Vacancy Formation and Clustering Behavior in δ-MoN: A Systematic Density Functional Theory Study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Molybdenum nitrides (MoN) exhibit desirable physical properties due to their unique electronic structure.
• Synthesized MoN often contains structural defects, specifically metal (Mo) or non-metal (N) vacancies, impacting performance.

Purpose of the Study:

• To theoretically investigate the formation and impact of vacancies in delta-phase Molybdenum Nitride (δ-MoN) using density functional theory.
• To analyze the electronic structure changes and vacancy clustering behavior in δ-MoN.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Construction and systematic study of various single, double, and triple vacancy configurations in δ-MoN.
• Analysis of electron distribution, vacancy binding energies, and electronic conductivity.

Main Results:

• Molybdenum vacancies (V_Mo) lead to localized electron loss, while Nitrogen vacancies (V_N) result in trapped excess electrons forming an electron gas.
• Four types of vacancy binding clusters were identified: V_Mo-V_N, V_N-V_Mo-V_N (sandwich), V_N-V_N, and V_N-V_N-V_N.
• Both Mo and N vacancies induce anisotropic degradation of electronic conductivity, dependent on vacancy type and concentration.

Conclusions:

• Vacancy formation significantly alters the electronic landscape of δ-MoN, influencing its conductive properties.
• Understanding vacancy clustering and their electronic effects is crucial for tailoring MoN materials for specific applications.
• The study provides theoretical insights into defect engineering for optimizing molybdenum nitride-based devices.