Key issues for the growth of high quality (Al,Ga)N/GaN and GaN/(In,Ga)N heterostructures on SiC(0 0 0 1) by molecular beam epitaxy

We identify and discuss the essential strategies for the growth of (Al,Ga)N/GaN and GaN/(In,Ga)N heterostructures on SiC(0 0 0 1) by both plasma-assisted and reactive molecular beam epitaxy. Substrate preparation, nucleation, and growth conditions are optimized for simultaneously satisfying the requirement of a high structural, morphological, optical and electrical quality. The results demonstrate that molecular beam epitaxy is a competitive technique for the growth of group III-nitrides.