Accession Number : ADA303665

Title :   Pseudomorphic Semiconducting Heterostructures from Combinations of AlN, GaN and Selected SiC Polytypes. Theoretical Advancement and its Coordination with Experimental Studies of Nucleation, Growth, Characterization and Device Development.

Descriptive Note : Final rept. 1 Jul-31 Dec 95,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Davis, Robert F. ; Kern, R. S. ; Linthicum, K. ; Perry, W.

PDF Url : ADA303665

Report Date : DEC 1995

Pagination or Media Count : 72

Abstract : The effect of the C2H4/Si2H6 gas flow rate ratios on the growth mode of SiC thin films via gas source (GS) MBE was investigated via cross-sectional TEM. Step flow and step bunching occurred at the outset of deposition under any ratio. Subsequent deposition resulted in step flow and continued growth of 6H-SiC films or formation and coalescence of 3C-SiC islands using the gas flow ratio of one or C2H4-rich ratios, respectively. The growth of the 6H regions occurred via layer-by-layer mode; the nucleation and growth of the 3C regions occurred primarily on terraces between closely spaced steps. Double positioning boundaries were observed at the intersections of these latter regions. Using similar growth and characterization techniques, essentially atomically flat surfaces of AlN were grown on the surfaces of on-axis 6H-SiC wafers; coalesced island-like features separated by anti-phase boundaries at SiC steps were observed on the vicinal surfaces. The activated N was derived from an ECR plasma source. Pseudomorphic multilayer heterostructures containing 6H- and 3C-SiC separated by 2H-AlN as well as films of (AN)(x)(SiC)(1 -x) solid solutions have been grown. Metal-insulator-semiconductor diodes (Al/AlN/6H-SiC) have also been fabricated using (GSMBE and several insulator (AlN) thicknesses and subsequently characterized using C-V measurements between 10 kHz and 1 MHz. The diodes could be accumulated and depleted over the entire frequency range studied with no frequency dispersion observed. Inversion was not achieved at room temperature. Thin layers (<1000A) of AlN exhibited moderate leakage currents; these currents were reduced in thicker layers. The dielectric constant was calculated and matched well with other measured values. jg p3

Descriptors :   *SEMICONDUCTORS, *NUCLEATION, *NITRIDES, *ALUMINUM, *GALLIUM, *SILICON CARBIDES, DIODES, FREQUENCY, DEPLETION, SOURCES, MEASUREMENT, THICKNESS, EXPERIMENTAL DATA, DISPERSING, LAYERS, GROWTH(GENERAL), PLASMAS(PHYSICS), STRUCTURES, THIN FILMS, EPITAXIAL GROWTH, ROOM TEMPERATURE, HYDROGEN, GASES, ELECTRON MICROSCOPY, SURFACES, BOUNDARIES, DEPOSITION, ELECTRONS, DIELECTRIC PROPERTIES, FLOW, ACCUMULATION, MATCHING, SOLID SOLUTIONS, CURRENTS, CYCLOTRON RESONANCE, GAS FLOW, MOLECULAR BEAM EPITAXY.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrical and Electronic Equipment
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE