Fast gate-tunable photodetection in the graphene sandwiched WSe2/GaSe heterojunctionsElectronic supplementary information (ESI) available. See DOI: 10.1039/c7nr03124f

• Main Authors: Wei, Xia, Yan, Faguang, Lv, Quanshan, Shen, Chao, Wang, Kaiyou
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c7nr03124f

We investigated electrical and photoelectrical properties of graphene sandwiched WSe 2 /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 WSe 2 , 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 μW. The device also showed great external quantum efficiency of (1490 ± 50)% and fast response time of ∼30 μs. Our study identified the graphene sandwiched heterojunctions based on 2D materials have great potential for gate-tunable electronic and optoelectronic applications. We investigated electrical and photoelectrical properties of graphene sandwiched WSe 2 /GaSe van der Waals heterojunctions. The heterojunctions not only can be effectively tunable by back gate, but also show excellent photoresponse such as fast response time down to ∼30 μs.