Nearly amorphous to epitaxial growth of aluminum nitride films

Aluminum nitride (AlN) films were prepared by using reactive magnetron sputtering. Substrate temperature Ts, radio frequency power Pw, and substrate materials (including silicon, platinum coated silicon and sapphire) were varied as deposition parameters. Ts-Pw diagrams were worked out to illustrate how the film structure can be controlled to vary over a broad range covering nearly amorphous, polycrystalline, texture, and epitaxial structures. Increases in Ts and Pw have the effects of increasing the thermal energy of the species on the substrate surface, and enhancing the crystallization of the deposits and preferential orientation of grains. Sapphire substrate has better lattice matching with the AlN structure, which further facilitates the epitaxial growth of the AlN structure