Ultrathin oxide interfaces on 6H–SiC formed by plasma hydrogenation: Ultra shallow depth profile study

Silicon oxide ultrathin films grown on silicon carbide (6H–SiC) by plasma hydrogenation have been studied using ultrashallow depth profiling with time–of–flight secondary ion mass spectrometry. Plasma hydrogenation gives rise to an epitaxial 3×3R30° silicate structure on 6H–SiC(0001) and 6H–SiC(0001). By selecting appropriate sputtering conditions, an ultrathin and atomically abrupt interface delineating the boundary between the silicate epilayer (SiO+,Si2O+, and SiO3−,SiO2−) and bulk silicon carbide (SiC+) was observed on both C(0001) and Si(0001) faces. Differences in the sputtering profile between the C and Si faces suggest an enrichment of the interface stoichiometry by Si and O on the Si face. Our results support the structural models of the silicate on the C and Si-face 6H–SiC(0001) proposed by Starke [Appl. Phys. Lett. 74, 1084 (1999); J. Vac. Sci. Technol. A 17, 688 (1999)].