▎ 摘　　要

We investigated electrical and photoelectrical properties of graphene sandwiched WSe2/GaSe van der Waals heterojunctions. The device showed a high rectification ratio up to 300 at V-ds = 1.5/-1.5 V, which is attributed to the built-in electric field in the device. Due to the bipolar property of WSe2, gate-tunable rectification inversion was observed. Meanwhile, the graphene sandwiched heterojunction showed excellent performances on photodetection, where the photoresponsivity of (6.2 +/- 0.2) A W-1 can be reached under V-ds = -1.5 V and P = 0.2 mu W. The device also showed great external quantum efficiency of (1490 +/- 50)% and fast response time of similar to 30 mu s. Our study identified the graphene sandwiched heterojunctions based on 2D materials have great potential for gate-tunable electronic and optoelectronic applications.