Hardness, elastic modulus and structure of indium nitride thin films on AlN-nucleated sapphire substrates

The structural properties of epitaxial indium nitride thin films were characterized and related to the mechanical properties as measured by nanoindentation. The seven epitaxial InN films examined were deposited over the temperature range 200-400 degrees C by reactive magnetron sputtering on (00.1) sapphire substrates buffered with a thin AlN layer. The hardness, surface texture and crystal quality of the InN films were functions of the deposition temperature, with the maximum hardness (11.2 GPa), the smoothest surface, the minimum c-lattice constant (0.5708 nm), and the minimum (00.4) X-ray rocking curve width (0.6 degrees) all occurring at the deposition temperature of 350 degrees C. The crystal quality and the hardness of the InN films degraded at both higher and lower temperatures.