Thickness-Dependent Dielectric Properties in Doped Relaxor Films by the Phase-Field Model

With the trend of device miniaturization, the application of ultrathin relaxor films is becoming widespread and receiving more attention. However, the mechanism by which film thickness affects the dielectric properties of relaxor ferroelectrics is still unclear. Therefore, an investigation of the effect of size on the dielectric properties is particularly important. In this paper, we employ a phase-field model to simulate the doping of point defects in BaTiO₃ film to construct relaxor ferroelectric film. The simulation results reveal size effects on the dielectric constant, domain structure, and energy storage performance of the relaxor films. With increasing film thickness, particularly when exceeding 15 nm, the dielectric constant increases by a factor of 2, the domain size enlarges, and the energy storage performance is significantly enhanced. The domain structure and dielectric constant maps demonstrate that the size effect on the dielectric constant is the result of the interplay between the reduction in polar nanoregions and the decrease in the energy barrier. Our investigations provide valuable insights for the application of relaxor films.