Surface, structural and optical properties of AlN thin films grown on different face sapphire substrates by metalorganic chemical vapor deposition

AIN thin films grown on different face sapphire substrates by metalorganic chemical vapor deposition were studied comprehensively by a variety of techniques including high resolution X-ray diffraction (HR-XRD), X-ray photoelectron spectroscopy (XPS), Raman scattering (RS) and theoretical calculations. Our results showed that substrate orientation has a drastic effect on the initial growth of AIN. The AIN films showed dominant semipolar (101) orientation but with slightly weaker individual features. Optical reflectance measurements confirmed that AIN films grown on different surface orientation sapphire substrates at the same time possessed different film thicknesses. It was found that the surface orientation also has a major influence on the dislocation density, crystallite size, and surface oxygen incorporation. Raman line width exhibited good correlation with XPS measurements. The combined analyses led to a better understanding of the variation in the quality of the AIN films grown on different faces of sapphires.