First principles calculation of dopant solution energy in HfO2 polymorphs

The solution behavior of dopants, Si, La, and N, in HfO2 polymorphs, monoclinic, tetragonal, and cubic was investigated by using a first principles calculation based on density functional theory within the local density approximation. It was found that the Si and La solutions are more preferable under oxidization atmosphere than reduction atmosphere, and the most efficient nitridation condition for the HfO2 is NO/NO2 atmosphere. By comparing the energy difference between the monoclinic and the tetragonal phases, it was found that the energy difference is decreased by the Si or La doping, whereas influence of the N doping is small, indicating that the phase transition from the monoclinic to tetragonal phase would be enhanced by the Si or La doping.