Energy storage performance of silicon-integrated epitaxial lead-free BaTiO₃-based capacitor

With the rapid development of advanced electronic devices towards miniaturization and integration, silicon integrated lead-free ferroelectric film capacitors have attracted extensive attention due to their excellent energy storage performance and fast charge/discharge speed. In this study, the BaZr_0.15Ti_0.85O₃ (BZT15) film capacitors have been epitaxially integrated on Si (0 0 1) substrate with the buffer layers of Graphene/La_0.67Sr_0.33MnO₃/CeO₂/Y₂O₃-stabilized ZrO₂ (G/L-C-Y). The highly epitaxial crystalline quality improves significantly the energy storage performance. The layer of G has been found to further improve the high temperature energy storage performance due to its heat dissipation effect. The energy storage density (W_re) of the BZT15 film capacitor with the buffer layers reaches 112.35 J/cm³ with energy storage efficiency (η) of 76.7 % at room temperature, which is about 55.29 % and 9.18 % higher than that of the BZT15 film capacitor without buffer layers, respectively. Moreover, the BZT15 film capacitor with the buffer layer shows an ultra-high W_re of 70.36 J/cm³ and an ultra-high η of 81.22 % at 200 °C, which are 74.55 % and 17.13 % higher than that of BZT15 film capacitor without buffer layer. More importantly, the fluctuation of W_re and η of optimized BZT15 film capacitor is only 8.85 % and 1.30 % in the wide temperature range from −100 to 200 °C, respectively. Our studies provide an effective multi-strategy approach combining interface designing and thermal management for the epitaxially integration of dielectric film capacitors on Si substrates to obtain ultra-high energy storage performance in ultra-wide working temperature.