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NMR Spin Lattice Relaxation in NITROGEN-Doped 6H Silicon Carbide

Published online by Cambridge University Press:  21 February 2011

J. Stephen Hartman ,
Arjun Narayanan  and
Youxiang Wang
J. Stephen Hartman
Affiliation:
Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada
Arjun Narayanan
Affiliation:
Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada
Youxiang Wang
Affiliation:
Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada
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Abstract

Nuclear magnetic resonance (NMR) spin lattice relaxation is highly sensitive to the nature, amount, and homogeneity of unpaired-electron-containing impurities in silicon carbide and similar solids, and is a promising tool for the study of dopants and impurities. In nitrogen-doped 6H silicon carbide, 13C and 29Si NMR spin lattice relaxation is highly site-dependent. Not only do carbon sites relax much more rapidly than the corresponding silicon sites, but also there are unprecedented differences in relaxation efficiency among the different carbon (and silicon) sites, consistent with much higher unpaired electron density at the higher-symmetry (Types A and B) sites than at the lowest-symmetry (Type C) site. In contrast, all sites relax at equivalent rates in undoped samples and in commercial abrasive grade material with high levels of impurities, although there are large differences in relaxation efficiency among samples. The change in the nature of the relaxation process, from exponential in high-purity to stretched exponential in lower-purity samples, is apparently related to changes in unpaired-electron mobility.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 339: Symposium D – Diamond, Silicon Carbide and Nitride Wide Bandgap Semiconductors , 1994 , 523
Copyright
Copyright © Materials Research Society 1994

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References

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