Tunneling properties of MOS systems based on high-k oxides

In this work, we show full-band calculations of the tunneling properties of ZrO2 and HfO2 high-kappa oxides. First, we have determined serniernpirical sp(3)s*d tight-binding (TB) parameters which reproduce ab-initio band dispersions of the high-kappa oxides; then we have calculated transmission coefficients and tunneling currents for Si/ZrO2/Si and Si/HfO2/Si MOS structures. Results show a very low gate leakage current in comparison to SiO2-based structures with the same equivalent oxide thickness. The complex band structures of ZrO2 and HfO2 have been calculated; based on them we develop an energy dependent effective tunneling mass model. It is shown that this model can be used to obtain effective mass tunneling currents close to full band results.