Dangling Bonds in Hexagonal Boron Nitride as Single-Photon Emitters

Hexagonal boron nitride has been found to host color centers that exhibit single-photon emission, but the microscopic origin of these emitters is unknown. We propose boron dangling bonds as the likely source of the observed single-photon emission around 2 eV. An optical transition where an electron...

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Bibliographic Details
Published in:Physical review letters 2019-09, Vol.123 (12), p.1-127401, Article 127401
Main Authors: Turiansky, Mark E., Alkauskas, Audrius, Bassett, Lee C., Van de Walle, Chris G.
Format: Article
Language:English
Subjects:
Absorptivity
Atomic energy levels
Boron
Boron nitride
Color centers
Conduction bands
Dipoles
Emitters
Emitters (electron)
Excitation
Linear polarization
Misalignment
Optical transition
Photon emission
Photons
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Summary:Hexagonal boron nitride has been found to host color centers that exhibit single-photon emission, but the microscopic origin of these emitters is unknown. We propose boron dangling bonds as the likely source of the observed single-photon emission around 2 eV. An optical transition where an electron is excited from a doubly occupied boron dangling bond to a localized B pz state gives rise to a zero-phonon line of 2.06 eV and emission with a Huang-Rhys factor of 2.3. This transition is linearly polarized with the absorptive and emissive dipole aligned. Because of the energetic position of the states within the band gap, indirect excitation through the conduction band will occur for sufficiently large excitation energies, leading to the misalignment of the absorptive and emissive dipoles seen in experiment. Our calculations predict a singlet ground state and the existence of a metastable triplet state, in agreement with experiment.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.123.127401