▎ 摘　　要

Graphene photodetectors grown by chemical vapor deposition are fabricated for unfocused laser and white light sensing. The unfocused light enlarges the illuminated graphene area and mimics the real-life sensing conditions, yielding a responsivity of 104 mA/W at room temperature without enhancing absorbance by waveguide and plasmonics. The devices are based on positive photoconductivity from the electron-hole photocarrier pairs and the bolometric-effect-induced negative photoconductivity. The buried off-center local gate induces a net internal potential in the graphene. The relative strength of the two photoconductivities depends on the gate voltage. The technology is scalable, which is a step ahead toward real applications. (C) 2016 Optical Society of America