Enhanced Dielectric Energy Storage in Hf_0.5Zr_0.5O₂-Based Oxides by Structure-Evolution Amorphization

The scale-down demands of electronic power devices make high-energy-density dielectric thin-film capacitors highly desirable. Most recently, improved dielectric energy storage properties have been reported in high-k binary materials, particularly the HfO2-based oxides, showing promising applications. Here, we show a record-high energy storage density of 185 J/cm3 in this community achieved in Ba2+-doped Hf0.5Zr0.5O2 (BHZO) thin films by structure-evolution amorphization. Employing molecular dynamics simulations, we reveal the amorphization mechanism of the structure transformation between the fluorite Hf0.5Zr0.5O2 and perovskite Ba(Hf0.5Zr0.5)O3, in which the oxygen instability and diffusion spreading over the Hf/Zr metal sublattices result in the collapse of long-range orderings. Strong disorder is achieved in the Hf0.5Zr0.5O2 matrix, giving rise to an ultrahigh breakdown strength of 13.3 MV/cm in amorphous structure with the Ba2+ concentration of 12 at%. In addition, the maintenance of metal frames also allows further modulation of the amorphous BHZO films by substrate clamping and improved dielectric permittivity is achieved when the lattice mismatch is large. As a result, a giant energy storage density is obtained owing to the dielectric properties that are far beyond the trade-off between breakdown strength and permittivity. Our findings give theoretical and experimental insights for creating high-quality amorphous dielectric oxides and shed light on the exploitation of dielectric energy storage for advanced electronic devices.