Epitaxiall growth of cubic and hexagonal GaN films on GaAs(001) substratesby MBE

GaN films of about 300 nm were grown on GaAs(001) substrates by molecular b eam epitaxy (MBE). X-ray double-crystal diffraction and room-temperature ph otoluminescence measurements show that the films grown on nitridized GaAs n ucleation layer are pure cubic GaN while the films grown on nitridized AlAs nucleation layer are pure hexagonal GaN. The present study shows that the phase of GaN samples grown on GaAs substrates can be controlled using diffe rent nucleation layers.