Study on the phase transition dynamics of HfO2-based ferroelectric films under ultrafast electric pulse

Wake-up effect and fatigue in HfO2-based ferroelectric films are closely related to the phase transition dynamics of the film subjected to ultrafast electric pulses. Here, we establish a multiphase coexistence phase field dynamics model for HfO2-based ferroelectric films in the ultrafast time scale and study the effects of the amplitude, width and frequency of the electric pulse on the phase transition dynamics. Based on the simulation results, we obtain the analytical equation of the volume fraction of switched c-domains under low fields as a function of pulse duration. And we found that monoclinic phase can transform into ferroelectric c-domains under high amplitude electric field (E > 2.8 MV cm(-1)). The electric pulse duration affects the film's retention properties. When the duration of the electric pulse is less than 1.2 ns or longer than 1.8 ns, the ferroelectric c-domains will respectively invert into other phases or increase cumulatively after removing the electric field. The frequency of cyclic pulse is related to the degree of wake up effect. The lower the pulse frequency is, the more obvious the 'wake up' effect is.