Atomic localization of quantum emitters in multilayer hexagonal boron nitride

The recent discovery of single-photon emitting defects hosted by the two-dimensional wide band gap semiconductor hexagonal boron nitride (hBN) has inspired a great number of experiments. Key characteristics of these quantum emitters are their capability to operate at room temperature with a high lum...

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Bibliographic Details
Published in:Nanoscale 2019-08, Vol.11 (3), p.14362-14371
Main Authors: Vogl, Tobias, Doherty, Marcus W, Buchler, Ben C, Lu, Yuerui, Lam, Ping Koy
Format: Article
Language:English
Subjects:
Boron nitride
Crystal defects
Crystal surfaces
Density functional theory
Electron irradiation
Emitters (electron)
Kinetic energy
Localization
Luminosity
Multilayers
Photonic band gaps
Surface defects
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Summary:The recent discovery of single-photon emitting defects hosted by the two-dimensional wide band gap semiconductor hexagonal boron nitride (hBN) has inspired a great number of experiments. Key characteristics of these quantum emitters are their capability to operate at room temperature with a high luminosity. In spite of large theoretical and experimental research efforts, the exact nature of the emission remains unresolved. In this work we utilize layer-by-layer etching of multilayer hBN to localize the quantum emitters with atomic precision. Our results suggest the position of the emitters correlates with the fabrication method: emitters formed under plasma treatment are always in close proximity to the crystal surface, while emitters created under electron irradiation are distributed randomly throughout the entire crystal. This disparity could be traced back to the lower kinetic energy of the ions in the plasma compared to the kinetic energy of the electrons in the particle accelerator. The emitter distance to the surface also correlates with the excited state lifetime: near-surface emitters have a shorter one compared to emitters deep within the crystal. Finite-difference time-domain and density functional theory simulations show that optical and electronic effects are not responsible for this difference, indicating effects such as coupling to surface defects or phonons might cause the reduced lifetime. Our results pave a way toward identification of the defect, as well as engineering the emitter properties. The atomic plasma etching removes one hBN monolayer at a time. After some etching step, the quantum emitter disappears.
ISSN:2040-3364
2040-3372
DOI:10.1039/c9nr04269e