Defect Engineering in Hexagonal Boron Nitride: Optical Properties of Stable Defect Complexes Arising from Boron...

Area of Science:

• Materials Science
• Quantum Physics
• Solid-State Physics

Background:

• Hexagonal boron nitride (hBN) is a wide-band-gap semiconductor with potential for quantum technologies.
• Defect engineering in hBN, specifically boron vacancies and interstitials, is crucial for developing quantum emitters.
• The optical properties of boron-interstitial defects remain largely unexplored compared to boron vacancies.

Purpose of the Study:

• To computationally investigate the electronic and optical properties of boron interstitials (B_int) and their complexes with carbon impurities in hBN.
• To assess the stability and suitability of these B_int-related defects as single-photon emitters.
• To provide theoretical insights into recently observed blue emitters in hBN.

Main Methods:

• First-principles calculations, including GW-Bethe-Salpeter equation (BSE) and constrained density functional theory (DFT).
• Prediction of electronic band structures and optical transition energies.
• Evaluation of defect stability and zero-phonon line energies.

Main Results:

• Boron interstitials (B_int) form stable complexes with substitutional carbon (C_B and C_N) at room temperature.
• B_int-C_B and B_int-C_N complexes exhibit isolated, low-energy optical transitions, suitable for single-photon emission.
• Predicted zero-phonon lines for B_int-C_B and B_int-C_N are approximately 2.0 eV and 2.6 eV, respectively.
• These defects are proposed as the source of recently observed blue emitters in hBN.

Conclusions:

• Defects involving boron interstitials and carbon impurities are stable and possess optical properties suitable for single-photon emission.
• These B_int-related defects offer a new pathway for intentionally creating quantum emitters in hBN.
• The findings provide a theoretical basis for understanding blue emitters in hBN and advance the development of solid-state quantum technologies.