High energy storage properties of calcium-doped barium titanate thin films with high breakdown field strength

Barium titanate (BaTiO3; BTO) has excellent energy storage properties; however, the breakdown field strength of BTO thin films must be improved for high energy storage. In this study, calcium (Ca)-doped BTO thin films, Ba1_xCaxTiO3 (x = 0, 0.03, 0.06, 0.09, 0.12, and 0.15), were prepared on Pt(111)/Ti/SiO2/Si substrates using the sol-gel method. Further, the energy storage properties of Ba1_xCaxTiO3 thin films with different Ca concentrations were characterized and analyzed. Results revealed that the only 165-nm-thick Ba0.91Ca0.09TiO3 film exhibits a high-energy storage density of 32.0 J/cm3 and a high energy storage efficiency of 87.8 % at a high breakdown field strength of 7879 kV/cm. Moreover, Ca-doped BTO thin films have excellent energy storage potential and can be used for fabricating high-breakdown-field, lead-free, and miniaturized dielectric capacitors.