Accession Number : ADA311059

Title :   Defects and Impurities in 4H- and 6H-SiC Homoepitaxial Layers: Identification, Origin, Effect on Properties of Ohmic Contacts and Insulating Layers and Reduction.

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

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Davis, R. F. ; Aboelfotoh, M. O. ; Baliga, B. J. ; Nemanich, R. J. ; Benjamin, M. C.

PDF Url : ADA311059

Report Date : JUN 1996

Pagination or Media Count : 30

Abstract : A chemical vapor deposition system has been designed and is being constructed for the purpose of depositing 4H- and 6H-SiC and AlN thin films. The design incorporates a separate load lock from which the growth chamber and a RHEED chamber are attached. Comparisons between the wetting characteristics of 6H-SiC(0001)Si and Si(111) surfaces in various acids and bases were conducted. The 10:1 HF dipped Si(111) surfaces were hydrophobic; the (0001)Si 6H-SiC surfaces were hydrophilic. The 6H-SiC(0001)Si surfaces capped with a 20A Si layer, however, were hydrophobic after HF dipping and exhibited outgassing levels on annealing which were several orders of magnitude lower than SiC wafers dipped in HF without the capping layer. Annealing the Si capped (0001)Si 6H-SiC surfaces in UHV at 1100 deg C for 5 min. caused thermal desorption of the Si capping layer and the formation of a (3x3) Si rich, oxygen free (0001)Si 6H-SiC surface. As-deposited (at RT)NiAl, Au, and Ni contacts were rectifying on p-type 6H-SiC (0001) with very low leakage current densities (approx. 1x10(exp. -8) A/sq cm at 10 V). The Schottky barrier heights showed a reduced dependence on the metal work functions, a result which is in agreement with those for n-type SiC. Ni/NiAl contacts on p+ (1x10(exp. -19/cu cm) SiC were ohmic after annealing for 10-80 s at 1000 deg C in a N2 ambient. The estimated specific contact resistivity was 2-3x10(exp. -2)W.sq cm.

Descriptors :   *LAYERS, *INSULATION, *THIN FILMS, *IMPURITIES, *REDUCTION, *CRYSTAL DEFECTS, *SILICON CARBIDES, METALS, ANNEALING, PREPARATION, RESISTANCE, CHEMICAL VAPOR DEPOSITION, EPITAXIAL GROWTH, REFLECTION, METAL OXIDE SEMICONDUCTORS, IDENTIFICATION, SURFACES, HIGH ENERGY, OXYGEN, CHEMISTRY, OXIDATION, OXIDES, ALUMINUM, WORK FUNCTIONS, NICKEL, ELECTRICAL RESISTANCE, GOLD, ELECTRON DIFFRACTION, DESORPTION, CHAMBERS, THERMAL RADIATION, HYDROPHOBIC PROPERTIES, ELECTRIC CONTACTS, ACIDS, OUTGASSING, CAPPING, HYDROGEN FLUORIDE.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Crystallography
      Electricity and Magnetism
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE