Single photon emitters in hBN: Limitations of atomic resolution imaging and potential sources of error
Abstract
There is a growing interest in identifying the origin of single-photon emission in hexagonal boron nitride (hBN), with proposed candidates including boron and nitrogen vacancies as well as carbon substitutional dopants. Because photon emission intensity often increases with sample thickness, hBN flakes used in these studies commonly exceed 30 atomic layers. To identify potential emitters at the atomic scale, annular dark-field scanning transmission electron microscopy (ADF-STEM) is frequently employed. However, due to the intrinsic AA’ stacking of hBN with vertically alternating boron and nitrogen atoms, this approach is complicated even in few-layer systems. Here, we demonstrate using STEM image simulations and experiments that, even under idealized conditions, the intensity differences between boron- and nitrogen-dominated columns and carbon substitutions become indistinguishable at thicknesses beyond 17 atomic layers (ca. 6 nm). While vacancy-type defects can remain detectable at somewhat larger thicknesses, also their detection becomes unreliable at thicknesses typically used in photonic studies. We further show that common residual aberrations, particularly threefold astigmatism, can lead to artificial contrast differences between columns, which may result in misidentification of atomic defects. We systematically study the effects of non-radially symmetric aberrations on multilayer hBN and demonstrate that even small residual threefold astigmatism can significantly distort the STEM contrast, leading to misleading interpretations. • Single atomic defects are not detectable with ADF-STEM in near-bulk hBN. • The appearance of B/N contrast in thick hBN samples is an artifact of aberrations. • Image processing, contamination and instrumental limitations have to be considered. • For proper correlation of atomic structures and optical properties advanced methodologies are needed.
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BibTeX
@article{lamprecht2026single,
title = {{Single photon emitters in hBN: Limitations of atomic resolution imaging and potential sources of error}},
author = {David Lamprecht and Shrirang Chokappa and Alissa Freilinger and Barbara Maria Mayer and Maximilian Melchior and Jana Dzíbelová and Darwin Lorber and Luiz H.G. Tizei and Mathieu Kociak and Clemens Mangler and Lado Filipovic and Jani Kotakoski},
journal = {Ultramicroscopy},
year = {2026},
month = sep,
doi = {10.1016/j.ultramic.2026.114318},
eprint = {2511.03674},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05761689v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Single photon emitters in hBN: Limitations of atomic resolution imaging and potential sources of error
AU - David Lamprecht
AU - Shrirang Chokappa
AU - Alissa Freilinger
AU - Barbara Maria Mayer
AU - Maximilian Melchior
AU - Jana Dzíbelová
AU - Darwin Lorber
AU - Luiz H.G. Tizei
AU - Mathieu Kociak
AU - Clemens Mangler
AU - Lado Filipovic
AU - Jani Kotakoski
PY - 2026
DA - 2026/09/23
JO - Ultramicroscopy
DO - 10.1016/j.ultramic.2026.114318
UR - https://hal.science/hal-05761689v1
AB - There is a growing interest in identifying the origin of single-photon emission in hexagonal boron nitride (hBN), with proposed candidates including boron and nitrogen vacancies as well as carbon substitutional dopants. Because photon emission intensity often increases with sample thickness, hBN flakes used in these studies commonly exceed 30 atomic layers. To identify potential emitters at the atomic scale, annular dark-field scanning transmission electron microscopy (ADF-STEM) is frequently employed. However, due to the intrinsic AA’ stacking of hBN with vertically alternating boron and nitrogen atoms, this approach is complicated even in few-layer systems. Here, we demonstrate using STEM image simulations and experiments that, even under idealized conditions, the intensity differences between boron- and nitrogen-dominated columns and carbon substitutions become indistinguishable at thicknesses beyond 17 atomic layers (ca. 6 nm). While vacancy-type defects can remain detectable at somewhat larger thicknesses, also their detection becomes unreliable at thicknesses typically used in photonic studies. We further show that common residual aberrations, particularly threefold astigmatism, can lead to artificial contrast differences between columns, which may result in misidentification of atomic defects. We systematically study the effects of non-radially symmetric aberrations on multilayer hBN and demonstrate that even small residual threefold astigmatism can significantly distort the STEM contrast, leading to misleading interpretations. • Single atomic defects are not detectable with ADF-STEM in near-bulk hBN. • The appearance of B/N contrast in thick hBN samples is an artifact of aberrations. • Image processing, contamination and instrumental limitations have to be considered. • For proper correlation of atomic structures and optical properties advanced methodologies are needed.
SN - 0304-3991
ER -