Growth of cubic GaN by phosphorus-mediated molecular beam epitaxy

GaN epitaxial layers were grown on wurtzite GaN-on-sapphire substrates by phosphorus-mediated molecular beam epitaxy at different growth temperatures. The films were characterized by reflection high-energy electron diffraction, x-ray diffraction, energy-dispersive x-ray spectroscopy, and transmission electron microscopy. The growth temperature plays an important role in P incorporation as well as GaN crystallization. The introduction of the phosphorus flux during growth leads to a preferential growth of zinc-blende epilayers. The phase transition during growth is attributed to the modification of surface stoichiometry by the impinging phosphorus flux.