High quality GaN epitaxial layers are grown by modulated beam growth method. It is found that we can achieve a smaller X-ray diffraction full-width-half-maximum, a much stronger photoluminescence intensity and a much smaller vertical striations from the GaN epitaxial layers grown under Ga flux modulation method. These observations can all be attributed to the enhanced lateral growth of the modulated beam growth method. (C) 2004 Elsevier B.V. All rights reserved.