2011/05/31 by Justin C. W. Song, Mark S. Rudner, Charles M. Marcus +1 · 2 citations
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1021/nl202318u
published as Nano Lett., 11 (11), pp 4688-4692 (2011) · 4 pgs, 2 fgs
arxiv created 2011/09/17 · arxiv updated 2011/11/29
Strong electron-electron interactions in graphene are expected to result in multiple-excitation generation by the absorption of a single photon. We show that the impact of carrier multiplication on photocurrent response is enhanced by very inefficient electron cooling, resulting in an abundance of hot carriers. The hot-carrier-mediated energy transport dominates the photoresponse and manifests itself in quantum efficiencies that can exceed unity, as well as in a characteristic dependence of the photocurrent on gate voltages. The pattern of multiple photocurrent sign changes as a function of gate voltage provides a fingerprint of hot-carrier-dominated transport and carrier multiplication.