The Optical Admittance Spectroscopy of the Vanadium Donor and Acceptor Levels in Semi-Insulating 4H-SiC and 6H-SiC
The purpose of this study is to determine the vanadium defect levels in semi-insulating 4H-SiC and 6H-SiC using optical admittance spectroscopy (OAS). OAS data show several distinct peaks for the vanadium-doped SI 4H-SiC and 6H-SiC. Comparison of the data for the two polytypes suggests that peaks at 0.67 ± 0.02 eV and 0.70 ± 0.02 eV in 6H substrates and 0.75 ± 0.02 eV in 4H substrates are related to V3+/4+ levels at the cubic sites. A peak at 0.87 ± 0.02 eV in the 6H sample is assigned to the same defect level at the hexagonal site and the associated transition in 4H was observed at 0.94 ± 0.02 eV in our spectra. The donor levels are thought to be related to peaks at 1.94 ± 0.05 eV and 1.87 ± 0.05 eV in 4H and 6H samples, respectively. The differences between the values obtained from the optical admittance measurements and those reported in the literature are attributed to thermal relaxation and/or contributions from defect complexes.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
W. W. Lee and M. E. Zvanut, "The Optical Admittance Spectroscopy of the Vanadium Donor and Acceptor Levels in Semi-Insulating 4H-SiC and 6H-SiC", Materials Science Forum, Vols. 527-529, pp. 647-650, 2006