ABSTRACT
Many crystal-growth technologies have been exploited for zinc oxide (ZnO) bulk crystal and thin film formations, leading to potential low cost for ZnO-based devices. ZnO nanowall networks with a honeycomb-like pattern on GaN/sapphire substrates were deposited by metalorganic chemical vapor deposition without using any metal catalysts. The influences of Diethyl-zinc flow rate on growth rate, surface morphology, and the optical properties of ZnO nanostructures on the GaN/sapphire have also been studied. Thus, the ZnO buffer layer can serve as the nucleation template to control the growth direction and the density of the zinc oxide nanorod arrays (ZNRs). The sixfold symmetry peaks, with an equivalent distance of 60°, confirm that the ZNRs have a homogeneous in-plane alignment on the oriented sapphire. The ZnO sacrificial layer can be effectively removed by proper acid solution during the separation of GaN from sapphire. The uniform GaN epilayer was successfully transferred from sapphire substrate to the copper template by electroplating and wet etching techniques.
