High Energy Performance Ferroelectric (Ba,Sr)(Zr,Ti)O3 Film Capacitors Integrated on Si at 400 °C

BaTiO3-based ferroelectrics have been extensively studied due to their large dielectric constants and a high saturated polarization, which have the potential to store or supply electricity of very high energy and power densities. In order to further improve the energy efficiency eta and the recyclable energy density W-rec, an A, B-site co-doped (Ba-0.95,Sr-0.05)(Zr-0.2,Ti-0.8)O-3 ceramic target was used for sputter deposition of film capacitor structures on Si. This film composition reduces the remnant polarization P-r, while the choice of a low-temperature, templated sputtering process facilitates the formation of high-density arrays of columnar nanograins (average diameter d similar to 20 nm) and grain boundary dead layers. This self-assembled nanostructure further delays the saturation of the electric polarization, leading to a high energy density W-rec of similar to 148 J/cm(3) and a high energy efficiency eta of similar to 90%. Moreover, the (Ba-0.95,Sr-0.05)(Zr-0.2,Ti-0.8)O-3 film capacitors retain their high energy storage performance in a broad range of working temperature (-175-300 degrees C) and operating frequency (1 Hz-20 kHz). They are also fatigue-free after up to 2 x 10(9) switching cycles. Our work provides a new method and a cost-effective processing route for the creation and integration of high-performance dielectric capacitors for energy storage applications.