Ab initiostudies of GaN epitaxial growth on SiC

Ab initio methods were used to investigate the initial stages of GaN epitaxial growth on (0001) 6H-SiC. Total energies of four types of interfaces were calculated. Polarity matching at the interface plays a fundamental role in determining the lower-energy structures, yielding strong binding for Si-N and C-Ga interfaces and very weak binding for Si-Ga and C-N. We therefore predict that Si-terminated substrates will produce ideally Ga-terminated films, whereas C-terminated substrates will produce ideally N-terminated films. This prediction suggests reinterpretation of recent experiments.