High‐Responsivity Near‐Infrared Photodetector Using Gate‐Modulated Graphene/Germanium Schottky Junction

Abstract A high‐responsivity near‐infrared photodetector is demonstrated using a transparent ZnO top gate‐modulated graphene/Ge Schottky junction. The responsivity of a graphene/Ge junction photodetector characterized with a scanning photocurrent microscopy system is improved to 0.75 A W −1 . This result is 5 to 35 times higher than the previously reported graphene/Ge photodetectors that did not use gate modulation. The detectivity is also improved to 2.53 × 10 9 cm Hz 1/2 W −1 at V g = −10 V from 0.43 × 10 9 cm Hz 1/2 W −1 at V g = 0 V. The performance of this gate‐modulated graphene/Ge Schottky junction base infrared (IR) detector is comparable to a commercially available IR photodetector, but the fabrication process is much simpler and compatible with glass or flexible substrates.