The GaN epitaxial layer was grown by hydride vapor-phase epitaxy (HVPE) on Si(1 1 1) substrate with AlN buffer layer. Structural and optical properties of GaN layer were characterized by high-resolution X-ray diffraction, transmission electron microscopy (TEM) and photoluminescence (PL) measurements. TEM images showed that the dislocation density in the GaN layer was similar to 9 x 10(9)/cm(2). The full-width at half-maximum (FWHM) values of the X-ray rocking curve for GaN (0 0 0 2) and (1 0 1 2) were 13.7 and 35.3 arcmin, respectively. The PL spectra of our sample exhibited a predominant band-edge emission of the wurzite GaN epilayer near 3.36 eV with FWHM = 64.2 meV at 50 K and 76.5 meV at room temperature. The experimental data indicated that the HVPE-grown GaN layers exhibited superior quality compared to GaN layers grown by metal organic chemical vapor deposition in prior literatures. (c) 2005 Elsevier B.V. All rights reserved.