Publications by April S. Brown.

Papers Published

  1. Gon Namkoong and Doolittle, W.A. and Sangbeom Kang and Huang Sa and Brown, A.S. and Stock, S.R., Low temperature nitridation combined with high temperature buffer annealing for high quality GaN grown by plasma-assisted MBE, MRS Internet J. Nitride Semicond. Res. (USA), vol. 5S1 (2000) .
    (last updated on 2007/04/14)

    The effect of the initial nitridation of the sapphire substrate on the GaN crystal quality as a function of substrate temperature was studied. GaN layers were grown by plasma-assisted molecular beam epitaxy (MBE) on sapphire substrates nitridated at different substrate temperatures. A strong improvement in the GaN crystal quality was observed at 100°C nitridation temperature. Symmetric (0004) and asymmetric (10-5) full widths at half maximum (FWHM) of the X-ray rocking curves were 136 and 261 arcsec, respectively. This compares to an X-ray rocking curve full width at half maximum of 818 arcsec (0004) for conventional MBE buffer conditions. For our conventional buffer conditions, sapphire substrates were exposed to a N plasma at temperatures above 500°C for 10 min and then 25-50 nm buffers were deposited without annealing at high temperature. The low temperature nitridation also shows an enhancement of the lateral growth of the GaN, resulting in larger grain sizes. The largest grain size achieved was approximately 2.8 μm, while the average grain size was approximately 2.4 μm at 100°C nitridation temperature

    annealing;gallium compounds;grain size;III-V semiconductors;molecular beam epitaxial growth;nitridation;plasma deposition;wide band gap semiconductors;