Ultrasensitive and fast photoresponse in graphene/silicon-on-insulator hybrid structure by manipulating the photogating effect

The hybrid structures of graphene with semiconductor materials based on photogating effect have attracted extensive interest in recent years due to the ultrahigh responsivity. However, the responsivity (or gain) was increased at the expense of response time. In this paper, we devise a mechanism which can obtain an enhanced responsivity and fast response time simultaneously by manipulating the photogating effect (MPE). This concept is demonstrated by using a graphene/silicon-on-insulator (GSOI) hybrid structure. An ultrahigh responsivity of more than 107 A/W and a fast response time of 90 µs were obtained. The specific detectivity D* was measured to be 1.46 ⨯ 1013 Jones at a wavelength of 532 nm. The Silvaco TCAD modeling was carried out to explain the manipulation effect, which was further verified by the GSOI devices with different doping levels of graphene in the experiment. The proposed mechanism provides excellent guidance for modulating carrier distribution and transport, representing a new route to improve the performance of graphene/semiconductor hybrid photodetectors.