Growth and Characterization of Epitaxial ZnO Nanowall Networks Using Metal Organic Chemical Vapor Deposition

Abstract

ZnO nanowall networks with a honeycomblike pattern on GaN/sapphire substrates were deposited by metalorganic chemical vapor deposition (MOCVD) without using any metal catalysts. The effects of growth temperature and VI/II ratio on the surface morphology and optical properties of ZnO nanowall networks were investigated by scanning electron microscopy (SEM) and photoluminescence (PL) analysis. The SEM image obtained shows a prominent nanowall-network structure when the growth temperature is higher than 550 °C. The wall width and network size of ZnO nanowall-network structures grown by MOCVD were found to change depending on DEZn flow rate. The surface morphology of ZnO structures was observed at different time intervals from 10 to 40 min to investigate the formation mechanism of ZnO nanowall networks. The room-temperature PL measurement of ZnO nanostructures grown on GaN/sapphire substrates shows high-intensity ultraviolet peaks at 385 nm without any "green peak". The PL spectrum suggests that the quantum confinement effects are caused by the nanostructure of ZnO.