InGaN was grown on bare ZnO as well as Al2O3 deposited ZnO substrates by orgarrometallic vapor-phase epitaxy (OMVPE). The Al2O3 transition layer was grown by atomic layer deposition (ALD) in order to prevent Zn and O diffusion from the ZnO substrate and promote nitride growth. In-situ annealing of the transition layer was first performed right before InGaN growth in the chamber. High-resolution X-ray diffraction (HRXRD) measurements revealed that the thin Al2O3 layer after annealing was an effective transition layer for the InGaN films grown epitaxially on ZnO substrates. Optical transmission (OT) was performed to measure the bandgap energy using Sigmoidal fitting. Auger electron spectroscopy (AES) atomic depth profile shows a decrease in Zn in the InGaN layer. The diffusivity of Zn in the GaN layer grown on the bare ZnO substrate is about 5 x 10(-16) cm(2)/s. Moreover, (0002) InGaN layers were successfully grown on 20nm Al2O3/ZnO substrates after 10min annealing in a high-temperature furnace. (C) 2008 Published by Elsevier B.V.