The sublimation epitaxial growth process was studied, and the structural quality of the grown layers was found to be improved, as compared with the substrate, due mainly to a decreased domain structure misorientation. Optical microscopy showed that the as-grown surfaces were free from the typical defects of SiC epitaxy, whereas atomic force microscopy revealed macro-steps. As a possible technique for producing high-quality 4H-SiC, sublimation epitaxy was applied to substrates which contained a layer that had been grown via liquid-phase epitaxy; a growth process for closing micro-pipes in the initial substrate. It was found that, in spite of the initial surface roughness of the liquid-phase epitaxial layer, the surface morphology of the sublimation-grown epilayers remained smooth and structural quality improvement was maintained. This did not occur if the initial surfaces were too rough.

Structural Improvement in Sublimation Epitaxy of 4H-SiC. M.Syväjärvi, R.Yakimova, H.Jacobsson, E.Janzén: Journal of Applied Physics, 2000, 88[3], 1407-11