Photoconductive Effects in Single Crystals of BaZrS$_3$

Abstract

Chalcogenide perovskites, such as BaZrS$_3$, are emerging semiconductors with potential for high photovoltaic power conversion efficiency. The role of defects in the efficiency of the generation and collection of photo-excited carriers has not been experimentally investigated extensively. We study the effect of processing-induced defects on the photoconductive properties of single crystals of BaZrS$_3$. We achieved ohmic contacts to single crystals of BaZrS$_3$ and observed positive surface photovoltage, which is typically observed in p-type semiconductors. However, mechanical polishing of BaZrS$_3$ to remove the surface oxide leads to dense deformation grain boundaries and leads 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 high photon-to-excited electron conversion efficiency in BaZrS$_3$.