Broadband Photosensitive Medium Based on Amorphous Equichalcogenides

A photosensitive medium based on amorphous equichalcogenide thin films containing germanium and antimony is proposed with characteristics promising for applications in all-chalcogenide photonics, sensors, and photovoltaics. Optical properties, temperature, and exposure wavelength dependence of DC electrical conductivity are shown to be comparable with those for halide perovskites, which potentially makes amorphous equichalcogenides a very attractive alternative. The change in dark resistivity with temperature is found to follow exponential decay, covering 2 orders of magnitude over a 70 K temperature interval. Light exposure leads to several orders of relative changes in a current when compared to its dark value. A strong photocurrent response is observed under low power (milliwatts range) exposure across the entire 400-1000 nm range of the investigated wavelengths. An increase in temperature leads to a decrease in the photoresponse of the developed material, which is found to vanish at temperatures higher than 120 degrees C when only a few milliwatts of exposure power is used.