Ion energy effects in AlN thin films grown on Si(111)

We report growth of epitaxial AlN thin films on Si(111) in a N2 glow discharge using a modified direct current magnetron sputter source in ultrahigh vacuum. Using such a device, we show that the plasma potential of the glow discharge can be varied over a wide range without significant changes in film growth rate and ion density. We show further that changing the plasma potential significantly and systematically affects the lattice strain and the mosaic structure of the AlN films. We show significant straining of the AlN lattice and suggest the occurrence of AlN lattice damage when N+2 ions acquire energies in excess of +50 eV.