Characterization of annealing effect on the surface, interface and bulk of AlN grown on SiC

AlN films are synthesized by using hollow cathode discharge sputtering technique. Typical transverse optical and longitudinal optical modes in Raman spectrum of AlN sample are observed at the gas pressures of 200 Pa and 500 Pa discharge sputtering deposition, respectively. The results show evidence that the structures of the films can be controlled by variations of discharge gas pressures. High discharge electric field used for sputtering deposition of AlN film causes transverse optical mode in Raman spectrum shift toward relatively low wave numbers. After annealing at 600 °C for 5 h in air at atmospheric pressure, the profile of the Raman longitudinal optical band appears narrow, probably indicating better quality of the film.