Transmission electron microscopy study of semi-polar gallium nitride layer grown by hydride-chloride vapour-phase epitaxy on SiC/(001)Si heterostructure

The structure of 10-mu m-thick GaN layer grown by chloride vapour-phase epitaxy on 1.5-inch SiC/(001)Si templates has been investigated by transmission electron microscopy (TEM). The silicon carbide buffer layer has been fabricated by a new method of solid-phase synthesis. It was found that the GaN layer consists of oriented grains with size of tenths of a micron. The grains have wurtzite structure, and the {0001} GaN planes are oriented parallel to {111} Si, that is, the deviation of the axis c of GaN crystallite from the normal to the substrate is about 52 degrees. The revealed epitaxial relationship between substrate and most grains is (02 (2) over bar3) GaN parallel to(001)3C-Si parallel to(001) Si and [2 (1) over bar(1) over bar0] GaN parallel to[110]3C-SiC parallel to[110]Si. Some inclusions of sphalerite gallium nitride were also found in the epilayer.