scholarly journals Preparation of Few-Layered Wide Bandgap MoS2 with Nanometer Lateral Dimensions by Applying Laser Irradiation

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 164 ◽  
Author(s):  
Mitra Mahdavi ◽  
Salimeh Kimiagar ◽  
Fahimeh Abrinaei
Keyword(s):  
Laser Irradiation ◽  
Laser Energy ◽  
Transition Metal Dichalcogenides ◽  
Wide Bandgap ◽  
Mos2 Nanosheets ◽  
Uniform Size ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
One Step ◽  
Layered Mos2

In this study, we report a new method for the quick, green, and one-step preparation of few-layered molybdenum disulfide (MoS2) nanosheets with wide bandgap. MoS2 nanosheets with small lateral dimension and uniform size distribution were synthesized for various applications. MoS2 powder was synthesized using the hydrothermal method; then, thinned by applying laser irradiation with different energies from 40 to 80 mJ. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectra, and photoluminescence (PL) spectra were applied for the characterization of the MoS2 nanosheets in terms of morphology, crystal structures, and optical properties. The widest calculated bandgap 4.7 eV was for the sample under 80 mJ laser energy. The results confirmed the successful preparation of highly pure, uniform, and few-layered MoS2 nanosheets. Furthermore, it was possible to enhance the production rate of MoS2 nanosheets (including nanosheets and nanoparticles) through laser irradiation. Thus, the present paper introduces a simple and green alternative approach for preparing few-layered MoS2 nanosheets of transition metal dichalcogenides or other layered materials.

scholarly journals Carbon-coated magnetic particles increase tissue temperatures after laser irradiation

2015 ◽  
Vol 08 (05) ◽  
pp. 1550018 ◽  
Author(s):  
Shupeng Liu ◽  
Na Chen ◽  
Fufei Pang ◽  
Zhengyi Chen ◽  
Tingyun Wang
Keyword(s):  
Laser Irradiation ◽  
Magnetic Particles ◽  
Laser Energy ◽  
Thermal Therapy ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fbg Sensor ◽  
Transmission Electron ◽  
Carbon Coated

Purpose: This work focused on the investigation the hyperthermia performance of the carbon-coated magnetic particles (CCMPs) in laser-induced hyperthermia. Materials and methods: We prepared CCMPs using the organic carbonization method, and then characterized them with transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectrophotometry, vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). In order to evaluate their performance in hyperthermia, the CCMPs were tested in laser-induced thermal therapy (LITT) experiments, in which we employed a fully distributed fiber Bragg grating (FBG) sensor to profile the tissue's dynamic temperature change under laser irradiation in real time. Results: The sizes of prepared CCMPs were about several micrometers, and the LITT results show that the tissue injected with the CCMPs absorbed more laser energy, and its temperature increased faster than the contrast tissue without CCMPs. Conclusions: The CCMPs may be of great help in hyperthermia applications.

scholarly journals The Photodetectors Based on Lateral Monolayer MoS2/WS2 Heterojunctions

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Caihong Li ◽  
Juntong Zhu ◽  
Wen Du ◽  
Yixuan Huang ◽  
Hao Xu ◽  
...  
Keyword(s):  
Communication Systems ◽  
Transition Metal Dichalcogenides ◽  
Chemical Vapor ◽  
Large Area ◽  
Optical Signals ◽  
Metal Dichalcogenides ◽  
One Step ◽  
The One ◽  
Charge Carrier Trapping ◽  
Sharp Interfaces

AbstractMonolayer transition metal dichalcogenides (TMDs) show promising potential for next-generation optoelectronics due to excellent light capturing and photodetection capabilities. Photodetectors, as important components of sensing, imaging and communication systems, are able to perceive and convert optical signals to electrical signals. Herein, the large-area and high-quality lateral monolayer MoS2/WS2 heterojunctions were synthesized via the one-step liquid-phase chemical vapor deposition approach. Systematic characterization measurements have verified good uniformity and sharp interfaces of the channel materials. As a result, the photodetectors enhanced by the photogating effect can deliver competitive performance, including responsivity of ~ 567.6 A/W and detectivity of ~ 7.17 × 1011 Jones. In addition, the 1/f noise obtained from the current power spectrum is not conductive to the development of photodetectors, which is considered as originating from charge carrier trapping/detrapping. Therefore, this work may contribute to efficient optoelectronic devices based on lateral monolayer TMD heterostructures.

scholarly journals Realization of Lasing Emission from One Step Fabricated WSe2 Quantum Dots

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 538
Author(s):  
Pengpeng Ren ◽  
Wenfei Zhang ◽  
Yiqun Ni ◽  
Di Xiao ◽  
Honghao Wan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Threshold Value ◽  
Gain Medium ◽  
Excitation Wavelength ◽  
Excitation Threshold ◽  
Ultrasonic Probe ◽  
Metal Dichalcogenides ◽  
One Step

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) quantum dots (QDs) are the vanguard due to their unique properties. In this work, WSe2 QDs were fabricated via one step ultrasonic probe sonication. Excitation wavelength dependent photoluminescence (PL) is observed from WSe2 QDs. Room-temperature lasing emission which benefits from 3.7 times enhancement of PL intensity by thermal treatment at ~470 nm was achieved with an excitation threshold value of ~3.5 kW/cm2 in a Fabry–Perot laser cavity. To the best of our knowledge, this is the first demonstration of lasing emission from TMDCs QDs. This indicates that TMDCs QDs are a superior candidate as a new type of laser gain medium.

scholarly journals One-Step Hydrothermal Synthesis of P25 @ Few Layered MoS2 Nanosheets toward Enhanced Bi-catalytic Activities: Photocatalysis and Electrocatalysis

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1636 ◽  
Author(s):  
Zhou ◽  
Zhang ◽  
Wang ◽  
Wang ◽  
Xu ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Active Sites ◽  
Photocatalytic Performance ◽  
Transformation Efficiency ◽  
Hydrothermal Process ◽  
Mos2 Nanosheets ◽  
Sunlight Irradiation ◽  
Catalytic Activities ◽  
One Step ◽  
Layered Mos2

P25 loaded few layered molybdenum disulfide (MoS2) nanosheets (P25@MoS2) are successfully synthesized through a facile one-step hydrothermal process. The bi-catalytic activities, i.e., photocatalytic and electrocatalytic activities, of the as-prepared nanomaterials have been investigated. For the as-prepared products, the photocatalytic performances were investigated by degrading simulated pollutant under sunlight irradiation, and the hydrogen evolution reaction evaluated the electrocatalytic performances. The results indicate that P25@MoS2 possesses excellent activities in both photocatalysis and electrocatalysis. The presence of MoS2 broadens the light absorption range of P25 and improves the separation and transformation efficiency of photogenerated carriers, thus improving its photocatalytic performance. The existence of P25 inhibits the aggregation of MoS2 to form more dispersed MoS2 nanosheets with only few layers increasing its active sites. Thereby, the electrocatalytic performance is heightened. The excellent multifunction makes the as-prepared P25@MoS2 a promising material in the fields of environment and energy.

scholarly journals Probing magnetism in atomically thin semiconducting PtSe2

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmet Avsar ◽  
Cheol-Yeon Cheon ◽  
Michele Pizzochero ◽  
Mukesh Tripathi ◽  
Alberto Ciarrocchi ◽  
...  
Keyword(s):  
Long Range ◽  
Magnetic Moments ◽  
Transition Metal Dichalcogenides ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
First Principles Calculations ◽  
Microscopy Imaging ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
The One

Abstract Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range magnetic ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of long-range magnetic orderings in defective mono- and bi-layer semiconducting PtSe2 by performing magnetoresistance measurements under both lateral and vertical measurement configurations. As the material is thinned down from bi- to mono-layer thickness, we observe a ferromagnetic-to-antiferromagnetic crossover, a behavior which is opposite to the one observed in the prototypical 2D magnet CrI3. Our first-principles calculations, supported by aberration-corrected transmission electron microscopy imaging of point defects, associate this transition to the interplay between the defect-induced magnetism and the interlayer interactions in PtSe2. Furthermore, we show that graphene can be effectively used to probe the magnetization of adjacent semiconducting PtSe2. Our findings in an ultimately scaled monolayer system lay the foundation for atom-by-atom engineering of magnetism in otherwise non-magnetic 2D materials.

Processing Grinding-Damaged Silicon Wafers by High-Frequency Nano-Second Laser Irradiation

2009 ◽  
Vol 76-78 ◽  
pp. 451-456
Author(s):  
Ji Wang Yan ◽  
Sei Ya Muto ◽  
Tsunemoto Kuriyagawa
Keyword(s):  
Energy Density ◽  
Amorphous Silicon ◽  
Laser Irradiation ◽  
High Frequency ◽  
Laser Energy ◽  
Large Diameter ◽  
Silicon Wafers ◽  
Density Level ◽  
Transmission Electron ◽  
Beam Center

Ultraprecision diamond-ground silicon wafers were irradiated by a high-frequency nanosecond pulsed Nd:YAG laser equipped on a four-axis numerically controlled stage. The resulting specimens were characterized using a white-light interferometer, a micro-Raman spectroscope and a transmission electron microscope. The results indicate that around the laser beam center where the laser energy density is sufficiently high, the grinding-induced amorphous silicon was completely transformed into the single-crystal structure. The optimum conditions for one- and two-dimensional overlapping irradiation were experimentally obtained for processing large-diameter silicon wafers. It was found that the energy density level required for completely removing the dislocations is higher than that for recrystallizing the amorphous silicon. After laser irradiation, the surface unevenness has been remarkably flattened.

scholarly journals Atomic structure of defects and dopants in 2D layered transition metal dichalcogenides

2018 ◽  
Vol 47 (17) ◽  
pp. 6764-6794 ◽  
Author(s):  
Shanshan Wang ◽  
Alex Robertson ◽  
Jamie H. Warner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transition Metal ◽  
Atomic Structure ◽  
Transition Metal Dichalcogenides ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

Transmission electron microscopy can directly image the detailed atomic structure of layered transition metal dichalcogenides, revealing defects and dopants.

scholarly journals Comparative Study of DC and RF Sputtered MoSe2 Coatings Containing Carbon—An Approach to Optimize Stoichiometry, Microstructure, Crystallinity and Hardness

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 133 ◽  
Author(s):  
Talha Bin Yaqub ◽  
Todor Vuchkov ◽  
Pedro Sanguino ◽  
Tomas Polcar ◽  
Albano Cavaleiro
Keyword(s):  
Electron Microscopy ◽  
Magnetron Sputtering ◽  
Solid Lubricant ◽  
Transition Metal Dichalcogenides ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Wavelength Dispersive Spectroscopy ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
Carbon Additions

Low stoichiometry, low crystallinity, low hardness and incongruencies involving the reported microstructure have limited the applicability of TMD-C (Transition metal dichalcogenides with carbon) solid-lubricant coatings. In this work, optimized Mo–Se–C coatings were deposited using confocal plasma magnetron sputtering to overcome the above-mentioned issues. Two different approaches were used; MoSe2 target powered by DC (direct current) or RF (radio frequency) magnetron sputtering. Carbon was always added by DC magnetron sputtering. Wavelength dispersive spectroscopy displayed Se/Mo stoichiometry of ~2, values higher than the literature. The Se/Mo ratio for RF-deposited coatings was lower than for their DC counterparts. Scanning electron microscopy showed that irrespective of the low carbon additions, the Mo–Se–C coatings were highly compact with no vestiges of columnar growth due to optimal bombardment of sputtered species. Application of substrate bias further improved compactness at the expense of lower Se/Mo ratio. X-ray diffraction, transmission electron microscopy, and Raman spectroscopy confirmed the presence of MoSe2 crystals, and (002) basal planes. Even very low carbon additions led to an improvement of the hardness of the coatings. The work reports a comparison between RF and DC sputtering of MoSe2 coatings with carbon and provides a guideline to optimize the composition, morphology, structure, and mechanical properties.

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