Back-gate tuning of Schottky barrier height in graphene/zinc-oxide photodiodes

Abstract

We demonstrate back-gate-tuning of the Schottky barrier height in graphene/zinc oxide photodiodes that are devised by a selective sputter-growth of ZnO on pre-patterned single-layer graphene sheets. The devices show a clear rectifying behavior (e. g., Schottky barrier height similar to 0.65 eV and ideality factor similar to 1.15) and an improvement in the photo-response via application of a back-gate voltage. The back-gate bias tunes the effective Schottky barrier-height and also promotes the activation of photo-excited carriers, which leads to an enhancement in the thermionic emission process. (C) 2013 AIP Publishing LLC.