Dan'ko V. Physical and technological foundations of the formation processes of nanostructures by methods of interference lithography and thermostimulated phase separation

The dissertation presents the results of investigations of the mechanisms of photostimulated etching and etching on reversible transformations in thin annealed films of chalcogenide vitreous semiconductors (CGS), as well as reversible photodarkening in As2S3/SiO1.5 nanocomposite structures. The technology of the formation of nanocomposite porous structures of nc-Si-SiOx is proposed and their light-emitting properties are experimentally studied. It was found that the rate of photostimulated dissolution of thin films of CGS increases with increasing light intensity, and its spectral dependence correlates with the absorption spectrum of films of CGS, which indicates that the main factor that determines the effect of photostimulated etching is the amount of absorbed light energy per unit time and accordingly, the concentration of broken bonds and self-trapped excitons in the exposed film. Mechanisms explaining these phenomena have been proposed and a new class of inorganic photoresists has been developed. It was shown that reversible photostimulated changes in annealed Ge25Se75 films are accompanied by the destruction of their basic structural units and an increase in the concentration of chalcogen homopolar bonds, which leads to an increase in the dissolution rate of the exposed Ge25Se75 films in the etchant. It was found that the efficiency of reverse photo darkening in nanocomposite As2S3/SiO1.5 structures monotonically increases with a decrease in the size of chalcogenide nanoclusters. It was found that during the formation of As2S3/SiO1.5 nanocomposites, the chalcogenide phases are separated into clusters enriched in arsenic and sulfur, the exposure of which leads to a redistribution of bonds. The processes of interference photolithography on annealed films of CGS (including compounds without arsenic) based on the photo-etching and etching on reverse transformations effects were developed and patented. The advantages of these technologies and the possibilities of their practical application for the manufacture of micro- and nanostructured elements for various purposes are demonstrated. It has been established that the process of thermally stimulated phase separation in SiOx films can be described as the process of diffusion of oxygen atoms from regions near silicon nuclei and the diffusion coefficients of oxygen in these films have been determined. It was shown that as a result of implantation of porous SiOx films by carbon ions, annealing in vacuum, and selective etching in HF vapors, a thin-layer light-emitting structure is formed, the PL spectrum of which covers the visible and near-IR spectral regions. The possibilities of the influence of various treatments on the light-emitting properties of annealed porous nc-Si-SiOx films are demonstrated. Due to a decrease in the size of nc-Si and passivation of dangling bonds at the nc-Si / SiOx interface an increase in the photoluminescence intensity of these structures by more than two orders of magnitude and a controlled shift of its band to the high-energy region of the spectrum were achieved by fluoride-hydrogen treatment