GaN epilayers were grown on Si(111) at 980 degrees C by a hydride vapor phase epitaxy (HVPE) method. AlxGa1-xN with thickness of similar to 900 nm was inserted between Si substrate and GaN epilayer to act as a buffer layer. The investigation of the influence of different V/III ratios on GaN epilayer qualities reveals that high GaCl flow rate can increase the growth rate and improve the surface morphologies of GaN epilayers while high NH3 flow rate is not good for reducing dislocations in GaN epilayers, which can be proved from the analysis of X-ray diffraction rocking curve (XRC), cross-sectional image of scanning electron microscopy (SEM) and image of atomic force microscopy (AFM). Finally, 1.22 mu m GaN epilayer without cracks was successfully obtained with a three-step growth method. The surface roughness average (Ra) was measured to be 1.45 nm and the FWHM of GaN(0002) was 599 arcsec. The measured lattice constants for GaN epilayer were a=3.210 angstrom and c=5.177 angstrom, indicating the in-plane tensile stress and out-of-plane compressive stress of GaN epilayer. (C) 2012 Elsevier B.V. All rights reserved.