Intrinsic response time of graphene photodetectors

TL;DR

This paper measures the intrinsic response time of monolayer graphene photodetectors, revealing a 2.1 ps response time that limits their bandwidth to approximately 262 GHz, and explores how this response varies with gate voltage and laser power.

Contribution

It provides the first direct measurement of the intrinsic response time of graphene photodetectors using ultrafast laser pulses, clarifying the speed limit of these devices.

Findings

Response time of 2.1 ps measured

Bandwidth of approximately 262 GHz

Response time depends on gate voltage and laser power

Abstract

Graphene-based photodetectors are promising new devices for high-speed optoelectronic applications. However, despite recent efforts, it is not clear what determines the ultimate speed limit of these devices. Here, we present measurements of the intrinsic response time of metal-graphene-metal photodetectors with monolayer graphene using an optical correlation technique with ultrashort laser pulses. We obtain a response time of 2.1 ps that is mainly given by the short lifetime of the photogenerated carriers. This time translates into a bandwidth of ~262 GHz. Moreover, we investigate the dependence of the response time on gate voltage and illumination laser power.