Performance enhancement of graphene/Ge near-infrared photodetector by modulating the doping level of graphene

Abstract

In this paper, we improved the performance of a near-infrared graphene/germanium heterojunction photodetector at atmospheric pressure and at room temperature. We applied graphene with p-type chemical doping (doping chemical: polyacrylic acid) to lower the graphene Fermi level and increase the Schottky barrier formed at the junction with Ge. The responsivity at 1550 nm is improved from 0.87 to 1.27 A/W after the doping process. At the same time, the dark current is reduced by 20 times and the detectivity of the optimized device is improved to 9.6 × 109 Jones, which is 540% improvement compared to the undoped graphene device. With the result of improving performance through this simple process, it will be able to contribute to the fabrication of highly reactive graphene/semiconductor based photodetectors and the development of near-infrared sensors.