Optical identification of sulfur vacancies: Bound excitons at the edges of monolayer tungsten disulfide.
Victor Carozo,Yuanxi Wang,Kazunori Fujisawa,Bruno R. Carvalho,Bruno R. Carvalho,Amber McCreary,Simin Feng,Zhong Lin,Chanjing Zhou,Nestor Perea-Lopez,Ana Laura Elías,Bernd Kabius,Vincent H. Crespi,Mauricio Terrones +13 more
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TLDR
It is demonstrated that bound-exciton emission induced by monosulfur vacancies is concentrated near the edges of as-grown monolayer tungsten disulfide.Abstract:
Defects play a significant role in tailoring the optical properties of two-dimensional materials. Optical signatures of defect-bound excitons are important tools to probe defective regions and thus interrogate the optical quality of as-grown semiconducting monolayer materials. We have performed a systematic study of defect-bound excitons using photoluminescence (PL) spectroscopy combined with atomically resolved scanning electron microscopy and first-principles calculations. Spatially resolved PL spectroscopy at low temperatures revealed bound excitons that were present only on the edges of monolayer tungsten disulfide and not in the interior. Optical pumping of the bound excitons was sublinear, confirming their bound nature. Atomic-resolution images reveal that the areal density of monosulfur vacancies is much larger near the edges (0.92 ± 0.45 nm−2) than in the interior (0.33 ± 0.11 nm−2). Temperature-dependent PL measurements found a thermal activation energy of ~36 meV; surprisingly, this is much smaller than the bound-exciton binding energy of ~300 meV. We show that this apparent inconsistency is related to a thermal dissociation of the bound exciton that liberates the neutral excitons from negatively charged point defects. First-principles calculations confirm that sulfur monovacancies introduce midgap states that host optical transitions with finite matrix elements, with emission energies ranging from 200 to 400 meV below the neutral-exciton emission line. These results demonstrate that bound-exciton emission induced by monosulfur vacancies is concentrated near the edges of as-grown monolayer tungsten disulfide.read more
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Group 6 transition metal dichalcogenide nanomaterials: synthesis, applications and future perspectives
TL;DR: All aspects of the basic science, physicochemical properties and characterization techniques as well as all existing production methods and applications of G6-TMD nanomaterials are provided in a comprehensive yet concise treatment.
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Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides.
Sara Barja,Sivan Refaely-Abramson,Sivan Refaely-Abramson,Sivan Refaely-Abramson,Bruno Schuler,Diana Y. Qiu,Diana Y. Qiu,Artem Pulkin,Sebastian Wickenburg,Hyejin Ryu,Hyejin Ryu,Miguel M. Ugeda,Miguel M. Ugeda,Miguel M. Ugeda,Christoph Kastl,Christopher T. Chen,Choongyu Hwang,Adam M. Schwartzberg,Shaul Aloni,Sung-Kwan Mo,D. Frank Ogletree,Michael F. Crommie,Michael F. Crommie,Oleg V. Yazyev,Steven G. Louie,Steven G. Louie,Jeffrey B. Neaton,Jeffrey B. Neaton,Alexander Weber-Bargioni +28 more
TL;DR: The authors determine the atomic structure and electronic properties of chalcogen-site point defects common to monolayer MoSe2 and WS2, and find that these are substitutional defects, where a chalCogen atom is substituted by an oxygen atom, rather than vacancies.
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Defect Structure of Localized Excitons in a WSe 2 Monolayer
Shuai Zhang,Chen-Guang Wang,Ming-Yang Li,Ming-Yang Li,Di Huang,Lain-Jong Li,Wei Ji,Shiwei Wu +7 more
TL;DR: This work provided the first atomic-scale understanding of defect excitons and paved the way toward deciphering the defect structure of single quantum emitters previously discovered in the WSe_{2} monolayer.
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Exciton Dynamics, Transport, and Annihilation in Atomically Thin Two-Dimensional Semiconductors
TL;DR: The exciton-exciton annihilation process in single-layer TMDCs is highly efficient, playing an important role in the nonradiative recombination rate in the high exciton density regime.
Journal ArticleDOI
Site-selectively generated photon emitters in monolayer MoS2 via local helium ion irradiation
Julian Klein,Michael Lorke,Matthias Florian,Florian Sigger,Florian Sigger,Lukas Sigl,Sergio Rey,Jakob Wierzbowski,J. Cerne,Kai Müller,Elmar Mitterreiter,Philipp Zimmermann,T. Taniguchi,Kenji Watanabe,Ursula Wurstbauer,Ursula Wurstbauer,Michael Kaniber,Michael Kaniber,Michael Knap,Richard Schmidt,Jonathan J. Finley,Jonathan J. Finley,Alexander W. Holleitner,Alexander W. Holleitner +23 more
TL;DR: In this article, the authors used a sub-nm focused helium ion beam to deterministically write optically active defect states in a single transition metal dichalcogenide layer and obtain spectrally narrow emission lines that produce photons in the visible spectral range.
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