Accession Number : ADA332413

Title :   Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films

Descriptive Note : Quarterly technical rept. 1 Jul-30 Sep 97

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Davis, R. F. ; Lamb, H. H. ; Tsong, I. S. T.

PDF Url : ADA332413

Report Date : SEP 1997

Pagination or Media Count : 40

Abstract : The kinematic conditions under which III-Nitrides films can be grown were determined using efficient local-orbital molecular-dynamics simulations. Reaction paths for the impact of ammonia molecules on the cation- and anion-terminated surfaces of GaN and AlN were also determined. In situ growth experiments of GaN on 6H-SiC(0001) substrates were conducted in the low-energy electron microscope (LEEM). Initial nucleation at the steps and subsequent growth across the terraces were observed. The LEED patterns indicated three-dimensional crystal growth with pronounced formation of facets. Such growth behavior occurred irrespective of the method of deposition. A seeded beam source chamber has been interfaced with a UHV deposition chamber. Films of A1N have been grown with this system. Smooth, homoepitaxial GaN films were grown using an effusive Ga source and an NH3-seeded supersonic molecular beam. A small Ga flux-substrate temperature window was found that allows for two-dimensional homoepitaxial growth under MBE-like conditions (TS=730 deg C, pb-2x10(exp -6) Torr). Mass-analyzed Ga(+),N2(+) and N(+) ions at approx. 20 eV with a small energy spread of tilde 1 eV at FWHM were produced via two Colutron units with deceleration lenses. Ion beams of N2(+) and N(+) were used to perform nitridation of Si(100) surfaces. Subsequent SIMS depth profiles indicated the presence of nitride layers on the Si(100) substrates. Codeposition of Ga and N on Si(111) and Si(100) substrates was conducted with the Ga(+) and N2(+) ion beams. SIMS depth profiles showed the presence of both Ga and N on the Si substrate surfaces suggesting the formation of a GaN layer. A second generation arc-heated jet source and an inexpensive corona discharge source were designed, fabricated and characterized. Preliminary optical spectra of theses sources were obtained and evaluated. An improved optical and elec

Descriptors :   *ALUMINUM COMPOUNDS, *THIN FILMS, *EPITAXIAL GROWTH, *NITRIDES, *ELECTRON MICROSCOPY, *LOW ENERGY, *SILICON CARBIDES, *GALLIUM COMPOUNDS, KINEMATICS, ELECTRONICS, CATIONS, OPTICS, MOLECULES, PATHS, SUBSTRATES, ION BEAMS, NUCLEATION, AMMONIA, DEPOSITION, CHEMICAL REACTIONS, GROUP III COMPOUNDS, CRYSTAL GROWTH, ANIONS, CRYSTALLOGRAPHY, ULTRAHIGH VACUUM, ELECTRICAL CORONA, ARC HEATING, MOLECULAR BEAM EPITAXY.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrooptical and Optoelectronic Devices
      Atomic and Molecular Physics and Spectroscopy
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE