertation is devoted to development of the method of formation of thin homogeneous nc-Si films of large area and to complex study of their properties with the purpose of their application in solar cells and gas sensors. The mechanism of nc-Si formation during stain etching is analyzed. It is found that the process of nc-Si formation consists of two stages and results not only in the reorganization of surface structure of substrates, but also in the change of element composition of nc-Si films. It is shown, that photoluminescence band of nc-Si is a superposition of the band caused by a recombination of excitons in silicon nanoclusters and the band caused by a recombination of carriers through surface defects. Two processes of nc-Si characteristic degradation under ultraviolet irradiation are revealed: a irreversible one resulted in the change of reflection index and caused by a photostimulated oxidation of porous layer, and a reversible one resulted in the decrease of the photoluminescence intensity. The model of nc-Si photoluminescence degradation consisted in the tunneling of carriers generated in silicon clusters to the traps in their oxide shell is proposed. An efficiency of nc-Si application for the improvement of mono- and multicrystalline silicon solar cell and gas sensor characteristics is confirmed experimentally.