Self-organization of the composition of Al$_{x}$Ga$_{1-x}$N films grown on hybrid SiC/Si substrates

Using spectral ellipsometry, Raman spectroscopy, and scanning microscopy with an X-ray spectrometer (EDS), the phenomenon of self-organized change in the composition of Al$_{x}$Ga$_{1-x}$N epitaxial layers during their growth by chloride-hydride epitaxy (EDX) on SiC/Si(111) hybrid substrates was revealed. It was found that during the growth of Al$_{x}$Ga$_{1-x}$N layers with a low, about 11–24% Al content, interlayers (domains) appear, consisting of AlGaN stoichiometric composition. A qualitative model has been proposed, according to which self-organization in composition arises due to the effect of two processes on the growth kinetics of the Al$_{x}$Ga$_{1-x}$N film. The first process is associated with the competition of two chemical reactions proceeding at different rates. One of these reactions is the AlN formation reaction; the second is the reaction of GaN formation. The second process, closely related to the first, is the appearance of elastic compressive and tensile stresses during the growth of Al$_{x}$Ga$_{1-x}$N films by the CGE method on SiC/Si(111). Both processes influence each other, which leads to a complex pattern of aperiodic changes in the composition over the thickness of the film layer.