A graphene/GaAs near-infrared photodetector enabled by interfacial passivation with fast response and high sensitivity

We report a simple AlOx passivation approach to optimize the device performance of a bilayer graphene/gallium arsenide (BLG/GaAs) Schottky junction based near infrared photodetector (NIRPD). The as-fabricated NIRPD is highly sensitive to NIR illumination at zero bias voltage, with a detectivity of 2.88 x 10(11), which is much higher than that without passivation (7.3 x 10(9) cm Hz(1/2) W-1). The corresponding responsivity is 5 mA W-1. Additionally, the surface passivation can substantially increase both the response rate (rise/fall time tau(r)/tau(f) from 32/48 mu s to 320/380 ns), and lift time. It is expected that such a self-driven NIRPD with fast response and high detectivity will have great potential in the future optoelectronic devices.