Accession Number : ADA317435

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 rept. 1 Jul-30 Sep 96,

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

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

PDF Url : ADA317435

Report Date : SEP 1996

Pagination or Media Count : 36

Abstract : A SiC CVD system has been assembled to grow and dope 4H- and 6H-SiC thin films. The design incorporates a separate load lock from which the growth chamber and a RHEED chamber are attached. Power supply components remain to be received. Comparisons between the wetting characteristics of the on- and off-axis as well as the oxidized and unoxidized 6H-SiC(0001)subSi surfaces in various acids and bases were made to that of Si(111). Both on- and off-axis oxidized 6H surfaces were hydrophilic after removal of the oxide with 10:1 HF and rinsing in DI water. In contrast, it was observed that both on and off axis as received/as polished (0001)subSi 6H-SiC surfaces were hydrophobic before and after dipping in 10:1 HF. Wet chemical cleans, specifically, RCA SC1 (1:1:5 NH3OH:H2O2:H2O) and Piranha Etch (7:3 H2SO4:H2O2) converted these hydrophobic surfaces into hydrophilic surfaces. The use of 200 A of Si as a hydrophobic passivating layer has also been demonstrated. As deposited NiAl, Au, Ni, and Pt contacts were rectifying on p-type 6H-SiC with very low leakage current densities (^1x10(exp -8) A/sq cm at 10 V) and displayed a similar Schottky barrier trend as previously found for n-typeH-SiC. Ni/NiAl contacts on p-type (1x10(exp 19)/cu cm) SiC were ohmic after annealing for 10-80 S at 1000 deg C with a specific contact resistivity of 2-3x10(exp -2) Ohms .sq cm. Cr-B contacts were semi-ohmic on p-type SiC (1x10(exp 18)/sq cm) after annealing at 1000 deg C for 60-240 s in Ar, but became rectifying after annealing for 300 s, a result which may be due to the formation of B4C. Oxidation of the Cr-B contacts was not observed. A mask set and associated MOS capacitors and MOS gated diodes on 4H- and 6H-SiC(0001) were designed and fabricated to characterize the SiO2/SiC interfaces.

Descriptors :   *INSULATION, *EPITAXIAL GROWTH, *IMPURITIES, *REDUCTION, *DEFECTS(MATERIALS), *SILICON CARBIDES, MEASUREMENT, ANNEALING, REMOVAL, INTERFACES, LAYERS, RESISTANCE, METAL OXIDE SEMICONDUCTORS, IDENTIFICATION, SURFACES, WETTING, OXIDATION, OXIDES, POWER SUPPLIES, PATTERNS, CHARGE DENSITY, SCHOTTKY BARRIER DEVICES, CHAMBERS, MASKS, HYDROPHOBIC PROPERTIES, ELECTRIC CONTACTS, ACIDS, CAPACITORS.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Crystallography
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE