n-ZnO:Ga/p-GaN:Mg heterojunction light emitting diodes (LEDs) were fabricated at different growth temperatures and carrier concentrations in the n-type region. The effects of growth temperature and carrier concentration on the electrical and emission properties were investigated. The I-V and EL results showed that the improved device performances such as lower turn-on voltage and true ultraviolet emission were achieved with the insertion of a thin intrinsic layer between n-ZnO:Ga and p-GaN:Mg. This observation was attributed to a lowering of energy barriers for the supply of electrons and holes into intrinsic ZnO and recombination in the intrinsic ZnO with the absence of deep-level emission. (c) 2009 Elsevier B.V. All rights reserved.