Simultaneously achieving high energy density and responsivity in submicron BaTiO3 film capacitors integrated on Si

Abstract

In the research field of energy storage dielectrics, the “responsivity” parameter, defined as the recyclable/recoverable energy density per unit electric field, has become critically important for a comprehensive evaluation of the energy storage capability of a dielectric. In this work, high recyclable energy density and responsivity, i.e., Wrec = 161.1 J·cm–3 and ξ = 373.8 J·(kV·m2)–1, have been simultaneously achieved in a prototype perovskite dielectric, BaTiO3, which is integrated on Si at 500 ℃ in the form of a submicron thick film. This ferroelectric film features a multi-scale polar structure consisting of ferroelectric grains with different orientations and inner-grain ferroelastic domains. A LaNiO3 buffer layer is used to induce a {001} textured, columnar nanograin microstructure, while an elevated deposition temperature promotes lateral growth of the nanograins (in-plane diameter increases from ~10–20 nm at lower temperatures to ~30 nm). These preferably oriented and periodically regulated nanograins have resulted in a small remnant polarization and a delayed polarization saturation in the film’s P–E behavior, leading to a high recyclable energy density. Meanwhile, an improved polarizability/dielectric constant of the BaTiO3 film has produced a much larger maximum polarization than those deposited at lower temperatures at the same electric field, leading to a record-breaking responsivity for this simple perovskite.

Keywords

• energy storage
• energy density
• responsivity
• batio3
• dielectric capacitor
• si