Improved Electronic Performance of $\hbox{HfO}_{2}/ \hbox{SiO}_{2}$ Stacking Gate Dielectric on 4H SiC

The MOS characteristics of an atomic layer-deposited $\hbox{HfO}_{2}/ \hbox{N}_{2}\hbox{O}$-nitrided $\hbox{SiO}_{2}$ stacking gate dielectric on n-type 4H SiC (0001) has been investigated. Three different thicknesses of nitrided $\hbox{SiO}_{2}$ (2, 4, and 6 nm) have been sandwiched between $\hbox{HfO}_{2}$ and SiC. The electronic performance of the stacking dielectric depends on the thickness of the nitrided $\hbox{SiO}_{2}$ . Among the stacking dielectrics, the lowest effective oxide charge and interface-trap density as well as the most reliable dielectric has been demonstrated by a sample with the thickest nitrided $\hbox{SiO}_{2}$. The reason for this observation is proposed.