Polaronic defects in monolayer CeO₂: Quantum confinement effect and strain engineering.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Polaronic defects significantly influence the electronic properties of oxide materials.
• Understanding defects in ultrathin films is crucial for nanoscale device applications.

Purpose of the Study:

• To investigate the structure, stability, and electronic properties of polaronic defects in monolayer cerium dioxide (ML CeO2).
• To explore the impact of quantum confinement and epitaxial strain on these defects.

Main Methods:

• First-principles calculations were employed to model defect behavior.
• Analysis focused on polaronic defects, oxygen vacancies (Vo2+), and their complexes in ML CeO2.

Main Results:

• Polarons are more stabilized in ML CeO2 compared to bulk.
• Formation of oxygen vacancies and polaron-vacancy complexes is more difficult in ML CeO2.
• Defect states are deeper within the bandgap of ML CeO2.
• Epitaxial tensile strain reduces formation energies, enabling strain- and temperature-controlled defect concentrations.

Conclusions:

• Monolayer ceria exhibits unique polaronic defect characteristics due to quantum confinement.
• Epitaxial strain is a key factor in tuning defect energetics and electronic structures in ceria films.
• Findings offer insights for potential applications in nanoelectronics, fuel cells, and catalysis.