Controlling the defects and transition layer in SiO films grown on 4H-SiC via direct plasma-assisted oxidation.

The structural stability and electrical performance of SiO grown on SiC via direct plasma-assisted oxidation were investigated. To investigate the changes in the electronic structure and electrical characteristics caused by the interfacial reaction between the SiO film (thickness ~5 nm) and SiC, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), density functional theory (DFT) calculations, and electrical measurements were performed. The SiO films grown via direct plasma-assisted oxidation at room temperature for 300s exhibited significantly decreased concentrations of silicon oxycarbides (SiOC) in the transition layer compared to that of conventionally grown (i.e., thermally grown) SiO films. Moreover, the plasma-assisted SiO films exhibited enhanced electrical characteristics, such as reduced frequency dispersion, hysteresis, and interface trap density (D ≈ 10 cm · eV). In particular, stress induced leakage current (SILC) characteristics showed that the generation of defect states can be dramatically suppressed in metal oxide semiconductor (MOS) structures with plasma-assisted oxide layer due to the formation of stable Si-O bonds and the reduced concentrations of SiOC species defect states in the transition layer. That is, energetically stable interfacial states of high quality SiO on SiC can be obtained by the controlling the formation of SiOC through the highly reactive direct plasma-assisted oxidation process.