Layer-dependent photoresponse of 2D MoS ₂ films prepared by pulsed laser deposition

Due to the layered structure and thickness-dependent bandgap of MoS ₂ , it is intriguing to investigate the layer-dependent performance of MoS ₂ based photodetectors. In this work, centimeter-scale layered MoS ₂ films with different layer numbers are achieved by using pulsed laser deposition by controlling the number of laser pulses. The measurement of transport characteristics in the dark indicates a Schottky barrier contact formed at the Au/MoS ₂ interface. The obtained metal-semiconductor-metal MoS ₂ based photodetectors present a UV-to-NIR photoresponse with high stability. When the thickness of the film is decreased, the photoresponse of the MoS ₂ photodetectors gradually increases from multilayer to bilayer, and more importantly, a notable enhancement in the photoresponse for the monolayer can be observed. In particular, a photoresponsivity of 1.96 A W ^-1 is achieved in monolayer MoS ₂ samples under illumination with a wavelength of 300 nm. The physical mechanism responsible for the observation is discussed based on the layer dependent Schottky barrier variation and the indirect-to-direct energy band transition in MoS ₂ . Our work provides an insight into layer-dependent optical behavior in MoS ₂ films, which should be helpful for developing further large-scale photosensing applications in the atomic limit.