Achieving a Record-High Capacitive Energy Density on Si with Columnar Nanograined Ferroelectric Films.

High energy density dielectric film capacitors are desirable in modern electronic devices. Their miniaturization and integration into Si-based microsystems create opportunities for in-circuit energy supply, buffering, and conditioning. Here, we present a CMOS (complementary metal oxide semiconductor)-compatible route for the fabrication of BaTiO 3 film capacitors on Si with a record-high recoverable energy density and good efficiency (∼242 J/cm 3 and ∼76% at 8.75 MV/cm). These BaTiO 3 films were sputter-deposited at 350 °C and consisted of slightly compressed superfine columnar nanograins with a (001) texture. Such a nanostructure was endowed with a high breakdown strength, a reduced remnant polarization, and an enhanced maximum polarization, which are accountable for their excellent energy storage performance. Moreover, these BaTiO 3 film capacitors displayed a high electrical fatigue resistance, a wide range of operating temperatures, and an excellent frequency stability. With an engineered nanostructure, the prototype perovskite of BaTiO 3 has shown great promise for capacitive energy storage applications.