Effect of oxidation method and post-oxidation annealing on interface properties of metal–oxide–semiconductor structures formed on n-type 4H-SiC C(0001̄) face

Abstract

The $\mathrm{C(0001̄)}$ face of silicon carbide (SiC) has superior properties such as a faster oxidation ratio and a smoother surface compared with the Si(0001) face. We have investigated the oxidation and post-oxidation annealing effects on the capacitance–voltage and the interface state density ${\mathrm{(D}}_{\mathrm{it}})$ of n-type SiC metal–oxide–semiconductor (MOS) structures formed on the $\mathrm{C(0001̄)}$ face. It was found that pyrogenic oxidation and hydrogen annealing above 700 °C reduced $D_{\mathrm{it}}$ near the conduction-band edge. The value of $D_{\mathrm{it}}$ at $E_c\text{−E=0.2\hspace{0.05em}}\mathrm{eV}$ is ${\text{1×10}}^{12} {\mathrm{eV}}^{\text{−1}} {\mathrm{cm}}^{\mathrm{-2}},$ which is comparable with that of the MOS structure formed on the Si(0001) face. However, the value of $D_{\mathrm{it}}$ around the deep level at $E_c\text{−E=0.6\hspace{0.05em}}\mathrm{eV}$ is one order of magnitude higher than that of n-type MOS structures formed on the Si(0001) face. It is very important to reduce $D_{\mathrm{it}}$ at the deep level for a high-quality ${\mathrm{SiO}}_{\mathrm{2}}\mathrm{/SiC}$ interface on the 4H-SiC $\mathrm{C(0001̄)}$ face.