Significantly enhanced energy storage density of epitaxial Ba0.53Sr0.47TiO3 thin films by optimizing bottom electrode material

Abstract

Electrode materials of dielectric thin-film capacitors have significant effect on their energy storage properties. In this work, Ba0.53Sr0.47TiO3 thin films were successfully deposited on LaNiO3 or La0.7Sr0.3MnO3 buffered (001) SrTiO3 substrates by pulsed laser deposition method (abbreviated as BST/LNO/STO and BST/LSMO/STO, respectively). The effect of LNO or LSMO bottom electrode on energy storage properties of BST films was systematically studied. It was found that the recoverable energy density of BST/LSMO/STO films is 36.1 J/cm3 at 3400 kV/cm, which is 59.1% higher than that of BST/LNO/STO thin films, i.e., 22.7 J/cm3 at 2765 kV/cm. Besides, the breakdown strength of the BST/LSMO/STO thin films is 22.9% higher than that of the BST/LNO/STO films. Both films show the good thermal stability from 20 °C to 160 °C as well as excellent fatigue resistance after up to 109 electrical cycles. The results show that the lattice mismatch strain of the film, surface roughness of the electrode and Schottky barrier height at the electrode-dielectric interface greatly affect the energy storage properties of BST thin-film capacitors. Our work offers a practical methodology to enhance the energy storage performances of thin-film capacitors by optimizing bottom electrode materials.