The effect of surface-step-terrace on energy storage density and working temperature of BaZr_0.2Ti_0.8O₃ epitaxial films

Dielectric film capacitors have been widely used in various electronic devices due to the high energy storage density and high charge-discharge speed. The energy storage performances are highly determined by the strain status of the films. Herein, we improved the energy storage performances of epitaxial BaZr_0.2Ti_0.8O₃ film through surface-step-terrace in the vicinal substrate. It is found that the terraces in the vicinal substrate create an additional strain parallel to the terraces and a compressive strain along the out-of-plane direction. The strains result in the increase in the energy storage density of the BZT film up to 66.9 J/cm³ with an energy storage efficiency of 73.2% at room temperature, which is 2.2 times as high as that of the films on regular substrates. Moreover, the strains also lead to the reduction of the hysteresis loss and increase in the up-limited working temperature from 125 to 225 °C with an energy storage density of 52.35 J/cm³ and an efficiency of 70.25%, exhibiting excellent thermal stability. Our work demonstrates that the strains generated by vicinal substrates can improve the energy storage performance greatly and provide a method to improve the energy storage performances of dielectric thin film capacitors.