Energy storage performance in lead-free antiferroelectric 0.92(Bi_0.54Na_0.46)TiO₃-0.08BaTiO₃ ultrathin films by pulsed laser deposition

In this study, we report the recoverable energy density (U_rec) of lead-free antiferroelectric perovskite 0.92(Bi_0.54Na_0.46)TiO₃-0.08BaTiO₃ (BNT-BT) ultrathin films deposited directly on highly boron-doped silicon (p-Si) by a pulsed laser deposition method. Two pressure values were used in the growing conditions, 4.67 × 10⁻⁵ and 13.3 Pa, at a fixed substrate temperature of 700 °C. After that, the films were subjected to postannealing under an oxidizing atmosphere at 700 °C for 1 h. A conventional lithography process was used to define vertical metal–ferroelectric–p-Si structures and evaluate the energy storage characteristics. Cross-sectional SEM images showed achieved thicknesses of about 11–13 nm. The high electric field strengths of 3.8 and 4.5 MV/cm supported for BNT-BT ultrathin films deposited at 4.67 × 10⁻⁵ and 13.3 Pa, respectively, imply a high-quality perovskite thin-film growth on p-Si. The 11-nm ultrathin film grown at 13.3 Pa showed higher U_rec, efficiency (η), and a maximum applied electric field of 30 J/cm³, 83%, and 4.5 MV/cm, respectively.