Single crystalline wurtzite a-plane GaN films were deposited on (3 0 2) LiAlO2 (LAO) substrates by metal organic chemical vapor deposition (MOCVD). The high resolution X-ray diffraction (HRXRD) results and selected area electron diffraction (SAED) patterns in cross section indicated that the crystallographic orientation between LAO and wurtzite GaN was: [3 0 2](LAO) parallel to [1 1 (2) over bar 0](GaN), [(2) over bar 0 3](LAO) parallel to [1 (1) over bar 0 0](GaN) and [0 1 0](LAO) parallel to [0 0 0 1](GaN), the mismatches were -4.43%, -2.86% and -0.31%, respectively. When the incident beam parallel (or perpendicular) to the [0 0 0 1] direction of GaN, the FWHM values of omega-scans reached the minimum (or maximum). The a-GaN film was found to have steps along [1 0 (1) over bar 0] direction and strips coalesced parallel to [0 0 0 1] direction. The PL intensity of the emission peak around 364 nm reduced a lot when the polarization changed from E perpendicular to c to E parallel to c. Crown Copyright (C) 2010 Published by Elsevier B. V. All rights reserved.