Epitaxial growth of GaN/AlN heterostructures

GaN/AlN heterostructures were grown on sapphire by reactive molecular beam epitaxy. The electrical and luminescent properties of the GaN have been studied. The GaN films on AlN have larger Hall mobilities and show more intense cathodoluminescence at the peak of 360 nm, compared with GaN films grown on sapphire. This suggests that the crystalline quality of the GaN is improved by making GaN/AlN heterostructures. The improvement is thought to result from the small mismatch of lattices and the small difference of thermal expansion coefficients between GaN and AlN.