We demonstrate on the basis of first-principles calculations that the formation of carbonate-like moiety in SiO2 could be the intrinsic origin of negative fixed charge in SiC thermal oxidation. We find that two possible origins for the negative fixed charges are O-lone-pair state and a negatively charged CO3 ion in SiO2. Such CO3 ion is able to be formed as a result of the existence of residual C atoms in SiO2, which are expected to be emitted from the interface between SiC and SiO2, and the incorporation of H atoms during wet oxidation.
@article{arxiv.1204.5556,
title = {Intrinsic Origin of Negative Fixed Charge in Wet Oxidation for Silicon Carbide},
author = {Yasuhiro Ebihara and Kenta Chokawa and Shigenori Kato and Katsumasa Kamiya and Kenji Shiraishi},
journal= {arXiv preprint arXiv:1204.5556},
year = {2012}
}