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

Abstract

We report a simple AlO_x 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 × 10¹¹, which is much higher than that without passivation (7.3 × 10⁹ 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 τ_r/τ_f from 32/48 μs 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.