Halian V. Light emission in chalcogenide single crystals of Ga–In(La)–S systems and glassy alloys formed by binary erbium-doped chalcogenides of Ag2S(Se), HgS, Ga(La)2S(Se)3, GeS2

The thesis is devoted to the studying the patterns of influence of component composition, defect formation, -irradiation, and temperature on absorption processes, emission mechanisms in chalcogenide single crystals and erbium-doped glassy alloys. The influence of modifying and doping impurities on the optical properties of chalcogenides is analyzed. The study of the optical absorption spectra of the erbium-doped chalcogenide semiconductors showed that the narrow absorption bands, which are associated with transitions of Er3+ ions in the f-shell, appear in the impurity absorption region. It is established of excitation mechanisms, emitting / non- emitting relaxation of emission centers and the study of nonlinear optical properties in chalcogenide glassy alloys. The model of energy levels in Er3+ ions denote the ways of transition of Er3+ ions into the excited states and occurrence of photoluminescence due to non-emitting relaxation from the excited state of higher energy and / or cross-relaxation processes between neighboring erbium ions. It was found the high sensitivity of photoluminescence emission to the temperature changes in chalcogenide glasses and radiation resistance to -irradiation of single crystals. The radiation-induced defects in the glassy alloys of Er2S3–Ag0,05Ga0,05Ge0,95S2 affect the photoluminescence properties, cause a change in mechanism of occurrence of excitation states and emitting relaxation in Er3+ ions. Experimental results of EPR and theoretical analysis show that the change in concentration of paramagnetic centers from time of annealing is stipulated by the movement of vacancies (fast component) and relaxation of glass-forming matrix (long-term component). It is proved that -induced paramagnetic centers in the glassy alloys under study are Ga-VS.