Probing biexciton in monolayer WS2 through controlled many-body interaction

2D Materials ◽  
2021 ◽  
Author(s):  
Suman Chatterjee ◽  
Sarthak Das ◽  
Garima Gupta ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Transition Metal Dichalcogenides ◽  
Excitation Power ◽  
Equation Model ◽  
Final States ◽  
Many Body ◽  
Time Resolved ◽  
Spectral Separation ◽  
Metal Dichalcogenides ◽  
Time Resolved Photoluminescence

Abstract The monolayers of semiconducting transition metal dichalcogenides host strongly bound excitonic complexes and are an excellent platform for exploring many-body physics. Here we demonstrate a controlled kinetic manipulation of the five-particle excitonic complex, the charged biexciton, through a systematic dependence of the biexciton peak on excitation power, gate voltage, and temperature using steady-state and time-resolved photoluminescence (PL). With the help of a combination of the experimental data and a rate equation model, we argue that the binding energy of the charged biexciton is less than the spectral separation of its peak from the neutral exciton. We also note that while the momentum-direct radiative recombination of the neutral exciton is restricted within the light cone, such restriction is relaxed for a charged biexciton recombination due to the presence of near-parallel excited and final states in the momentum space.

Optical Study of Localized and Delocalized States in GaAsN/GaAs

2003 ◽  
Vol 798 ◽  
Author(s):  
Z. Y. Xu ◽  
X. D. Luo ◽  
X. D. Yang ◽  
P. H. Tan ◽  
C. L. Yang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Rapid Thermal Annealing ◽  
Short Pulse ◽  
Selective Excitation ◽  
Excitation Power ◽  
Pulse Excitation ◽  
Optical Study ◽  
Time Resolved ◽  
Exciton Localization ◽  
Time Resolved Photoluminescence

ABSTRACTTaking advantages of short pulse excitation and time-resolved photoluminescence (PL), we have studied the exciton localization effect in a number of GaAsN alloys and GaAsN/GaAs quantum wells (QWs). In the PL spectra, an extra transition located at the higher energy side of the commonly reported N-related emissions is observed. By measuring PL dependence on temperature and excitation power along with PL dynamics study, the new PL peak has been identified as a transition of the band edge-related recombination in dilute GaAsN alloy and delocalized transition in QWs. Using selective excitation PL we further attribute the localized emission in QWs to the excitons localized at the GaAsN/GaAs interfaces. This interface-related exciton localization could be greatly reduced by a rapid thermal annealing.

scholarly journals Exciton-polaron Rydberg states in monolayer MoSe2 and WSe2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfu Liu ◽  
Jeremiah van Baren ◽  
Zhengguang Lu ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Excited States ◽  
Ground State ◽  
Transition Metal Dichalcogenides ◽  
Rydberg States ◽  
Energy Shift ◽  
Many Body ◽  
Electron Hole ◽  
Metal Dichalcogenides ◽  
Excitonic States

AbstractExciton polaron is a hypothetical many-body quasiparticle that involves an exciton dressed with a polarized electron-hole cloud in the Fermi sea. It has been evoked to explain the excitonic spectra of charged monolayer transition metal dichalcogenides, but the studies were limited to the ground state. Here we measure the reflection and photoluminescence of monolayer MoSe2 and WSe2 gating devices encapsulated by boron nitride. We observe gate-tunable exciton polarons associated with the 1 s–3 s exciton Rydberg states. The ground and excited exciton polarons exhibit comparable energy redshift (15~30 meV) from their respective bare excitons. The robust excited states contradict the trion picture because the trions are expected to dissociate in the excited states. When the Fermi sea expands, we observe increasingly severe suppression and steep energy shift from low to high exciton-polaron Rydberg states. Their gate-dependent energy shifts go beyond the trion description but match our exciton-polaron theory. Our experiment and theory demonstrate the exciton-polaron nature of both the ground and excited excitonic states in charged monolayer MoSe2 and WSe2.

Radiative recombination of excitons in the transition-metal dichalcogenides MoS2:Cl2 and WS2:Br2

2005 ◽  
Vol 112 (1-4) ◽  
pp. 45-49 ◽  
Author(s):  
L. Charron ◽  
D. Dumchenko ◽  
E. Fortin ◽  
C. Gherman ◽  
L. Kulyuk
Keyword(s):  
Transition Metal ◽  
Radiative Recombination ◽  
Transition Metal Dichalcogenides ◽  
Metal Dichalcogenides

Robust single-mode lasers based on hexagonal CdS microflakes

2020 ◽  
Vol 8 (32) ◽  
pp. 11201-11208
Author(s):  
Yang Mi ◽  
Yaoyao Wu ◽  
Jinchun Shi ◽  
Sheng-Nian Luo
Keyword(s):  
Radiative Recombination ◽  
Single Mode ◽  
Whispering Gallery Mode ◽  
Radiative Recombination Rate ◽  
Electron Hole ◽  
High Quality ◽  
Time Resolved ◽  
Whispering Gallery ◽  
Electron Hole Plasma ◽  
Time Resolved Photoluminescence

We have achieved single-mode whispering-gallery-mode lasing in CdS microflakes with sharp linewidth (∼0.12 nm) and high quality factor (∼4200). Such lasers are superior to previous CdS lasers in these lasing parameters. Through time-resolved photoluminescence measurements, electron–hole plasma recombination is established to be the lasing mechanism. The radiative recombination rate of CdS microflakes is enhanced by a factor of ∼4.7 due to the Purcell effect.

scholarly journals Strain-induced effects on the electronic properties of 2D materials

2020 ◽  
Vol 10 ◽  
pp. 184798042090256 ◽  
Author(s):  
Sara Postorino ◽  
Davide Grassano ◽  
Marco D’Alessandro ◽  
Andrea Pianetti ◽  
Olivia Pulci ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Many Body ◽  
Functional Theory ◽  
Metal Dichalcogenides ◽  
Extreme Sensitivity ◽  
Nonuniform Strain

Thanks to the ultrahigh flexibility of 2D materials and to their extreme sensitivity to applied strain, there is currently a strong interest in studying and understanding how their electronic properties can be modulated by applying a uniform or nonuniform strain. In this work, using density functional theory (DFT) calculations, we discuss how uniform biaxial strain affects the electronic properties, such as ionization potential, electron affinity, electronic gap, and work function, of different classes of 2D materials from X-enes to nitrides and transition metal dichalcogenides. The analysis of the states in terms of atomic orbitals allows to explain the observed trends and to highlight similarities and differences among the various materials. Moreover, the role of many-body effects on the predicted electronic properties is discussed in one of the studied systems. We show that the trends with strain, calculated at the GW level of approximation, are qualitatively similar to the DFT ones solely when there is no change in the character of the valence and conduction states near the gap.

scholarly journals Many-body dynamics and exciton formation studied by time-resolved photoluminescence

2005 ◽  
Vol 72 (7) ◽  
Author(s):  
W. Hoyer ◽  
C. Ell ◽  
M. Kira ◽  
S. W. Koch ◽  
S. Chatterjee ◽  
...  
Keyword(s):  
Many Body ◽  
Time Resolved ◽  
Body Dynamics ◽  
Time Resolved Photoluminescence

Preparation and Time Resolved Photoluminescence of Nanoscale InP Islands in In0.48Ga0.52P

1995 ◽  
Vol 379 ◽  
Author(s):  
K. Eberl ◽  
A. Kurtenbach ◽  
K. HÄusler ◽  
F. Noll ◽  
W.W. RÜhle
Keyword(s):  
Lattice Mismatch ◽  
Excitation Power ◽  
Buffer Layers ◽  
Time Resolved ◽  
Force Microscopy ◽  
Self Assembling ◽  
Atomic Force ◽  
Transmission Electron ◽  
Decay Times ◽  
Time Resolved Photoluminescence

ABSTRACTNanoscale InP islands are formed during InP/In0 48Ga0.52P heteroepitaxy due to the lattice mismatch of about 3.7%. The samples are prepared by solid source molecular beam epitaxy on (001) GaAs substrate. Atomic force microscopy measurements show that the size of the islands is typically 15 to 50 nm in diameter and about 5 to 10 nm high depending on the nominally deposited InP layer thickness, which is between 1 and 7.5 monolayers. Transmission electron micrographs show the coherent incorporation into the In0.48Ga0.52P matrix for InP islands with 2.5 monolayers. Resonantly excited time-resolved photoluminescence (PL) measurements of the self assembling InP dots are performed for optical characterisation. The decay times are typically 400 ps. The dependence on excitation power and temperature indicates the quantum dot nature of the InP islands. Finally a pronounced alignment of the InP islands is obtained on strained In0.61Ga0.39P buffer layers.

scholarly journals Enhanced Photoresponsivity of 2H-MoTe2 by Inserting 1T-MoTe2 Interlayer Contact for Photodetector Applications

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 964
Author(s):  
Der-Yuh Lin ◽  
Hung-Pin Hsu ◽  
Guang-Hsin Liu ◽  
Ting-Zhong Dai ◽  
Yu-Tai Shih
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Thermionic Emission ◽  
Decay Process ◽  
Frequency Dependent ◽  
Time Resolved ◽  
Barrier Heights ◽  
Potential Applicability ◽  
Metal Dichalcogenides ◽  
Electrode Contact ◽  
Layered Transition Metal

The 2H molybdenum telluride (MoTe2) photodetector structures were made with inserting 1T-MoTe2 interlayer contacts. The optical response properties such as photoconductivity (PC) spectroscopy, illumination intensity dependent photoresponsivity, frequency dependent photocurrent, and time-resolved photoresponse were carried out in this study. In PC spectra, a much higher photoresponsivity of 2H-MoTe2 were observed by inserting 1T-MoTe2 interlayer contact. The frequency dependent photocurrent and time-resolved photoresponse investigations explore the carrier kinetic decay process of MoTe2 with different electrode contact. The Schottky barrier heights (SBH) extracted by thermionic emission theory were also investigated by inserting 1T-MoTe2 interlayer contacts. The results show the potential applicability for photodetection devices based MoTe2 layered transition metal dichalcogenides semiconductors.

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