Self-powered, high response and fast response speed metal-insulator-semiconductor structured photodetector based on 2D MoS 2 .

Here, we firstly fabricated a metal-insulator-semiconductor (MIS) (Pd/Al 2 O 3 /MoS 2 ) self-powered photodetector based on MoS 2 , which is sensitive to the illumination of light without any external bias, exhibiting a high responsivity of 308 mA W -1 . Under bias, it shows a ratio of photocurrent to dark current exceeding 3705, a high photoresponsivity of 5.04 A W -1 , and a fast response/recovery time of 468 ms/543 ms. The optoelectronic performances of the photodetector are closely related to the insulating layer, which can suppress the dark current of the photodetectors, and prevent strong current drifting and degradation by environmental effects, playing a key role in carrier tunneling. Furthermore, we used a thin HfO 2 film as the insulating layer to improve the optoelectronics performance of the MIS structured self-powered photodetector, which presented a high responsivity of 538 mA W -1 at 0 bias. With an applied bias, it exhibits an on/off ratio up to 6653, a photoresponsivity of 25.46 A W -1 , and a response/recovery time of 7.53 ms/159 ms. Our results lead to a new way for future application of high performance MIS structured photodetectors based on 2D MoS 2 .