Approaching theoretical polarization limit in HfZrO2/HfLaO2 multilayers.

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Hafnia-based ferroelectrics are crucial for silicon technology due to their robust ferroelectricity in thin films.
• Experimental polarization values in hafnia-based ferroelectrics often fall short of theoretical predictions.
• Achieving high intrinsic polarization is key for next-generation ferroelectric devices.

Purpose of the Study:

• To achieve high intrinsic remnant polarization in hafnia-based ferroelectric materials.
• To explore the role of lanthanum doping and multilayer structures in enhancing ferroelectric properties.
• To establish a design paradigm for high-performance ferroelectric devices.

Main Methods:

• Epitaxial growth of (111)-oriented Hf_0.5Zr_0.5O₂/Hf_0.9La_0.1O₂ multilayer films.
• Structural analysis to determine the material phase and strain.
• Density functional theory (DFT) calculations to investigate polarization mechanisms and doping effects.

Main Results:

• An intrinsic remnant polarization of 40 μC/cm² was achieved, corresponding to 69.3 μC/cm² along [001], nearing theoretical limits.
• A rhombohedral-distorted orthorhombic phase stabilized by in-plane compressive strain was identified.
• DFT calculations revealed that La doping facilitates an unconventional switching pathway, boosting polarization.

Conclusions:

• Lanthanum doping in Hf_0.5Zr_0.5O₂/Hf_0.9La_0.1O₂ multilayers significantly enhances intrinsic polarization.
• The study provides a viable strategy for realizing high-performance hafnia-based ferroelectric devices.
• This work establishes a design framework for optimizing ferroelectric properties in advanced materials.