The effect of growth rate in the early stage of high temperature (HT) GaN layer growth on the quality of GaN by MOCVD has been investigated. The properties of GaN layers were measured by double crystal Xray diffraction (DCXRD), Hall method, photoluminescence, and atomic force microscopy, respectively. The results reveal that the quality of GaN layers is influenced by the growth rate of HT GaN growth in the early stage. The properties of GaN layers are obviously improved by decreasing the growth rate in the early stage of HT GaN growth properly. However, when the growth rate decreases to some extent, the quality of GaN layer deteriorates instead. The reasons behind this phenomenon were discussed. (c) 2008 Elsevier B.V. All rights reserved.