Defects and Impurities in 4H- and 6H-SiC Homoepitaxial Layers: Identification, Origin, Effect on Properties of Ohmic Contacts and Insulating Layers and Reduction.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1996
- Accession Number
- ADA317435
Entities
People
- Bayant Jayant Baliga
- M. O. Aboelfotoh
- Robert F Davis
- Robert J. Nemanich
Organizations
- North Carolina State University