Epitaxial growth of AlN and Al0.5Ca0.5N layers on aluminum nitride substrates

High-quality epitaxial A1N and AlxGa1-xN layers have been grown by organo-m etallic vapor-phase epitaxy (OMVPE) on single-crystal A1N substrates. Here we report the characterization of these layers on a-face substrates using R utherford backscattering/ion channeling spectroscopy (RBS), atomic force mi croscopy (AFM), double-crystal X-ray diffraction (XRD), and preliminary ele ctrical results. ion channeling along the [1 1 (2) over bar 0] axis gave a minimum yield of 1.5% for an AIN layer and 2.2% for an Al0.5Ga0.5N, indicat ing excellent crystal quality. A resistivity of 20 Omega cm and a mobility of 20 cm(2)/V s was measured in a Si-doped, 1 mu m-thick, epitaxial Al0.5Ga 0.5N grown epitaxially on the A1N substrates. (C) 2000 Elsevier Science B.V . All rights reserved.