Improvement of Interfacial Properties of 4H-SiC/SiO2 by Nitrogen Plasma Treatment

In this work, the effect of nitrogen plasma treatment and post-deposition annealing (PDA) on the interfacial properties of 4H-SiC/SiO2 were studied. The results showed that both nitrogen plasma treatment and PDA could reduce interface trap density (Dit), and a minimal Dit of 1.30×10¹¹ cm⁻²eV⁻¹ at 0.5 eV below 4H-SiC conduction band was obtained. Based on the characterization of X-ray photoelectron spectroscopy (XPS) and theoretical calculation, it is found that nitrogen plasma treatment, on one hand, can remove the surficial by-product of SiOxCy, and on the other hand, result in the passivation of interfacial dangling bonds and the formation of Si≡N, which contribute to the reduction of Dit. This work provides a guidance for the development of high-performance 4H-SiC power devices.