Energy-band alignment of HfO2∕SiO2∕SiC gate dielectric stack

The band alignment of HfO2∕SiO2∕SiC gate dielectric stack has been investigated by x-ray photoelectron spectroscopy and electrical characterization. Two types of valence band offsets are observed in the stack layer; the smaller value of 1.5eV corresponds to the HfO2∕SiC band offset while the larger one of 2.2eV is due to the interfacial SiO2∕SiC. The barrier height is extracted to be 1.5eV from the Schottky emission characteristics and is higher than the reported value for HfO2 on SiC without interfacial SiO2. Thus, presence of an interfacial SiO2 layer increases band offsets to reduce the leakage current characteristics.