Thermal stability and photoconductive properties of photosensors with an alternating multilayer structure of amorphous Se and AsxSe1−x

Abstract

In this study, we fabricated a-Se based photosensors with an alternating multilayer structure of a-Se and AsxSe1−x by rotational thermal evaporation deposition. During the deposition of the amorphous AsxSe1−x layers, As diffuses into the underlying a-Se component layers, thereby improving the thermal stability of the multilayer photosensor and thus increasing the breakdown electric field. Although the As doping introduces carrier traps in the a-Se layers, the multilayer photosensors demonstrate an effective quantum efficiency comparable to the single-layered a-Se sensor under the blue light illumination but are with a lower dark current density by two orders of magnitude. In addition to the top AsxSe1−x layer being functioning as an electron blocking layer, carrier traps present in the multilayer structure may decrease the drift mobility of charge carriers and disturb electric field distribution in the photosensors, thereby suppressing the dark current.