Enhanced performance of graphene/GaAs nanowire photoelectric conversion devices by improving the Schottky barrier height

Abstract

Graphene/nanowire (NW) Schottky junctions have shown great potential in nanoscale photoelectric conversion devices. However, due to the relatively small difference in work functions, the graphene/NW junctions typically have a low Schottky barrier height, which dramatically limits the performance of devices. Here, the authors demonstrate that the performance of graphene/GaAs nanowire photoelectric conversion devices could be significantly enhanced by improving the Schottky barrier height through chemical doping of graphene. After nitric acid treatment, the Schottky barrier height is increased from 0.29 to 0.35 eV, leading to a much lower dark current, larger detectivity, higher on/off ratio, and higher speed due to the enhanced built-in electric field. The open-circuit voltage of the graphene/GaAs nanowire solar cell is significantly increased after doping due to the enhanced Schottky barrier height, yielding a remarkable conversion efficiency of 15.88%. This work provides an effective way for improving the graphene/nanowire junction properties and enabling high performance photoelectric conversion devices.