Highly-Rectifying Graphene/GaN Schottky Contact for Self-Powered UV Photodetector

In this study, we demonstrated self-powered fast-response ultraviolet (UV) detection based on a highly-rectifying graphene/GaN Schottky contact. The device was fabricated by mechanically transferring a monolayer graphene onto lightly-doped GaN and showed excellent Schottky behaviors, including a high rectification ratio (
$> 10^{8}$
), a close-to-unity ideality factor and a relatively high Schottky barrier height (1.01 eV). At zero bias, the graphene/GaN Schottky photodiodes exhibited a strong photovoltaic response to UV illumination with a competitively short rise/decay time of 221/
$546~\mu \text{s}$
. A trap-associated photoconductive mechanism started to dominate the device’s response when its bias went beyond −1 V, which could be identified from the suddenly increased responsivity and response time.