N2O-grown oxides/4H-SiC (0001), (0338), and (1120) interface properties characterized by using p-type gate-controlled diodes

The N2O-grown SiO2/4H-SiC (0001), (0338), and (1120) interface properties in p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) have been characterized by using gate-controlled diodes. Although the inversion layer is not formed in simple SiC MOS capacitors at room temperature due to its large bandgap, a standard low frequency capacitance-voltage (C-V) curve can be obtained for the gate-controlled diodes, owing to the supply of minority carriers from the source region. From the quasistatic C-V curves measured by using gate-controlled diodes, the interface state density has been evaluated by an original method proposed in this study. The interface state density near the valence band edge evaluated by the method is the lowest at the oxides/4H-SiC (0338) interface. Comparison with the channel mobility is also discussed.