Journal ArticleDOI
Excited Excitonic States in 1L, 2L, 3L, and Bulk WSe2 Observed by Resonant Raman Spectroscopy
Elena del Corro,Humberto Terrones,Ana Laura Elías,Cristiano Fantini,Simin Feng,Minh An T. Nguyen,Thomas E. Mallouk,Mauricio Terrones,Marcos A. Pimenta +8 more
TLDR
A RRS study of samples of WSe2 with one, two, and three layers, as well as bulk 2H-WSe2, using up to 20 different laser lines covering the visible range shows that Raman enhancement is much stronger for the excited A' and B' states.Abstract:
Resonant Raman spectroscopy (RRS) is a very useful tool to study physical properties of materials since it provides information about excitons and their coupling with phonons. We present in this work a RRS study of samples of WSe2 with one, two, and three layers (1L, 2L, and 3L), as well as bulk 2H-WSe2, using up to 20 different laser lines covering the visible range. The first- and second-order Raman features exhibit different resonant behavior, in agreement with the double (and triple) resonance mechanism(s). From the laser energy dependence of the Raman intensities (Raman excitation profile, or REP), we obtained the energies of the excited excitonic states and their dependence with the number of atomic layers. Our results show that Raman enhancement is much stronger for the excited A' and B' states, and this result is ascribed to the different exciton-phonon coupling with fundamental and excited excitonic states.read more
Citations
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Beyond Graphene: Progress in Novel Two-Dimensional Materials and van der Waals Solids
TL;DR: In this paper, the authors provide a holistic overview of the different synthesis and characterization techniques, electronic and photonic device characteristics, and catalytic properties of transition metal dichalcogenides and their heterostructures, and comment on the challenges that need to be overcome for full-scale commercial implementation of this novel class of layered materials.
Journal ArticleDOI
Raman Spectroscopy Analysis of the Structure and Surface Chemistry of Ti3C2Tx MXene
Asia Sarycheva,Yury Gogotsi +1 more
TL;DR: In this article, a large family of 2D transition metal carbides and nitrides has been used for Ramaman spectroscopy of two-dimensional (2D) materials.
Journal Article
Theory of double-resonant Raman spectra in graphene: intensity and line shape of defect-induced and two-phonon bands
TL;DR: In this article, the double resonant (DR) Raman spectrum of graphene was calculated and the lines associated to both phonon-defect processes and two-phonons ones were determined.
Journal ArticleDOI
Highly Scalable, Atomically Thin WSe2 Grown via Metal–Organic Chemical Vapor Deposition
Sarah M. Eichfeld,Lorraine Hossain,Yu-Chuan Lin,Aleksander F. Piasecki,Benjamin M. Kupp,A. Glen Birdwell,Robert A. Burke,Ning Lu,Xin Peng,Jie Li,Angelica Azcatl,Stephen McDonnell,Robert M. Wallace,Moon J. Kim,Theresa S. Mayer,Joan M. Redwing,Joshua A. Robinson +16 more
TL;DR: It is shown that temperature, pressure, Se:W ratio, and substrate choice have a strong impact on the ensuing atomic layer structure, with optimized conditions yielding >8 μm size domains and a pristine van der Waals gap exists in WSe2/graphene heterostructures.
Journal ArticleDOI
Excitonic resonances in thin films of WSe2: from monolayer to bulk material
Ashish Arora,Maciej Koperski,Maciej Koperski,K. Nogajewski,Jacques Marcus,Clément Faugeras,Marek Potemski +6 more
TL;DR: In this article, optical spectroscopy studies of thin layers of the transition metal dichalcogenide WSe2, with thickness ranging from mono-to tetra-layer and in the bulk limit, are presented.
References
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Atomically thin MoS2: a new direct-gap semiconductor
TL;DR: The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,…,6 S-Mo-S monolayers have been investigated by optical spectroscopy and the effect of quantum confinement on the material's electronic structure is traced.
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Studying Disorder in Graphite-Based Systems by Raman Spectroscopy
Marcos A. Pimenta,G. Dresselhaus,Mildred S. Dresselhaus,Luiz Gustavo Cançado,Ado Jorio,Riichiro Saito +5 more
TL;DR: In this review, experimental results for the D, D' and G' bands obtained with different laser lines, and in samples with different crystallite sizes and different types of defects are presented and discussed.
Journal ArticleDOI
Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2
Weijie Zhao,Zohreh Ghorannevis,Leiqiang Chu,Minglin Toh,Christian Kloc,Ping-Heng Tan,Goki Eda +6 more
TL;DR: In this paper, the authors report differential reflectance and PL spectra of mono-to-few-layer Molybdenum disulfide (MoS2) and WSe2 that indicate that the band structure of these materials undergoes similar indirect-todirect gap transition when thinned to a single monolayer.
Journal ArticleDOI
Influence of quantum confinement on the electronic structure of the transition metal sulfide T S 2
TL;DR: In this article, it was shown that quantum confinement in layered d-electron dichalcogenides results in tuning the electronic structure at the nanoscale, and the properties of related TmS2 nanolayers (Tm = W, Nb, Re) were studied.