Gate-Activated Photoresponse in a Graphene p–n Junction

Abstract

We study photodetection in graphene near a local electrostatic gate, which enables active control of the potential landscape and carrier polarity. We find that a strong photoresponse only appears when and where a p–n junction is formed, allowing on–off control of photodetection. Photocurrents generated near p–n junctions do not require biasing and can be realized using submicrometer gates. Locally modulated photoresponse enables a new range of applications for graphene-based photodetectors including, for example, pixilated infrared imaging with control of response on subwavelength dimensions.