Fabrication and Electrical Properties of Thermally Oxidized p-Channel Metal–Oxide–Semiconductor Field-Effect Transistors on 4H-SiC C-Face

Abstract

We characterized the SiO2/SiC interface by capacitance–voltage (C–V) measurement in order to obtain p-channel metal–oxide–semiconductor field-effect transistors (MOSFETs) on the 4H-SiC(0001̄) C-face. Wet gate oxidation was preferable for both n- and p-type MOS capacitors, but p-type MOS interface properties were inferior to those of n-type MOS capacitors. The cause of the large flat-band shift for the p-type sample was discussed on the basis of C–V measurements by the light illumination technique. We also investigated the influence of the high-temperature annealing process after gate oxidation on the MOS interface properties. The p-type MOS interface was more sensitive to the annealing process than the n-type MOS interface. We fabricated 4H-SiC C-face p-channel MOSFETs by wet gate oxidation and low-temperature postdeposition annealing in He–H2 ambient. The normal FET operation was accomplished on the 4H-SiC C-face for the first time. Those devices, however, indicated low channel mobility and large threshold voltage.