Inversion domains in GaN layers grown on (111) silicon by molecular-beam epitaxy

Transmission electron microscopy is used to investigate GaN layers grown on Si(111) substrates by plasma-assisted molecular-beam epitaxy. These layers were grown on top of different AlN buffer layers. Multiple-beam dark-field techniques applied to both cross-sectional and planar-view samples show th e presence of inversion domains. These domains grow directly from the inter face with the Si(111) substrate. Such observations are related, as in the c ase of growth on sapphire, to the symmetry difference between wurtzite and diamond. (C) 2001 American Institute of Physics.