Effect of Discharge Power on the Properties of GaN Thin Films on AlN-(002) Prepared by Magnetron Sputtering Deposition

Aluminum nitride (AlN) and gallium nitride (GaN) thin films were grown on silicon (Si) substrates using the conventional RF magnetron sputtering plasma deposition system. The growth rate of GaN increased as the deposition power of GaN increased. There was no crystalline peak of GaN observed, since there was no additional substrate heating. However, a highly crystalline AlN was observed and its peak orientations of (001) and (002) changed with the growth of GaN films at various RF discharge powers. The film's composition analysis using energy-dispersive X-ray spectroscopy (EDS) confirmed the existence of Ga and N in the thin films. AFM results showed that the surface roughness (Ra) of the GaN/AlN thin films increased with increased RF discharge power. FESEM images showed a good agreement with the AFM results, since the grain size increased as the surface roughness increased. The electrical properties studied using Hall effect showed that a low discharge power of GaN led to low resistance, high carrier concentration and low Hall mobility, which are good for devices in optoelectronic applications.