Performance enhancement of graphene/Ge near-infrared photodetector by modulating the doping level of graphene
Min Gyu Kwon, Cihyun Kim, Kyoung Eun Chang, Tae Jin Yoo, Soyoung Kim, Hyeon Jun Hwang, Sanghan Lee, Byoung Hun Lee
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.