Ultrahigh dielectric permittivity in Hf₀.₅Zr₀.₅O₂ thin-film capacitors

Abstract

The ever-shrinking electrostatic capacitor, which is capable of storing substantial quantities of electrical charge, has found widespread applications in high-storage-density dynamic random access memory and energy-efficient complementary metal-oxide-semiconductor devices. Despite the high energy storage densities (133–152 J/cm3) and efficiencies (75–90%) that have been realized using relaxor ferroelectric thick films, low-permittivity interfacial layers in the ultrathin films have caused the overall permittivity to be one to two orders of magnitude lower than expected. However, innovative use of complementary metal-oxide-semiconductor-compatible HfO<inf>2</inf>-based materials with high permittivities (~52) could enable integration of these capacitors into few-nanometre-scale devices. This study reports an ultrahigh dielectric permittivity of 921, stored charge density of 349 μC/cm2, and energy density of 584 J/cm3 with nearly 100% efficiency within near-edge plasma-treated Hf<inf>0.5</inf>Zr<inf>0.5</inf>O<inf>2</inf> thin-film capacitors when the Hf-based material’s ferroelectricity disappears suddenly after polarization fatigue. The ultrahigh dielectric permittivity originates from a distorted orthorhombic phase with ordered oxygen vacancies that enables high-density integration of extremely scaled logic and memory devices for low-voltage applications.