Intrinsic ferroelectricity in Y-doped HfO2 thin films

Abstract

Ferroelectric HfO2-based materials hold great potential for widespread integration of ferroelectricity into modern electronics due to their robust ferroelectric properties at the nanoscale and compatibility with the existing Si technology. Earlier work indicated that the nanometer crystal grain size was crucial for stabilization of the ferroelectric phase of hafnia. This constraint caused high density of unavoidable structural defects of the HfO2-based ferroelectrics, obscuring the intrinsic ferroelectricity inherited from the crystal space group of bulk HfO2. Here, we demonstrate the intrinsic ferroelectricity in Y-doped HfO2 films of high crystallinity. Contrary to the common expectation, we show that in the 5% Y-doped HfO2 epitaxial thin films, high crystallinity enhances the spontaneous polarization up to a record-high 50 μC/cm2 value at room temperature. The high spontaneous polarization persists at reduced temperature, with polarization values consistent with our theoretical predictions, indicating the dominant contribution from the intrinsic ferroelectricity. The crystal structure of these films reveals the Pca21 orthorhombic phase with a small rhombohedral distortion, underlining the role of the anisotropic stress and strain. These results open a pathway to controlling the intrinsic ferroelectricity in the HfO2-based materials and optimizing their performance in applications.

References in corpus (5)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• The Origin of Ferroelectricity in Hf${}_x$ Zr${}_{1-x}$ O${}_2$: A Computational Investigation and a Surface Energy Model
• Growth Window of Ferroelectric Epitaxial Hf0.5Zr0.5O2 Thin Films
• Domain Matching Epitaxy of Ferroelectric Hf0.5Zr0.5O2(111) on La2/3Sr1/3MnO3(001)
• Epitaxial Ferroelectric La-doped Hf0.5Zr0.5O2 Thin Films

Cited by in corpus (18)

• Structural Polymorphism Kinetics Promoted by Charged Oxygen Vacancies in HfO${}_2$
• Ferroelectricity in layered bismuth oxide down to 1 nanometer
• Progress in Computational Understanding of Ferroelectric Mechanisms in HfO${}_2$
• Ultrahigh oxygen ion mobility in ferroelectric hafnia
• Ferroelectricity in $\mathrm{Hf}{\mathrm{O}}_2$ from a chemical perspective
• Epitaxial ferroelectric hafnia stabilized by symmetry constraints
• Flexoelectricity-stabilized ferroelectric phase with enhanced reliability in ultrathin La:HfO2 films
• Electro-optic properties of ZrO2, HfO2 and LiNbO3 ferroelectric phases: A comprehensive and comparative study with density functional theory
• Ferroelectric AlBN Films by Molecular Beam Epitaxy
• Engineering ferroelectricity in monoclinic hafnia
• The anti-symmetric and anisotropic symmetric exchange interactions between electric dipoles in hafnia
• Ferro-ionic States and Domains Morphology in Hf${}_x$Zr${}_{1-x}$O${}_2$ Nanoparticles
• The origin of the ferroelectric-like orthorhombic phase in oxygen-deficient HfO2-y nanoparticles
• Colossal dielectric response of HfxZr1-xO2 nanoparticles
• Resistive switching and charge accumulation in Hf0.5Zr0.5O2 nanoparticles
• Antiferroelectricity with metastable polar state from Kittel model
• Guidelines for the optimization of hafnia-based ferroelectrics through superlattice engineering
• Sliding and superlubric moiré twisting ferroelectric transition in HfO2