Effect of an Al 2O 3 transition layer on InGaN on ZnO substrates by organometallic vapor-phase epitaxy

Abstract

InGaN was grown on bare ZnO as well as Al 2O 3 deposited ZnO substrates by organometallic vapor-phase epitaxy (OMVPE). The Al 2O 3 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 Al 2O 3 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 5×10 −16 cm 2/s. Moreover, (0 0 0 2) InGaN layers were successfully grown on 20 nm Al 2O 3/ZnO substrates after 10 min annealing in a high-temperature furnace.