Effect of carbon in Si oxide interlayers of the Al2O3/4H-SiC structure on interfacial reaction by oxygen radical treatment

Abstract

The interface state density of Al2O3/4H-SiC can be decreased by oxygen radical treatment at room temperature, so we have systematically investigated the mechanism of the interfacial reaction at Al2O3/4H-SiC during oxygen radical treatment. In this study we focus on the characteristics of the Si oxide interlayer, namely whether carbon atoms are included in the film or not, because the interfacial reactions induced by oxygen radical treatment for Al2O3/4H-SiC and Al2O3/Si are different. It is revealed that decarbonization of the SiCxOy layer occurs when the SiCxOy surface is directly exposed to oxygen radicals. Then, the difference in the interfacial reaction caused by oxygen radical treatment between Al2O3/4H-SiC and Al2O3/Si is investigated by intentionally forming SiCxOy and SiO2 interlayers at the Al2O3/4H-SiC interface. Finally, the possible reaction mechanism is discussed on the basis of experimental results. All the results are qualitatively (but clearly) understood by considering that decarbonization of SiCxOy occurs as the starting point.