The Research On The Properties Of SiC MOS Interface By Conductance Method

The electrical and physical properties of silicon carbide (SiC) and its ability to form insulating SiO2 layers by thermal oxidation make it a promising material for high power, high-temperature, and high-frequency metal-oxide-semiconductor field effect transistors(MOSFETs). Historically, the development of SiC MOSFETs has been hindered by the high density of interface states(Dit) at the SiO2/SiC interface, which results in a reduced electron mobility in n-channel inversion layers. So the focus of research efforts is SiO2/SiC interface.In this paper, considering the different characteristic of SiC, the classic theory of characterization of Silicon MOS capacitor should be modified and developed, especially common charateriztion methods such as Capacitance-Voltage method and Conductance method. And then conductance method was applied to evaluate SiO2/SiC interface treated by nitrogen and hydrogen plasma. The results showed that nitrogen and hydrogen plasma treatment can reduce the interface state density and improve the MOS interface characteristics effectively. The lowest density of interface states, which was 3.65×1012 cm-2eV-1 near the conduction band edge, was obtained when the treatment time was about 10min. Meanwhile Conductance method was more accurate than C-V method though its measuring range was limited.The results demonstrated that Conductance method is more accurate and sensitive than C-V method and meanwhile nitrogen and hydrogen plasma treatment could improve the SiO2/ SiC interface properties effectively.