Optical and Electrical Characterization of Vandium-Doped SiC
Abstract
The purpose of this investigation was to characterize the material produced by Northrop Grumman during an effort to obtain semi-insulating SiC. The semi-insulating SiC is needed to further develop devices operating at microwave frequencies. High temperature Hall effect, Deep Level Transient Spectroscopy (DLTS), optical absorption, Fourier Transform Infrared (FTIR) spectroscopy, and Thermally Stimulated Current (TSC) measurements were employed in concert to examine the resultant boules. The polytypes examined were 4H, 6H, and 15R. The product of these experiments was that three levels were detected which were related to the vanadium incorporation. The deepest level (at E sub c -1.35 eV) detected in 6H-SiC as a part of these experiments was identified as the isolated substitutional vanadium donor level (0/+). This confirmed previous predictions about the depth of the donor level. Wafers were found whose Fermi level was pinned at the vanadium donor resulting in insulating crystals (extrapolated to the 10 to the 18th power OMEGAcm at RT). The donor level was occupied due to the partial compensation by the boron acceptor which is ubiquitous in undoped SiC samples. The other level related to the isolated, substitutional configuration of vanadium is the acceptor level. This investigation was the first to discover the position of this level within the SiC band gap. DLTS and Hall effect evinced an acceptor level position of E sub c -0.8 eV for the 4H polytype. Hall effect was employed exclusively to ascertain the position in the 6H polytype (at E sub c -0.66 eV). This level was observed in samples whose boron acceptor and vanadium donor levels were compensated by the common donor dopant, nitrogen. The DLTS results also indicated that the vanadium level can be incorporated in concentrations up to 3 x 10 to the 17th power per cu cm.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1996
- Accession Number
- ADA342839
Entities
People
- Jason R. Jenny
Organizations
- Carnegie Mellon University