Accession Number : ADA307311

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

Descriptive Note : Quarterly technical rept. 1 Jan-31 Mar 96,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

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

PDF Url : ADA307311

Report Date : MAR 1996

Pagination or Media Count : 24

Abstract : Gallium nitride has been deposited using hyperthermal and thermal beams of NH3 and triethylgallium seeded in He and Ar supersonic jets, respectively. The V/III ratio = 344. The growth rates were lower and the film character poor when Ar was used as the carrier. The films deposited using He were continuous and adherent and exhibited a characteristic wavy surface morphology. The major components of a new SEED facility have been received and verified. In research regarding direct ion beam deposition of GaN, it has been determined that ion current densities for N2(+) at 10 and 20 eV using a Colutron ion beam unit are an order of magnitude higher at the latter energy; the peak current density at 20 eV is approx. 200 nA /sq cm, which corresponds to approx. 10(exp -3) ML/sec deposition rate. The time of flight technique has been employed to characterize the intensity, energy, energy spread, and composition of a 10% NH3 seeded He supersonic beam between 200 and 600 deg C and as a function of stagnation pressure and beam diameter. Clustering played a major role in determining the mean kinetic energy, as well as the energy spread. Initial density-functional calculations focused on the construction of various pseudopotentials for Ga involving the core states have been made to determine a proper treatment of the Ga d shell.

Descriptors :   *THIN FILMS, *EPITAXIAL GROWTH, *ELECTRON MICROSCOPY, *DEPOSITION, *ELECTRON ENERGY, *LOW ENERGY, *ALUMINUM, *GALLIUM, *SILICON CARBIDES, MORPHOLOGY, ENERGY, FILMS, CURRENT DENSITY, ION BEAMS, NITRIDES, PEAK POWER, SURFACE PROPERTIES, KINETIC ENERGY, ELECTRIC CURRENT, SUPERSONIC CHARACTERISTICS, STAGNATION PRESSURE, ION DENSITY, IONIC CURRENT.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Fluid Mechanics
      Optics
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE