Study on electron trapping and interface states of various gate dielectric materials in 4H–SiC metal-oxide-semiconductor capacitors

The characteristics of electron trapping and interface states for various gate dielectrics formed on the 4H–SiC metal-oxide-semiconductor capacitors have been studied. Thermal gate oxides prepared by dry oxidation (in pure O2) or wet oxidation (in H2:O2=1:2), oxide-nitride-oxide (ONO) stacked films and low-temperature oxide (LTO) films formed by low-pressure chemical vapor deposition were used. Post-oxidation anneal was performed at 1200 °C for 1 h in Ar ambient. It is found that the LTO film has lower interface state density and effective oxide charge density than the other gate dielectrics. Also, the LTO film showed excellent electron trapping characteristics against the electron injection. On the contrary, the electron trapping of ONO stacked film was larger than that of the thermal oxide and LTO film.