Thin Films

Recently, HfO₂ based ferroelectric thin films have attracted attention as a promising candidate for ferroelectric random access memories (FRAM). A lot of researches demonstrated robust ferroelectricity with large polarization value comparable with conventional ferroelectric perovskites, e. g., BaTiO₃. In addition, an enhancement of remnant polarization, namely, wake-up effect was reported after external electric field cycling which usually cause the decrease of remnant polarization. Elucidation of ferroelectric switching dynamics is required to clarify an underlying mechanism for practical device applications.
In this presentation, we report on the polarization switching kinetics of silicon doped hafnium oxide thin films. We measured write pulse-width dependences of polarization switching under various applied electric fields. Their switching dynamics under various electric fields will be explained by Kolmogorov-Avrami-Ishibashi (KAI) model and nucleation-limited-switching (NLS) model for the fast and slow ferroelectric switching behaviors, respectively.