Accession Number : ADA311737

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

Descriptive Note : Quarterly Technical rept. 1 Apr-30 Jun 96,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

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

PDF Url : ADA311737

Report Date : 30 JUN 1996

Pagination or Media Count : 20

Abstract : The ionicity of the III-V nitrides requires going beyond the original approach of the multicenter tight-binding method based on the Harris functional for the total energy. By including a self-consistent treatment of the electronic charge density in the formalism, a significant improvement of the static and dynamical properties calculated for GaN and AlN can be achieved. The extension of the generalized ab initio tight-binding scheme to slab calculations makes it necessary, to optimize the updating procedure for the output charge density in the self-consistent cycle, so that convergence is achieved already after a small number of iterations. The assembly of a supersonic molecular beam source has been completed. Beam intensities as a function of flow through the nozzle have been determined to be in the range of 2x 10(exp 19) atoms/srrad/s. An arc-heated nozzle for the production of atomic N beams has been designed and is being fabricated. The selected energy epitaxial deposition (SEED)/x-ray photoelectron spectroscopy (XPS) facility is complete. Exposure of oxygen-passivated Al and sapphire(0001) at 300 deg C to a remote nitrogen plasma containing primarily electronically excited molecular N2 species results in partial nitridation of the surfaces, as evidenced by Auger electron spectroscopy (AES) and XPS. Determination of the alignment and energy distribution of the ion beams of two colutron units is underway.

Descriptors :   *THIN FILMS, *EPITAXIAL GROWTH, *ELECTRON MICROSCOPY, *DEPOSITION, *LOW ENERGY, *ALUMINUM, *GALLIUM, *SILICON CARBIDES, OUTPUT, SOURCES, COMPUTATIONS, PRODUCTION, DYNAMICS, PLASMAS(PHYSICS), ELECTRON DENSITY, INTENSITY, ION BEAMS, ATOMS, CYCLES, MOLECULAR BEAMS, NITRIDES, NITROGEN, ALIGNMENT, CONSISTENCY, SAPPHIRE, ELECTRON ENERGY, X RAY PHOTOELECTRON SPECTROSCOPY, NOZZLES, GROUP III COMPOUNDS, GROUP IV COMPOUNDS, GROUP V COMPOUNDS, CHARGE DENSITY, SUPERSONIC CHARACTERISTICS, STATICS, ITERATIONS, AUGER ELECTRON SPECTROSCOPY, ATOMIC BEAMS, ARC HEATING.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Crystallography
      Optics
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE