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Identifying the Limits of Strain Engineering in NaNbO3 Ultrathin Films
Shengwei Zeng1, Khuong Phuong Ong2, Samantha Faye Duran Solco1
1Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore.
ACS Applied Materials & Interfaces
|July 16, 2025
Summary
Epitaxial sodium niobate (NaNbO3) ultrathin films exhibit distinct ferroelectric domain structures under varying strain conditions. Strain engineering is crucial for controlling and optimizing the properties of these functional thin films.
Area of Science:
- Materials Science
- Solid State Physics
- Thin Film Technology
Background:
- Sodium niobate (NaNbO3) is a promising perovskite material with potential ferroelectric applications.
- Controlling strain in ultrathin films is critical for tuning their physical properties.
Purpose of the Study:
- To investigate the impact of epitaxial strain on the structural and ferroelectric properties of NaNbO3 ultrathin films.
- To understand the relationship between strain, growth mode, and ferroelectric domain structure.
Main Methods:
- Epitaxial growth of NaNbO3 ultrathin films on single-crystal substrates.
- High-resolution X-ray diffraction for structural analysis.
- Piezoresponse force microscopy for characterizing ferroelectric domains.
- First-principles calculations for theoretical validation.
Main Results:
- Films exhibited coherently strained states within -1.42% to 1.86% strain, transitioning to relaxed states outside this range.
- Growth mode shifted from step-flow to coalesced island growth with increasing strain relaxation.
- Compressively strained films showed single vertical ferroelectric domains, while tensile films displayed multiple domains.
Conclusions:
- Epitaxial strain significantly influences the growth mode and ferroelectric domain configuration of NaNbO3 ultrathin films.
- The findings offer insights into strain engineering for developing advanced functional thin film devices.
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