Origin of high solubility of silicon in La_2O_3: A first-principles study

摘要

The solubility of silicon in high-permittivity (high-κ) oxides significantly affects the performance of field-effect transistors. Our comparative study of silicon impurities in La_2O_3 and HfO_2 reveals that the stability of silicon at substitutional sites strongly depends on its coordination number. When substituted for lanthanum, a silicon atom fits comfortably in La_2O_3, thanks to the formation of a SiO_4 tetrahedral structure. In addition, the substitutional silicon acts as a donor impurity in La_2O_3, increasing oxygen content in the oxide. This contributes to absorbing silicon and oxygen from the interface region, leading to the formation of lanthanum silicate at the La_2O_3/silicon interface.