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Abstract A key advantage of utilizing van‐der‐Waals (vdW) materials as defect‐hosting platforms for quantum applications is the controllable proximity of the defect to the surface or the substrate allowing for improved light extraction, enhanced coupling with photonic elements, or more sensitive metrology. However, this aspect results in a significant challenge for defect identification and characterization, as the defect's properties depend on the the atomic environment. This study explores how the environment can influence the properties of carbon impurity centers in hexagonal boron nitride (hBN). It compares the optical and electronic properties of such defects between bulk‐like and few‐layer films, showing alteration of the zero‐phonon line energies and their phonon sidebands, and enhancements of inhomogeneous broadenings. To disentangle the mechanisms responsible for these changes, including the atomic structure, electronic wavefunctions, and dielectric screening, it combines ab initio calculations with a quantum‐embedding approach. By studying various carbon‐based defects embedded in monolayer and bulk hBN, it demonstrates that the dominant effect of the change in the environment is the screening of density–density Coulomb interactions between the defect orbitals. The comparative analysis of experimental and theoretical findings paves the way for improved identification of defects in low‐dimensional materials and the development of atomic scale sensors for dielectric environments.
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This content will become publicly available on June 3, 2026
Direct Observation of Optically Active Mid‐Gap Electronic States in Hexagonal Boron Nitride by Electron Spectroscopy
Abstract Optically active point defects in wide‐bandgap semiconductors have been demonstrated to be attractive for a variety of quantum and nanoscale applications. In particular, color centers in hexagonal boron nitride (hBN) have recently gained substantial attention owing to their spectral tunability, brightness, stability, and room‐temperature operation. Despite all of the recent studies, precise detection of the defect‐induced mid‐gap electronic states (MESs) and their simultaneous correlations with the observed emission in hBN remain elusive. Directly probing these MESs provides a powerful approach toward atomic identification and optical control of the defect centers underlying the sub‐bandgap emission in hBN. Combining optical and electron spectroscopy, the existence of mid‐gap absorptive features is revealed at the emissive sites in hBN, along with an atom‐by‐atom identification of the underlying defect configuration. The atomically resolved defect structure, primarily constituted by vacancies and carbon/oxygen substitutions, is further studied via first‐principles calculations, which support the correlation with the observed MESs through the electronic density of states. This work provides a direct relationship between the observed visible emission in hBN, the underlying defect structure, and its absorptive MESs, opening venues for atomic‐scale and optical control in hBN for quantum technology.
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- Award ID(s):
- 2237674
- PAR ID:
- 10602517
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 37
- Issue:
- 33
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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