Enhancing excitons by oleic acid treatment in WS2, MoS2, and WS2/MoS2 heterostructure

2022 ◽  
Author(s):  
Yishu Wang ◽  
Xiaokun Zhai ◽  
Liefeng Feng ◽  
Tingge Gao
Keyword(s):  
Oleic Acid ◽  
Acid Treatment ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Interlayer Coupling ◽  
Fold Increase ◽  
Two Dimensional ◽  
Peak Intensity ◽  
Energy Peak ◽  
Metal Dichalcogenides

Abstract The neutral and interlayer exciton originates from intralayer and interlayer coupling, respectively. Unlike neutral exciton, the interlayer excitons at room temperature are hard to observe and manipulate due to instability. In this work, we show the photoluminescence of WS$_2$ and MoS$_2$ neutral exciton can be improved by oleic acid passivation, allowing trion peaks to be observed at room temperature. More importantly, a 3-fold increase in peak intensity of interlayer excitons is achieved, and the energy peak is blue-shifted 107 meV. Our work paves the way to investigate excitons in two-dimensional transition metal dichalcogenides monolayers and heterostructures at room temperature.

Lowering the Schottky barrier height of G/WSSe van der Waals heterostructures by changing the interlayer coupling and applying external biaxial strain

2020 ◽  
Vol 22 (45) ◽  
pp. 26231-26240
Author(s):  
W. X. Zhang ◽  
Y. Yin ◽  
C. He
Keyword(s):  
Field Effect ◽  
Schottky Barrier Height ◽  
Field Effect Transistors ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Interlayer Coupling ◽  
Two Dimensional ◽  
Biaxial Strain ◽  
Metal Dichalcogenides ◽  
Design And Manufacture

Graphene-based van der Waals (vdW) heterostructures composed of two-dimensional transition metal dichalcogenides (TMDs) and graphene show great potential in the design and manufacture of field effect transistors.

scholarly journals Optical activity in chiral stacks of 2D semiconductors

Nanophotonics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 753-762 ◽  
Author(s):  
Alexander V. Poshakinskiy ◽  
Dmitrii R. Kazanov ◽  
Tatiana V. Shubina ◽  
Sergey A. Tarasenko
Keyword(s):  
Optical Activity ◽  
Transition Metal Dichalcogenides ◽  
Microscopic Theory ◽  
Interlayer Coupling ◽  
Two Dimensional ◽  
Circularly Polarized ◽  
Semiconductor Crystals ◽  
2D Semiconductors ◽  
Metal Dichalcogenides ◽  
Dark Exciton

AbstractWe show that the stacks of two-dimensional semiconductor crystals with the chiral packing exhibit optical activity and circular dichroism. We develop a microscopic theory of these phenomena in the spectral range of exciton transitions that takes into account the spin-dependent hopping of excitons between the layers in the stack and the interlayer coupling of excitons via electromagnetic field. For the stacks of realistic two-dimensional semiconductors such as transition metal dichalcogenides, we calculate the rotation and ellipticity angles of radiation transmitted through such structures. The angles are resonantly enhanced at the frequencies of both bright and dark exciton modes in the stack. We also study the photoluminescence of chiral stacks and show that it is circularly polarized.

Trap-free exciton dynamics in monolayer WS2 via oleic acid passivation

Nanoscale ◽  
2021 ◽  
Author(s):  
Dabin Lin ◽  
Wenjun Ni ◽  
Gagik G. Gurzadyan ◽  
Fangteng Zhang ◽  
Weiren Zhao ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Transition Metal ◽  
Free Exciton ◽  
Transition Metal Dichalcogenides ◽  
Photonic Devices ◽  
Optoelectronic Properties ◽  
Two Dimensional ◽  
Exciton Dynamics ◽  
The Past ◽  
Metal Dichalcogenides

Two-dimensional transition metal dichalcogenides have attracted tremendous attention in the past few decades due to their attractive optoelectronic properties. However, their widespread utility in photonic devices and components is still...

scholarly journals Magnetoresistance Effect in NiFe/BP/NiFe Vertical Spin Valve Devices

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Leilei Xu ◽  
Jiafeng Feng ◽  
Kangkang Zhao ◽  
Weiming Lv ◽  
Xiufeng Han ◽  
...  
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Spin Valve ◽  
Layered Materials ◽  
Two Dimensional ◽  
Magnetoresistance Effect ◽  
2D Layered Materials ◽  
Metal Dichalcogenides ◽  
Valve Effect

Two-dimensional (2D) layered materials such as graphene and transition metal dichalcogenides are emerging candidates for spintronic applications. Here, we report magnetoresistance (MR) properties of a black phosphorus (BP) spin valve devices consisting of thin BP flakes contacted by NiFe ferromagnetic (FM) electrodes. The spin valve effect has been observed from room temperature to 4 K, with MR magnitudes of 0.57% at 4 K and 0.23% at 300 K. In addition, the spin valve resistance is found to decrease monotonically as temperature is decreased, indicating that the BP thin film works as a conductive interlayer between the NiFe electrodes.

scholarly journals Super-resolved Optical Mapping of Reactive Sulfur-Vacancies in Two-Dimensional Transition Metal Dichalcogenides

ACS Nano ◽  
2021 ◽  
Author(s):  
Miao Zhang ◽  
Martina Lihter ◽  
Tzu-Heng Chen ◽  
Michal Macha ◽  
Archith Rayabharam ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Mapping ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

scholarly journals The influence of Coulomb interaction screening on the excitons in disordered two-dimensional insulators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. V. Kirichenko ◽  
V. A. Stephanovich
Keyword(s):  
Coulomb Interaction ◽  
Energy Levels ◽  
Transition Metal Dichalcogenides ◽  
Extreme Case ◽  
Bound State ◽  
Joint Effect ◽  
Two Dimensional ◽  
Inorganic Substances ◽  
Metal Dichalcogenides ◽  
Interaction Screening

AbstractWe study the joint effect of disorder and Coulomb interaction screening on the exciton spectra in two-dimensional (2D) structures. These can be van der Waals structures or heterostructures of organic (polymeric) semiconductors as well as inorganic substances like transition metal dichalcogenides. We consider 2D screened hydrogenic problem with Rytova–Keldysh interaction by means of so-called fractional Scrödinger equation. Our main finding is that above synergy between screening and disorder either destroys the exciton (strong screening) or promote the creation of a bound state, leading to its collapse in the extreme case. Our second finding is energy levels crossing, i.e. the degeneracy (with respect to index $$\mu $$ μ ) of the exciton eigenenergies at certain discrete value of screening radius. Latter effects may also be related to the quantum manifestations of chaotic exciton behavior in above 2D semiconductor structures. Hence, they should be considered in device applications, where the interplay between dielectric screening and disorder is important.

Combined Healing and Doping of Transition Metal Dichalcogenides Through Molecular Functionalization

2021 ◽  
Author(s):  
Sai Manoj Gali ◽  
David Beljonne
Keyword(s):  
Transition Metal ◽  
Charge Transport ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides

Transition Metal Dichalcogenides (TMDCs) are emerging as promising two-dimensional (2D) materials. Yet, TMDCs are prone to inherent defects such as chalcogen vacancies, which are detrimental to charge transport. Passivation of...

scholarly journals Giant Photoluminescence Enhancement and Carrier Dynamics in MoS2 Bilayers with Anomalous Interlayer Coupling

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1994
Author(s):  
Han Li ◽  
Yating Ma ◽  
Zhongjie Xu ◽  
Xiang’ai Cheng ◽  
Tian Jiang
Keyword(s):  
Optical Properties ◽  
Transition Metal Dichalcogenides ◽  
Interlayer Coupling ◽  
Carrier Dynamics ◽  
Probe Signal ◽  
Exciton Resonance ◽  
Pump Probe ◽  
Metal Dichalcogenides ◽  
Photoluminescence Enhancement ◽  
Probe Measurements

Fundamental researches and explorations based on transition metal dichalcogenides (TMDCs) mainly focus on their monolayer counterparts, where optical densities are limited owing to the atomic monolayer thickness. Photoluminescence (PL) yield in bilayer TMDCs is much suppressed owing to indirect-bandgap properties. Here, optical properties are explored in artificially twisted bilayers of molybdenum disulfide (MoS2). Anomalous interlayer coupling and resultant giant PL enhancement are firstly observed in MoS2 bilayers, related to the suspension of the top layer material and independent of twisted angle. Moreover, carrier dynamics in MoS2 bilayers with anomalous interlayer coupling are revealed with pump-probe measurements, and the secondary rising behavior in pump-probe signal of B-exciton resonance, originating from valley depolarization of A-exciton, is firstly reported and discussed in this work. These results lay the groundwork for future advancement and applications beyond TMDCs monolayers.

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