Accession Number : ADA302914

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

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

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Davis, Robert F. ; Nemanich, Robert J. ; Benjamin, M. C. ; Fleming, S. ; Kern, S.

PDF Url : ADA302914

Report Date : DEC 1995

Pagination or Media Count : 41

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 contacts with Ni passivating layers on p-type 6H-SiC(0001) substrates were rectifying with very low P( sub L) (approx. 1x10(exp -8) A/sq cm at 10 V), I(sub D) values between 1.4 and 2.4, and a SBH of approx. 1.37 eV. As-deposited (at RT) Ni and Au contacts on p-type 6H-SiC displayed similar C-V characteristics with SBH values of 1.31 and 1.27 eV, respectively. The Fermi level is partially pinned in p-type 6H-SiC. The Ni/NiAl contacts on p+ (1x10(exp-19)/cu cm) 6H-SiC (0001) were ohmic after annealing for 10-80 s at 1000 deg C in a N2 ambient. The estimated specific contact resistivity from a non-mesa etched TLM pattern was 2-3x10(exp -2) W./sq cm. Several boron compounds were selected as alternatives to Al materials. UPS measurements of Al(0.75)Ga(0.25)N films deposited in situ via GSMBE and Si-doped GaN, Al(0.13)Ga(0.87)N and Al(0.55)Ga(0.45)N films deposited ex situ via OMVPE on 6H-SiC(0001) exhibited NEA characteristics in the former material, but not in the latter three samples. Annealing of the Al(0.55)Ga(0.45)N sample to >400 deg C resulted in the disappearance of the sharp emission features. This effect was related to surface contammation. jg p2

Descriptors :   *LOW TEMPERATURE, *THIN FILMS, *DEPOSITION, *SCHOTTKY BARRIER DEVICES, *SILICON CARBIDES, EMISSION, ANNEALING, RESISTANCE, SINGLE CRYSTALS, EPITAXIAL GROWTH, CARBON, REFLECTION, HIGH RESOLUTION, FERMI SURFACES, NITRIDES, NITROGEN, HYDROGEN, GASES, ESTIMATES, ELECTRON MICROSCOPY, HIGH ENERGY, ETHYLENE, ALUMINUM, SAMPLING, GALLIUM, NICKEL, DOPING, N TYPE SEMICONDUCTORS, GOLD, ELECTRON DIFFRACTION, P TYPE SEMICONDUCTORS, ELECTRIC CONTACTS, ALUMINIDES, BORON COMPOUNDS, MOLECULAR BEAM EPITAXY.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy
      Optics
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE