Tunneling properties of MOS systems based on high-k oxides

Abstract

In this work, we show full-band calculations of the tunneling properties of ZrO2 and HfO2 high-κ oxides. First, we have determined semiempirical sp3s*d tight-binding (TB) parameters which reproduce ab-initio band dispersions of the high-κ 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.