Low-dimensional wide bandgap semiconductors open a new playing field inquantum optics using sub-bandgap excitation. In this field, hexagonal boronnitride (h-BN) has been reported to host single quantum emitters (QEs), linkingQE density to perimeters. Furthermore, curvature/perimeters in transition metaldichalcogenides (TMDCs) have demonstrated a key role in QE formation. Weinvestigate a curvature-abundant BN system - quasi one-dimensional BN nanotubes(BNNTs) fabricated via a catalyst-free method. We find that non-treated BNNT isan abundant source of stable QEs and analyze their emission features down tosingle nanotubes, comparing dispersed/suspended material. Combining highspatial resolution of a scanning electron microscope, we categorize andpin-point emission origin to a scale of less than 20 nm, giving us a one-to-onevalidation of emission source with dimensions smaller than the laser excitationwavelength, elucidating nano-antenna effects. Two emission origins emerge:hybrid/entwined BNNT. By artificially curving h-BN flakes, similar QE spectralfeatures are observed. The impact on emission of solvents used in commercialproducts and curved regions is also demonstrated. The 'out of the box'availability of QEs in BNNT, lacking processing contamination, is a milestonefor unraveling their atomic features. These findings open possibilities forprecision engineering of QEs, puts h-BN under a similar 'umbrella' of TMDC'sQEs and provides a model explaining QEs spatial localization/formation usingelectron/ion irradiation and chemical etching.
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