Mapping Ferroelectric Fields Reveals the Origins of the Coercivity Distribution

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Accurate imaging of ferroelectric polarization is crucial for developing novel ferroelectric materials and optimizing existing ones.
• Current techniques for imaging ferroelectric polarization can be complex and lack straightforward interpretability.

Purpose of the Study:

• To introduce and validate a new imaging technique for ferroelectric polarization using scanning transmission electron microscope electron beam-induced current (STEM EBIC).
• To demonstrate the capability of STEM EBIC for characterizing ferroelectric materials and devices at various scales.

Main Methods:

• Utilized scanning transmission electron microscope (STEM) electron beam-induced current (EBIC) imaging to visualize ferroelectric polarization.
• Performed in situ polarization measurements using the positive-up, negative-down (PUND) method on hafnium zirconium oxide (HZO) capacitors.
• Mapped coercive fields and background electric fields within ferroelectric domains.

Main Results:

• STEM EBIC imaging revealed ferroelectric polarization with clear, easily interpretable contrast.
• The EBIC response showed a linear relationship with polarization determined by the PUND method.
• The technique proved magnification-independent, effective on both microscale devices and nanoscale domains.
• Coercive-field mapping indicated domain bias rather than switching ease, with isolatable remanent background fields.

Conclusions:

• STEM EBIC imaging is a revolutionary tool for characterizing ferroelectric materials and devices, offering direct visualization of polarization.
• The technique provides calibrated contrast and magnification-independent operation, suitable for diverse scales.
• It enables detailed analysis of domain bias and background electric fields, crucial for understanding ferroelectric behavior.