AlN films prepared on 6H–SiC substrates under various sputtering pressures by RF reactive magnetron sputtering

In this paper, we studied the growth of AlN films on 6H–SiC substrates under various sputtering pressures by RF reactive magnetron sputtering at low deposition temperature (300 °C). The composition, chemical structure and oxygen impurity of the deposited films were investigated by X-ray photoelectron spectroscopy (XPS). It is suggested that the Al/N ratio of the high purity film is 1.13:1 which is very close to the stoichiometric value (1:1), and a few oxygen impurities exist in the grain boundaries in the form of Alsingle bondO bonding. The two-dimensional X-ray diffraction (2D-XRD) was used to study the crystal structure of the deposited films. 2D-XRD patterns indicate that a low sputtering pressure favor the growth of AlN film with c-axis oriented, and a highly c-axis oriented AlN film resemble single crystal structure was prepared at the sputtering pressure of 0.3 Pa. Surface morphology of the deposited films were investigated by SEM and AFM. The images show that the surface morphology of the films with (0 0 0 2) preferred orientation present a pebble-like structure, and the grain size and surface roughness of the films decrease with increasing the sputtering pressure.