Photoconductive Effects in Single Crystals of BaZrS3

Abstract

Chalcogenide perovskites, such as BaZrS₃, are emerging semiconductors with the potential for high photovoltaic power conversion efficiency. The role of defects in the efficiency of the generation and collection of photoexcited carriers has not been experimentally investigated extensively. We studied the effect of processing-induced defects on the photoconductive properties of single crystals of BaZrS₃. We achieved Ohmic contacts to single crystals of BaZrS₃ and observed positive surface photovoltage, which is typically observed in p-type semiconductors. However, mechanical polishing of BaZrS₃ to remove the surface oxide leads to dense deformation grain boundaries and to trap-dominated photoconductive response. In comparison, Ohmic contacts achieved in cleaved crystals leave fewer deformation defects and greatly improve optoelectronic properties. Defect-controlled crystal growth and contact fabrication are potentially limiting factors for achieving a high photon-to-excited-electron conversion efficiency in BaZrS₃.