Effect of the oxidation process on SiO2/4H-SiC interface electrical characteristics

In this work we have compared the SiO2/SiC interface electrical characteristics for three different oxidations processes (dry oxygen, water-containing oxygen and water-containing nitrogen atmospheres). MOS structures were fabricated on 8° off-axis 4H-SiC(0 0 0 1) n- and p-type epi-wafers. Electrical characteristics were obtained by I–V measurements, high-frequency capacitance–voltage (C–V) and ac conductance (G–ω) methods. Comparing the results, one observes remarkable differences between samples which underwent different oxidation routes. Among the MOS structures analyzed, the sample which underwent wet oxidation with oxygen as carrier gas presented the higher dielectric strength and lower values of interface states density.