Current-induced enhancement of photo-response in graphene THz radiation detectors

TL;DR

This paper demonstrates that applying a dc current can break symmetry in graphene THz detectors with latent p-n junctions, significantly enhancing their photo-response and simplifying detector design.

Contribution

It introduces a method to enhance graphene THz detector sensitivity by current-induced symmetry breaking of latent p-n junctions, enabling simpler and more controllable devices.

Findings

Enhanced rectified signal due to Peltier effect-induced symmetry breaking

Simplified detector design with improved sensitivity

Control of detector response via dc current application

Abstract

Thermoelectric readout in a graphene THz radiation detector requires a p-n junction across the graphene channel. Even without an intentional p-n junction, two latent junctions can exist in the vicinity of the electrodes/antennas through the proximity to metal. In a symmetrical structure, these junctions are connected back-to-back and therefore counterbalance each other with regard to rectification of the ac signal. Because of the Peltier effect, a small dc current results in additional heating in one- and cooling in another p-n junction, thereby breaking the symmetry. The p-n junctions then no longer cancel, resulting in a greatly enhanced rectified signal. This allows to simplify the design and effectively control the sensitivity of the THz-radiation detectors.