Cubic GaN films were grown onto Si(001), which was coated with an ultra-thin SiC buffer-layer, under Ga-rich or N-rich conditions. The SiC buffer layer (about 2.5nm-thick) was grown by carbonization of the Si(001) substrate. The GaN films which were prepared under Ga-rich conditions had a local atomically smooth surface. High-resolution transmission electron microscopy showed that the main defects in the GaN films were stacking faults which lay along the [1¯11] and [¯111] directions. Plan-view transmission electron microscopy showed that the dislocation density within grains was much lower than the overall dislocation density in the GaN films. The dislocation density within grains was equal to about 4 x 105/cm2. The use of X-ray diffraction and transmission electron microscopy showed that the GaN films had a mosaic structure. The full-width at half-maximum of the (002) X-ray diffraction peak of a 0.82μm-thick film was equal to 19min. This was one of the lowest values yet reported for cubic GaN films. The GaN films which were prepared under both Ga-rich and N-rich conditions exhibited a strong near-bandedge photoluminescence. Yellow-band luminescence and donor-acceptor recombination peaks were also detected when the GaN films contained more extended defects and/or native-point defects.

Growth of High-Quality Cubic GaN on Si(001) Coated with Ultra-Thin Flat SiC by Plasma-Assisted Molecular-Beam Epitaxy. D.Wang, Y.Hiroyama, M.Tamura, M.Ichikawa, S.Yoshida: Journal of Crystal Growth, 2000, 216[1-4], 44-50