OVERGROWTH OF INDIUM NITRIDE THIN-FILMS ON ALUMINUM NITRIDE NUCLEATED (00.1) SAPPHIRE BY REACTIVE MAGNETRON SPUTTERING

The growth and properties of thin films of InN on (00.1) sapphire and (00.1) sapphire nucleated by a 400 angstrom layer of AlN have been found to be radically different. The unnucleated InN films exhibit a mixed morphology (largely textured with lesser amounts of epitaxial grains), a monofunctional thickness dependence on sputtering time, uniformly low mobility and carrier concentration, and high resistivity. In contrast, the AlN-nucleated overlayers show only heteroepitaxial grains, a bifunctional dependence for the film thickness and surface roughness on sputtering time, higher mobility and carrier concentration, and lower resistivity-even in the limit of an InN overlayer on the order of 20-40 angstrom.