Lattice-matching SiC substrates with GaN

Using arguments based on both electronic structure calculations and ionic radii, we propose that interfacial charges contribute to the ionic part of the lattice mismatch. As a result, the Si-terminated 6H–SiC(0001) surface is a superior substrate for GaN to the C-terminated surface. This viewpoint unifies (i) the Sasaki–Matsuoka proposal that substrate quality depends on electrical polarity and (ii) the conventional viewpoint that the best substrate has zero lattice mismatch with the film deposited on it.