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Journal articles on the topic "MoS2 multilayers"
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Fraih, Ali Jabbar, and Zainab Ali Hrbe. "Enhanced photocatalytic performance of molybdenum disulfide-copper oxide nanoparticles photoanodes." European Physical Journal Applied Physics 96, no. 3 (December 2021): 30102. http://dx.doi.org/10.1051/epjap/2021210192.
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In this paper, the molybdenum disulfide (MoS2)/copper oxide (CuO) heterostructure is introduced in a very simple way for photoelectrochemical application. MoS2 multilayers were prepared by sonication method and decorated with copper oxide nanoparticles through its thin film deposition layer and heating in argon atmosphere. SEM, TEM, AFM, absorption and Raman analyses were employed to characterize the nanostructures. The results show that the presence of copper oxide nanoparticles reduces the recombination rate of photogenerated electron-holes in MoS2 multilayers and produces a significant photocurrent compared to the individual MoS2 electrode. Such a proposed structure demonstrates a high potential for photoelectrochemical applications.
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Lince, Jeffrey R., Michael R. Hilton, and Arun S. Bommannavar. "Metal incorporation in sputter-deposited MoS2 films studied by extended x-ray absorption fine structure." Journal of Materials Research 10, no. 8 (August 1995): 2091–105. http://dx.doi.org/10.1557/jmr.1995.2091.
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Solid lubricant films produced by cosputtering metals with MoS2 and by forming metal/MoS2 multilayers are being planned for use in the next generation of solid lubricated devices on spacecraft, including gimbal and sensor bearings, actuators, and sliding electrical contacts. The films exhibit increased densities and wear lives compared to films without additives, but the mechanism of density enhancement is not well understood. The extended x-ray absorption fine structure (EXAFS) technique is ideal for elucidating the structure of these poorly crystalline films. We analyzed MoS2 films cosputtered with 0, 2, and 10% Ni, as well as Ni/MoS2 and Au(Pd)/MoS2 multilayer films. The results obtained at the Mo-K absorption edge showed that the metal-containing films comprised predominantly the same nanocrystalline phases present in similar films without added metals: pure MoS2 and a MoS2−xOx phase. MoS2−xOx is isostructural with MoS2, with O atoms substituting for S atoms in the MoS2 crystal lattice. For all Ni-containing films, EXAFS data obtained at the Ni-K absorption edge showed that the Ni had not chemically reacted with the MoS2−xOx and MoS2, but formed a disordered NiOx phase. However, Ni-cosputtered films showed decreasing Mo-Mo bond lengths in the MoS2−xOx phase with increasing Ni content, probably due to preferential oxidation of Ni compared to MoS2. EXAFS of these Ni-cosputtcred films showed only a small decrease in short-range order with Ni content, while x-ray diffraction showed a concurrent large decrease in long-range order. The results indicate that film densification in Ni-cosputtered films is caused by NiOx formation at the edges of nucleating MoS2−xOx/MoS2 crystallites, limiting the crystallite size attainable within the films.
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Vaknin, Yonatan, Ronen Dagan, and Yossi Rosenwaks. "Pinch-Off Formation in Monolayer and Multilayers MoS2 Field-Effect Transistors." Nanomaterials 9, no. 6 (June 14, 2019): 882. http://dx.doi.org/10.3390/nano9060882.
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The discovery of layered materials, including transition metal dichalcogenides (TMD), gives rise to a variety of novel nanoelectronic devices, including fast switching field-effect transistors (FET), assembled heterostructures, flexible electronics, etc. Molybdenum disulfide (MoS2), a transition metal dichalcogenides semiconductor, is considered an auspicious candidate for the post-silicon era due to its outstanding chemical and thermal stability. We present a Kelvin probe force microscopy (KPFM) study of a MoS2 FET device, showing direct evidence for pinch-off formation in the channel by in situ monitoring of the electrostatic potential distribution along the conducting channel of the transistor. In addition, we present a systematic comparison between a monolayer MoS2 FET and a few-layer MoS2 FET regarding gating effects, electric field distribution, depletion region, and pinch-off formation in such devices.
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Shakya, Jyoti, Gayathri H N, and Arindam Ghosh. "Defects-assisted piezoelectric response in liquid exfoliated MoS2 nanosheets." Nanotechnology 33, no. 7 (November 26, 2021): 075710. http://dx.doi.org/10.1088/1361-6528/ac368b.
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Abstract MoS2 is an intrinsic piezoelectric material which offers applications such as energy harvesting, sensors, actuators, flexible electronics, energy storage and more. Surprisingly, there are not any suitable, yet economical methods that can produce quality nanosheets of MoS2 in large quantities, hence limiting the possibility of commercialisation of its applications. Here, we demonstrate controlled synthesis of highly crystalline MoS2 nanosheets via liquid phase exfoliation of bulk MoS2, following which we report piezoelectric response from the exfoliated nanosheets. The method of piezo force microscopy was employed to explore the piezo response in mono, bi, tri and multilayers of MoS2 nanosheets. The effective piezoelectric coefficient of MoS2 varies from 9.6 to 25.14 pm V−1. We attribute piezoelectric response in MoS2 nanosheets to the defects formed in it during the synthesis procedure. The presence of defects is confirmed by x-ray photoelectron spectroscopy.
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Panasci, Salvatore E., Antal Koos, Emanuela Schilirò, Salvatore Di Franco, Giuseppe Greco, Patrick Fiorenza, Fabrizio Roccaforte, et al. "Multiscale Investigation of the Structural, Electrical and Photoluminescence Properties of MoS2 Obtained by MoO3 Sulfurization." Nanomaterials 12, no. 2 (January 6, 2022): 182. http://dx.doi.org/10.3390/nano12020182.
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In this paper, we report a multiscale investigation of the compositional, morphological, structural, electrical, and optical emission properties of 2H-MoS2 obtained by sulfurization at 800 °C of very thin MoO3 films (with thickness ranging from ~2.8 nm to ~4.2 nm) on a SiO2/Si substrate. XPS analyses confirmed that the sulfurization was very effective in the reduction of the oxide to MoS2, with only a small percentage of residual MoO3 present in the final film. High-resolution TEM/STEM analyses revealed the formation of few (i.e., 2–3 layers) of MoS2 nearly aligned with the SiO2 surface in the case of the thinnest (~2.8 nm) MoO3 film, whereas multilayers of MoS2 partially standing up with respect to the substrate were observed for the ~4.2 nm one. Such different configurations indicate the prevalence of different mechanisms (i.e., vapour-solid surface reaction or S diffusion within the film) as a function of the thickness. The uniform thickness distribution of the few-layer and multilayer MoS2 was confirmed by Raman mapping. Furthermore, the correlative plot of the characteristic A1g-E2g Raman modes revealed a compressive strain (ε ≈ −0.78 ± 0.18%) and the coexistence of n- and p-type doped areas in the few-layer MoS2 on SiO2, where the p-type doping is probably due to the presence of residual MoO3. Nanoscale resolution current mapping by C-AFM showed local inhomogeneities in the conductivity of the few-layer MoS2, which are well correlated to the lateral changes in the strain detected by Raman. Finally, characteristic spectroscopic signatures of the defects/disorder in MoS2 films produced by sulfurization were identified by a comparative analysis of Raman and photoluminescence (PL) spectra with CVD grown MoS2 flakes.
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Joo, Piljae, Kiyoung Jo, Gwanghyun Ahn, Damien Voiry, Hu Young Jeong, Sunmin Ryu, Manish Chhowalla, and Byeong-Su Kim. "Functional Polyelectrolyte Nanospaced MoS2 Multilayers for Enhanced Photoluminescence." Nano Letters 14, no. 11 (October 2, 2014): 6456–62. http://dx.doi.org/10.1021/nl502883a.
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Wei, Yuefan, Van-Thai Tran, Chenyang Zhao, Hongfei Liu, Junhua Kong, and Hejun Du. "Robust Photodetectable Paper from Chemically Exfoliated MoS2–MoO3 Multilayers." ACS Applied Materials & Interfaces 11, no. 24 (June 5, 2019): 21445–53. http://dx.doi.org/10.1021/acsami.9b01515.
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Li, Wei, Mahboobeh Shahbazi, Kaijian Xing, Tuquabo Tesfamichael, Nunzio Motta, and Dong-Chen Qi. "Highly Sensitive NO2 Gas Sensors Based on MoS2@MoO3 Magnetic Heterostructure." Nanomaterials 12, no. 8 (April 11, 2022): 1303. http://dx.doi.org/10.3390/nano12081303.
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Recently, two-dimensional (2D) materials and their heterostructures have attracted considerable attention in gas sensing applications. In this work, we synthesized 2D MoS2@MoO3 heterostructures through post-sulfurization of α-MoO3 nanoribbons grown via vapor phase transport (VPT) and demonstrated highly sensitive NO2 gas sensors based on the hybrid heterostructures. The morphological, structural, and compositional properties of the MoS2@MoO3 hybrids were studied by a combination of advanced characterization techniques revealing a core-shell structure with the coexistence of 2H-MoS2 multilayers and intermediate molybdenum oxysulfides on the surface of α-MoO3. The MoS2@MoO3 hybrids also exhibit room-temperature ferromagnetism, revealed by vibrating sample magnetometry (VSM), as a result of the sulfurization process. The MoS2@MoO3 gas sensors display a p-type-like response towards NO2 with a detection limit of 0.15 ppm at a working temperature of 125 °C, as well as superb selectivity and reversibility. This p-type-like sensing behavior is attributed to the heterointerface of MoS2-MoO3 where interfacial charge transfer leads to a p-type inversion layer in MoS2, and is enhanced by magnetic dipole interactions between the paramagnetic NO2 and the ferromagnetic sensing layer. Our study demonstrates the promising application of 2D molybdenum hybrid compounds in gas sensing applications with a unique combination of electronic and magnetic properties.
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Dagan, R., Y. Vaknin, A. Henning, J. Y. Shang, L. J. Lauhon, and Y. Rosenwaks. "Two-dimensional charge carrier distribution in MoS2 monolayer and multilayers." Applied Physics Letters 114, no. 10 (March 11, 2019): 101602. http://dx.doi.org/10.1063/1.5078711.
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Jiao, Lei, Yuehui Wang, Yusong Zhi, Wei Cui, Zhengwei Chen, Xiao Zhang, Wenjing Jie, and Zhenping Wu. "Fabrication and Characterization of Two-Dimensional Layered MoS2 Thin Films by Pulsed Laser Deposition." Advances in Condensed Matter Physics 2018 (2018): 1–5. http://dx.doi.org/10.1155/2018/3485380.
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Direct growth of uniform wafer-scale two-dimensional (2D) layered materials using a universal method is of vital importance for utilizing 2D layers into practical applications. Here, we report on the structural and transport properties of large-scale few-layer MoS2 back-gated field effect transistors (FETs), fabricated using conventional pulsed laser deposition (PLD) technique. Raman spectroscopy and transmission electron microscopy results confirmed that the obtained MoS2 layers on SiO2/Si substrate are multilayers. The FETs devices exhibit a relative high on/off ratio of 5 × 102 and mobility of 0.124 cm2V−1S−1. Our results suggest that the PLD would be a suitable pathway to grow 2D layers for future industrial device applications.
Dissertations / Theses on the topic "MoS2 multilayers"
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Leonavičius, Romas. "Melizmų sintezė dirbtinių neuronų tinklais." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20070112_145929-44906.
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Modern methods of speech synthesis are not suitable for restoration of song signals due to lack of vitality and intonation in the resulted sounds. The aim of presented work is to synthesize melismas met in Lithuanian folk songs, by applying Artificial Neural Networks. An analytical survey of rather a widespread literature is presented. First classification and comprehensive discussion of melismas are given. The theory of dynamic systems which will make the basis for studying melismas is presented and finally the relationship for modeling a melisma with nonlinear and dynamic systems is outlined. Investigation of the most widely used Linear Prediction Coding method and possibilities of its improvement. The modification of original Linear Prediction method based on dynamic LPC frame positioning is proposed. On its basis, the new melisma synthesis technique is presented. Developed flexible generalized melisma model, based on two Artificial Neural Networks – a Multilayer Perceptron and Adaline – as well as on two network training algorithms – Levenberg- Marquardt and the Least Squares error minimization – is presented. Moreover, original mathematical models of Fortis, Gruppett, Mordent and Trill are created, fit for synthesizing melismas, and their minimal sizes are proposed. The last chapter concerns experimental investigation, using over 500 melisma records, and corroborates application of the new mathematical models to melisma synthesis of one performer.
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Wu, Tsuei-Shin, and 吳翠心. "Optoelectronic Properties of MoS2 Monolayer/Multilayer Lateral Heterojunction." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/13384373949663996574.
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碩士國立臺灣大學
應用物理所
102
The spin/valley degree of freedom and the bandgap in visible light range make MoS2 a promising material for optoelectronic applications. Several groups have reported construction of p-n junction based on Transition-Metal Dichalcogenide (TMD) recently. In this thesis, a new architecture – lateal heterojunction – based on MoS2 is demonstrated. The optoelectronic properties of the lateal heterostructure is determined by the difference of intrinsic band structures of monolalyer and multilayer MoS2. The lateralheterojunction devices are realized by choosing monolayer/multilayer MoS2 after mechanical exfoliation. The existence of built-in field is examined by Kelvin Probe Force Microscope (KPFM), photocurrent mapping at off state, bias-voltage dependent photocurrent mapping, and the asymmetric J-V curve. The photovoltaic effect is observed by performing photocurrent mapping and J-V curve under illumination. Prompt optical switching with robust performance are observed. From the back-gate voltage dependent photocurrent mapping and J-V curves, we achieve the modulation of band alignment by global gating. We observed the enhanced photocurrent at the interface as back-gate voltage lowered and the J-V curve grew linear as back-gate voltage increased, both suggesting that the the Fermi level of monolayer MoS2 is more sensitive to the back-gate voltage. The realization of the lateral heterojunction based on the novel two-dimensional TMD materials and the band alignment modulation by global gating open the avenue to both physical research and technological applications.
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Tang, Chih-che, and 湯志哲. "Electronic Transport Properties in MoSe2 Multilayer Nanostructures." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09877592963228272422.
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碩士國立臺灣科技大學
電子工程系
101
The electronic transport properties of the molybdenum diselenide (MoSe2) layer semiconductor with nanometer and micrometer –thicknesses have been investigated. It is found that the very thin multilayer MoSe2 with thickness at 7?{88 nm exhibit much higher average conductivity at 440?b100 S/cm, which is over three orders of magnitude higher than the bulk counterparts. The statistic conductivity values showing significant thickness dependence are also observed. In addition, by the temperature-dependent measurement, the nanometer-thick MoSe2 layer crystals reveal weak semiconducting behavior with very low activation energies at 6?{11 meV which are relatively lower than those of the micrometer-sized samples. The potential presence of the higher surface conductivity induced by the donor-like surface states is proposed to explain the highly conductive nature and its thickness dependence in this layer semiconductor.
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Yang, Cheng-Han, and 楊昌翰. "Fabrication of Multilayer Ge Quantum-Dots MOS Photodetectors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/45ygh7.
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碩士國立中央大學
電機工程研究所
97
In this thesis, multilayer Ge quantum-dots (QDs) have been fabricated and applied to photodetectors. Since the Si will be preferentially oxidized during the high-temperature annealing of SiGeO alloy and the segregated Ge atom will pile-up along the SiO2/SiON interface, it could be expected that the Ge quantum-dots could be tentatively formed with the Ge atom segregation and agglomeration. The QDs’ size depend on annealing process conditions, including temperature, ambient, and duration. The multilayer a-SiGeO/a-SiON thin-films have been prepared with a plasma-enhanced chemical vapor deposition system, then with a thermal annealing for a-SiGeO/a-SiON thin-films, the multilayer, well-separated, and 2~8 nm-sized Ge QDs were obtained. The crystallinity of Ge quantum-dots has been checked with a Raman spectroscopy. Increasing the thickness of a-SiON was beneficial to the formation of upper Ge QD layer, and a more uniform density of multilayer Ge QDs was obtained. The metal-oxide-semiconductor (MOS) photodetector (PD) structures with multilayer Ge QDs embedded in oxide have been fabricated. From the obtained C-V hysteresis phenomena, the formation of Ge QDs and their charge storage effects were investigated. The obtainable memory window for MOS structure with multilayer Ge quantum-dots was 3.39 V. Increasing the oxide thickness was effective to decrease the PD dark current and obtained a higher ratio of hotocurrent to dark current of PD. A higher density of Ge QDs resulted in a higher photo-current, a better photo responsivity, and a blue-shift of peak response wavelength. Moreover, the amplified responsivity of PDs also can be seen in the spectra. The PD with a higher density of Ge QDs and a thinner oxide thickness could be used to detect the weak (0.02 mW) incident light effectively. By applying a large bias voltage or using a thinner oxide, the larger electric-field in the PD would increase the drift velocity of photo-generated carriers, and the response speed of PD became faster. The effect of device RC constant to rise-time and fall-time was significant. A large RC constant brought about the longer rise-time and fall-time and smaller response bandwidth.
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Huang, Fei-Sheng, and 黃飛盛. "Growth of MoS2 and WS2 multilayer using Chemical Vapor Deposition and their Optical Characterization." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/23705526437337699353.
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碩士國立臺灣科技大學
電子工程系
103
The theme of this thesis is focused on the growth and analysis in the MoS2 and WS2 multilayer crystal on Quartz and Sapphire substrate grown by chemical vapor deposition (CVD). Detailed characterizations of the materials were carried out by using X-ray diffraction (XRD), Raman scattering, atomic force microscopy (AFM), and photoluminescence (PL) techniques. XRD analysis observe that MoS2/Sapphire is of c-plane (002) and MoO3 (002) peak, while dependent by growth time. The two main active modes A1g and E2g of bulk MoS2/WS2 in Raman spectrum are 408cm-1/420cm-1 and 382cm-1/355cm-1, respectively. The E2g mode corresponds to the sulfur atoms vibrating in one direction and the Molybdenum or tungsten atom in the other, while the A1g mode is a mode of the sulfur atoms vibrating out-of-plane. When the thickness of MoS2 in multilayer (less ~five layers), these two modes becomes thickness dependent. The separation between the A1g and the E2g is smaller than that in bulk. Illustrated by AFM, shows the thickness of triangle WS2 flake increases with increasing growth time. Whereas, such growth mechanism are not observed in MoS2.The optical properties of WS2 and MoS2 grown on sapphire were also investigated by PL. The luminescence detected by (PL) indicates the transition is direct behavior with multilayer (less than five layers) thickness. The room temperature direct transition of WS2 and MoS2 were determined to be 1.99 eV and 1.85 eV.
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Peng, Chao-Wun, and 彭朝文. "Fabrication of Multilayer Ge Nanocrystal and Its Application in Floating-Dot MOS Capacitor." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/z24zc4.
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碩士國立中央大學
電機工程研究所
96
Abstract Since the Si will be preferentially oxidized during the high-temperature oxidation of SiGe alloy or annealing of SiGeO alloy and the segregated Ge atom will pile-up along the SiGe/SiO2 interface, it could be expected that the Ge nanocrystals would be tentatively formed with the Ge atom segregation and agglomeration. In this thesis, the multilayer a-SiGe/a-SiON, a-SiGe/a-SiN, and a-SiGeO/a-SiN thin-films have been prepared with a plasma enhanced chemical vapor deposition system, then with a thermal oxidation for a-SiGe/a-SiON and a-SiGe/a-SiN or a thermal annealing for a-SiGeO/a-SiN thin-films, the single /multilayer nano-meter scale Ge crystal dots have been obtained. The multilayer, well-separated, and 5 nm-sized Ge nanocrystals could be obtained with a thermal annealing technique. The crystallinity of Ge nanodots has been checked with a Raman spectroscopy. The metal-oxide-semiconductor (MOS) capacitors ( MOS-Cs ) with Ge nanocrystals embedded in oxide have been fabricated to investigate the charge trapping effect of Ge nanocrystals. A current spike phenomenon in I-V curve has been observed. This was ascribed to the transient current of hole charging from p-type Si substrate. In addition, the hysteresis phenomenon has also been observed in C-V measurement. This indicated that the charge storage effect resulted from the formed Ge nanocrystals. The highest obtainable memory window with multilayer Ge nanocrystals was 3 V. Furthermore, the charge storage effects have been investigated by using the C-V measurement at various frequencies.
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Chakraborty, Biswanath. "Raman Spectroscopy Of Graphene And Graphene Analogue MoS2 Transistors." Thesis, 2012. http://hdl.handle.net/2005/2539.
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The thesis presents experimental studies of device characteristics and vibrational properties of atomic layer thin graphene and molybdenum disulphide (MoS2). We carried out Raman spectroscopic studies on field effect transistors (FET) fabricated from these materials to investigate the phonons renormalized by carrier doping thus giving quantitative information on electron-phonon coupling. Below, we furnish a synoptic presentation of our work on these systems.
Chapter1: Introduction
Chapter1, presents a detailed introduction of the systems studied in this the¬sis, namely single layer graphene (SLG), bilayer graphene (BLG) and single layer molybdenum disulphide (MoS2). We have mainly discussed their electronic and vibrational properties in the light of Raman spectroscopy. A review of the Raman studies on graphene layers is presented.
Chapter2: Methodology and Experimental Techniques
Chapter 2 starts with a description of Raman instrumentation. The steps for isolating graphene and MoS 2 flakes and the subsequent device fabrication procedures involving lithography are discussed in detail. A brief account of the top gated field effect transistor (FET) using solid polymer electrolyte is presented.
Chapter3: Band gap opening in bilayer graphene and formation of p-n junction in top gated graphene transistors: Transport and Raman studies
In Chapter3 the bilayer graphene (BLG) field effect transistor is fabricated in a dual gate configuration which enables us to control the energy band gap and the Fermi level independently. The gap in bilayer energy spectrum is observed through different values of the resistance maximum in the back gate sweep curves, each taken at a fixed top gate voltage. The gate capacitance of the polymer electrolyte is estimated from the experimental data to be 1.5μF/cm2 . The energy gap opened between the valence and conduction bands using this dual-gated geometry is es¬timated invoking a simple model which takes into account the screening of gate induced charges between the two layers. The presence of the controlled gap in the energy band structure along with the p-n junction creates a new possibility for the bilayer to be used as possible source of terahertz source. The formation of p-n junction along a bilayer graphene (BLG) channel is achieved in a electrolytically top gated BLG FET, where the drain-source voltage VDS across the channel is continuously varied at a fixed top gate voltage VT(VT>0). Three cases may arise as VDS is varied keeping VT fixed: (i) for VT-VDS0, the entire channel is doped with electron, (ii) for VT-VDS= 0, the drain end becomes depleted of carriers and kink in the IDS vs VDS curve appears, (iii) for VT-VDS « 0, carrier reversal takes place at the drain end, accumulation of holes starts taking place at the drain end while the source side is still doped with electrton.
The verification of the spatial variation of carrier concentration in a similar top gated single layer graphene (SLG) FET device is done using spatially resolved Ra¬man spectroscopy. The signature 2D Raman band in a single layer graphene shows opposite trend when doped: 2D peak position decreases for electron doping while it increases for hole doping. On the other hand, the G mode response being symmetric in doping can act as a read-out for the carrier concentration. We monitor the peak position of the G and the 2D bands at different locations along the SLG FET channel. For a fixed top gate voltage V T , both G and the 2D band frequencies vary along the channel. For a positive VTsuch that VT-VDS= 0, the peak frequencies ωGand ω2DωG/2D occur at the undoped frequency (ωG/2D)n=0 near the drain end while the source end corresponds to non-zero concentration. When VT-VDS<0, Raman spectra from hole doped regions (drain end) in the channels show an blue-shift in ω2Dwhile from the electron doped regions (near source) ω2Dis softened.
Chapter4: Mixing Of Mode Symmetries In Top Gated Bilayer And Multilayer Graphene Field Effect Devices
In Chapter4, the effect of gating on a bilayer graphene is captured by using Raman spectroscopy which shows a mixing of different optical modes belonging to differ¬ent symmetries. The zone-center G phonon mode splits into a low frequency (Glow) and a high frequency (Ghigh) mode and the two modes show different dependence on doping. The two G bands show different trends with doping, implying different electron-phonon coupling. The frequency separation between the two sub-bands in¬creases with increased doping. The mode with higher frequency, termed as Ghigh, shows stiffening as we increase the doping whereas the other mode, Glow, shows softening for low electron doping and then hardening at higher doping. The mode splitting is explained in terms of mixing of zone-center in-plane optical phonons rep¬resenting in-phase and out-of-phase inter-layer atomic motions. The experimental results are combined with the theoretical predictions made using density functional theory by Gava et al.[PRB 80, 155422 (2009)]. Similar G band splitting is observed in the Raman spectra from multilayer graphene showing influence of stacking on the symmetry properties.
Chapter5: Anomalous dispersion of D and 2D modes in graphene and doping dependence of 2D ′and 2D+G bands
Chapter 5 consists of two parts: Part A titled “Doping dependent anomalous dispersion of D and 2D modes in graphene” describes the tunability of electron-phonon coupling (EPC) associated with the highest optical phonon branch (K-A) around the zone corner K using a top gated single layer graphene field effect transistor. Raman D and 2D modes originate from this branch and are dispersive with laser excitation energy. Since the EPC is proportional to the slope of the phonon branch, doping dependence of the D and 2D modes is carried out for different laser energies. The dispersion of the D mode decreases for both the electron and the hole doping, in agreement with the recent theory of Attaccalite et. al [Nano Letters, 10, 1172 (2010)]. In order to observe D-band in the SLG samples, low energy argon ion bombardment was carried out. The D peak positions for variable carrier concentration using top-gated FET geometry are determined for three laser energies, 1.96 eV, 2.41 eV and 2.54 eV. However, the dispersion of the 2D band as a function of doping shows an opposite trend. This most curious result is quantitatively explained us¬ing a fifth order process rather than the usual fourth order double resonant process usually considered for both the D and 2D modes.
Part B titled “Raman spectral features of second order 2D’ and 2D+G modes in doped graphene transistor” deals with doping dependence of 2D’ and 2D+G bands in single layer graphene transistor. The phonon frequency blue shifts for the hole doping and whereas it red shifts for electron doping, similar to the behaviour of the 2D band. The linewidth of the 2D+G combination mode too follows the 2D trend increasing with doping while that of 2D’ mode remains invariant.
Chapter6: New Raman modes in graphene layers using 2eV light
Unique resonant Raman modes are identified at 1530 cm−1 and 1445 cm−1 in single, bi, tri and few layers graphene samples using 1.96 eV (633 nm) laser excitation energy (EL). These modes are absent in Raman spectra using 2.41 eV excitation energy. In addition, the defect-induced D band which is observed only from the edges of a pristine graphene sample, is observed from the entire sample region using E L = 1.96 eV. Raman images with peak frequencies centered at 1530 cm−1, 1445 cm−1 and D band are recorded to show their correlations. With 1.96 eV, we also observe a very clear splitting of the D mode with a separation of ∼32 cm−1, recently predicted in the context of armchair graphene nanoribbons due to trigonal warping effect for phonon dispersion. All these findings suggest a resonance condition at ∼2eVdue to homo-lumo gap of a defect in graphene energy band structure.
Chapter7: Single and few layer MoS2: Resonant Raman and Phonon Renormalization
Chapter 7 is divided into two parts. In Part A “Layer dependent Resonant Raman scattering of a few layer MoS2”, we discuss resonant Raman scattering from single, bi, four and seven layers MoS2. As bulk crystal of MoS2is thinned down to a few atomic layers, the indirect gap widens turning into a direct gap semiconductor with a band gap of 1.96 eV in its monolayer form. We perform Raman study from MoS 2 layers employing 1.96 eV laser excitation in order to achieve resonance condition. The prominent Raman modes for MoS 2 include first order E12g mode at ∼383 cm−1 and the A1gmode at ∼408 cm−1 which are observed under both non resonant and resonant conditions. A1gphonon involves the sulphur atomic vibration in opposite direction along the c axis (perpendicular to the basal plane) whereas for E12g mode, displacement of Mo and sulphur atoms are in the basal plane. With decreasing layer thickness, these two modes shifts in opposite direction, the E12g mode shows a blue shift of ∼2cm−1 while the A1gis red shifted by ∼4cm−1 . Under resonant condi¬tion, apart from E12g and A1gmodes, several new Raman spectral features, which are completely absent in bulk, are observed in single, bi and few layer spectra pointing out the importance of Raman characterization. New Raman mode attributed to the longitudinal acoustic mode belonging to the phonon branch at M along the Γ-M direction of the Brillouin zone is seen at ∼230 cm−1 for bi, four and seven layers. The most intense region of the spectrum around 460 cm−1 is characterized by layer dependent frequencies and spectral intensities with the band near 460 cm−1 becoming asymmetric as the sample thickness is increased. In the high frequency region between 510-630 cm−1, new bands are seen for bi, four and seven layers.
In Part B titled “Symmetry-dependent phonon renormalization in monolayer MoS2transistor”, we show that in monolayer MoS2the two Raman-active phonons, A1g and E21 g, behave very differently as a function of doping induced by the top gate voltage in FET geometry. The FET achieves an on-off ratio of ∼ 105 for electron doping. We show that while E12g phonon is essentially unaffected, the A1gphonon is strongly influenced by the level of doping. We quantitatively understand our experimental results through the use of first-principles calculations to determine frequencies and electron-phonon coupling for both the phonons as a function of carrier concentration. We present symmetry arguments to explain why only A1g mode is renormalized significantly by doping. Our results bring out a quantitative under¬standing of electron-phonon interaction in single layer MoS2.
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Hou, Tzu-Ching, and 侯姿清. "Study of 1nm-oxide-equivalent-thickness La2O3 and HfO2 Multilayer Composite Oxides on In0.53Ga0.47As for MOS Capacitor Application." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/7z75t4.
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碩士國立交通大學
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In this study, La2O3 and HfO2 were used as gate oxides on InGaAs metal oxide semiconductor (MOS) capacitor. There are many advantages of Hafnium–Lanthanum-Based gate dielectrics, such as high dielectric constant, large energy bandgap and high crystallization temperature, etc. These results suggest that the (Hf–La)Ox system will become a potential candidate for advanced CMOS applications The composite oxide was formed by MBD depositing 4 layers of La2O3 (1nm)/ HfO2(1nm) and 8 layers of La2O3 (0.5nm)/ HfO2(0.5nm) on InGaAs with varied post deposition annealing (PDA) temperatures. We have the characterized properties of the La2O3/ HfO2 on InGaAs MOS structure by using XPS, TEM, EDX and C-V measurement. The design of the stack structure can improve the capacitance meanwhile prevent the diffusion between the oxide and the semiconductor. Finally, we have demonstrated the 1.2-nm-thick capacitance equivalent thickness in the La2O3/HfO2/n-InGaAs MOS capacitors with good interface properties and small hysteresis of 78mV.
Books on the topic "MoS2 multilayers"
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Bianconi, Ginestra. Multilayer Networks. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198753919.001.0001.
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Multilayer networks are formed by several networks that interact with each other and co-evolve. Multilayer networks include social networks, financial markets, transportation systems, infrastructures and molecular networks and the brain. The multilayer structure of these networks strongly affects the properties of dynamical and stochastic processes defined on them, which can display unexpected characteristics. For example, interdependencies between different networks of a multilayer structure can cause cascades of failure events that can dramatically increase the fragility of these systems; spreading of diseases, opinions and ideas might take advantage of multilayer network topology and spread even when its single layers cannot sustain an epidemic when taken in isolation; diffusion on multilayer transportation networks can significantly speed up with respect to diffusion on single layers; finally, the interplay between multiplexity and controllability of multilayer networks is a problem with major consequences in financial, transportation, molecular biology and brain networks. This field is one of the most prosperous recent developments of Network Science and Data Science. Multilayer networks include multiplex networks, multi-slice temporal networks, networks of networks, interdependent networks. Multilayer networks are characterized by having a highly correlated multilayer network structure, providing a significant advantage for extracting information from them using multilayer network measures and centralities and community detection methods. The multilayer network dynamics (including percolation, epidemic spreading, diffusion, synchronization, game theory and control) is strongly affected by the multilayer network topology. This book will present a comprehensive account of this emerging field.
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Bianconi, Ginestra. The Mathematical Definition. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198753919.003.0005.
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This chapter provides the mathematical definition of multilayer networks and it is of fundamental importance for the rest of the book. The mathematical definition of multilayer networks is given in full generality and subsequently applied to specific types of multilayer networks including multiplex networks, multi-slice networks and networks of networks, motivating the discussion with examples and applications. The fundamental terminology used in multilayer networks is here introduced, including replica nodes, supernetworks and the supra-adjacency matrix. Additionally, this chapter describes the most efficient way to store a multilayer network dataset using a Multilayer Network Edgelist. Although this chapter focuses mostly on a matrix formalism to describe multilayer networks, a paragraph is devoted to the tensorial formalism for studying multilayer networks.
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Bianconi, Ginestra. Basic Structural Properties. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198753919.003.0006.
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In this chapter the basic structural properties of multilayer networks are given. This chapter reveals that on multilayer networks the most basic structural properties of a network such as the degree or the clustering coefficient are also significantly modified. Therefore, it is necessary to define the multiplex degree and the multiplex degree distribution, the multilayer degree and the multilayer degree distribution, and the multilayer clustering coefficients. The chapter also discusses the relation between the properties of multiplex and multi-slice networks and the corresponding properties of their aggregated network. Finally, the chapter introduces multilayer distance-dependent measures, including generalization of the betweenness centrality (interdependence, cross-betweenness) and of the closeness centrality.
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Bianconi, Ginestra. Epidemic Spreading. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198753919.003.0013.
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Epidemic processes are relevant to studying the propagation of infectious diseases, but their current use extends also to the study of propagation of ideas in the society or memes and news in online social media. In most of the relevant applications epidemic spreading does not actually take place on a single network but propagates in a multilayer network where different types of interaction play different roles. This chapter provides a comprehensive view of the effect that multilayer network structures have on epidemic processes. The Susceptible–Infected–Susceptible (SIS) Model and the Susceptible–Infected–Removed (SIR) Model are characterized on multilayer networks. Additionally, it is shown that the multilayer networks framework can also allow us to study interacting Awareness and epidemic spreading, competing networks and epidemics in temporal networks.
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Bianconi, Ginestra. Centrality Measures. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198753919.003.0009.
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Defining the centrality of nodes and layers in multilayer networks is of fundamental importance for a variety of applications from sociology to biology and finance. This chapter presents the state-of-the-art centrality measures able to characterize the centrality of nodes, the influences of layers or the centrality of replica nodes in multilayer and multiplex networks. These centrality measures include modifications of the eigenvector centrality, Katz centrality, PageRank centrality and Communicability to the multilayer network scenario. The chapter provides a comprehensive description of the research of the field and discusses the main advantages and limitations of the different definitions, allowing the readers that wish to apply these techniques to choose the most suitable definition for his or her case study.
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Brataas, A., Y. Tserkovnyak, G. E. W. Bauer, and P. J. Kelly. Spin pumping and spin transfer. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0008.
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This chapter discusses the interaction between currents and magnetization, which can cause undesirable effects such as enhanced magnetic noise in read heads made from magnetic multilayers. While most research has been carried out on metallic structures, current-induced magnetization dynamics in semiconductors or even insulators has been pursued as well. These issues have attracted many physicists because, on top of the practical aspects, the underlying phenomena are fascinating. Berger and Slonczewski are acknowledged to have started the field in general through their introduction of the concept of current-induced magnetization dynamics by the transfer of spin. The reciprocal effect, i.e., spin pumping, was expected long ago, but it took some time before Tserkovnyak et al. developed a rigorous theory of spin pumping for magnetic multilayers, including the associated increased magnetization damping.
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Stucky, Kirk J., and Jennifer Stevenson Jutte, eds. Critical Care Psychology and Rehabilitation. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190077013.001.0001.
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When contemplating the broad field of critical care and all of its complexities, rehabilitation and psychology practice is not likely among the top 10 things that clinicians, patients, or the public think of. However, just beneath the surface of this fascinating, multilayered environment, the need for psychologists and rehabilitation-oriented clinicians is everywhere, in large part because intensive care stands among the most emotionally intense and physically taxing hospital-based settings for everyone involved. This book provides an introduction to critical care for professionals who are interested in, or who are already providing services in, intensive care environments. It also organizes and expands upon the growing literature that emphasizes the benefits of integrating rehabilitative and psychological principles into the continuum of critical care practice. Chapters from international experts, on a broad range of topics, provide summative reviews of the literature, treatment techniques, and innovative developments in various intensive care settings geared toward helping professionals appreciate how integrated critical care practice can benefit all stakeholders—patients, families, caregivers, staff, institutions, and society at large.
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Shemtov, Noam. Beyond the Code. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198716792.001.0001.
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Although the law of infringement is relatively straightforward on the copying of literal and textual elements of software, the copying of non-literal and functional elements poses complex and topical questions in the context of intellectual property protection. In most cases, such elements contain the real value of a software product. This book examines the copying of non-literal and functional elements of software in both the United States and the European Union, using a holistic approach to address the most topical questions facing experts concerned with legal protection of software products across a range of technological platforms. The book focuses on five distinct but interrelated areas: contract, copyright, patent, trade-mark and trade-dress laws, and trade secrets. It also considers the protection of designs, in the context of graphical user interfaces. The book looks at software as a multilayered functional product, setting the scene for other legal discussions by highlighting software’s unique characteristics. It analyses models for the provision of software, addressing licensing patterns and overall enforceability, as well as the statutory and judicial tools for regulating the use of such licences. Further, it explores the protection of non-literal and functional software elements under EU and US copyright law, with emphasis on internal architecture and behavioural elements. Finally, it describes the application of trade-dress protection to software’s ‘look and feel’, particularly relevant to the provision of software in the cloud environment.
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Capp, Bernard. British Slaves and Barbary Corsairs, 1580-1750. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780192857378.001.0001.
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This is the first comprehensive study of the thousands of Britons captured and enslaved in North Africa in the early modern period, charting their lives from capture to eventual liberation, death in Barbary, or for a lucky few, escape. It outlines the character of Barbary’s government and society, the world of the corsairs, and the wider context of Mediterranean slavery. Using letters from slaves and accounts by former slaves, the book describes the trauma of the slave market, the lives of galley-slaves and labourers, and the fate of female captives. It explores the significance of their faith for some captives, especially puritans, but shows how a significant minority apostatized and accepted Islam, seduced by promises or hoping to ease their conditions. For them, and for other Britons who joined the corsairs voluntarily, identity became fluid and multilayered. The book also explores in depth how ransoms were raised by families and by state-sponsored charitable collections, and how redemptions were organized by merchants, consuls, and other intermediaries. Most families were too poor to raise a ransom, and the state came under intense pressure to intervene. The book shows how from the mid-seventeenth century, the state practised a form of ‘gunboat diplomacy’ that eventually curbed the corsairs. The Barbary corsairs posed a threat to all European powers, and the book places the British story within the wider context of Mediterranean slavery, which saw Moors and Christians as both captors and captives.
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Alonso, Paul. Satiric TV in the Americas. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190636500.001.0001.
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In the post-truth era, postmodern satiric media have emerged as prominent critical voices playing an unprecedented role at the heart of public debate, filling the gaps left not only by traditional media but also by weak social institutions and discredited political elites. Satiric TV in the Americas analyzes some of the most representative and influential satiric TV shows on the continent (focusing on cases in Argentina, Peru, Ecuador, Mexico, Chile, and the United States) in order to understand their critical role in challenging the status quo, traditional journalism, and the prevalent local media culture. It illuminates the phenomenon of satire as resistance and negotiation in public discourse, the role of entertainment media as a site where sociopolitical tensions are played out, and the changing notions of journalism in today’s democratic societies. Introducing the notion of “critical metatainment”—a postmodern, carnivalesque result of and a transgressive, self-referential reaction to the process of tabloidization and the cult of celebrity in the media spectacle era—Satiric TV in the Americas is the first book to map, contextualize, and analyze relevant cases to understand the relation between political information, social and cultural dissent, critical humor, and entertainment in the region. Evaluating contemporary satiric media as distinctively postmodern, multilayered, and complex discursive objects that emerge from the collapse of modernity and its arbitrary dichotomies, Satiric TV in the Americas also shows that, as satiric formats travel to a particular national context, they are appropriated in different ways and adapted to local circumstances, thus having distinctive implications.
Book chapters on the topic "MoS2 multilayers"
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Zhao, Zhilong, Xiaoling Zhong, Ting Ting Guo, Bing Wu, Li Wen, Liangyi Deng, and Yuting Jiang. "Design of Microwave Triple-Frequency Multimeter Based on Multilayer MoS2." In New Developments of IT, IoT and ICT Applied to Agriculture, 47–54. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5073-7_5.
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Tiwari, Pranjala, and Ramesh Chandra. "In-situ Fabrication of Alternately Stacked MoS2/Au Multilayered Thin-Film Electrodes for Electrochemical Energy Storage Application." In Recent Research Trends in Energy Storage Devices, 105–14. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6394-2_13.
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Gangopadhyay, S., R. Acharya, A. K. Chattopadhyay, and S. Paul. "On deposition and characterisation of MoS x -Ti multilayer coating and performance evaluation in dry turning of aluminium alloy and steel." In Proceedings of the 36th International MATADOR Conference, 247–50. London: Springer London, 2010. http://dx.doi.org/10.1007/978-1-84996-432-6_57.
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Casanove, M. J., E. Snoeck, C. Penchenat, H. Ardhuin, R. Mamy, B. Raquet, M. D. Ortega, M. Goiran, A. R. Fert, and J. C. Ousset. "Microstructural studies and magneto-optic properties of Co/Au multilayers epitaxially grown on MoS2 substrates." In Small Scale Structures, 129–32. Elsevier, 1996. http://dx.doi.org/10.1016/b978-0-444-82312-0.50082-7.
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Brandão, Jeovani, Marcos Vinicius Puydinger dos Santos, and Fanny Béron. "Stabilizing Zero-Field Skyrmions at Room-Temperature in Perpendicularly Magnetized Multilayers." In Magnetic Skyrmions. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97179.
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Magnetic skyrmions are twirling spin structures observed in bulk, thin films, and multilayers with several features for both fundamental physics understanding and spintronic applications, i.e., nanoscale size, efficient transport under electrical current, and topological protection against defects. However, most magnetic skyrmions have been observed under the assistance of an out-of-plane magnetic field, which may limit their use in magnetic memory technologies. In this chapter, we review and present two recent mechanisms to create zero-field skyrmions at room-temperature in ferromagnetic multilayers. First, by tuning the perpendicular magnetic anisotropy (PMA) and remnant magnetization (near magnetization saturation) in unpatterned symmetric multilayer systems, it was achieved a transition from worm-like domains to isolated skyrmions. Besides, we present how to find stable zero-field skyrmions in arrays of ferrimagnetic discs by tailoring their diameter. Both methods demonstrate a robust route to stabilize zero-field skyrmions at room temperature, thus providing an important contribution to possible applications of these textures in the next generation of skyrmionics devices.
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S. Bhat, Ramesh. "Fabrication of Multi-Layered Zn-Fe Alloy Coatings for Better Corrosion Performance." In Liquid Metals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99630.
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Zn-Fe compositionally modulated multilayer alloy (CMMA) coatings were developed onto low carbon steel from acid sulphate bath; and their corrosion resistance was calculated using Tafel polarization and impedance methods. The deposit layers were formed galvanostatically by single bath technique (SBT), using square current pulses. An optimal configuration for the growth of most corrosion resistant Zn-Fe coating was proposed and discussed. At maximum switching cathode current density (SCCD) (2.0–5.0 A dm−2), the deposit with 300 layers showed ~43 times superior corrosion resistance than the same thickness of monolayer coating. The improved corrosion resistance of multilayered coatings is due to small change in iron content, leading to change the phase structure of the alternate-layers of the alloy coatings. The surface morphology and structure of film and roughness of the deposit were assessed using Scanning Electron Microscopy and Atomic Force Microscopy. Thus, superior corrosion resistance of Zn-Fe multilayer coatings was used for industrial applications including defense, machinery and automobile etc.
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Tlili, Brahim. "Fretting Wear Performance of PVD Thin Films." In Tribology [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93460.
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Nowadays, most surface treatments are realized through vapor deposition techniques as thin hard coatings to guarantee high surface hardness, low friction coefficient, and improve wear resistance. Several experimental investigations have led to the development of multilayer coatings in preference to the traditional TiN coating. In the current chapter, research was conducted on the fretting wear of (TiAlCN/TiAlN/TiAl) and (TiAlZrN/TiAlN/TiAl) multilayer coatings deposited by reactive DC (magnetron sputtering) of Ti-Al and Ti-Al-Zr alloys on AISI4140 steel. Fretting wear tests (20,000 cycles at 5 Hz) were conducted in ambient conditions, where the interaction between normal load and displacement amplitude determined the fretting regime. The influence of the normal load and displacement amplitude on the coefficients of instantaneous coefficient of friction and stabilized coefficient of friction is different in the two multilayer, coated steels. The PVD coating (TiAlZrN/TiAlN/TiAl) reduces the friction. The worn volume of coated AISI4140 steel is sensitive to normal load and displacement amplitude. The relation between worn volume and cumulative dissipated energy was established for the two coated steels. The energetic fretting wear coefficients were also determined. A multilayer (TiAlZrN/TiAlN/TiAl) coating has a low energetic wear coefficient.
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Saravana Kumar N. M., Tamilselvi S., Hariprasath K., Kavinya A., and Kaviyavarshini N. "Deep Learning Model for Diagnosing Diabetes." In Advances in Medical Technologies and Clinical Practice, 1–26. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3791-9.ch001.
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Diabetes is one of the most prevalent chronic diseases among all the age groups in developing nations like India. The work collates various machine learning techniques such as SVM, random forests, naive bayes and proposed MLP to perform better detection of diabetes in humans. The goal of this study is to predict the diabetes through neural network of multilayer perceptron. In this study, multilayer perceptron of deep learning algorithm is compared with different machine learning algorithms. The model for the different algorithm is validated with fivefold cross validation. The machine learning algorithms in this study are support vector machine, random forest, and naive bayes. The dataset used for this study is taken from UCI machine learning repository. This algorithm is trained and tested with all the features of the dataset. The algorithms are evaluated based on the accuracy measures. The result obtained shows that the multilayer perceptron of deep learning algorithm gives an accuracy of 98%.
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Msimanga, Mandla. "Depth Profiling of Multilayer Thin Films Using Ion Beam Techniques." In Thin Film Deposition - Fundamentals, Processes, and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105986.
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Functional properties of thin film structures depend a lot on the thickness and chemical composition of the layer stack. There are many analytical techniques available for the identification and quantification of chemical species of thin film depositions on substrates, down to a few monolayers thickness. For the majority of these techniques, extending the analysis to several tens of nanometres or more requires some form of surface sputtering to access deeper layers. While this has been done successfully, the analysis tends to become quite complex when samples analysed consist of multilayer films of different chemical composition. Ion beam analysis (IBA) techniques using projectile ions of energies in the MeV range have a demonstrated advantage in the study of multilayer thin films in that the analysis is possible without necessarily rupturing the film, up to over 500 nm deep in some cases, and without the use of standards. This chapter looks at theoretical principles, and some unique applications of two of the most widespread IBA techniques: Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA), as applied to multilayer thin film analyses.
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Hassanin, Mohamed F., Abdullah M. Shoeb, and Aboul Ella Hassanien. "Designing Multilayer Feedforward Neural Networks Using Multi-Verse Optimizer." In Handbook of Research on Machine Learning Innovations and Trends, 1076–93. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2229-4.ch048.
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Artificial neural network (ANN) models are involved in many applications because of its great computational capabilities. Training of multi-layer perceptron (MLP) is the most challenging problem during the network preparation. Many techniques have been introduced to alleviate this problem. Back-propagation algorithm is a powerful technique to train multilayer feedforward ANN. However, it suffers from the local minima drawback. Recently, meta-heuristic methods have introduced to train MLP like Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Cuckoo Search (CS), Ant Colony Optimizer (ACO), Social Spider Optimization (SSO), Evolutionary Strategy (ES) and Grey Wolf Optimization (GWO). This chapter applied Multi-Verse Optimizer (MVO) for MLP training. Seven datasets are used to show MVO capabilities as a promising trainer for multilayer perceptron. Comparisons with PSO, GA, SSO, ES, ACO and GWO proved that MVO outperforms all these algorithms.
Conference papers on the topic "MoS2 multilayers"
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Sanaullah, Muhammad, and Masud H. Chowdhury. "Multilayer molybdenum disulfide (MoS2) based tunnel transistor." In 2015 IEEE International Symposium on Circuits and Systems (ISCAS). IEEE, 2015. http://dx.doi.org/10.1109/iscas.2015.7169050.
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Das, Saptarshi, and Joerg Appenzeller. "Evaluating the scalability of multilayer MoS2 transistors." In 2013 71st Annual Device Research Conference (DRC). IEEE, 2013. http://dx.doi.org/10.1109/drc.2013.6633839.
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Ghobadi, Nayereh. "Molecular dynamics simulation of elastic properties of multilayer MoS2 and graphene/MoS2 heterostructure." In 2017 Iranian Conference on Electrical Engineering (ICEE). IEEE, 2017. http://dx.doi.org/10.1109/iraniancee.2017.7985466.
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Kwak, Joon Young, Jeonghyun Hwang, Brian Calderon, Hussain Alsalman, Brian Schutter, and Michael G. Spencer. "Photothermal electric effect of multilayer MoS2-graphene heterojunction." In 2015 73rd Annual Device Research Conference (DRC). IEEE, 2015. http://dx.doi.org/10.1109/drc.2015.7175585.
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Sanaullah, Muhammad, and Masud H. Chowdhury. "Subthreshold swing characteristics of multilayer MoS2 tunnel FET." In 2015 IEEE 58th International Midwest Symposium on Circuits and Systems (MWSCAS). IEEE, 2015. http://dx.doi.org/10.1109/mwscas.2015.7282101.
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Sebastian, Suneetha, S. Sridhar, Rachel A. Jilin, Sandhya A. V. Varu, A. Sreejith, and S. Asokan. "Multilayer MoS2 Coated Etched Fiber Bragg Grating Based Hydrophone." In 2018 IEEE Sensors. IEEE, 2018. http://dx.doi.org/10.1109/icsens.2018.8589940.
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Ullah, Muhammad S., and Masud H. Chowdhury. "Optimization of subthreshold swing for multilayer MoS2 tunnel transistor." In 2017 IEEE 60th International Midwest Symposium on Circuits and Systems (MWSCAS). IEEE, 2017. http://dx.doi.org/10.1109/mwscas.2017.8053090.
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Oviroh, Peter Ozaveshe, Sunday Temitope Oyinbo, Sina Karimzadeh, and Tien-Chien Jen. "Multilayer Separation Effects on MoS2 Membranes in Water Desalination." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69156.
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Abstract Climate change and its related effects are imposing severe stress on the current freshwater supplies. This has been exacerbated due to the growth in population, rapid industrialization, and increased energy demand. Increased water requirement is a global challenge. Although more than 70% of the Earth is covered by water, much of it is unusable for human use. Freshwater reservoirs, ponds, and subterranean aquifers account for just 2.5% of the world’s overall freshwater availability. Unfortunately, these water supplies are not very unevenly spread. Therefore, the need to augment these supplies through the desalination of seawater or brackish water. Reverse osmosis (RO) is currently the most widespread method of desalination. However, the unit cost of water is still high partly due to the thin-film composite (TFC) polymer membranes used in the current desalination system. Thus the need for low-cost nanomaterials for Water Desalination and Purification. A promising way to meet this demand is to use two-dimensional (2D) nanoporous materials such as graphene and MoS2 to minimize energy consumption during the desalination process. New nanotechnology methodologies that apply reverse osmosis have been developed. Among some of these technologies is using 2D materials such as graphene and MoS2, which have been studied extensively for water desalination. Single-layer nanoporous 2D materials such as graphene and MoS2 promises better filtrations in the water channel. Although single-layer MoS2 (SL_MoS2) membrane have much promise in the RO desalination membrane, multilayer MoS2 are simpler to make and more cost-efficient. Building on the SL_MoS2 membrane knowledge, we have used the molecular dynamics method (MD) to explore the effects of multilayer MoS2 in water desalination. This comparison is made as a function of the pore size, water flow rate and salt rejection. In addition, we also looked at the effect of the increased interlayer spacing between layers of the nanoporous 2D membrane and then made the comparison. The ions rejection follows the trend trilayer> bilayer> monolayer from results obtained, averaging over all three membrane types studied for the MoS2, the ions rejection follows the trend trilayer > bilayer > monolayer. We find that the thin, narrow layer separation plays a vital role in the successful rejection of salt ions in bilayers and trilayers membranes. These findings will help build and proliferate tunable nanodevices for filtration and other applications.
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Ko, P. J., T. V. Thu, H. Takahashi, A. Abderrahmane, T. Takamura, and A. Sandhu. "High precision laser induced etching of multilayered MoS2." In THE IRAGO CONFERENCE 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4866622.
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Yang, Rui, Zhenyu Li, and Philip X. L. Feng. "Molybdenum Disulfide (MoS2) Nanomechanical Resonators Integrated on Microchannels." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48590.
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We report on experimental demonstration of multilayer molybdenum disulfide (MoS2) nanomechanical resonators integrated on microchannels, with the potential for resonant operation and sensing applications in microfluidics. Microchannels with width of ∼5μm and depth of ∼1–2μm are fabricated on polydimethylsiloxane (PDMS) substrate. We transfer MoS2 flakes with both singly-clamped cantilever and doubly-clamped membrane structure onto the PDMS channels, and measure both undriven thermomechanical resonances and optically driven responses from the devices. The devices show up to 6 thermomechanical resonances, with highest resonance frequency (fres) of 16.3MHz and quality (Q) factor ∼200. This type of MoS2 nanomechanical resonators, when integrated with microfluidics in microchannels, would make new interesting candidates for biosensing and chemical sensing in fluids.
Reports on the topic "MoS2 multilayers"
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Russo, Margherita, Fabrizio Alboni, Jorge Carreto Sanginés, Manlio De Domenico, Giuseppe Mangioni, Simone Righi, and Annamaria Simonazzi. The Changing Shape of the World Automobile Industry: A Multilayer Network Analysis of International Trade in Components and Parts. Institute for New Economic Thinking Working Paper Series, January 2022. http://dx.doi.org/10.36687/inetwp173.
Full textAbstract:
In 2018, after 25 years of the North America Trade Agreement (NAFTA), the United States requested new rules which, among other requirements, increased the regional con-tent in the production of automotive components and parts traded between the three part-ner countries, United States, Canada and Mexico. Signed by all three countries, the new trade agreement, USMCA, is to go into force in 2022. Nonetheless, after the 2020 Presi-dential election, the new treaty's future is under discussion, and its impact on the automo-tive industry is not entirely defined. Another significant shift in this industry – the acceler-ated rise of electric vehicles – also occurred in 2020: while the COVID-19 pandemic largely halted most plants in the automotive value chain all over the world, at the reopen-ing, the tide is now running against internal combustion engine vehicles, at least in the an-nouncements and in some large investments planned in Europe, Asia and the US. The definition of the pre-pandemic situation is a very helpful starting point for the analysis of the possible repercussions of the technological and geo-political transition, which has been accelerated by the epidemic, on geographical clusters and sectorial special-isations of the main regions and countries. This paper analyses the trade networks emerg-ing in the past 25 years in a new analytical framework. In the economic literature on inter-national trade, the study of the automotive global value chains has been addressed by us-ing network analysis, focusing on the centrality of geographical regions and countries while largely overlooking the contribution of countries' bilateral trading in components and parts as structuring forces of the subnetwork of countries and their specific position in the overall trade network. The paper focuses on such subnetworks as meso-level structures emerging in trade network over the last 25 years. Using the Infomap multilayer clustering algorithm, we are able to identify clusters of countries and their specific trades in the automotive internation-al trade network and to highlight the relative importance of each cluster, the interconnec-tions between them, and the contribution of countries and of components and parts in the clusters. We draw the data from the UN Comtrade database of directed export and import flows of 30 automotive components and parts among 42 countries (accounting for 98% of world trade flows of those items). The paper highlights the changes that occurred over 25 years in the geography of the trade relations, with particular with regard to denser and more hierarchical network gener-ated by Germany’s trade relations within EU countries and by the US preferential trade agreements with Canada and Mexico, and the upsurge of China. With a similar overall va-riety of traded components and parts within the main clusters (dominated respectively by Germany, US and Japan-China), the Infomap multilayer analysis singles out which com-ponents and parts determined the relative positions of countries in the various clusters and the changes over time in the relative positions of countries and their specialisations in mul-tilateral trades. Connections between clusters increase over time, while the relative im-portance of the main clusters and of some individual countries change significantly. The focus on US and Mexico and on Germany and Central Eastern European countries (Czech Republic, Hungary, Poland, Slovakia) will drive the comparative analysis.