Divacancies in diamond: a stepwise formation mechanism

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Monovacancy diffusion in diamond leads to multivacancy clusters.
• Divacancy (V2) formation is a key step in creating larger vacancy clusters.
• Understanding vacancy behavior is crucial for applications like NV-centers in diamond.

Purpose of the Study:

• To explore the potential energy surfaces for divacancy formation in diamond.
• To determine the structures, energies, diffusion barriers, and reaction pathways for V2 formation.
• To investigate the stability and transformation of novel divacancy configurations.

Main Methods:

• Utilizing ab initio density functional theory (DFT) calculations.
• Analyzing relaxed potential energy surfaces.
• Characterizing defect structures, relative energies, and diffusion barriers.

Main Results:

• Identified unusual carbon-carbon bonding with multicenter character in the diamond lattice.
• Found that divacancies separated by a single carbon atom are unstable.
• A novel isolated divacancy [V-C=C-V] has a high transformation barrier (>4.3 eV) to V2 formation.
• Divacancy formation impacts the development of NV-defects in nitrogen-implanted diamond.

Conclusions:

• The V-C=C-V defect is a stable, observable defect in irradiated diamonds due to its high transformation barrier.
• Divacancy formation significantly influences NV-defect development, relevant for diamond-based technologies.
• DFT provides crucial insights into vacancy behavior and defect formation in diamond.