OXIDATION OF SINGLE-CRYSTAL SILICON-CARBIDE .2. KINETIC-MODEL

The oxidation of single-crystal SiC in dry oxygen (10-3-1 atm and 1200°-1500°C) followed parabolic kinetics. The oxygen partial pressure dependence of the oxidation rate of the (0001) carbon face decreased with increasing temperature (from 0.6 at 1200°C to 0.3 at 1500°C). A kinetic model based on parallel transport of oxidants through the oxide via molecular and ionic oxygen diffusion mechanisms fits the observed oxidation behavior. Both diffusivity and activation energy values for oxidants permeating through the oxide derived from the model using the experimental data are similar to those for molecular oxygen permeating through vitreous Si02. Ionic oxygen diffusion inward via the lattice presumably via a vacancy mechanism becomes more important when oxidation takes place at higher temperatures and at low oxygen partial pressures. Both diffusivity and activation energy values for the ionic oxidant diffusion derived from the model using the experimental data are similar to those values for the diffusion of oxygen through silica reported in the literature. copyright. © 1990, The Electrochemical Society, Inc. All rights reserved.