scholarly journals Layer-dependent quantum cooperation of electron and hole states in the anomalous semimetal WTe2

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Pranab Kumar Das ◽  
D. Di Sante ◽  
I. Vobornik ◽  
J. Fujii ◽  
T. Okuda ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Transition Metal Dichalcogenides ◽  
Photoemission Spectroscopy ◽  
Two Dimensional ◽  
Quantum Phenomenon ◽  
Two Dimensional Materials ◽  
Metal Dichalcogenides ◽  
Electron And Hole States ◽  
Dependent Behaviour

Abstract The behaviour of electrons and holes in a crystal lattice is a fundamental quantum phenomenon, accounting for a rich variety of material properties. Boosted by the remarkable electronic and physical properties of two-dimensional materials such as graphene and topological insulators, transition metal dichalcogenides have recently received renewed attention. In this context, the anomalous bulk properties of semimetallic WTe2 have attracted considerable interest. Here we report angle- and spin-resolved photoemission spectroscopy of WTe2 single crystals, through which we disentangle the role of W and Te atoms in the formation of the band structure and identify the interplay of charge, spin and orbital degrees of freedom. Supported by first-principles calculations and high-resolution surface topography, we reveal the existence of a layer-dependent behaviour. The balance of electron and hole states is found only when considering at least three Te–W–Te layers, showing that the behaviour of WTe2 is not strictly two dimensional.

Phonon Coupling and Dielectric Response in 2D Semiconductor

NANO ◽  
2021 ◽  
Author(s):  
Arslan Usman ◽  
Abdul Sattar ◽  
Hamid Latif ◽  
Muhammad Imran
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Coupling Mechanism ◽  
Two Dimensional ◽  
Electron Hole ◽  
Exciton Coupling ◽  
Gain Energy ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal ◽  
The Impact

The impact of phonon and their surrounding environment on exciton and its complexes were investigated in monolayer WSe2 semiconductor. Phonon up-conversion has been studied in past for conventional III–V semiconductors, but its role in two-dimensional layered transition metal dichalcogenides has rarely been explored. We investigated the photoluminescence up-conversion mechanism in WSe2 monolayer and found that a lower energy photon gain energy upto 64[Formula: see text]meV to be up-converted to emission photon at room temperature. Moreover, the phonon-exciton coupling mechanism has also been investigated and the role of dielectric screening has been explored to get complete insight of coulomb’s interaction in these electron-hole pairs. Investigations of charge carrier’s lifetime reveal that boron nitride encapsulated monolayer has shorter recombination time as low as 41 ps as compared to a bare monolayer on SiO2 substrate. These results are very promising for realizing spintronics-based application from two-dimensional layered semiconductors.

Strong coupling in two-dimensional materials-based nanostructures: a review

2022 ◽  
Author(s):  
Ye Ming Qing ◽  
Yongze Ren ◽  
Dangyuan Lei ◽  
Hui Feng Ma ◽  
Tie Jun Cui
Keyword(s):  
Strong Coupling ◽  
Coupling Effect ◽  
Transition Metal Dichalcogenides ◽  
Hybrid Nanostructures ◽  
Two Dimensional ◽  
Strong Light ◽  
Two Dimensional Materials ◽  
Potential Applications ◽  
Metal Dichalcogenides ◽  
Emission Behavior

Abstract Strong interaction between electromagnetic radiation and matter leads to the formation of hybrid light-matter states, making the absorption and emission behavior different from those of the uncoupled states. Strong coupling effect results in the famous Rabi splitting and the emergence of new polaritonic eigenmodes, exhibiting spectral anticrossing behavior and unique energy-transfer properties. In recent years, there has been a rapidly increasing number of works focusing on strong coupling between nanostructures and two-dimensional materials (2DMs), because of the exceptional properties and applications they demonstrate. Here, we review the significant recent advances and important developments of strong light-matter interactions in 2DMs-based nanostructures. We adopt the coupled oscillator model to describe the strong coupling and give an overview of various hybrid nanostructures to realize this regime, including graphene-based nanostructures, black phosphorus-based nanostructures, transition-metal dichalcogenides-based nanostructures, etc. In addition, we discuss potential applications that can benefit from these effects and conclude our review with a perspective on the future of this rapidly emerging field.

scholarly journals A Horizontal-Gate Monolayer MoS2 Transistor Based on Image Force Barrier Reduction

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1245 ◽  
Author(s):  
Kun Yang ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Wei Li ◽  
Tao Han
Keyword(s):  
Carrier Mobility ◽  
Transition Metal Dichalcogenides ◽  
Image Force ◽  
Drain Current ◽  
Equivalent Model ◽  
Two Dimensional ◽  
Monolayer Mos2 ◽  
Two Dimensional Materials ◽  
Metal Dichalcogenides ◽  
New Generation

Transition metal dichalcogenides (TMDCs) have received wide attention as a new generation of semiconductor materials. However, there are still many problems to be solved, such as low carrier mobility, contact characteristics between metal and two-dimensional materials, and complicated fabrication processes. In order to overcome these problems, a large amount of research has been carried out so that the performance of the device has been greatly improved. However, most of these studies are based on complicated fabrication processes which are not conducive to the improvement of integration. In view of this problem, a horizontal-gate monolayer MoS2 transistor based on image force barrier reduction is proposed, in which the gate is in the same plane as the source and drain and comparable to back-gated transistors on-off ratios up to 1 × 104 have been obtained. Subsequently, by combining the Y-Function method (YFM) and the proposed diode equivalent model, it is verified that Schottky barrier height reduction is the main reason giving rise to the observed source-drain current variations. The proposed structure of the device not only provides a new idea for the high integration of two-dimensional devices, but also provides some help for the study of contact characteristics between two-dimensional materials and metals.

scholarly journals Photo-Detectors Based on Two Dimensional Materials

2021 ◽  
Author(s):  
Mubashir A. Kharadi ◽  
Gul Faroz A. Malik ◽  
Farooq A. Khanday
Keyword(s):  
Transition Metal ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Optoelectronic Devices ◽  
Two Dimensional ◽  
Wide Range ◽  
Two Dimensional Materials ◽  
Photo Detectors ◽  
Metal Dichalcogenides ◽  
Application Specific

2D materials like transition metal dichalcogenides, black phosphorous, silicene, graphene are at the forefront of being the most potent 2D materials for optoelectronic applications because of their exceptional properties. Several application-specific photodetectors based on 2D materials have been designed and manufactured due to a wide range and layer-dependent bandgaps. Different 2D materials stacked together give rise to many surprising electronic and optoelectronic phenomena of the junctions based on 2D materials. This has resulted in a lot of popularity of 2D heterostructures as compared to the original 2D materials. This chapter presents the progress of optoelectronic devices (photodetectors) based on 2D materials and their heterostructures.

scholarly journals Ultra-Thin SnS2-Pt Nanocatalyst for Efficient Hydrogen Evolution Reaction

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2337
Author(s):  
Yanying Yu ◽  
Jie Xu ◽  
Jianwei Zhang ◽  
Fan Li ◽  
Jiantao Fu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Pt Nanoclusters ◽  
Two Dimensional Materials ◽  
Low Load ◽  
Metal Dichalcogenides ◽  
Poor Stability

Transition-metal dichalcogenides (TMDs) materials have attracted much attention for hydrogen evolution reaction (HER) as a new catalyst, but they still have challenges in poor stability and high reaction over-potential. In this study, Ultra-thin SnS2 nanocatalysts were synthesized by simple hydrothermal method, and low load of Pt was added to form stable SnS2-Pt-3 (the content of platinum is 0.5 wt %). The synergistic effect between ultra-thin SnS2 rich in active sites and individual dispersed Pt nanoclusters can significantly reduce the reaction barrier and further accelerate HER reaction kinetics. Hence, SnS2-Pt-3 exhibits a low overpotential of 210 mV at the current density of 10 mA cm−2. It is worth noting that SnS2-Pt-3 has a small Tafel slope (126 mV dec−1) in 0.5 M H2SO4, as well as stability. This work provides a new option for the application of TMDs materials in efficient hydrogen evolution reaction. Moreover, this method can be easily extended to other catalysts with desired two-dimensional materials.

The Role of Two-Dimensional Materials in Electromagnetic Interference Shielding

2021 ◽  
pp. 1254-1270
Author(s):  
Rafael Vargas-Bernal
Keyword(s):  
Electromagnetic Interference ◽  
Transition Metal Dichalcogenides ◽  
Environmental Stability ◽  
Two Dimensional ◽  
Shielding Effectiveness ◽  
Electromagnetic Interference Shielding ◽  
Two Dimensional Materials ◽  
Metal Dichalcogenides ◽  
Materials Used ◽  
The Impact

Commonly, metallic materials are used in practical ways to increase the shielding effectiveness (SE) through an appropriately designed assembly process. Unfortunately, the high density of devices that require it and the poor environmental stability of metals have impeded their massive use. In addition, for applications in the automotive, aerospace, and electronics industries, materials with light weight and good chemical stability are also required. The purpose of this chapter is to describe the impact that two-dimensional materials (or 2D materials) are having on the development of materials used for electromagnetic interference shielding, particularly the impulse of materials such as graphene, MXenes, transition metal dichalcogenides (TMDs), and phosphorene. The advances in the last decade are analyzed and alternatives are proposed that will come in the next decades. The shielding mechanisms presented by the two-dimensional materials are analyzed in detail and the specific applications in which these materials can be used are presented.

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