Revutskaya L. The influence of composition and doping on the short-range structure of chalcogenide glasses and formation of surface reliefs on thin films and nanocomposites based on them

Modern information technologies need new and effective solutions in the field of recording and storage of information. The key direction for solving these problems is the development of new functional materials. One of such materials are chalcogenide glasses, that are characterized by: transparency in the IR range of the spectrum, relatively large values of linear and nonlinear refractive indices and the manifestation of various photoinduced phenomena. It makes them promising materials for the designing of devices for infrared optics, information recording, photonics and optoelectronics, etc. It is known that the physicochemical properties of chalcogenide glasses can be varied by changing the composition, doping and by influence of external factors. Detailed study of the structural properties of chalcogenide glasses will provide a deeper understanding of the processes of surface relief formation on thin films and multilayer chalcogenide nanostructures and will expand the possibilities of using these materials as media for information recording. Therefore, the study of the relationship between atomic structure and local, integral physical properties of modified chalcogenide glasses is necessary to solve an amount of fundamental problems in the disordered state physics, that determines the relevance and practical value of this work. The aim of the dissertation is to analyze the influence of composition, doping on the structural properties of bulk chalcogenide glasses and the possibility of application of thin chalcogenide films and multilayer nanostructures based on them as materials for holography and photonics. The following scientific results were obtained in the dissertation: • It was found the changes in short-range order for the glasses As-S-Sb, As-Se-S, As2Se3: Mn. At the same time for As2S3: Ag, As-S-Ge systems these changes are insignificant. • It was found the relative change in the concentration of basic structural units and non-stoichiometric molecular fragments of As-S-Sb, As-Se-Ge, As-Se-S, As-S-Ge, As2Se3:Mn, As2S3:Ag due to the changing of the composition or doping with silver and manganese. • For the first time it was shown the possibility of direct electron beam recording on chalcogenide films As38S36Se26 and As3S77Ge20. The relief formation was described by the exponential dependence on the exposure time and can be explained by the charge model. • It was shown that composite multilayer nanostructures As2S3:Ag/Se are suitable for realization of the one-stage optical recording of the surface relief of holographic gratings without the stage of selective etching. The practical value of the dissertation is that the research expands the scientific basis for better understanding the structure of chalcogenide glasses, allows to optimize the processes of surface relief on thin films and multilayer chalcogenide nanostructures. The obtained results show the prospects of using these materials as media for information recording and optical elements manufacturing.