Dual Origin of Room Temperature Sub-Terahertz Photoresponse in Graphene Field Effect Transistors

TL;DR

This study investigates the mechanisms behind room temperature sub-terahertz photoresponse in graphene FETs, revealing the combined roles of thermoelectric, p-n junction, and plasmonic effects through temperature-dependent experiments and theory.

Contribution

It provides a comprehensive analysis distinguishing multiple rectification effects contributing to the sub-THz photoresponse in graphene FETs, which was previously challenging.

Findings

Thermoelectric effect plays a significant role at certain temperatures.

P-n junction rectification influences the photoresponse.

Plasmonic rectification contributes to the overall response.

Abstract

Graphene is considered as a promising platform for detectors of high-frequency radiation up to the terahertz (THz) range due to graphene$'$s superior electron mobility. Previously it has been shown that graphene field effect transistors (FETs) exhibit room temperature broadband photoresponse to incoming THz radiation thanks to the thermoelectric and/or plasma wave rectification. Both effects exhibit similar functional dependences on the gate voltage and therefore it was found to be difficult to disentangle these contributions in the previous studies. In this letter, we report on combined experimental and theoretical studies of sub-THz response in graphene field-effect transistors analyzed at different temperatures. This temperature-dependent study allowed us to reveal the role of photo-thermoelectric effect, p-n junction rectification, and plasmonic rectification in the sub-THz photoresponse of graphene FETs.