Date of Award
Master of Science
Department of Engineering Physics
Robert L. Hengehold, PhD
Typical undoped bulk grown SiC shows n- or p-type conductivity due to residual impurities such as nitrogen, boron, or aluminum. In order to produce high resistivity material, vanadium can be used as a compensating dopant. Since vanadium is an amphoteric dopant in SiC, it produces either a donor state, VSi4+(3d1) → VSi5+(3d0), or an acceptor state, VSi4+(3d1) → VSi3+(3d2). Thus, vanadium doping can compensate both n- and p-type conductivity. In this work, vanadium doped and undoped 4H- and 6H-SiC grown by the sublimation method have been studied using low temperature photoluminescence (PL). It was found that the luminescence observed between 0.85 to 0.95 eV of the intra-3d-shell transition of VSi4+(3d1) increased by an order of magnitude in samples intentionally doped with vanadium compared to samples unintentionally doped. In addition, the dominant visible-region luminescence was attributed to titanium which is an isoelectronic trap in SiC. The presence of a broad peak centered at approx. 1.90 eV in some samples is believed to be attributed to donor-acceptor pair recombination between a TiSi-Nc complex donor and the boron defect complex acting as an acceptor. Finally, the TiSi-Nc complex donor location in the bandgap of 6H-SiC is estimated to be Ec-0.54 eV.
DTIC Accession Number
Davis, William A., "Photoluminescence Spectroscopy of 4H- and 6H-SiC" (1994). Theses and Dissertations. 6360.