Exciton Self-Trapping in Twisted Hexagonal Boron Nitride homostructures

One of the main interests of 2D materials is their ability to be assembled with many degrees of freedom for tuning and manipulating excitonic properties. There is a need to understand how the structure of the interfaces between atomic layers influences exciton properties. Here we use cathodoluminescence and time-resolved cathodoluminescence experiments to study how excitons interact with the interface between two twisted hexagonal boron nitride (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>h</a:mi></a:mrow></a:math>-BN) crystals with various angles. An efficient capture of free excitons by the interface is demonstrated, which leads to a population of long-lived and interface-localized (2D) excitons. Temperature-dependent experiments indicate that for high twist angles, these excitons localized at the interface further undergo a self-trapping. It consists in a distortion of the lattice around the exciton on which the exciton traps itself. Our results suggest that this exciton-interface interaction causes the broad 4-eV optical emission of highly twisted <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mi>h</c:mi></c:mrow></c:math>-BN–<e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mi>h</e:mi></e:mrow></e:math>-BN structures. Exciton self-trapping is finally discussed as a common feature of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>s</g:mi><g:msup><g:mi>p</g:mi><g:mn>2</g:mn></g:msup></g:math> hybridized boron nitride polytypes and nanostructures due to the ionic nature of the B—N bond and the small size of their excitons.

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Publication Details

Journal
Physical Review X
Published
2025-05-27
DOI
https://doi.org/10.1103/physrevx.15.021067
Citations
2
Primary Topic
2D Materials and Applications
Type
article
Field-Weighted Citation Impact
1.04

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article

Exciton Self-Trapping in Twisted Hexagonal Boron Nitride homostructures

Camille Maestre, Eli Janzen, Bérangère Toury, Lei Ren et al.
2 citations
Physical Review X
2D Materials and Applications
1.04
article

Exciton Self-Trapping in Twisted Hexagonal Boron Nitride homostructures

Camille Maestre, Eli Janzen, Bérangère Toury, Lei Ren, James H. Edgar, Frédéric Fossard, Catherine Journet, Takashi Taniguchi, Kenji Watanabe, X. Marie, Christophe Arnold, Nicolas Horezan, Philippe Steyer, Vincent Garnier, Etienne Carré, Sébastien Roux, Annick Loiseau, Cédric Robert, F. Ducastelle, Julien Barjon, Alexandre Plaud
article en
2 citations

Abstract

One of the main interests of 2D materials is their ability to be assembled with many degrees of freedom for tuning and manipulating excitonic properties. There is a need to understand how the structure of the interfaces between atomic layers influences exciton properties. Here we use cathodoluminescence and time-resolved cathodoluminescence experiments to study how excitons interact with the interface between two twisted hexagonal boron nitride (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>h</a:mi></a:mrow></a:math>-BN) crystals with various angles. An efficient capture of free excitons by the interface is demonstrated, which leads to a population of long-lived and interface-localized (2D) excitons. Temperature-dependent experiments indicate that for high twist angles, these excitons localized at the interface further undergo a self-trapping. It consists in a distortion of the lattice around the exciton on which the exciton traps itself. Our results suggest that this exciton-interface interaction causes the broad 4-eV optical emission of highly twisted <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mi>h</c:mi></c:mrow></c:math>-BN–<e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mi>h</e:mi></e:mrow></e:math>-BN structures. Exciton self-trapping is finally discussed as a common feature of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>s</g:mi><g:msup><g:mi>p</g:mi><g:mn>2</g:mn></g:msup></g:math> hybridized boron nitride polytypes and nanostructures due to the ionic nature of the B—N bond and the small size of their excitons.

Physical Review XVol. 15(2)
Université Claude Bernard Lyon 1 (FR), Université Fédérale de Toulouse Midi-Pyrénées (FR), Kansas State University (US), National Institute for Materials Science (JP), Université Paris-Saclay (FR), Matériaux Ingénierie et Science (FR)
Equipex, European Commission, Agence Nationale de la Recherche, Ministry of Education, Culture, Sports, Science and Technology, Horizon 2020 Framework Programme, Japan Society for the Promotion of Science, Office of Naval Research
Openalex Percentile: Top 25%
2D Materials and Applications
1.04
DOIOpen Access PDFOpenAlex
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