Domain Wall Evolution in Hf_0.5Zr_0.5O₂ Ferroelectrics under Field-Cycling Behavior

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Hafnium oxide (HfO2)-based ferroelectrics are crucial for semiconductor applications due to their compatibility and robust ferroelectricity.
• The wake-up effect in these materials hinders performance, and their domain structure remains poorly understood.

Purpose of the Study:

• To investigate the domain structure and domain wall characteristics of Hf0.5Zr0.5O2 ferroelectric thin films.
• To understand the atomic-scale differences between 90° and 180° domains before and after the wake-up effect.

Main Methods:

• Growth of Hf0.5Zr0.5O2 ferroelectric thin film on a TiN-buffered Si substrate.
• Observation of domain structures using Cs-corrected scanning transmission electron microscopy.
• Atomic-scale mapping of polarization distributions to characterize domain walls.

Main Results:

• Pristine Hf0.5Zr0.5O2 films exhibit 90° domains (Pca21 phase) with head-to-tail and tail-to-tail configurations.
• After the wake-up effect, 180° domains become apparent.
• Significant differences in domain wall structures were observed, with the domain wall changing from $$ to [001] orientation.

Conclusions:

• The study elucidates the distinct nature of 90° and 180° domain walls in Hf0.5Zr0.5O2 ferroelectrics.
• This fundamental understanding of domain structures is vital for optimizing the performance of HfO2-based ferroelectric devices.