The evolution of preferred orientation and morphology of AlN films under various RF sputtering powers

Wurtzite AlN films were deposited by RF reactive sputtering technique in argon and nitrogen gas mixtures. The evolution of preferred orientation and morphology of AlN films with the change in RF power was studied. X-ray diffraction (XRD), field emission scanning electron microscopy and scanning probe microscopy were employed to characterize the deposited films. It was found that at low RF powers, the preferred orientation was not distinct: (1 0 0), (0 0 2) and (1 0 1) peaks appeared in the θ–2θ XRD pattern. Increasing the RF power to 500 W led to the development of (1 0 1) preferred orientation. The grain morphology of the deposited films changed from pebble-like to pyramid cones with the increase in RF power, leading to the roughening of the film surface.