Stara T. The nature of emission and aging processes of structures with silicon nanoparticles in oxide matrix

The thesis deals with the investigation of thermostimulated transformations in SiOx systems prepared by magnetron sputtering as well as the study of the nature of luminescence and aging processes of a set of low-dimensional silicon based nanostructures. It is shown, that in systems prepared by magnetron sputtering with high silicon content the crystallites surrounded by oxide originate mainly from the decomposition of SіОх which arises after oxidation of a silicon phase during deposition or storage processes. In annealed layers with CSi> 40 % the Si depletion region is found near the layer/substrate interface. In the layers with CSi > 55 % the effect of orientation of crystallites is found for the first time. It is shown, that the photoluminescence (PL) of as-prepared samples of nanoporous silicon obtained by electrolytic etching is caused by exciton recombination in Si nanoparticles. During aging, in the PL spectra of these samples the additional emission bands caused by carrier recombination throughoxide-related centers arise. In the PL spectra of macroporous and nanoporous Si layers prepared by chemical etching these emission bands are present just after fabrication. It is established, that the main reason of instability of characteristics of the systems with silicon nanoparticles is their oxidation. Stability of the systems studied is determined by several factors: oxidation degree of as-prepared samples, presence of chemical complexes on their surface and porosity of the material with silicon nanoparticles.