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

Report Date:

1996-09-01

Pagination or Media Count:

36.0

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-SiC0001subSi surfaces in various acids and bases were made to that of Si111. Both on- and off-axis oxidized 6H surfaces were hydrophilic after removal of the oxide with 101 HF and rinsing in DI water. In contrast, it was observed that both on and off axis as receivedas polished 0001subSi 6H-SiC surfaces were hydrophobic before and after dipping in 101 HF. Wet chemical cleans, specifically, RCA SC1 115 NH3OHH2O2H2O and Piranha Etch 73 H2SO4H2O2 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 1x10exp -8 Asq cm at 10 V and displayed a similar Schottky barrier trend as previously found for n-typeH-SiC. NiNiAl contacts on p-type 1x10exp 19cu cm SiC were ohmic after annealing for 10-80 S at 1000 deg C with a specific contact resistivity of 2-3x10exp -2 Ohms .sq cm. Cr-B contacts were semi-ohmic on p-type SiC 1x10exp 18sq 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-SiC0001 were designed and fabricated to characterize the SiO2SiC interfaces.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry
  • Crystallography
  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE