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Article Dans Une Revue Physical Review B Année : 2018

Optical gap and optically active intragap defects in cubic BN

Résumé

We report a comprehensive study on the optical properties of cubic boron nitride (c-BN) and its optically active defects. Using electron energy-loss spectroscopy (EELS) within a monochromated scanning transmission electron microscope (STEM) on the highest-quality crystals available, we demonstrate unequivocally that the optical-gap energy of c-BN slightly exceeds 10 eV. Further theoretical analysis in the framework of the Bethe-Salpeter equation of many-body perturbation theory supports this result. The spatial localization of defect-related emissions has been investigated using nanometric resolved cathodoluminescence (nano-CL) in a STEM. By high-temperature annealing a c-BN powder, we have promoted phase transitions in nanometric domains which have been detected by the appearance of specific hexagonal-phase signatures in both EELS and CL spectra. A high number of intragap optically active centers are known in c-BN, but the literature is rather scattered and hence has been summarized here. For several emission lines we have obtained nano-CL maps which show emission spot sizes as small as few tens of nanometers. Finally, by coupling nano-CL to a Hanbury-Brown-Twiss intensity interferometer, we have addressed individual spots in order to identify the possible presence of single-photon sources. The observed CL bunching effect is compatible with a limited set of single-photon emitters and it permits obtaining emission lifetimes of the order of the nanosecond.
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Dates et versions

hal-02301034 , version 1 (23-01-2024)

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Anna Tararan, Stefano Di Sabatino, Matteo Gatti, Takashi Taniguchi, Kenji Watanabe, et al.. Optical gap and optically active intragap defects in cubic BN. Physical Review B, 2018, 98 (9), pp.094106. ⟨10.1103/PhysRevB.98.094106⟩. ⟨hal-02301034⟩
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