Accession Number : ADA310905

Title :   Low Temperature Deposition and Characterization of N- and P-Type Silicon Carbide Thin Films and Associated Ohmic and Schottky Contacts.

Descriptive Note : Final technical rept. 1 Jan-30 Jun 96,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF PHYSICS

Personal Author(s) : Davis, R. F. ; Nemanich, R. J. ; Benjamin, M. C. ; Kern, S. ; King, S. W.

PDF Url : ADA310905

Report Date : JUN 1996

Pagination or Media Count : 39

Abstract : Epitaxial, undoped films of 6H-SiC(0001) and 3C-SiC(111) have been grown by gas source (GS) MBE on 6H-SiC((0001) substrates and 2H-AlN(0001) layers between 1050-1250 deg C using SiH4 and C2H4 for Si and C, respectively. Controlled n- and p-type doping was achieved via NH3 and evaporated Al. REED and HRTEM showed the films to be monocrystalline and of either the 6H or 3C polytype. 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) ohm sq cm. The high contact resistivities are partly attributed to an insulating oxide layer which formed at the surface of the contacts during the annealing process. Cr-B contacts were semi-ohmic on p-type SiC (1x1018 /sq cm) after annealing at 1000 deg C for 60-300 s in Ar; oxidation of these latter contacts did not occur. Al/AlN/a-SiC MIS diodes with several AlN thicknesses have been fabricated via GSMBE. C-V measurements at RT between 10 kHz and 1 MHz showed accumulation and depletion over the entire frequency range without dispersion. Inversion was not achieved. Thin layers (<1000A) of AlN exhibited moderate leakage currents, but thicker layers reduced this problem. Calculated values of the dielectric constant matched the measured values. Results of UV-photoemission spectroscopy (UPS), Auger electron spectroscopy, and LEED studies of the surface and interface properties of heteroepitaxial AlN on 6H-SiC grown in situ.

Descriptors :   *LOW TEMPERATURE, *THIN FILMS, *DEPOSITION, *N TYPE SEMICONDUCTORS, *SCHOTTKY BARRIER DEVICES, *SILICON CARBIDES, *P TYPE SEMICONDUCTORS, *MOLECULAR BEAM EPITAXY, DIODES, FREQUENCY, SOURCES, MEASUREMENT, THICKNESS, ANNEALING, INTERFACES, LAYERS, INSULATION, RESISTANCE, ALLOYS, REFLECTION, NITRIDES, GASES, REDUCTION, ELECTRON MICROSCOPY, DIELECTRIC PROPERTIES, SURFACE PROPERTIES, OXIDATION, OXIDES, ALUMINUM, WORK FUNCTIONS, NICKEL, ELECTRICAL RESISTANCE, DOPING, ACCUMULATION, ELECTRON DIFFRACTION, AUGER ELECTRON SPECTROSCOPY, CURRENTS, ELECTRIC CONTACTS, COLD CATHODE TUBES.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrical and Electronic Equipment
      Coatings, Colorants and Finishes
      Crystallography
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE