A first-principles study of enhanced dielectric responses in Ti and Ce doped HfO_(2)

摘要

In this letter, the dielectric response in Ti and Ce doped hafnia (HfO_(2)) has been investigated by density functional theory calculations based on pseudopotentials, plane wave basis, and local density approximation. It is found that Ti doped samples give greater dielectric response than Ce doped HfO_(2), with Hf_(0.5)Ti_(0.5)O_(2) having the highest response. The Born effective charges on atoms and infrared-active phonon modes have been studied; soft phonon modes cause enhancement in the responses. The materials remain insulating upon doping of HfO_(2) and are of potential importance for applications as gate oxide.