Self-powered, visible-blind ultraviolet photodetector based on n-ZnO nanorods/i-MgO/p-GaN structure light-emitting diodes

Abstract

A self-powered, visible-blind ultraviolet (UV) photodetector based on an n-ZnO nanorod (NRs)/i-MgO/p-GaN structure, light-emitting diode assembled by p-GaN and solution-processed i-MgO/n-ZnO nanorods is reported. We found that the device with a MgO insertion layer under 365 nm UV illumination with the light density of 11.2 μw cm⁻² showed good UV photovoltaic properties with the open-circuit voltage and short-circuit current of 1.02 V and 510 nA, respectively. It showed good visible-blind UV photo-response characteristic with the ratio of photocurrent to dark current to as high as 8000 at 365 nm and the UV-visible responsivity ratio (R_{350 nm}/R_{500 nm}) reached 34.5. Moreover, the responsivity of the device with MgO insertion layer was 5 times greater than that of a n-ZnO NRs/p-GaN heterojunction at 254 nm. Furthermore, the n-ZnO NRs/i-MgO/p-GaN heterojunction can display electroluminescence characteristic at a forward bias, which was analyzed by the peak-deconvolution with Gaussian functions.