scholarly journals Room Temperature Terahertz Electroabsorption Modulation by Excitons in Monolayer Transition Metal Dichalcogenides

Nano Letters ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 5214-5220
Author(s):  
Jiaojian Shi ◽  
Edoardo Baldini ◽  
Simone Latini ◽  
Shunsuke A. Sato ◽  
Yaqing Zhang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Metal Dichalcogenides

scholarly journals Intrinsic lifetime of higher excitonic states in tungsten diselenide monolayers

Nanoscale ◽  
2019 ◽  
Vol 11 (25) ◽  
pp. 12381-12387 ◽  
Author(s):  
Samuel Brem ◽  
Jonas Zipfel ◽  
Malte Selig ◽  
Archana Raja ◽  
Lutz Waldecker ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Optical Spectra ◽  
Tungsten Diselenide ◽  
Dielectric Screening ◽  
Metal Dichalcogenides ◽  
Excitonic States

The reduced dielectric screening in atomically thin transition metal dichalcogenides allows to study the hydrogen-like series of higher exciton states in optical spectra even at room temperature.

scholarly journals Valley-Selective Response of Nanostructures Coupled to 2D Transition-Metal Dichalcogenides

2018 ◽  
Vol 8 (7) ◽  
pp. 1157 ◽  
Author(s):  
Alexander Krasnok ◽  
Andrea Alù
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
State Of The Art ◽  
Transition Metal Dichalcogenides ◽  
Zone Boundary ◽  
Brillouin Zone Boundary ◽  
Directional Emission ◽  
Metal Dichalcogenides ◽  
On Chip ◽  
Valley Hall Effect

Monolayer (1L) transition-metal dichalcogenides (TMDCs) are attractive materials for several optoelectronic applications because of their strong excitonic resonances and valley-selective response. Valley excitons in 1L-TMDCs are formed at opposite points of the Brillouin zone boundary, giving rise to a valley degree of freedom that can be treated as a pseudospin, and may be used as a platform for information transport and processing. However, short valley depolarization times and relatively short exciton lifetimes at room temperature prevent using valley pseudospins in on-chip integrated valley devices. Recently, it was demonstrated how coupling these materials to optical nanoantennas and metasurfaces can overcome this obstacle. Here, we review the state-of-the-art advances in valley-selective directional emission and exciton sorting in 1L-TMDC mediated by nanostructures and nanoantennas. We briefly discuss the optical properties of 1L-TMDCs paying special attention to their photoluminescence/absorption spectra, dynamics of valley depolarization, and the valley Hall effect. Then, we review recent works on nanostructures for valley-selective directional emission from 1L-TMDCs.

scholarly journals Optically initialized robust valley-polarized holes in monolayer WSe2

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Wei-Ting Hsu ◽  
Yen-Lun Chen ◽  
Chang-Hsiao Chen ◽  
Pang-Shiuan Liu ◽  
Tuo-Hung Hou ◽  
...  
Keyword(s):  
Transition Metal ◽  
Low Temperatures ◽  
Room Temperature ◽  
Optical Pumping ◽  
Transition Metal Dichalcogenides ◽  
Kerr Rotation ◽  
Time Resolved ◽  
Recombination Lifetime ◽  
Valley Polarization ◽  
Metal Dichalcogenides

Abstract A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (∼10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

scholarly journals Encapsulation of transition metal dichalcogenides crystals with room temperature plasma deposited carbonaceous films

RSC Advances ◽  
2017 ◽  
Vol 7 (65) ◽  
pp. 41136-41143
Author(s):  
Rakesh D. Mahyavanshi ◽  
Golap Kalita ◽  
Rupesh Singh ◽  
Masaharu Kondo ◽  
Takehisa Dewa ◽  
...  
Keyword(s):  
Surface Wave ◽  
Transition Metal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Temperature Plasma ◽  
Plasma Technique ◽  
Metal Dichalcogenides

Demonstrated encapsulation of dichalcogenides layer by coating a carbonaceous film by surface wave plasma technique.

scholarly journals Valley depolarization in downconversion and upconversion emission of monolayer WS2 at room temperature

Nanophotonics ◽  
2020 ◽  
Vol 9 (16) ◽  
pp. 4809-4818
Author(s):  
Han Li ◽  
Yating Ma ◽  
Yizhen Sui ◽  
Yuxiang Tang ◽  
Ke Wei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Upconversion Emission ◽  
Pump Probe ◽  
Saturated Absorption ◽  
Metal Dichalcogenides ◽  
Exciton Interactions ◽  
Anti Stokes ◽  
Probe Measurements

AbstractBenefiting from strong photon–exciton and phonon–exciton interactions in atomic thickness, transition metal dichalcogenides (TMDCs) are viewed as one promising platform for exploring elementary excitonic photoluminescence (PL) and intrinsic spin–valley properties at the monolayer limit. Despite well-studied Stokes downconversion (DC) PL, the anti-Stokes upconversion (UC) PL has been recently reported in TMDC monolayers, which mainly focus on UC mechanisms while detailed valley-related dynamical processes are unwittingly less concerned. Here, we carry out an in-depth investigation on both DC and UC emission features of monolayer WS2 at room temperature, where UC PL persists with energy gain up to 190 meV. The PL excitation and power-dependent experiments clearly distinguish the origins of DC PL and UC PL, which refer to saturated absorption and phonon-assisted transition from charged trions to neutral A-excitons. And contrast valley properties are observed in DC and UC scenarios with polarization-resolved PL and pump–probe measurements. According to the experimental facts, phenomenological dynamical DC and UC scenarios are modeled with intervalley depolarization taken into consideration, in which intermediates from spontaneous intervalley depolarization account for the observed emission and valley properties. This work can help understand the light–matter interactions and valley properties in monolayer TMDCs.

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