Photo-thermal response in dual-gated bilayer graphene

TL;DR

This study investigates the photoresponse mechanisms in gapped bilayer graphene, revealing that both photovoltaic and bolometric responses are governed by hot electron thermal relaxation with rapid response times.

Contribution

It demonstrates that the photovoltaic response in bilayer graphene is dominated by hot electron thermal relaxation, with measured response times across a range of temperatures.

Findings

Response times of 100-20 ps from 3-100 K

Photovoltaic and bolometric responses have identical times

Relaxation time is temperature-independent above 10 K

Abstract

The photovoltaic and bolometric photoresponse in gapped bilayer graphene was investigated by optical and transport measurements. A pulse coincidence technique at 1.5 um was used to measure the response times as a function of temperature. The bolometric and photovoltaic response times were found to be identical implying that the photovoltaic response is also governed by hot electron thermal relaxation. Response times of tau ~ 100 - 20 ps were found for temperatures from 3 - 100 K. Above 10 K, the relaxation time was observed to be tau = 25 +/- 5 ps, independent of temperature within noise.