Fig. 4From: Direct Observation of High Photoresponsivity in Pure Graphene PhotodetectorsPhotoresponsivity dependence on the biased source-drain voltage. a The gate voltage dependence of the photoresponsivity characteristics on the source-drain bias voltage. The decrease of the photocurrent with an increase of the gate voltage originates from the doping induced by the internal electric field. b and c present the source-drain voltage dependence of the external gain and photoresponsivity respectively without the substrate effectBack to article page