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.
ASJC Scopus subject areas
- Materials Chemistry