Improved electronic performance of HfO2/SiO2 stacking gate dielectric on 4H SiC

The MOS characteristics of an atomic layer-deposited HfO2/N2O-nitrided SiO2 stacking gate dielectric on n-type 4H SiC (0001) has been investigated. Three different thicknesses of nitrided SiO2 (2, 4, and 6 nm) have been sandwiched between HfO2 and SiC. The electronic performance of the stacking dielectric depends on the thickness of the nitrided SiO2. 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 SiO2. The reason for this observation is proposed.