Ultraviolet electroluminescence from n-ZnO/NiO/p-GaN light-emitting diode fabricated by MOCVD

Ultraviolet light-emitting diodes (LED) based on n-ZnO/NiO/p-GaN were realized by metal-organic chemical vapor deposition (MOCVD). The devices exhibited diode-like rectifying current-voltage characteristics and had a turn-on voltage of 7.5 V. High quality NiO film as an electron blocking layer inserted between the ZnO and GaN films showed high resistance state with preferred [1 1 1] orientation, which produced a larger ZnO/NiO conduction band offset of 2.93 eV than that of ZnO/GaN (0.15 eV). The electroluminescence spectra of the n-ZnO/i-NiO/p-GaN heterostructure demonstrated that electrons were effectively confined in the ZnO active region, and thus leading to the enhancement of the excitonic emission from the ZnO side. (C) 2014 Elsevier B.V. All rights reserved.