High-performance ultraviolet-visible photodetector with high sensitivity and fast response speed based on MoS2-on-ZnO photogating heterojunction

Photogating is an effective strategy to modulate the channel conductance of the device with light-induced gate field or voltage, thereby improving the performance of optoelectronic devices. In this work, to overcome the long response time and low photoresponse of one-dimensional ZnO, a MoS2-on-ZnO photogating vertical heterojunction photodetector is design and constructed. Herein, the ZnO nanowire with high carrier mobility can response ultraviolet light and supply a high-speed carrier transport channel, while the MoS2 flake as a photogating layer can response with visible light and transfer photogenerated electrons into the ZnO nanowire to adjust its conductivity. Thus, the irradiation of visible light is equivalent to applying a photo-induced gate voltage on the ZnO nanowire. In addition, the photogenerated electrons will not transmit through the MoS2 with low carrier mobility, so that not only the visible light response of the photodetector can be realized, but also its ultraviolet light response is able to be improved. Under ultraviolet light irradiation, the photoresponsivity of the photodetector can be reached to 273 A W−1 and the response speed is less than 24 ms. More important, based on this unique heterojunction structure, MoS2-on-ZnO photodetector also illustrates an excellent visible light response with a high photoresponsivity (74 A W−1) and fast response speed (< 24 ms) due to the photogating effect. This work not only paves the way to design high-performance photodetectors with high photoresponsivity and fast response speed, but also provide a promising approach to improve the performance of optoelectronic devices using photogating effect.