Pure ultraviolet light-emitting diode based on the p-NiO/i-NiO/n-GaN structure by magnetron sputtering

Abstract

Owing to its exceptional optical and electrical properties, NiO had gained considerable attention in the past few years. A broad spectrum of its applications was expected, particularly in light-emitting diodes (LEDs). NiO thin films were concocted using radio frequency (RF) magnetron sputtering, then this study systematically investigated the correlation between substrate temperature and the film properties. Exceptional NiO thin films with excellent characteristics were successfully obtained. Moreover, leveraging the optimized substrate temperature, we fabricated a p-NiO/i-NiO/n-GaN LED. With this configuration, p-NiO served as the hole transport layer, while i-NiO, obtained through rapid annealing, functioned as the electron barrier layer (EBL), thus avoiding the lattice mismatch between the hole transport layer and the EBL. It demonstrated pronounced diode rectification characteristics, manifesting an impressively low leakage current of 3.76 × 10−12 A. Furthermore, it achieved ultraviolet electroluminescence with a wavelength (∼375 nm) and a narrow FWHM (∼5 nm). Analysis revealed that the ultraviolet light emission in the diode predominantly originated from GaN-based near-band edge (NBE) luminescence.