Photoresponse in reduced graphene oxide thin films*

We examine photo-response and positional dependent photocurrent generation in chemically reduced graphene oxide (RGO) thin film under near infrared illumination. We have observed that the photocurrent depends strongly on the position of laser spot with maximum photocurrent occurring at the metal-film interface. A slow time constant ($\sim $2.8 seconds) was observed and the photocurrent exhibits a linear dependence on the incident laser intensity. In light of our observations, the positional sensitive photocurrent generation is explained as originating from the diffusion of photo-excited carriers around the Schottky barriers at the RGO thin film electrode junctions.