2 - Thermally Stimulated Depolarization Currents in Amorphous Chalcogenides

Abstract

Chalcogenide glasses are oxygen-free inorganic glasses containing one or more kind of chalcogen elements. The amorphous material is a noncrystalline solid, and the glass is amorphous material produced through melt quenching. Chalcogenide glasses based on sulfide, selenide, and telluride alloys in binary and multi component systems have evolved much interest in terms of the understanding of basic physics of noncrystalline solids as well as for the development of various semiconductor devices. Various unique phenomena are inherent for these glasses, and the most intriguing among them is photo darkening. The preceding phenomena cannot be found in crystalline chalcogenides or in any other amorphous semiconductors and are an interesting subject for fundamental research in the field of disordered materials. As far as amorphous materials are concerned, it must be remembered that the validity of a pure trapping model is still a moot point. At the same time, in such nonperiodic structures (long-range order is absent), the immobilization of charge carriers for long periods necessarily indicates the presence of traps. In addition, it should be noted that although chalcogenide glasses may have traps distributed throughout the mobility gap, it appears justifiable to use the single-trap approach to calculate the trapping parameters (especially activation energy) of the materials under study.