Effect of Ce doping on ferroelectric HfO2 from first-principles: Implications for ferroelectric thin films and phase regulation

In this work, the effect of Ce doping on the structure and oxygen defects of ferroelectric HfO2 is studied by first-principles calculation. According to the formation energy of Ce doping and the influence of Ce doping on the formation enthalpy of each phase, it is concluded that the concentration of Ce doping is 8-9.375 formula unit% which is most beneficial to the formation of ferroelectric orthorhombic phase. The phase transition from ferroelectric orthorhombic phase to cubic phase will occur when the doping concentration is greater than 12.5 formula unit%. The mechanism of Ce doping was also studied. From the view of electric balance, it is concluded that the existence of Ce3+ will promote the formation of oxygen vacancies in HfO2. These findings are helpful for the preparation of Ce-doped HfO2 ferroelectric thin films and deepen the understanding of the Ce doping mechanism.