Highly responsive near‐infrared photodetector with low dark current using graphene/germanium Schottky junction with Al 2 O 3 interfacial layer

The performance of a graphene/Ge Schottky junction near‐infrared photodetector is significantly enhanced by inserting a thin Al 2 O 3 interfacial layer between graphene and Ge. Dark current is reduced by two orders of magnitudes, and the specific detectivity is improved to 1.9 × 10 10 cm ⋅ Hz 1/2 W −1 . The responsivity is improved to 1.2 AW −1 with an interfacial layer from 0.5 AW −1 of the reference devices. The normalized photo‐to‐dark current ratio is improved to 4.3 × 10 7 W −1 at a wavelength of 1550 nm, which is 10–100 times higher than those of other Ge photodetectors.