Semipolar GaN on Si(001): the role of SiC buffer layer synthesized by method of substrate atom substitution


The new HVPE method has been developed for synthesis of semipolar gallium nitride on the substrate of Si(100) deviated on 2°-7° from the direction <100>. The method is based upon the formation of two buffer layers. First, the thin buffer layer (20-30nm) of SiC is formed, which is grown using the technology of substitution of part of silicon atoms in substrate of Si by carbon atoms, then the layer of AlN is deposited on this surface. It has been shown that the misorientation of Si substrate from the direction <100> and formation of the thin SiC layer permit to form the epitaxial layers of semipolar gallium nitride. The polar axis c of wurtzite crystal appeared to be deflected by 55° from the plane (100) of Si substrate. The obtained films of semipolar GaN had a half-width of the rocking curve FWHM of the order of ω~24'. The thickness of GaN films was in the limits of 10-14 microns. The structure GaN/AlN/SiC/Si(100) formed during this process exhibited a bending of a cylindrical form. The formation of this bending is explained by anisotropy of the deformation of semipolar GaN on silicon.