Stress-modulated ferroelectricity and dielectric response in HfO2

Abstract

HfO 2 -based ferroelectrics offer exceptional silicon compatibility and scalability for next-generation nonvolatile memory, yet the fundamental role of mechanical stress in their functional properties remains unresolved. This study provides direct experimental and theoretical evidence that tensile stress intrinsically governs the ferroelectric and dielectric response of Hf0.5Zr0.5O2. Using a uniquely designed stretchable ferroelectric capacitor (W/Hf0.5Zr0.5O2/TiN) on a polyimide substrate, we perform in situ measurements under controlled uniaxial tensile strain. Concurrent first-principles calculations simulate strain in the polar orthorhombic Pca21HfO2 phase. Both approaches conclusively demonstrate that switchable polarization monotonically decreases with strain, dielectric permittivity increases, leakage current reduces. These reversible trends are attributed to strain-induced rearrangement of the crystal structure (not electronic effects). In turn, domain reorientation and phase exchange are ruled out as the primary mechanism. Discrepancies in the absolute values between the experiment and the theory arise from polycrystallinity, interfacial tetragonal layers, and grain boundaries. Our findings resolve long-standing debates on stress-mediated ferroelectricity in HfO2, establishing that intrinsic lattice deformation—not extrinsic factors—primarily dictates property changes. This work enables precise stress engineering for HfO2-based electronic devices.