  We report first-principles static and dynamic calculations that clarify the
microscopic mechanism of carbon annihilation due to phosphorous treatment upon
oxidation of silicon carbide (SiC). We identify the most stable form of the
phosphorus (P) in the oxide as the four-fold coordinated with the dangling PO
unit and find that the unit attracts carbon ejected from the interface, thus
operating as a carbon absorber. This finding provides a microscopic reasoning
for the first time for the promotion of the oxidation reaction on one hand and
the annihilation of the C-related defects at the interface on the other.
Secondary ion mass spectrometry measurements are also performed and the
obtained carbon profile corroborates the theoretical finding above.
