Micro-structural and optical properties of reactive magnetron sputtered Aluminum Nitride (AlN) nanostructured films

The materials properties of nanostructured Aluminum nitride (AlN) film were studied. AlN films of about 2 μm thick were deposited on Si (100) and glass substrates by means of direct current reactive magnetron sputtering in an Ar + N2 gas mixture. A hexagonal wurtzite structure with a predominant peak was observed along the (002) plane from XRD analysis. Photoelectron peaks from Al, N, O, C and Ar are detected on the surface of the film. Microstructure and topography were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The images showed the presence of continuously covered pebble like spherical grains on the surface. AlN films are transparent in the visible region with an average transmittance of 60%. The optical absorption studies give direct band gap equal to 5.2 eV.