Effect of UV-O3 treatment on the performance of UV detector based on zinc oxide/molybdenum disulfide nanosheet heterostructures

Abstract

UV photodetectors based on ZnO nanostructures, using a metal-semiconductor-metal (MSM) configuration, are popular due to their simple fabrication. However, they experience high dark currents and slow photoresponse speeds. This is due to a high recombination rate for photogenerated electrons and holes as well as low charge carrier mobility attributable to ZnO's inherent defects. In this study, MoS2 nanosheets was employed to cover the surface of ZnO nanorods, creating a unique architecture that focuses the impact of MoS2 solely on light absorption and charge transfer on the ZnO surface. Subsequently, a 15-min UV-O3 exposure is applied to the ZnO/MoS2 structure. The ZnO/MoS2UVo heterostructure exhibits remarkable results, including a six-fold increase in sensitivity compared to pure ZnO, Additionally, the Detectivity increases by 265 %, while the Responsivity and Quantum Efficiency rise by up to 102 %. These enhancements are attributed to the reduction of dark current coming from the reduction of oxygen vacancies as sulfur edge atoms from MoS2 fill these vacancies. Furthermore, additional dark current reduction post UV-O3 treatment is due to both the reduced ZnO oxygen vacancies and the formation of a thin MoO3 passivation layer on the ZnO NR surface. Despite these achievements, the study acknowledges the presence of multiple junctions between ZnO, MoS2, and MoO3, which still pose challenges for efficient charge transfer to the electrodes.