Electrical characterization of silicon carbide semiconductor and SiC-SiO(2) interfaces

Fabrication processes of metal-oxide semiconductor (MOS) capacitors on n-type (Si-face and C-face) and p-type (Si-face) 6H-SiC were studied. The effects of the thermal oxidation temperature between (1100 and 1250{dollar}spcirc{dollar}C) on the electrical properties of MOS capacitor were studied. The C-V characteristics of the MOS capacitors were measured at high frequency in the dark and under illumination at room temperature. Under dark conditions, inversion did not occur, probably owing to the absence of minority carriers due to the large band gap of 6H-SiC. The C-V measurements made under illumination for both wet and dry thermally grown oxides show accumulation, depletion, and inversion regions. The interface trap densities and emission time constants of fast states were determined by ac conductance measurements. The electrical properties of n- and p-type 6H-SiC were compared. The oxidation rate of C-face was 5 to 7 times faster than that of Si-face on n-type SiC. The C-V characteristics of n-type (Si-face and C-face) MOS structures were also studied at 100{dollar}spcirc{dollar}C, 200{dollar}spcirc{dollar}C, 300{dollar}spcirc{dollar}C and 350{dollar}spcirc{dollar}C. At 350{dollar}spcirc{dollar}C for the Si-face, and at 200{dollar}spcirc{dollar}C and above for C-face, the SiC MOS capacitor behavior resembled a Si MOS structure at room temperature. Due to the large band gap of SiC, the room temperature C-V characteristics of SiC MOS capacitors resemble those of Si MOS capacitor at low temperature.