Gate-activated photoresponse in a graphene p-n junction

TL;DR

This paper demonstrates that graphene p-n junctions can be used for on-off photodetection control, enabling submicron, bias-free, and locally modulated photodetectors suitable for high-resolution infrared imaging.

Contribution

It introduces a method to control graphene photodetectors via local electrostatic gating, enabling on-off photoresponse without bias and at submicron scales.

Findings

Strong photoresponse occurs only at p-n junctions.

Photocurrents do not require external bias.

Potential for high-resolution infrared imaging.

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 submicron 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.