Effects of Low-Pressure Oxidation on the Surface Composition of Single Crystal Silicon Carbide

We report on thermodynamic modeling and experimental studies of the reaction of oxygen with the 4H‐ and 6H‐SiC surfaces at high temperatures T. It is observed that this reaction leads to the growth of passivating SiO2 layers at high pressures P(O2), etching of the surface at lower P(O2), and enhancement of the surface segregation of carbon at still lower P(O2). A unified P(O2)–T phase diagram for the reaction of O2 with SiC is presented and a thermodynamic model predicting these three distinct reaction regions is described. Evidence for the thermal decomposition of the SiO2 layer due to its reaction with the SiC substrate is also presented.