Thermal growth of SiO2 on SiC investigated by isotopic tracing and subnanometric depth profiling

Abstract We investigated the limiting step of thermal growth of SiO 2 on SiC. For that we determined the incorporation of oxygen during different stages of the oxidation process of 6H-SiC wafers as well as of Si wafers, for comparison. Oxidations in natural dry O 2 followed by oxidations in isotopically enriched oxygen ( 18 O 2 ) were performed. Different times of oxidation in natural gas and chemical etching of the grown oxides were used to obtain samples representing different starting conditions. 18 O depth profiles were determined using the 18 O (p,α) 15 N nuclear reaction in the 151 keV resonance region of the cross-section curve. The results evidence that in the thickness range studied, thermal growth of SiO 2 on SiC is limited by reaction of O 2 with SiC, whereas, on Si the growth is limited by diffusion of O 2 in the growing oxide film.