Report

Hot Carrier–Assisted Intrinsic Photoresponse in Graphene

Science  06 Oct 2011:

DOI: 10.1126/science.1211384

Abstract

We report on the intrinsic optoelectronic response of high-quality dual-gated monolayer and bilayer graphene p-n junction devices. Local laser excitation of wavelength λ = 850 nm at the p-n interface leads to striking six-fold photovoltage patterns as a function of bottom- and top-gate voltages. These patterns, together with the measured spatial and density dependence of the photoresponse, provide strong evidence that nonlocal hot-carrier transport, rather than the photovoltaic effect, dominates the intrinsic photoresponse in graphene. This regime, which features a long-lived and spatially distributed hot carrier population, may open the doorway for hot carrier–assisted thermoelectric technologies for efficient solar energy harvesting.