A study on the origin of emission of the annealed n-ZnO/p-GaN heterostructure LED

We report the effects of thermal annealing in air and N₂ ambient on the structural, optical, and electrical properties of zinc oxide (ZnO) films deposited on a p-GaN substrate. Also, we report on the fabrication and device characterization of heterojunction light-emitting diodes based on the n-ZnO/p-GaN systems. In the case of N₂ ambient, room-temperature electroluminescence (EL) in the violet region with peak wavelength 400 nm was observed under forward bias. In air ambient, EL spectrum consisted of a broad band from 400 nm to 700 nm due to the Ga-O mixed region formed interface between the ZnO and GaN layer.