MOLECULAR-BEAM EPITAXY GROWTH AND PROPERTIES OF GAN FILMS ON GAN SIC SUBSTRATES/

Two types of nitrogen plasma sources, an electron cyclotron resonance (ECR) plasma source and a radio frequency (rf) plasma source, were use d for the growth of GaN by molecular beam epitaxy (MBE). GaN film qual ity was correlated with the optical emission characteristics of each t ype of nitrogen plasma source employed. The best quality GaN films wer e those grown using the rf nitrogen plasma source. This source was fou nd to emit a much larger fraction of atomic nitrogen and 1st-positive series excited molecular nitrogen in contrast to the ECR plasma source which mainly produced 2nd-positive series excited molecular nitrogen and nitrogen molecular ions when operated under the same conditions. T he benefit of homoepitaxial growth of GaN, using metalorganic vapor ph ase epitaxy grown GaN layers on basal plane 6H-SiC, was seen by the ob servation of surface reconstructions before, during, and after GaN fil m growth by MBE. In addition, the MBE-grown GaN films exhibited remark ably intense photoluminescence dominated by a sharp band-edge peak at 3.409 eV having a full-width at half-maximum (FWHM) of 29.7 meV at roo m temperature. At lower temperatures, splitting of the near-edge excit ion peaks was observed. Double-crystal x-ray rocking curve measurement s of selected MBE-grown GaN films yielded (0002) diffraction peaks hav ing FWHMs as narrow as 156 arcsec. (C) 1995 American Vacuum Society.