Edge-State-Enhanced Ultrahigh Photoresponsivity of Graphene Nanosheet-Embedded Carbon Film/Silicon Heterojunction

Lacking of electron trapping centers hinders the development of plane graphene for sensitive photodetection. An ultrasensitive graphene nanosheet-embedded carbon (GNEC) film/silicon photodetector is proposed by introducing high-density edges of standing structured graphene nanosheets (GNs). The GNEC film is prepared to contain a large amount of vertically grown GNs. The high-density edges are able to trap itinerate electrons to tune the Fermi level of GNs in the growing process and to capture the photoexcited electrons to reduce the electron-hole recombination rate in the photovoltaic process. An ultrahigh responsivity of 61.52 A W-1 of GNEC film/Si photodetector is achieved, approximate to 20 times of graphene/Si photovoltaic detectors. A high specific detectivity of 3.05 x 10(14) Jones (approximately two orders improved) is obtained at bias-free mode. This work sheds light on the edge engineering of 2D materials in the third dimension in order for enhancing photoelectronic performance.