▎ 摘　　要

Graphene-based photodetectors have recently received much attention for their potential to detect weak signals and their short response time, both of which are crucial in applications such as optical positioning, remote sensing, and biomedical imaging. However, existing devices for detecting weak signals are limited by the current photogating mechanism, so the price for achieving ultrahigh sensitivity is to sacrifice response time. In this work, we bridge the gap between ultrafast response and ultrahigh sensitivity by employing a graphene/SiO2/lightly doped Si architecture with an interfacial gating mechanism. Our device is capable of detecting a signal of < 1 nW (with a responsivity of similar to 1000 AW(-1)), and the spectral response extends from the visible to near-IR. More important, the photoresponse time of our device has been pushed to similar to 400 ns. The current device structure does not need a complicated fabrication process and is fully compatible with silicon technology. This work not only will open up a route to graphene-based high-performance optoelectronic devices but also has great potential for ultrafast weak signal detection. (C) 2016 Optical Society of America