Defect Engineering in Large-Scale CVD-Grown Hexagonal Boron Nitride: Formation, Spectroscopy, and Spin Relaxation...

Area of Science:

• Quantum photonics
• Materials science
• Solid-state physics

Background:

• Optically active defects in hexagonal boron nitride (hBN) are crucial for quantum photonic devices.
• Scalable, on-demand generation of desired defect types in hBN films remains a significant challenge.

Purpose of the Study:

• To investigate the on-demand generation of negative boron vacancy defects (V_B^-) in large-area chemical vapor deposition (CVD)-grown hBN.
• To understand the influence of bombarding particles and irradiation conditions on defect formation.
• To differentiate between various optically active and dark paramagnetic defect types.

Main Methods:

• Irradiation of suspended and substrate-supported hBN films with ions, neutrons, and electrons.
• Spectroscopic analysis and optically detected magnetic resonance (ODMR) measurements.
• Correlation of defect properties with optical emission wavelengths and spin parameters.

Main Results:

• Defect formation in suspended hBN is highly dependent on the type of bombarding particles and irradiation parameters.
• Substrate-supported hBN defect formation is complex, influenced by substrate-generated secondary particles and hBN thickness.
• Boron vacancies (V_B^-) emitting at 800 nm were distinguished from anti-site nitrogen vacancy defects (N_BV_N) emitting at 650 nm.
• "Dark" paramagnetic defects were identified, impacting spin-lattice relaxation time (T₁) and zero-field splitting.

Conclusions:

• Precise engineering of defect formation in large-scale CVD-grown hBN is achievable.
• The findings pave the way for the scalable fabrication of quantum photonic devices using tailored defects in hBN.