Excellent Ferroelectricity and Thermal Stability in Ce-Doped HfO₂ Thin Films via Oxygen Vacancy Modulation

Area of Science:

• Materials Science
• Solid State Physics
• Thin Film Technology

Background:

• Hafnium oxide (HfO2) thin films are crucial for modern electronics.
• Stabilizing metastable phases like orthorhombic HfO2 is challenging.
• Controlling oxygen vacancy (VO) concentration is key to tuning HfO2 properties.

Purpose of the Study:

• To introduce cerium (Ce) doping as a method to stabilize the orthorhombic phase in HfO2.
• To investigate the role of Ce doping in regulating oxygen vacancy concentration.
• To evaluate the ferroelectric performance of Ce-doped HfO2 for high-temperature applications.

Main Methods:

• First-principles calculations to guide material design.
• Chemical solution deposition for preparing Ce-doped HfO2 thin films.
• Characterization of structural, electrical, and ferroelectric properties.

Main Results:

• Ce doping effectively stabilizes the orthorhombic phase of HfO2.
• Optimized Ce0.2Hf0.8O2 films show high remanent polarization (2Pr ≈ 45 μC/cm²) and low coercive field (Ec ≈ 1.08 MV/cm).
• The films exhibit excellent endurance (>10^10 cycles), retention (94.8%), and stable ferroelectricity up to 200 °C.

Conclusions:

• Ce doping provides a controllable route to enhance the stability and ferroelectric performance of HfO2 thin films.
• Ce-doped HfO2 demonstrates significant potential for high-temperature nonvolatile memory devices.
• This approach offers a pathway for designing advanced HfO2-based materials.