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The influence of Bi on the structure and physical properties of Ge2Se3-based equichalcogenide glasses and thin films is studied. Thermal analysis shows increased crystallization ability for Bi-modified glasses. Direct current (DC) and alternating current (AC) electrical conductivity for bulk glasses and thin films is investigated in a broad range of temperatures and frequencies, showing a strong dependence on the presence of Bi modifiers. Exposure wavelength dependence of photocurrent is studied at different temperatures for the visible range of spectrum, and correlated with the existence of localized states in the mobility gap of these amorphous semiconductors. Structural peculiarities of the obtained thin films and bulk samples are assessed from X-ray diffraction (XRD) and high-resolution X-ray photoelectron spectroscopy (XPS) measurements. Optical, electrical, and thermal properties are shown to be suitable for various applications in photonics, electronics, and sensor systems. 

Abstract Phase-change materials, demonstrating a rapid switching between two distinct states with a sharp contrast in electrical, optical or magnetic properties, are vital for modern photonic and electronic devices. To date, this effect is observed in chalcogenide compounds based on Se, Te or both, and most recently in stoichiometric Sb 2 S 3 composition. Yet, to achieve best integrability into modern photonics and electronics, the mixed S/Se/Te phase change medium is needed, which would allow a wide tuning range for such important physical properties as vitreous phase stability, radiation and photo-sensitivity, optical gap, electrical and thermal conductivity, non-linear optical effects, as well as the possibility of structural modification at nanoscale. In this work, a thermally-induced high-to-low resistivity switching below 200 °C is demonstrated in Sb-rich equichalcogenides (containing S, Se and Te in equal proportions). The nanoscale mechanism is associated with interchange between tetrahedral and octahedral coordination of Ge and Sb atoms, substitution of Te in the nearest Ge environment by S or Se, and Sb–Ge/Sb bonds formation upon further annealing. The material can be integrated into chalcogenide-based multifunctional platforms, neuromorphic computational systems, photonic devices and sensors.