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We combine linear and non-linear optical spectroscopy at 4K with ab initio calculations to study the electronic bandstructure of MoSe2 monolayers. In 1-photon photoluminescence excitation (PLE) and reflectivity we measure a separation…

Materials Science · Physics 2015-11-05 G. Wang , I. C. Gerber , L. Bouet , D. Lagarde , A. Balocchi , M. Vidal , E. Palleau , T. Amand , X. Marie , B. Urbaszek

We study the evolution of the band-gap structure in few-layer MoTe$_2$ crystals, by means of low-temperature micro-reflectance (MR) and temperature-dependent photoluminescence (PL) measurements. The analysis of the measurements indicate…

We investigate valley exciton dynamics in MoSe2 monolayers in polarization- and time-resolved photoluminescence (PL) spectroscopy at 4K. Following circularly polarized laser excitation, we record a low circular polarization degree of the PL…

Materials Science · Physics 2015-03-19 G. Wang , E. Palleau , T. Amand , S. Tongay , X. Marie , B. Urbaszek

Geometrical confinement effect in exfoliated sheets of layered materials leads to significant evolution of energy dispersion with decreasing layer thickness. Molybdenum disulphide (MoS2) was recently found to exhibit indirect to direct gap…

Materials Science · Physics 2014-03-13 Weijie Zhao , Zohreh Ghorannevis , Leiqiang Chua , Minglin Toh , Christian Kloc , Ping-Heng Tan , Goki Eda

TMDCs have attracted a lot of attention in recent years due to their unique indirect to direct band gap transition from bulk to monolayer thickness. Strong confinement in the out-of-plane direction enhances the Coulomb potential between the…

Transition metal dichalcogenides (TMDs) are layered materials that have a semiconducting phase with many advantageous optoelectronic properties, including tightly bound excitons and spin-valley locking. In Tungsten-based TMDs, spin and…

Mesoscale and Nanoscale Physics · Physics 2022-04-27 Saroj B. Chand , John M. Woods , Enrique Mejia , Takashi Taniguchi , Kenji Watanabe , Gabriele Grosso

We experimentally demonstrate hot exciton transport in h-BN encapsulated WSe2 monolayers via spatially and temporally resolved photoluminescence measurements at room temperature. We show that the nonlinear evolution of the mean squared…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 Darwin F. Cordovilla Leon , Zidong Li , Sung Woon Jang , Parag B. Deotare

Transition metal dichalcogenide (TMD) materials have received enormous attention due to their extraodinary optical and electrical properties, among which MoS2 is the most typical one. As thickness increases from monolayer to multilayer, the…

Phonon-assisted photoluminescence (PL) in molybdenum-based two-dimensional dichalcogenides is typically weak due to the dormant phonon coupling with optically inactive momentum-dark (intervalley) excitons, unlike in tungsten-based…

Materials Science · Physics 2025-04-01 Rishabh Saraswat , Rekha Verma , Sitangshu Bhattacharya

We have investigated the exciton dynamics in transition metal dichalcogenide mono-layers using time-resolved photoluminescence experiments performed with optimized time-resolution. For MoSe2 monolayers, we measure $\tau_{rad}=1.8\pm0.2$ ps…

Materials Science · Physics 2016-05-18 C. Robert , D. Lagarde , F. Cadiz , G. Wang , B. Lassagne , T. Amand , A. Balocchi , P. Renucci , S. Tongay , B. Urbaszek , X. Marie

Many-body interactions between quasiparticles (electrons, excitons, and phonons) have led to the emergence of new complex correlated states and are at the core of condensed matter physics and material science. In low-dimensional materials,…

Optical orientation of localized/bound excitons is shown to be effectively enhanced by the application of magnetic fields as low as 20 mT in monolayer WS$_2$. At low temperatures, the evolution of the polarization degree of different…

We investigate exciton dynamics in 2H-WSe2 bilayers in time-resolved photoluminescence (PL) spectroscopy. Fast PL emission times are recorded for both the direct exciton with $\tau_{D}$ ~ 3 ps and the indirect optical transition with…

Materials Science · Physics 2014-11-07 G. Wang , X. Marie , L. Bouet , M. Vidal , A. Balocchi , T. Amand , D. Lagarde , B. Urbaszek

We performed detailed photoluminescence (PL) spectroscopy studies of three different types of single-walled carbon nanotubes (SWNTs) by using samples that contain essentially only one chiral type of SWNT, (6,5), (7,5), or (10,5). The…

Materials Science · Physics 2009-07-31 Yoichi Murakami , Benjamin Lu , Said Kazaoui , Nobutsugu Minami , Tatsuya Okubo , Shigeo Maruyama

Color centers in hexagonal boron nitride (hBN) show stable single photon emission even at room temperature, making these systems a promising candidate for quantum information applications. Besides this remarkable property, also their…

Mesoscale and Nanoscale Physics · Physics 2021-02-19 Daniel Groll , Thilo Hahn , Paweł Machnikowski , Daniel Wigger , Tilmann Kuhn

Heterostructures of layered transition metal dichalcogenides (TMDs) host long-lived, tunable excitons, making them intriguing candidates for material-based quantum information applications. Light absorption in these systems induces a…

Materials Science · Physics 2023-08-25 Tomer Amit , Sivan Refaely-Abramson

Two-dimensional semiconductors exhibit pronounced many-body effects and intense optical responses due to strong coulombic interactions. Consequently, subtle differences in photoexcitation conditions can strongly influence how the material…

Developments in optoelectronics and spin-optronics based on transition metal dichalcogenide monolayers (MLs) need materials with efficient optical emission and well-defined transition energies. In as-exfoliated MoS2 MLs the…

Tungsten-based monolayer transition metal dichalcogenides host a long-lived dark exciton, an electron-hole pair in a spin-triplet configuration. The long lifetime and unique spin properties of the dark exciton provide exciting opportunities…

Monolayer transition metal dichalcogenides, known for exhibiting strong excitonic resonances, constitute a very interesting and versatile platform for investigation of light-matter interactions. In this work we report on a strong coupling…

Mesoscale and Nanoscale Physics · Physics 2019-05-20 M. Król , K. Lekenta , R. Mirek , K. Łempicka , D. Stephan , K. Nogajewski , M. R. Molas , A. Babiński , M. Potemski , J. Szczytko , B. Piętka