Ultrasensitive self-powered large area planar GaN UV-photodetector using reduced graphene oxide electrodes

A simplistic design of a self-powered UV-photodetector device based on hybrid reduced-graphene-oxide (r-GO)/gallium nitride (GaN) is demonstrated. Under zero bias, the fabricated hybrid photodetector shows a photosensivity of ∼85% while the ohmic contact GaN photodetector with an identical device structure exhibits only ∼5.3% photosensivity at 350 nm illumination (18 μW/cm2). The responsivity and detectivity of the hybrid device were found to be 1.54 mA/W and 1.45 × 1010 Jones (cm Hz½ W−1), respectively, at zero bias with fast response (60 ms), recovery time (267 ms), and excellent repeatability. Power density-dependent responsivity and detectivity revealed ultrasensitive behaviour under low light conditions. The source of the observed self-powered effect in the hybrid photodetector is attributed to the depletion region formed at the r-GO and GaN quasi-ohmic interface.