Journal articles: 'Tungsten Diselenide (WSe2)'

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Tien, Tsung-Mo, Yu-Jen Chung, Chen-Tang Huang, and Edward L. Chen. "Fabrication of WS2/WSe2 Z-Scheme Nano-Heterostructure for Efficient Photocatalytic Hydrogen Production and Removal of Congo Red under Visible Light." Catalysts 12, no. 8 (August 3, 2022): 852. http://dx.doi.org/10.3390/catal12080852.

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In this study, a novel tungsten disulfide/tungsten diselenide (WS2/WSe2) heterojunction photocatalyst by a facile hydrothermal process with great capable photocatalytic efficiency for hydrogen evolution from water and organic compound removal was discussed. The WS2/WSe2 heterojunction photocatalyst to form heterojunctions to inhibit the quick recombination rate of photo-response holes and electrons is reflected to be a useful method to enhance the capability of photocatalysis hydrogen production. The hydrogen production rate of the WS2/WSe2 photocatalyst approach is 3856.7 μmol/g/h, which is 12 and 11 folds the efficiency of bare WS2 and WSe2, respectively. Moreover, the excellent photocatalytic performance for Congo Red (CR) removal (92.4%) was 2.4 and 2.1 times higher than those of bare WS2 and WSe2, respectively. The great photocatalytic efficiency was owing to the capable electrons and holes separation of WS2/WSe2 and the construction of Z-scheme heterostructure, which possessed vigorous photocatalytic oxidation and reduction potentials. The novel one-dimensional structure of WS2/WSe2 heterojunction shortens the transport pathway of photo-induced electrons and holes. This work provided an insight to the pathway of interfacial separation and transferring for induced charge carriers, which can refer to the interfacial engineering of developed nanocomposite photocatalysts. It possessed great capable photocatalytic efficiency of hydrogen production and organic dye removal. This study offers an insight to the route of interfacial migration and separation for induced charge carriers to generating clean hydrogen energy and solve environmental pollution issue.

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Neupane, Tikaram, Quinton Rice, Sungsoo Jung, Bagher Tabibi, and Felix Jaetae Seo. "Exciton Dephasing in Tungsten Diselenide Atomic Layer." Journal of Nanoscience and Nanotechnology 20, no. 7 (July 1, 2020): 4502–4. http://dx.doi.org/10.1166/jnn.2020.17593.

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An intrinsic exciton dephasing is the coherence loss of exciton dipole oscillation, while the total exciton dephasing originates from coherence loss due to exciton–exciton interaction and excitonphonon coupling. In this article, the total exciton dephasing time of tungsten diselenide (WSe2) atomic layers was analyzed as functions of excitation intensity with exciton–exciton coupling strength and temperature with exciton–phonon coupling strength. It was hypothesized that the total exciton dephasing time is shortened as the exciton–exciton interaction and the exciton–phonon coupling are increased. The coherence loss analysis revealed that the exciton dephasing time of WSe2 atomic layers is due to mainly the temperature rather than the excitation intensity.

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Zhang, Xian. "Characterization of Layer Number of Two-Dimensional Transition Metal Diselenide Semiconducting Devices Using Si-Peak Analysis." Advances in Materials Science and Engineering 2019 (September 10, 2019): 1–7. http://dx.doi.org/10.1155/2019/7865698.

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Atomically thin materials such as semiconducting transition metal diselenide materials, like molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2), have received intensive interests in recent years due to their unique electronic structure, bandgap engineering, ambipolar behavior, and optical properties and have motivated investigations for the next-generation semiconducting electronic devices. In this work, we show a nondestructive method of characterizing the layer number of two-dimensional (2-D) MoSe2 and WSe2 including single- and few-layer materials by Raman spectroscopy. The related photoluminescence properties are also studied as a reference. Although Raman spectroscopy is a powerful tool for determining the layer number of 2-D materials such as graphene and molybdenum disulfide (MoS2), there have been difficulties in precisely characterizing the layer number for MoSe2 and WSe2 by Raman spectroscopy due to the uncertain shifts during the Raman measurement process and the lack of multiple separated Raman peaks in MoSe2 and WSe2 for referencing. We then compared the normalized Si peak with MoSe2 and WSe2 and successfully identified the layer number of MoSe2 and WSe2. Similar to graphene and MoS2, the sample layer number is found to modify their optical properties up to 4 layers.

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Yadav, Dr Saurabh Kumar. "Optoelectronic Behavior of Free Standing Al Wire Over Monolayer WSe2." International Journal of Recent Technology and Engineering (IJRTE) 11, no. 2 (July 30, 2022): 14–17. http://dx.doi.org/10.35940/ijrte.b7010.0711222.

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In this manuscript, we reported the electronic and optical behavior of free standing Aluminium nanowire mounted on tungsten diselenide (WSe2) sheet. The density functional theory has been used as a toolset for all computational calculations. We mounted the aluminum nanowire over a 2-dimensional sheet of tungsten diselenide and investigated the modulated optoelectronic properties of it. Based on our studies, we majorly found a conductive behavior of the proposed structure along with a strong absorption in visible range. Due to its prominent optical properties, the proposed structure will be very useful in futuristic optoelectronics devices such as photovoltaic, laser, optical sensors.

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Patel, P. R., J. R. Rathod, Haresh S. Patel, K. D. Patel, and V. M. Pathak. "Structural and Optical Characterization of Tungsten Diselenide Crystals Grown by DVT Technique." Advanced Materials Research 665 (February 2013): 53–57. http://dx.doi.org/10.4028/www.scientific.net/amr.665.53.

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WSe2 is a member of groupVI Transition Metal Dichalcogenides (TMDCs) and has been observed to be a highly stable semiconducting material. It has been grown in crystal form using a direct vapour transport technique in present case. The grown WSe2 crystals were characterized for the structural properties using X-ray diffraction technique (XRD). The hexagonal structure was confirmed through this analysis. Using the data of XRD, various parameters like crystalline size, lattice parameters, micro strain, dislocation density, unit cell volume, unit cell density, growth fault and deformation fault probability etc were found. It was seen that the micro strain, dislocation density and growth & deformation fault probabilities were found to be very low in WSe2 crystals. The grown WSe2 crystals were characterized for optical properties using UV-VIS-NIR spectroscopy. The absorption spectra of WSe2 grown in present case revealed the fact that WSe2 posses direct band gap around 1.38eV. Layered di-chalcogenides WSe2 (or MoSe2) are used for desired applications such as in photo-conversion devices.

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Bandyopadhyay, Avra S., Gustavo A. Saenz, and Anupama Kaul. "Characterization of Few layer Tungsten diselenide based FET under Thermal Excitation." MRS Advances 2, no. 60 (2017): 3721–26. http://dx.doi.org/10.1557/adv.2017.490.

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Abstract:Two-dimensional (2D) materials are very promising with respect to their integration into optoelectronic devices. Monolayer tungsten diselenide (WSe2) is a direct-gap semiconductor with a bandgap of ∼1.6eV, and is therefore a complement to other two-dimensional materials such as graphene, a gapless semimetal, and boron nitride, an insulator. The direct bandgap distinguishes monolayer WSe2 from its bulk and bilayer counterparts, which are both indirect gap materials with smaller bandgaps. This sizable direct bandgap in a two-dimensional layered material enables a host of new optical and electronic devices. In this work, a comprehensive analysis of the effect of optical excitation on the transport properties in few-layer WSe2 is studied. Monolayer WSe2 flakes from natural WSe2 crystals were transferred onto Si/SiO2 (270nm) substrates by mechanical exfoliation. The flakes were observed under an optical microscope. A FET based on mechanically exfoliated WSe2 was fabricated using photolithography with Molybdenum as metal contact and Silicon as back gate and the electronic properties were measured in a wide range of temperatures. The mobility of our device was found to be 0.2 cm /V-S at room temperature. The schottky barrier height was found to decrease from 80 meV to 25 meV as the gate voltage increases.

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Kagkoura, Antonia, Christina Stangel, Raul Arenal, and Nikos Tagmatarchis. "Molybdenum Diselenide and Tungsten Diselenide Interfacing Cobalt-Porphyrin for Electrocatalytic Hydrogen Evolution in Alkaline and Acidic Media." Nanomaterials 13, no. 1 (December 22, 2022): 35. http://dx.doi.org/10.3390/nano13010035.

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Easy and effective modification approaches for transition metal dichalcogenides are highly desired in order to make them active toward electrocatalysis. In this manner, we report functionalized molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2) via metal-ligand coordination with pyridine rings for the subsequent covalent grafting of a cobalt-porphyrin. The new hybrid materials were tested towards an electrocatalytic hydrogen evolution reaction in both acidic and alkaline media and showed enhanced activity compared to intact MoSe2 and WSe2. Hybrids exhibited lower overpotential, easier reaction kinetics, higher conductivity, and excellent stability after 10,000 ongoing cycles in acidic and alkaline electrolytes compared to MoSe2 and WSe2. Markedly, MoSe2-based hybrid material showed the best performance and marked a significantly low onset potential of −0.17 V vs RHE for acidic hydrogen evolution reaction. All in all, the ease and fast modification route provides a versatile functionalization procedure, extendable to other transition metal dichalcogenides, and can open new pathways for the realization of functional nanomaterials suitable in electrocatalysis.

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Zhao, Yuzhou, Chenyu Zhang, Daniel D. Kohler, Jason M. Scheeler, John C. Wright, Paul M. Voyles, and Song Jin. "Supertwisted spirals of layered materials enabled by growth on non-Euclidean surfaces." Science 370, no. 6515 (October 22, 2020): 442–45. http://dx.doi.org/10.1126/science.abc4284.

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Euclidean geometry is the fundamental mathematical framework of classical crystallography. Traditionally, layered materials are grown on flat substrates; growing Euclidean crystals on non-Euclidean surfaces has rarely been studied. We present a general model describing the growth of layered materials with screw-dislocation spirals on non-Euclidean surfaces and show that it leads to continuously twisted multilayer superstructures. This model is experimentally demonstrated by growing supertwisted spirals of tungsten disulfide (WS2) and tungsten diselenide (WSe2) draped over nanoparticles near the centers of spirals. Microscopic structural analysis shows that the crystal lattice twist is consistent with the geometric twist of the layers, leading to moiré superlattices between the atomic layers.

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Tran, Thi Nhan, Thi Theu Luong, Quang Huy Tran, Viet Bac T. Phung, and Van An Dinh. "Aromatic Volatile Organic Compounds Adsorption on Tungsten Diselenide Monolayer." Journal of Physics: Conference Series 2485, no. 1 (April 1, 2023): 012005. http://dx.doi.org/10.1088/1742-6596/2485/1/012005.

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Abstract In this work, we performed a density functional theory calculation to systematically investigate the adsorption and evaluate the adsorption performance of aromatic volatile organic compounds, benzene and toluene, on WSe2 monolayer. The most favourable adsorption configurations of gas molecules with the parallel orientation of the benzene ring to the substrate surface are explored by computing the binding energies as a function of spatial coordinates and carefully optimizing geometrical structures. The calculations pointed out that gas molecules could diffuse across the substrate along the diffusion paths with quite low diffusion potential barriers, about 180 meV for benzene and 130 meV for toluene molecules. We found that both gases are physisorbed on WSe2 monolayer with moderate adsorption energies, short recovery times, and large response lengths. The gas adsorption causes the bandgap reduction of 26 meV and a slight work function increase of the substrate. There is a charge transfer from the substrate onto the gas molecules, this may cause a resistance decrease of the p-type semiconductor substrate. WSe2 monolayer is quite sensitive to benzene and toluene, and could be suggested as an aromatic gas sensing material.

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Lee, Hyeonji, Seongin Hong, and Hocheon Yoo. "Interfacial Doping Effects in Fluoropolymer-Tungsten Diselenide Composites Providing High-Performance P-Type Transistors." Polymers 13, no. 7 (March 30, 2021): 1087. http://dx.doi.org/10.3390/polym13071087.

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In this study, we investigated the p-doping effects of a fluoropolymer, Cytop, on tungsten diselenides (WSe2). The hole current of the Cytop–WSe2 field-effect transistor (FET) was boosted by the C–F bonds of Cytop having a strong dipole moment, enabling increased hole accumulation. Analysis of the observed p-doping effects using atomic force microscopy (AFM) and Raman spectroscopy shed light on the doping mechanism. Moreover, Cytop reduces the electrical instability by preventing the adsorption of ambient molecules on the WSe2 surface. Annealing Cytop deposited on WSe2 eliminated the possible impurities associated with adsorbates (i.e., moisture and oxygen) that act as traps on the surface of WSe2. After thermal annealing, the Cytop–WSe2 FET afforded higher p-type conductivity and reduced hysteresis. The combination of the Cytop–WSe2 FET with annealing provides a promising method for obtaining high-performance WSe2 p-type transistors.

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Pandey, Sushil Kumar, Hussain Alsalman, Javad G. Azadani, Nezhueyotl Izquierdo, Tony Low, and Stephen A. Campbell. "Controlled p-type substitutional doping in large-area monolayer WSe2 crystals grown by chemical vapor deposition." Nanoscale 10, no. 45 (2018): 21374–85. http://dx.doi.org/10.1039/c8nr07070a.

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Luo, Xuyi, Kraig Andrews, Tianjiao Wang, Arthur Bowman, Zhixian Zhou, and Ya-Qiong Xu. "Reversible photo-induced doping in WSe2 field effect transistors." Nanoscale 11, no. 15 (2019): 7358–63. http://dx.doi.org/10.1039/c8nr09929d.

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We report a reversible photo-induced doping effect in two-dimensional (2D) tungsten diselenide (WSe₂) field effect transistors on hexagonal boron nitride (h-BN) substrates under low-intensity visible light illumination (∼10 nW μm⁻²).

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Marinova, Vera, Krastyo Buchkov, Vladimira Videva, Irnik Dionisiev, Nikolay Minev, Velichka Strijkova, Deyan Dimov, et al. "Evolution of WSe2 Flakes Synthesized by Thermally Assisted Conversion Method." Coatings 12, no. 3 (March 7, 2022): 353. http://dx.doi.org/10.3390/coatings12030353.

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We report the synthesis of tungsten diselenide (WSe2) flakes and continuous layers using an atmospheric pressure thermally assisted conversion (TAC) method, where the tungsten (W) layers were pre-deposited by a magnetron sputtering system onto fused silica substrates. Optical microscopy (OM) and atomic force microscopy (AFM) mapping predominantly revealed the formation of isolated flakes with different shapes, mainly concentrated near the substrate’s edges, which tended to form clusters and to further overlap to continuous layers, moving to the central part of the fused silica substrates. Raman spectroscopy and photoluminescence measurements confirmed the existence of atomically thin flakes and 2H-WSe2 continuous layers. The measured current–voltage characteristics indicated Ohmic behavior under dark conditions and photo illumination. Finally, the demonstrated resistor-like behavior suggested unlimited prospects for WSe2 integration into a variety of heterostructures.

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Khan, Muhammad Atif, Muhammad Qasim Mehmood, and Yehia Massoud. "High-Temperature Annealing Effects on Atomically Thin Tungsten Diselenide Field-Effect Transistor." Applied Sciences 12, no. 16 (August 13, 2022): 8119. http://dx.doi.org/10.3390/app12168119.

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Two-dimensional (2D) material-based devices are expected to operate under high temperatures induced by Joule heating and environmental conditions when integrated into compact integrated circuits for practical applications. However, the behavior of these materials at high operating temperatures is obscure as most studies emphasize only room temperature or low-temperature operation. Here, the high-temperature electrical response of the tungsten diselenide (WSe2) field-effect transistor was studied. It is revealed that 350 K is the optimal annealing temperature for the WSe2 transistor, and annealing at this temperature improves on-current, field-effect mobility and on/off ratio around three times. Annealing beyond this temperature (360 K to 670 K) adversely affects the device performance attributed to the partial oxidation of WSe2 at higher temperatures. An increase in hysteresis also confirms the formation of new traps as the device is annealed beyond 350 K. These findings explicate the thermal stability of WSe2 and can help design 2D materials-based durable devices for high-temperature practical applications.

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Sierra-Castillo, Ayrton, Emile Haye, Selene Acosta, Carla Bittencourt, and J. F. Colomer. "Synthesis and Characterization of Highly Crystalline Vertically Aligned WSe2 Nanosheets." Applied Sciences 10, no. 3 (January 27, 2020): 874. http://dx.doi.org/10.3390/app10030874.

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Here, we report on the synthesis of tungsten diselenide (WSe2) nanosheets using an atmospheric pressure chemical vapor deposition technique via the rapid selenization of thin tungsten films. The morphology and the structure, as well as the optical properties, of the so-produced material have been studied using electron microscopies, X-ray photoelectron spectroscopy, photoluminescence, UV–visible and Raman spectroscopies, and X-ray diffraction. These studies confirmed the high crystallinity, quality, purity, and orientation of the WSe2 nanosheets, in addition to the unexpected presence of mixed phases, instead of only the most thermodynamically stable 2H phase. The synthesized material might be useful for applications such as gas sensing or for hydrogen evolution reaction catalysis.

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Share, Keith, John Lewis, Landon Oakes, Rachel E. Carter, Adam P. Cohn, and Cary L. Pint. "Tungsten diselenide (WSe2) as a high capacity, low overpotential conversion electrode for sodium ion batteries." RSC Advances 5, no. 123 (2015): 101262–67. http://dx.doi.org/10.1039/c5ra19717a.

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Ezgi Eroglu, Zeynep, Dillon Contreras, Pouya Bahrami, Nurul Azam, Masoud Mahjouri-Samani, and Abdelaziz Boulesbaa. "Filling Exciton Trap-States in Two-Dimensional Tungsten Disulfide (WS2) and Diselenide (WSe2) Monolayers." Nanomaterials 11, no. 3 (March 18, 2021): 770. http://dx.doi.org/10.3390/nano11030770.

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Two-dimensional transition metal dichalcogenides (2D-TMDs) hold a great potential to platform future flexible optoelectronics. The beating hearts of these materials are their excitons known as XA and XB, which arise from transitions between spin-orbit split (SOS) levels in the conduction and valence bands at the K-point. The functionality of 2D-TMD-based devices is determined by the dynamics of these excitons. One of the most consequential channels of exciton decay on the device functionality is the defect-assisted recombination (DAR). Here, we employ steady-state absorption and emission spectroscopies, and pump density-dependent femtosecond transient absorption spectroscopy to report on the effect of DAR on the lifetime of excitons in monolayers of tungsten disulfide (2D-WS2) and diselenide (2D-WSe2). These pump-probe measurements suggested that while exciton decay dynamics in both monolayers are driven by DAR, in 2D-WS2, defect states near the XB exciton fill up before those near the XA exciton. However, in the 2D-WSe2 monolayer, the defect states fill up similarly. Understanding the contribution of DAR on the lifetime of excitons and the partition of this decay channel between XA and XB excitons may open new horizons for the incorporation of 2D-TMD materials in future optoelectronics.

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Buryakov A.M., Gorbatova A. V., Avdeev P. Yu., Bezvikonny N. V., Ovcharenko S. V., Klimov A. A., Stankevich K. L., and Mishina E. D. "Spintronic emitter of terahertz radiation based on two-dimensional semiconductor tungsten diselenide." Technical Physics Letters 48, no. 9 (2022): 53. http://dx.doi.org/10.21883/tpl.2022.09.55084.19246.

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We propose a new spintronic emitter based on the Co/WSe2 heterostructure. The time of ultrafast demagnetization is estimated. It is shown that the two-dimensional ferromagnet/semiconductor interface exhibits strong spin-orbit coupling. Approaches to the description of the mechanism of generation of THz radiation are implemented. It is shown that the polarization orientation of THz radiation depends on the direction of magnetization Keywords: Spintronic emitter, THz radiation, two-dimensional semiconductors, Co/WSe2, THz polarization.

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Arora, Ankit, Pramoda K. Nayak, Tejendra Dixit, Kolla Lakshmi Ganapathi, Ananth Krishnan, and Mamidanna Sri Ramachandra Rao. "Stacking angle dependent multiple excitonic resonances in bilayer tungsten diselenide." Nanophotonics 9, no. 12 (June 18, 2020): 3881–87. http://dx.doi.org/10.1515/nanoph-2020-0034.

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AbstractWe report on multiple excitonic resonances in bilayer tungsten diselenide (BL-WSe2) stacked at different angles and demonstrate the use of the stacking angle to control the occurrence of these excitations. BL-WSe2 with different stacking angles were fabricated by stacking chemical vapour deposited monolayers and analysed using photoluminescence measurements in the temperature range 300–100 K. At reduced temperatures, several excitonic features were observed and the occurrences of these exitonic resonances were found to be stacking angle dependent. Our results indicate that by controlling the stacking angle, it is possible to excite or quench higher order excitations to tune the excitonic flux in optoelectronic devices. We attribute the presence/absence of multiple higher order excitons to the strength of interlayer coupling and doping effect from SiO2/Si substrate. Understanding interlayer excitations will help in engineering excitonic devices and give an insight into the physics of many-body dynamics.

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Kawanago, Takamasa, Takahiro Matsuzaki, Ryosuke Kajikawa, Iriya Muneta, Takuya Hoshii, Kuniyuki Kakushima, Kazuo Tsutsui, and Hitoshi Wakabayashi. "Experimental demonstration of high-gain CMOS inverter operation at low V _dd down to 0.5 V consisting of WSe₂ n/p FETs." Japanese Journal of Applied Physics 61, SC (February 7, 2022): SC1004. http://dx.doi.org/10.35848/1347-4065/ac3a8e.

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Abstract In this paper, we report on the device concepts for high-gain operation of a tungsten diselenide (WSe2) complementary metal-oxide-semiconductor (CMOS) inverter at a low power supply voltage (V dd ), which was realized by developing a doping technique and gate stack technology. A spin-coating with a fluoropolymer and poly(vinyl alcohol) (PVA) results in the doping of both electrons and holes to WSe2. A hybrid self-assembled monolayer/aluminum oxide (AlO x ) gate dielectric is viable for achieving high gate capacitance and superior interfacial properties. By developing the doping technique and gate stack technology, we experimentally realized a high gain of 9 at V dd of 0.5 V in the WSe2 CMOS inverter. This study paves the way for the research and development of transition metal dichalcogenides-based devices and circuits.

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Jayanand, Kishan, and Anupama B. Kaul. "Photodetectors with Buckminsterfullerene Decorated WSe₂." Journal of The Electrochemical Society 169, no. 4 (April 1, 2022): 047503. http://dx.doi.org/10.1149/1945-7111/ac6074.

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In this work, we have studied the interactions of van der Waals (vdWs) hybrid structures composed of two-dimensional tungsten diselenide (WSe2) with zero-dimensional buckminsterfullerene (C60) spheres. The organic-inorganic vdWs heterostructure was fabricated using the spin coated dispersion of C60 over monolayer WSe2 crystallites. The morphology of the spin coated C60 on the surface of monolayer (1L) WSe2 was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Raman and photoluminescence spectroscopy were used to reveal the p -type doping of WSe2 by the C60 molecules. Photodetector devices were then fabricated with Ti-contacted electrodes and the photodetector figures of merit for WSe2 and C60-WSe2 hybrids were examined as a function of illumination power and incoming wavelength which showed the C60 decoration of 1L-WSe2 provides an improvement in device performance. Furthermore, the temporal response of the devices was analyzed which showed a reduction in response times by more than two times for the hybrid system. Our results indicate that the C60-WSe2 vdWs hybrid heterostructure appears to be an attractive architecture for enabling charge transfer and high performance photodetection capabilities.

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Li, Xian, Chengcheng Xu, Xiaosong Du, Zhen Wang, Wenjun Huang, Jie Sun, Yang Wang, and Zhemin Li. "Assembled Reduced Graphene Oxide/Tungsten Diselenide/Pd Heterojunction with Matching Energy Bands for Quick Banana Ripeness Detection." Foods 11, no. 13 (June 24, 2022): 1879. http://dx.doi.org/10.3390/foods11131879.

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The monitoring of ethylene is of great importance to fruit and vegetable quality, yet routine techniques rely on manual and complex operation. Herein, a chemiresistive ethylene sensor based on reduced graphene oxide (rGO)/tungsten diselenide (WSe2)/Pd heterojunctions was designed for room-temperature (RT) ethylene detection. The sensor exhibited high sensitivity and quick p-type response/recovery (33/13 s) to 10–100 ppm ethylene at RT, and full reversibility and excellent selectivity to ethylene were also achieved. Such excellent ethylene sensing behaviors could be attributed to the synergistic effects of ethylene adsorption abilities derived from the negative adsorption energy and the promoted electron transfer across the WSe2/Pd and rGO/WSe2 interfaces through band energy alignment. Furthermore, its application feasibility to banana ripeness detection was verified by comparison with routine technique through simulation experiments. This work provides a feasible methodology toward designing and fabricating RT ethylene sensors, and may greatly push forward the development of modernized intelligent agriculture.

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Zhang, Zijian, Guowei Chen, Mingyu Yang, Yunyao Ou, Luqi Luo, Dongqin Lu, Enze Zhang, et al. "Resonance-enhanced all-optical modulation of WSe2-based micro-resonator." Nanophotonics 9, no. 8 (December 9, 2019): 2387–96. http://dx.doi.org/10.1515/nanoph-2019-0425.

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AbstractTwo-dimensional material tungsten diselenide (WSe2) nanosheets are coated on a microfibre knot resonator (MKR) to achieve an all-optical power modulation functionality. On account of the strong absorption property of WSe2 and the resonance enhancement properties of MKR, the transmitted optical power of signal light within the WSe2-based MKR can be effectively modulated. The sensitivities of light–control–light experiments with 405- and 660-nm lasers are as high as 0.32 and 0.12 dB/mW, respectively. The sensitivities and power tuning can be enhanced by a higher resonance Q and a larger extinction ratio of MKR. In terms of the response time, the average rise and fall times are 3.5/3.7 and 3.5/4 ms with 405- and 660-nm lasers, respectively. This proposed structure is expected to achieve potential applications in all-fibre-optic–based tunable device such as optical modulator, detector, and so on.

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Jobayr, Mahmood Radhi, and Ebtisam M.-T. Salman. "Bilayer MSe₂ (M = Zr, Hf, Mo, W) performance as a hopeful thermoelectric materials." Journal of Semiconductors 44, no. 3 (March 1, 2023): 032001. http://dx.doi.org/10.1088/1674-4926/44/3/032001.

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Abstract Significant advancements in nanoscale material efficiency optimization have made it feasible to substantially adjust the thermoelectric transport characteristics of materials. Motivated by the prediction and enhanced understanding of the behavior of two-dimensional (2D) bilayers (BL) of zirconium diselenide (ZrSe2), hafnium diselenide (HfSe2), molybdenum diselenide (MoSe2), and tungsten diselenide (WSe2), we investigated the thermoelectric transport properties using information generated from experimental measurements to provide inputs to work with the functions of these materials and to determine the critical factor in the trade-off between thermoelectric materials. Based on the Boltzmann transport equation (BTE) and Barden-Shockley deformation potential (DP) theory, we carried out a series of investigative calculations related to the thermoelectric properties and characterization of these materials. The calculated dimensionless figure of merit (ZT) values of 2DBL-MSe2 (M = Zr, Hf, Mo, W) at room temperature were 3.007, 3.611, 1.287, and 1.353, respectively, with convenient electronic densities. In addition, the power factor is not critical in the trade-off between thermoelectric materials but it can indicate a good thermoelectric performance. Thus, the overall thermal conductivity and power factor must be considered to determine the preference of thermoelectric materials.

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Kim, Hyungjin, Geun Ho Ahn, Joy Cho, Matin Amani, James P. Mastandrea, Catherine K. Groschner, Der-Hsien Lien, et al. "Synthetic WSe2 monolayers with high photoluminescence quantum yield." Science Advances 5, no. 1 (January 2019): eaau4728. http://dx.doi.org/10.1126/sciadv.aau4728.

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In recent years, there have been tremendous advancements in the growth of monolayer transition metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). However, obtaining high photoluminescence quantum yield (PL QY), which is the key figure of merit for optoelectronics, is still challenging in the grown monolayers. Specifically, the as-grown monolayers often exhibit lower PL QY than their mechanically exfoliated counterparts. In this work, we demonstrate synthetic tungsten diselenide (WSe2) monolayers with PL QY exceeding that of exfoliated crystals by over an order of magnitude. PL QY of ~60% is obtained in monolayer films grown by CVD, which is the highest reported value to date for WSe2 prepared by any technique. The high optoelectronic quality is enabled by the combination of optimizing growth conditions via tuning the halide promoter ratio, and introducing a simple substrate decoupling method via solvent evaporation, which also mechanically relaxes the grown films. The achievement of scalable WSe2 with high PL QY could potentially enable the emergence of technologically relevant devices at the atomically thin limit.

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Islam, Arnob, and Philip X. L. Feng. "Effects of asymmetric Schottky contacts on photoresponse in tungsten diselenide (WSe2) phototransistor." Journal of Applied Physics 122, no. 8 (August 28, 2017): 085704. http://dx.doi.org/10.1063/1.4986122.

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Lin, Hsiang-Ting, Chiao-Yun Chang, Pi-Ju Cheng, Ming-Yang Li, Chia-Chin Cheng, Shu-Wei Chang, Lance L. J. Li, Chih-Wei Chu, Pei-Kuen Wei, and Min-Hsiung Shih. "Circular Dichroism Control of Tungsten Diselenide (WSe2) Atomic Layers with Plasmonic Metamolecules." ACS Applied Materials & Interfaces 10, no. 18 (April 16, 2018): 15996–6004. http://dx.doi.org/10.1021/acsami.8b01472.

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Prasad, G., N. N. Rao, and O. N. Srivastava. "Growth, Structural Characteristics and Photoelectrochemical Behaviour of Tungsten Diselenide (WSe2) Single Crystals." Crystal Research and Technology 21, no. 10 (October 1986): 1303–11. http://dx.doi.org/10.1002/crat.2170211012.

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Liu, Hailiang, Sajjad Hussain, Jehoon Lee, Dhanasekaran Vikraman, and Jungwon Kang. "Ultrasonically Processed WSe2 Nanosheets Blended Bulk Heterojunction Active Layer for High-Performance Polymer Solar Cells and X-ray Detectors." Materials 14, no. 12 (June 10, 2021): 3206. http://dx.doi.org/10.3390/ma14123206.

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Two-dimensional (2D) tungsten diselenide (WSe2) has attracted considerable attention in the field of photovoltaic devices owing to its excellent structure and photoelectric properties, such as ordered 2D network structure, high electrical conductivity, and high mobility. For this test, we firstly prepared different sizes (NS1–NS3) of WSe2 nanosheets (NSs) through the ultrasonication method and characterized their structures using the field emission scanning electron microscope (FE-SEM), Raman spectroscopy, and X-ray powder diffraction. Moreover, we investigated the photovoltaic performance of polymer solar cells based on 5,7-Bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione(PBDB-T):(6,6)-phenyl-C71 butyric acid methyl ester (PCBM) with different WSe2 NSs as the active layer. The fabricated PBDB-T:PCBM active layer with the addition of NS2 WSe2 NSs (1.5 wt%) exhibited an improved power conversion efficiency (PCE) of 9.2%, which is higher than the pure and NS1 and NS3 WSe2 blended active layer-encompassing devices. The improved PCE is attributed to the synergic enhancement of exciton dissociation and an improvement in the charge mobility through the modified active layer for polymer solar cells. Furthermore, the highest sensitivity of 2.97 mA/Gy·cm2 was achieved for the NS2 WSe2 NSs blended active layer detected by X-ray exposure over the pure polymer, and with the NS1 and NS2 WSe2 blended active layer. These results led to the use of transition metal dichalcogenide materials in polymer solar cells and X-ray detectors.

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Tien, Tsung-Mo, Yu-Jen Chung, Chen-Tang Huang, and Edward L. Chen. "WSSe Nanocomposites for Enhanced Photocatalytic Hydrogen Evolution and Methylene Blue Removal under Visible-Light Irradiation." Materials 15, no. 16 (August 16, 2022): 5616. http://dx.doi.org/10.3390/ma15165616.

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In this study, a novel tungsten disulfide diselenide (WSSe) nanocomposite by a facile hydrothermal process with great capable photocatalytic efficiency for hydrogen evolution from water and organic compound removal was discussed. The WSSe nanocomposites form heterojunctions in order to inhibit the quick recombination rate of photo-induced electrons and holes. This is considered to be a useful method in order to enhance the capability of photocatalytic hydrogen production. The hydrogen production rate of the WSSe nanocomposites approaches 3647.4 μmol/g/h, which is 12 and 11 folds the rates of the bare WS2 and WSe2, respectively. Moreover, the excellent photocatalytic performance for Methylene blue (MB) removal (88%) was 2.5 and 1.8 times higher than those of the bare WS2 and WSe2, respectively. The great photocatalytic efficiency was owing to the capable electrons and holes separation of WSSe and the construction of the heterostructure, which possessed vigorous photocatalytic oxidation and reduction potentials. The novel one-dimensional structure of the WSSe heterojunction shortens the transport pathway of the photo-induced electrons and holes. It possesses the great capable photocatalytic efficiency of the hydrogen production and organic dye removal. This study offers an insight into the route of interfacial migration and separation for induced charge carriers in order to generate clean hydrogen energy and to solve the issue of environmental pollution.

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James Singh, Konthoujam, Hao-Hsuan Ciou, Ya-Hui Chang, Yen-Shou Lin, Hsiang-Ting Lin, Po-Cheng Tsai, Shih-Yen Lin, Min-Hsiung Shih, and Hao-Chung Kuo. "Optical Mode Tuning of Monolayer Tungsten Diselenide (WSe2) by Integrating with One-Dimensional Photonic Crystal through Exciton–Photon Coupling." Nanomaterials 12, no. 3 (January 27, 2022): 425. http://dx.doi.org/10.3390/nano12030425.

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Two-dimensional materials, such as transition metal dichalogenides (TMDs), are emerging materials for optoelectronic applications due to their exceptional light–matter interaction characteristics. At room temperature, the coupling of excitons in monolayer TMDs with light opens up promising possibilities for realistic electronics. Controlling light–matter interactions could open up new possibilities for a variety of applications, and it could become a primary focus for mainstream nanophotonics. In this paper, we show how coupling can be achieved between excitons in the tungsten diselenide (WSe2) monolayer with band-edge resonance of one-dimensional (1-D) photonic crystal at room temperature. We achieved a Rabi splitting of 25.0 meV for the coupled system, indicating that the excitons in WSe2 and photons in 1-D photonic crystal were coupled successfully. In addition to this, controlling circularly polarized (CP) states of light is also important for the development of various applications in displays, quantum communications, polarization-tunable photon source, etc. TMDs are excellent chiroptical materials for CP photon emitters because of their intrinsic circular polarized light emissions. In this paper, we also demonstrate that integration between the TMDs and photonic crystal could help to manipulate the circular dichroism and hence the CP light emissions by enhancing the light–mater interaction. The degree of polarization of WSe2 was significantly enhanced through the coupling between excitons in WSe2 and the PhC resonant cavity mode. This coupled system could be used as a platform for manipulating polarized light states, which might be useful in optical information technology, chip-scale biosensing and various opto-valleytronic devices based on 2-D materials.

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Rehman, Malik Abdul, Minjae Kim, Sachin A. Pawar, Sewon Park, Naila Nasir, Dong-eun Kim, Mohammad Farooq Khan, et al. "A Simple Method to Produce an Aluminum Oxide-Passivated Tungsten Diselenide/n-Type Si Heterojunction Solar Cell with High Power Conversion Efficiency." International Journal of Energy Research 2023 (February 23, 2023): 1–11. http://dx.doi.org/10.1155/2023/8195624.

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Transition metal dichalcogenide (TMDC) materials are attractive candidates for 2D solar cell devices thanks to their straightforward integration with various substrates and traditional semiconductor technologies, wide band gap ranges over the visible light spectrum, and high absorption coefficient values. Although there are several previous reports on the fabrication of 2D material-based solar cells, difficult and complex processes in the fabrication are highly required to be modified for wider use in daily life applications. Photolithography, the most commonly used manufacturing process for TMDC-based solar cells, is complicated. In this study, we demonstrate that the fabrication of 2D tungsten diselenide (WSe2) by adopting a wet transfer process with thermal release tape simplifies the manufacturing steps for TMDC-based solar cell devices. This simplification not only reduces the production cost by excluding several factors such as transmittance, thermal expansion, surface flatness, and durability but also improves the yield. Furthermore, a proof-of-concept demonstration of creating a WSe2/Si junction with an aluminum oxide (Al2O3) antireflective coating provided a power conversion efficiency of 6.39%, which is a significant improvement over that of a WSe2/Si solar cell without the antireflective coating layer (1.08%).

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Kang, Miae, Kihyun Kim, Joona Bang, and Jihyun Kim. "Nano-Pattern Oxidation of WSe₂ Via Block Copolymer Self-Assembly for Highly Responsive Homojunction Phototransistors." ECS Meeting Abstracts MA2022-02, no. 36 (October 9, 2022): 1317. http://dx.doi.org/10.1149/ma2022-02361317mtgabs.

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Tungsten diselenide (WSe2), one of the two-dimensional (2D) materials, has emerged as a promising optoelectric candidate because of its thickness dependent bandgap, large optical absorption coefficient, good air stability and high carrier mobility. In addition, the electrical properties of the ambipolar WSe2 could be tuned through the electrostatic doping by the gate modulation. However, the low photo responsivity is a critical problem of WSe2-based optoelectric devices. To overcome this limitation, several approaches have been suggested such as stacking different 2D materials and coating with quantum dots. But these conventional methods were focused on the formation of heterojunctions, which requires complicated alignment process and leads to unavoidable defects and residues. Thus, the novel ways to build homojuction should be investigated for fabricating devices with a clean interface in a simple process. In this work, block copolymer (BCP) was used to prepare hexagonally packed cylinder nano-template as an oxidation mask for UV/ozone treatment, which resulted in numerous nanoscale homojunctions on WSe2. To fabricate the mask with hexagonally packed cylinders, asymmetric poly (styrene-block-methyl methacrylate) (PS-b-PMMA) was spin-coated. After thermal annealing for self-assembly, PMMA was selectively removed by reactive ion etching. UV/ozone treatment, one of the oxidation methods of the WSe2, leads to the formation of the the tungsten oxide (WOX) with high electron affinity and induces a p-doping effect. By using BCP as an oxidation mask, the only region of the WSe2 under the removed PMMA blocks could be converted into WOX. The responsivity of the nano-pattern oxidized WSe2 phototransistor manifests a dramatic change depending on the applied gate bias. The device exhibited a responsivity (532 nm, 8.515 mW/cm2) of 27.5 mA/W under applied gate bias of 0 V. However, under the gate bias of +60 V, the device showed an enhanced responsivity of 155.2 mA/W, as strong p-n junctions were induced. In conclusion, the nano-pattern oxidized WSe2 phototransistor presents increased responsivity (155.2 mA/W), external quantum efficiency (36.3%) and faster response time than the pristine WSe2. This work demonstrates that the responsivity of the WSe2 phototransistor can be improved though well-established perpendicular BCP and optimized by effective modulation of gate bias. By implementing homojunctions on the WSe2 via the nano-pattern oxidation method, this work greatly expands the potential applications of 2D TMDs materials for next-generation nanoscale optoelectronic devices.

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Nam, Hyo-Jik, Jinok Kim, and Jin-Hong Park. "Wide-Range Controllable Doping of Tungsten Diselenide (WSe2) based on Hydrochloric Acid Treatment." Journal of Physical Chemistry C 121, no. 26 (June 23, 2017): 14367–72. http://dx.doi.org/10.1021/acs.jpcc.7b04439.

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Mitioglu, A. A., P. Plochocka, Á. Granados del Aguila, P. C. M. Christianen, G. Deligeorgis, S. Anghel, L. Kulyuk, and D. K. Maude. "Optical Investigation of Monolayer and Bulk Tungsten Diselenide (WSe2) in High Magnetic Fields." Nano Letters 15, no. 7 (June 15, 2015): 4387–92. http://dx.doi.org/10.1021/acs.nanolett.5b00626.

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Lee, Hae Won, Dong-Ho Kang, Jeong Ho Cho, Sungjoo Lee, Dong-Hwan Jun, and Jin-Hong Park. "Highly Sensitive and Reusable Membraneless Field-Effect Transistor (FET)-Type Tungsten Diselenide (WSe2) Biosensors." ACS Applied Materials & Interfaces 10, no. 21 (May 16, 2018): 17639–45. http://dx.doi.org/10.1021/acsami.8b03432.

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Ghosh, Sujoy, Milinda Wasala, Nihar R. Pradhan, Daniel Rhodes, Prasanna D. Patil, Michael Fralaide, Yan Xin, Stephen A. McGill, Luis Balicas, and Saikat Talapatra. "Low temperature photoconductivity of few layer p-type tungsten diselenide (WSe2) field-effect transistors (FETs)." Nanotechnology 29, no. 48 (October 1, 2018): 484002. http://dx.doi.org/10.1088/1361-6528/aae049.

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Kim, Soojin, Chulmin Kim, Young Hyun Hwang, Seungwon Lee, Minjung Choi, and Byeong-Kwon Ju. "Carrier-type modulation of tungsten diselenide (WSe2) field-effect transistors (FETs) via benzyl viologen (BV) doping." Chemical Physics Letters 770 (May 2021): 138453. http://dx.doi.org/10.1016/j.cplett.2021.138453.

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Martanov, Sergey G., Natalia K. Zhurbina, Mikhail V. Pugachev, Aliaksandr I. Duleba, Mark A. Akmaev, Vasilii V. Belykh, and Aleksandr Y. Kuntsevich. "Making van der Waals Heterostructures Assembly Accessible to Everyone." Nanomaterials 10, no. 11 (November 21, 2020): 2305. http://dx.doi.org/10.3390/nano10112305.

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Van-der Waals heterostructures assembled from one or few atomic layer thickness crystals are becoming increasingly more popular in condensed matter physics. These structures are assembled using transfer machines, those are based on mask aligners, probe stations or are home-made. For many laboratories it is vital to build a simple, convenient and universal transfer machine. In this paper we discuss the guiding principles for the design of such a machine, review the existing machines and demonstrate our own construction, that is powerful and fast-in-operation. All components of this machine are extremely cheap and can be easily purchased using common online retail services. Moreover, assembling a heterostructure out of exfoliated commercially available hexagonal boron nitride and tungsten diselenide crystals with a pick-up technique and using the microphotolumenescence spectra, we show well-resolved exciton and trion lines, as a results of disorder suppression in WSe2 monolayer. Our results thus show that technology of the two-dimensional materials and heterostructures becomes accessible to anyone.

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Magonov, S. N., H. J. Cantow, and M. H. Whangbo. "On the nature of nanometer-scale ring structures in the scanning tunneling microscopy images of tungsten diselenide WSe2." Surface Science 318, no. 1-2 (October 1994): L1175—L1180. http://dx.doi.org/10.1016/0039-6028(94)90334-4.

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Ansh, Jeevesh Kumar, Gaurav Sheoran, Ravikesh Mishra, Srinivasan Raghavan, and Mayank Shrivastava. "Selective Electron or Hole Conduction in Tungsten Diselenide (WSe2) Field-Effect Transistors by Sulfur-Assisted Metal-Induced Gap State Engineering." IEEE Transactions on Electron Devices 67, no. 1 (January 2020): 383–88. http://dx.doi.org/10.1109/ted.2019.2956781.

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Thanopulos, Ioannis, Vasilios Karanikolas, and Emmanuel Paspalakis. "Reversible Population Dynamics at the Nanoscale for a Quantum Emitter Near a WSe2 Monolayer." Materials Proceedings 4, no. 1 (November 11, 2020): 56. http://dx.doi.org/10.3390/iocn2020-07865.

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The interaction of quantum emitters with photonic antennas created by nanoscale structures may lead to several interesting phenomena with many important potential applications in current and future technology. There are two distinct regimes of light–matter interaction between a quantum emitter and its modified photonic environment, the weak coupling regime and the strong coupling regime, where the quantum emitter has a completely different spontaneous emission response. In the weak coupling regime, an initially excited quantum emitter shows an exponential spontaneous emission dynamic (Markovian response), but the spontaneous decay rate can be markedly different from the free-space vacuum, and can be either enhanced or suppressed due to the Purcell effect. In the strong coupling regime, there is a coherent exchange of energy between the quantum emitter and its modified nanophotonic environment, which manifests itself in non-exponential spontaneous emission dynamics (non-Markovian response). We investigate the spontaneous emission dynamics of a two-level quantum emitter in proximity to an atomically thin tungsten diselenide (WSe2) layer at various distances of the emitter from the layer and various free-space decay rates of the emitter. Depending on the distance and the decay rate value, our studies cover the range of the weak to strong coupling regime of the light–matter interaction between the quantum emitter and the electromagnetic continuum modified by the WSe2 layer. We find that the decay dynamics is Markovian under weak coupling conditions, and it becomes strongly non-Markovian, characterized by oscillatory population emitter dynamics, on the top of the overall population decay, as well as population trapping in the emitter. Besides population evolution, we also discuss the non-Markovian spontaneous emission dynamics using a widely used non-Markovianity measure.

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Kawanago, Takamasa, Takahiro Matsuzaki, Ryosuke Kajikawa, Iriya Muneta, Takuya Hoshii, Kuniyuki Kakushima, Kazuo Tsutsui, and Hitoshi Wakabayashi. "(Invited, Digital Presentation) Low Voltage Operation of CMOS Inverter Based on WSe₂ n/p FETs." ECS Meeting Abstracts MA2022-02, no. 15 (October 9, 2022): 825. http://dx.doi.org/10.1149/ma2022-0215825mtgabs.

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Transition metal dichalcogenides (TMDC) have remarkable properties for the next generation of electronic devices [1]. A complementary metal-oxide-semiconductor (CMOS) inverter consisting of pairs of p-type and n-type field-effect transistor (FET) is a fundamental building block in modern digital electronics [2]. Therefore, realization of both p-type and n-type FETs based on semiconducting TMDC is of particular importance. Among various semiconducting TMDC, tungsten diselenide (WSe2) is a promising candidate for constructing a CMOS inverter because of its high mobility, symmetric electron and hole effective mass and ambipolar transport [3]. These prominent features of WSe2 motivates the fabrication and characterization of a CMOS inverter. One of the significant challenges is to develop a high-gain CMOS inverter for operation at a low power supply voltage (Vdd) for future low power digital electronics. Previous studies on a WSe2 CMOS inverter were limited to operation with a low gain of 3 or a high Vdd of more than 1 V under conditions of relatively low gate capacitance and degraded interfacial properties [3-5]. This study addressed these issues by developing a doping technique and gate stack technology to demonstrate the high-gain with low-Vdd operation of a WSe2 CMOS inverter [6]. The focus is on the doping technique of both electrons and holes to a WSe2 layer by simple spin-coating. Of particular interest in this study is the impact of gate stack technology on the CMOS inverter characteristics in low-Vdd operation. In this study, a hybrid self-assembled monolayer (SAM)/aluminum oxide (AlOx) gate dielectric is applied to a WSe2 CMOS inverter for high-gain low-Vdd operation since superior interfacial properties with high gate capacitance have been reported in molybdenum disulfide (MoS2) FETs. For p-type WSe2 FETs, the fluoropolymer CYTOP (AGC, CTX-809A) was applied since polarization in CYTOP due to the difference in electronegativity between C–F bonds generates holes in WSe2. On the other hand, poly(vinyl alcohol) (PVA) was utilized for n-type WSe2 FETs because positive charges in PVA accumulates electrons in WSe2. The resin solutions of both CYTOP and PVA were purchased from a commercial supplier. A heavily doped p-type silicon substrate (p+-Si) was thermally oxidized to form a 60 nm thick silicon dioxide (SiO2) layer for the global back-gate architecture. Palladium (Pd) and gold (Au) as the source and drain contacts for p-type and n-type WSe2 FETs were fabricated by the lift-off process, respectively. An aluminum (Al) gate was prepared and a hybrid SAM/AlOx gate dielectric was formed by oxygen (O2) plasma and an immersion process. After that, mechanically exfoliated WSe2 was transferred with a poly(dimethylsiloxane) (PDMS) stamp. Finally, CYTOP and PVA were deposited by spin-coating for p-type and n-type WSe2 FETs, respectively. Figures 1 (a) and (b) show the Id–Vg characteristics of fabricated FETs. For the p-type WSe2 FET, a small SS of 78 mV/dec and an on/off ratio of about 106 order were observed. On the other hand, the Id–Vg characteristics of the n-type WSe2 FET were degraded compared with those of the p-type WSe2 FET because of the Schottky contacts. Figures 2 (a) and (b) show the transfer characteristics and gain as a function of Vdd in CMOS inverter. The gain of the CMOS inverter increased to as high as 9 at Vdd of 0.5 V. Figure 3 shows the benchmark of this study. Our proposed concepts enabled the operation with high gain at a low Vdd as low as 0.5 V for the WSe2 CMOS inverter, which had not been realized in previous studies. The dangling-bond-free and ultrathin SAM/AlOx gate dielectric has an important role in the low-Vdd operation of the WSe2 CMOS inverter. This study opens up interesting directions for the research and development of TMDC-based devices and circuits. References [1] Q. H. Wang, K. K. Zadeh, A. Kis, J. N. Coleman, and M. S. Strano, Nat. Nanotechnol. 7, 699 (2012). [2] Y. Taur and T. H. Ning, Fundamentals of Modern VLSI Devices (Cambridge University Press, Cambridge, 1998). [3] L. Yu, A. Zubair, E. J. G. Santos, X. Zhang, Y. Lin, Y. Zhang, and T. Palacios, Nano Lett. 15, 4928 (2015). [4] C.-S. Pang and Z. Chen, 2018 76th Device Research Conf. (DRC), p. 1, 2018. [5] M. Tosun, S. Chuang, H. Fang, A. B. Sachid, M. Hettick, Y. Lin, Y. Zeng, and A. Javey, ACS Nano 8, 4948 (2014). [6] T. Kawanago, T. Matsuzaki, R. Kajikawa, I. Muneta, T. Hoshii, K. Kakushima, K. Tsutsui, and H. Wakabayashi, Jpn. J. Appl. Phys. 61, SC1004 (2022). Figure 1

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Bozheyev, Farabi, Dennis Friedrich, Man Nie, Mythili Rengachari, and Klaus Ellmer. "Preparation of highly (001)-oriented photoactive tungsten diselenide (WSe2 ) films by an amorphous solid-liquid-crystalline solid (aSLcS) rapid-crystallization process." physica status solidi (a) 211, no. 9 (May 16, 2014): 2013–19. http://dx.doi.org/10.1002/pssa.201400016.

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Konar, Rajashree, Rosy, Ilana Perelshtein, Eti Teblum, Madina Telkhozhayeva, Maria Tkachev, Jonathan J. Richter, et al. "Scalable Synthesis of Few-Layered 2D Tungsten Diselenide (2H-WSe2) Nanosheets Directly Grown on Tungsten (W) Foil Using Ambient-Pressure Chemical Vapor Deposition for Reversible Li-Ion Storage." ACS Omega 5, no. 31 (July 24, 2020): 19409–21. http://dx.doi.org/10.1021/acsomega.0c01155.

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O'Hare, P. A. G., Brett M. Lewis, and B. A. parkinson. "Standard molar enthalpy of formation by fluorine-combustion calorimetry of tungsten diselenide (WSe2). Thermodynamics of the high-temperature vaporization of WSe2. Revised value of the standard molar enthalpy of formation of molybdenite (MoS2)." Journal of Chemical Thermodynamics 20, no. 6 (June 1988): 681–91. http://dx.doi.org/10.1016/0021-9614(88)90019-5.

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Seo, Sehun, Hojoong Choi, So-Young Kim, Jongmin Lee, Kihyeun Kim, Sejun Yoon, Byoung Hun Lee, and Sanghan Lee. "Tungsten Diselenide: Growth of Centimeter-Scale Monolayer and Few-Layer WSe2 Thin Films on SiO2 /Si Substrate via Pulsed Laser Deposition (Adv. Mater. Interfaces 20/2018)." Advanced Materials Interfaces 5, no. 20 (October 2018): 1870098. http://dx.doi.org/10.1002/admi.201870098.

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Yao, Ting, and Xu Hun. "A design for the photoelectrochemical detection of miRNA-221 based on a tungsten diselenide–cysteine–dopamine nanoprobe coupled with mismatched catalytic hairpin assembly target recycling with ultra-low background noise." Chemical Communications 55, no. 70 (2019): 10380–83. http://dx.doi.org/10.1039/c9cc05625d.

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A strategy for the photoelectrochemical detection of miRNA with ultra-low background noise was developed using tungsten diselenide–cysteine–dopamine (WSe₂/Cys/DA) as a nanoprobe coupled with mismatched catalytic hairpin assembly target recycling.

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zhang, Wenhao, Xi Yang, and Zhihong Zhu. "An improved method for controllable growth of monolayer WSe₂ and its optical characterization." Journal of Physics: Conference Series 2334, no. 1 (August 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2334/1/012005.

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Abstract Due to the van der Waals interaction between the transition metal sulfide layers, it can be stripped into a single atomic layer, and tungsten diselenides(WSe2) as one of the typical p-type semiconductors has become a research hotspot. WSe2 thin flakes have been successfully prepared by chemical vapor deposition(CVD) methods, but the synthesis conditions of WSe2 are usually highly sensitive and difficult to control, which makes it difficult to grow monolayer WSe2 with good lattice quality in a large area. Here, we use a new CVD growth method to improve the product quality, through the combination of reverse gas flow and rapid heating method to improve the nucleation and lattice quality of WSe2.This work will systematically study the effects of key growth conditions, focus on elucidating the growth mechanism, and optimize the growth parameters. In order to verify the preparation of monolayer and multi-layer WSe2 thin flakes with good lattice quality. WSe2 thin flakes were characterized by optical microscope, atomic force microscope, Raman spectrum and photoluminescence (PL) spectrum. Moreover, monolayer WSe2 and multi-layer WSe2 can be distinguished by Raman test and fluorescence spectrum test, and they have different characteristic peaks. We can judge whether the material is monolayer by observing the peak position.

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Gammelgaard, Lene, Patrick R. Whelan, Timothy J. Booth, and Peter Bøggild. "Long-term stability and tree-ring oxidation of WSe₂ using phase-contrast AFM." Nanoscale 13, no. 45 (2021): 19238–46. http://dx.doi.org/10.1039/d1nr05413a.

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Phase contrast atomic force microscopy shows how tungsten diselenide oxidation evolves into complex patterns over 75 months, following season-dependent changes in the laboratory environment, in analogy with tree-rings in nature.

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Journal articles on the topic 'Tungsten Diselenide (WSe2)'

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