Effect of VI/II Gas Ratio on the Epitaxial Growth of ZnO Films by Metalorganic Chemical Vapor Deposition

Abstract

We report the effect of the VI/II ratio on the metalorganic chemical vapor deposition (MOCVD) growth of ZnO film. The surface of ZnO film becomes very smooth as the VI/II ratio increases. Atomic force microscopy measurement shows that ZnO films grown at a VI/II ratio of 25,000 have atomically flat terraces with a root-mean-square roughness of 0.2 nm. Low-temperature photoluminescence spectra also reveal a very sharp excitonic emission comprised of a neutral donor bound exciton emission and a free exciton emission with first and second longitudinal optical (LO) phonon replicas, indicating that the ZnO epilayer is of a high optical quality. (C) 2011 The Japan Society of Applied Physics