SIMS study of SiC single crystal oxidized in atmosphere containing isotopic water vapor

Double oxidation of SiC single crystal was carried out in oxidizing gas (O₂ or H₂O) at 1673 K first and then in isotopic water (H₂¹⁸O or D₂O) at 1473 K or 1573 K to trace diffusing species during oxidation at high temperatures. SIMS analysis revealed that deuterium was enriched near SiO₂/SiC interface when SiC was oxidized in Ar/D₂O gas mixture at the second oxidation step, indicating that water molecules or hydroxyls diffused in SiO₂ layer to the SiO₂/SiC interface. Large amount of carbon in SiO₂ scale near the SiO₂/SiC interface after oxidation in dry Ar/O ₂ gas mixture suggests a possibility that outward diffusion of carbonaceous species can be rate-controlling step during oxidation in dry Ar/O₂ atmosphere. Decrease in the amount of the carbon with oxidation time in Ar/H₂¹⁸O gas mixture at the second oxidation step implies that the outward diffusion of carbon-aceous species in SiO₂ scale was promoted during oxidation in atmosphere containing water vapor.