Ab initio study of high permittivity phase stabilization in HfSiO

Using ab initio simulations we calculate the influence of Si doping on the dielectric constant of HfSiO. It is shown that the tetragonal phase becomes more stable upon Si doping than the monoclinic phase which is preferred for pure HfO2. The stabilization of the tetragonal phase has a strong impact on the dielectric constant of crystalline HfSiO. Our data is in very good agreement with recent experimental findings and suggests why Si incorporation promotes the tetragonal phase. Further insight is gained by discussing Born effective charges and the infra-red absorption spectrum.