  In order to increase the response speed of the InSe-based photodetector with
high photoresponsivity, graphene is used as the transparent electrodes to
modify the difference of the work function between the electrodes and the InSe.
As expected, the response speed of InSe/graphene photodetectors is down to 120
{\mu}s, which is about 40 times faster than that of our InSe/metal device. And
it can also be tuned by the back-gate voltage from 310 {\mu}s down to 100
{\mu}s. With high response speed, the photoresponsivity can reach as high as 60
AW-1 simultaneously. Meanwhile the InSe/graphene photodetectors possess a broad
spectral range at 400-1000 nm. The design of 2D crystal/graphene electrical
contacts could be important for high performance optoelectronic devices.
