Shallow states at SiO2/4H-SiC interface on (112̄0) and (0001) faces

Shallow interface states at SiO2/4H-SiC were examined on (112̄0) and (0001) faces using metal–oxide–semiconductor (MOS) capacitors. The MOS capacitors were fabricated by wet oxidation on both faces to investigate the difference in the energy distribution of interface state density. The parallel conductance as a function of frequency was measured at room temperature, and high-frequency capacitance (C)–voltage (V) curves were measured both at room temperature and 100 K. By the conductance method, the interface state density on (112̄0) was revealed smaller than on (0001) at shallow energies, while at deeper energies the relation changes to opposite situation. High-frequency C–V curves at 100 K show a large positive flatband voltage shift and a large injection-type hysteresis on (0001) samples, while those were small on (112̄0), indicating another evidence of smaller interface state density near the conduction band edge on (112̄0).