Carbon-doped quasi-bulk hexagonal boron nitride grown by HVPE

We report characterization of 4-in. diameter carbon-doped hexagonal boron nitride (h-BN:C) quasi-bulk crystals (100 μm in thickness) produced by hydride vapor-phase epitaxy. X-ray diffraction characterization results revealed that carbon incorporation enhances crystalline quality due to carbon's role in mitigating native defect formation by substituting on both the B and N sites. Photoluminescence spectroscopy demonstrated that carbon doping fundamentally alters the optical properties. While the undoped wafer exhibits a broad emission line near 3.41 eV, the carbon-doped sample displays three distinct ultraviolet lines at 4.10, 3.91, and 3.74 eV. These peaks correspond to the zero-phonon line of a carbon defect quantum emitter and its associated phonon replicas, characterized by a room-temperature radiative lifetime of approximately 0.5 ns. Although carbon is unsuitable for conventional n- or p-type doping in h-BN, carbon doping appears to be a useful tool for improving crystalline quality and enabling the control of unique properties essential for high-efficiency neutron detectors, optoelectronics, and quantum technologies.