2015/05/07 by Jens Sonntag, Annika Kurzmann, Sonntag, Jens +9 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #cond-mat.mes-hall
paper · pdf · doi:10.48550/arxiv.1505.01762
11 Pages, 4 Figures
arxiv created 2015/05/22 · arxiv updated 2015/05/25
We study the optical response of a suspended graphene field-effect transistor in magnetic fields of up to 9 T (quantum Hall regime). With an illumination power of only 3 μW, we measure a photocurrent of up to 400 nA, corresponding to a photo-responsivity of 0.14 A/W, which we believe to be the highest value ever measured in single-layer graphene. We estimate that every absorbed photon creates more than 8 electron-hole pairs, which demonstrates highly effective carrier multiplication. As suggested by the dependence of the photocurrent on gate voltage and magnetic field, we propose a ballistic two-stage mechanism where the incident photons create primary charge carriers which then excite secondary charge carriers in the chiral edge states via Auger-type inelastic Coulomb scattering processes at the graphene edge.