New approach for fabrication of annealing-free ferroelectric HfO2-based films at room temperature

In this work, ferroelectric properties with a coercive field of 1.6 MV/cm and a remanent polarization of 17.9 μC/cm2 were achieved in Y-doped HfO2 thin films prepared by ion beam assisted RF magnetron sputtering without any heating and annealing. Systematic grazing incidence X-ray diffraction and polarization hysteresis measurements revealed that the structural and electrical properties of the films were strongly dependent on the applied ion beam energy. A model of phase transition kinetics during deposition was introduced to explain the variations in the crystal structure and electric properties with various ion beam energies. It was found that the bombardment of the Ar ion beam provided extra energy to the sputtering particles, therefore conducive to the increased atomic diffusion and overcoming the potential barriers of the phase transition. The current processing method provides great potential for ferroelectric device applications that cannot be addressed with heating and annealing.