Substrate effects on the structure and optical properties of GaN epitaxial films

Abstract

The phase composition and luminescent properties of GaN films grown by molecular beam epitaxy on (0001) sapphire and 6H-SiC substrates were studied. The films grown on SiC were found to consist only of the hexagonal phase and contain a lower concentration of impurities. Grains of cubic GaN, as well as donor and acceptor impurities, were found in the GaN film grown on sapphire. The formation of impurity centers is caused by the diffusion of oxygen and aluminum from the sapphire substrate during crystal growth.