Gate-Tunable Ultrahigh Photoresponsivity of 2D Heterostructures Based on Few Layer MoS2 and Solution-Processed rGO

2D materials heterostructures are built by vertical stacking of solution-processed reduced graphene oxide (rGO) film and few-layer MoS2. The Raman and photoluminescence of the MoS2/rGO heterostructures show more significant peak shift compared to individual MoS2 or rGO film. The field-effect transistors (FETs) based on such MoS2/rGO heterostructures show ambipolar behavior in the dark but n-type behavior under illumination. This phenomenon provides a way to investigate the charge transport in valence band of MoS2. Due to charge separation caused by built-in potential at MoS2/rGO interface, the recombination of photoexcited electron-hole pairs is effectively suppressed, leading to high photoresponsivity (approximate to 2.4 x 10(4) A W-1) and photogain (approximate to 4.7 x 10(4)) of the MoS2/rGO heterostructures in ambient air with modulation of gate bias and drain-source bias.