Hidden structural phase transition assisted ferroelectric domain orientation engineering in Hf_0.5Zr_0.5O₂ films

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Polarization in HfO2-based ferroelectrics is typically controlled by phase content, specifically the metastable orthorhombic phase during tetragonal to monoclinic transitions.
• Modulating ferroelectric domain orientations offers an alternative, yet underexplored, pathway to control polarization.

Purpose of the Study:

• To investigate a hidden tetragonal-orthorhombic phase transition pathway in polycrystalline Hf0.5Zr0.5O2.
• To engineer domain orientations and enhance polarization by utilizing single-crystalline TiN substrates.

Main Methods:

• Utilizing single-crystalline TiN substrates (001, 111, 110) to grow polycrystalline Hf0.5Zr0.5O2 films.
• Analyzing the role of periodic dislocations at the TiN/Hf0.5Zr0.5O2 interface in facilitating phase transitions.
• Controlling the orientation of orthorhombic domains ((001)O and/or (010)O) contributing to remanent polarization.

Main Results:

• A hidden tetragonal-orthorhombic phase transition pathway was uncovered, enabling control over domain orientations.
• Specific domain orientations ((001)O and/or (010)O) were successfully controlled on TiN (001) and (111) substrates.
• Enhanced remanent polarization was achieved compared to films grown on TiN (110) substrates, attributed to the modulation of domain orientations.

Conclusions:

• The study demonstrates that controlling polarization in Hf0.5Zr0.5O2 films can be achieved by engineering interface dislocations and subsequent domain orientations.
• This work provides a novel approach to tune ferroelectric properties by exploiting hidden phase transition pathways.
• Findings offer insights into advanced strategies for designing high-performance ferroelectric devices.