  A simplistic design of a self-powered UV-photodetector device based on hybrid
r-GO/GaN is demonstrated. Under zero bias, the fabricated hybrid photodetector
shows a photosensivity of ~ 85% while ohmic contact GaN photodetector with
identical device structure exhibits only ~ 5.3% photosensivity at 350 nm
illumination (18 microWatt/cm^2). The responsivity and detectivity of the
hybrid device were found to be 1.54 mA/W and 1.45x10^10 Jones (cm Hz^(1/2)
W^(-1)), respectively at zero bias under 350 nm illumination (18
microWatt/cm^2) with fast response (60 ms), recovery time (267 ms) and
excellent repeatability. Power density-dependent responsivity & detectivity
revealed ultrasensitive behaviour under low light conditions. The source of
observed self-powered effect in hybrid photodetector is attributed to the
depletion region formed at the r-GO and GaN quasi-ohmic interface.
