In this study, cubic GaN epitaxial films are grown on a 2 degrees miscut GaAs(0 0 1) substrate by hydride vapor-phase epitaxy reactor with a low-temperature GaN buffer layer before the growth of the GaN epitaxy him. X-ray diffraction spectra reveal that the epitaxial film contains most of the zinc-blende GaN with a few percent of wurtzite GaN also embedded in the film. The crystalline coherence length of the zinc-blende GaN is 30 nm and the rocking curve width is 4.8 degrees. In addition, in the phi-scan, are found, two small peaks in two-fold symmetry which did not correspond to the substrate orientation relation of GaN(0 0 1)parallel to GaAs(0 0 1) and GaN(0 1 0)parallel to GaAs(0 1 0). These two small peaks were grown along the miscut direction of the substrate. Photoluminescence spectra confirm that a cubic GaN edge emission peak appears at 388 nm as well as a strong yellow emission at 500 nm region. (C) 1999 Elsevier Science B.V. All rights reserved.