The m-plane GaN (1 (1) over bar 00) epilayers have been grown on LiAlO2 (100) substrate by a two-step growth method using a metal-organic chemical vapor deposition (MOCVD) system. The GaN buffer layer is introduced to overcome the drawbacks of thermal instability of LiAlO2 (LAO), and to relieve the strains due to large thermal mismatch between LAO and GaN. The results of X-ray diffraction (XRD) and polarized Raman scattering spectra demonstrate that the GaN (1 (1) over bar 00) epilayer is single crystal as the growth temperature of the buffer layer is in the range of 850-950 degrees C. Moreover, it is found that the surface nitridation process on LAO substrate can result in the formation of the GaN poly-crystalline films, which is due to the unintentional growth of a thin layer of c-phase AlN on LAO surface. (c) 2006 Elsevier B.V. All rights reserved.