Ultra-thin GaN nanostructures based self-powered ultraviolet photodetector via non-homogeneous Au-GaN interfaces

Abstract

We report the fabrication of ultra-thin GaN (0002) nanostructures based self-powered ultraviolet photodetector on Si (111) substrate. Non-homogeneous GaN nano-islands were perceived on Si surface with a thickness of ~30 nm and an average distribution density of 2 × 1010 cm−2. Even at low dimension GaN-nanostructures film, the capability of ultraviolet detection of fabricated photodetector added novelty to this work, where performance parameters such as photosensitivity (~102), detectivity (~109 Jones), responsivity (1.76 mA/W) and noise equivalent power (3.5 × 10−11 WHz−1/2) under self-powered mode were observed. The transient photo-response measurement revealed a rapid rise and decay time constants of ~18 ms and ~27 ms respectively. Under varying optical power (1 mW–13 mW), the GaN photodetector displayed significant enhancement in photocurrent with increasing optical power. The performance of the fabricated detector has been also analysed under varying bias voltage where it revealed significantly enhanced responsivity (23 fold) and detectivity (~1000 fold). Such nanostructured self-powered GaN-based ultraviolet photodetector paves the way towards the fabrication of energy-efficient optoelectronic devices.