Published online by Cambridge University Press: 31 January 2011
Thin films of wurtzitic AlN have been deposited by molecular-beam epitaxy onto (001) oriented MgO substrates. The films are epitactic and align with the and the
, as evidenced by transmission electron microscopy. This configuration, which matches a close-packed direction of the film and substrate, allows for growth of two symmetrically equivalent orientation variants of the AlN film. These variants are distinguished by a 90° rotation about the
direction that is normal to the substrate surface. Each variant also aligns the
and the
to within 5° of being parallel to the (200)MgO. The microstructure of the AlN films and origins of these novel alignments are discussed.