▎ 摘　　要

Graphene's advantages for sensor applications are offset by its low electric impedance and consequently low signal-to-noise ratio. We have improved the sensitivity of graphene based photosensors by integrating an energy filtering barrier as an amplifying element. The resulting graphene devices exhibit the highest reported photosensitivity (I-on/I-off similar to 4000, gain similar to 10 A/W) while retaining broad band detection and high speed response. In addition to this unprecedented photosensitivity, the proposed device structure renders the complete graphene photosensitive which enables large scale and flexible photodetectors. The presented approach represents a universal route to enhancing the performance of graphene sensors. (C) 2014 AIP Publishing LLC.