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[IEEE 2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC) - Singapore (2018.5.14-2018.5.18)] 2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC) - A possible information leakage from DVI cable corresponding to display color
摘要： In this paper, the possibility about information leakage from digital visual interface (DVI) cable for color display is analyzed. The principle of information leakage form DVI cable, which is already documented before, is reviewed. The electromagnetic emanations from DVI cable are measured for several cases of color display which have different color combination. Also, it is shown that the legibility of recovered image is different with respect to the color combination.
关键词： color display,TEMPEST,information recovery,DVI,TMDS
更新于2025-09-23 15:22:29
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Ultralow Thermal Conductivity of Turbostratically Disordered MoSe2 Ultra-Thin Films and Implications for Heterostructures
摘要： Films containing 8, 16, 24, 32 and 64 MoSe2 layers were synthesized using the modulated elemental reactants (MER) method. X-ray reflectivity patterns showed that the annealed films were the targeted number of MoSe2 layers thick with atomically smooth interfaces. In-plane x-ray diffraction scans contained only hk0 reflections for crystalline MoSe2 monolayers. Specular x-ray diffraction patterns contained only 00l reflections, also indicating that the hk0 plane of the MoSe2 layers are parallel to the substrate. Both x-ray diffraction and electron microscopy techniques indicated that the hk0 planes are rotationally disordered with respect to one another, with all orientations equally probable for large areas. The rotational disorder between MoSe2 layers is present even when analyzed spots are within 10 nm of one another. Cross-plane thermal conductivities of 0.07 – 0.09 W m-1 K-1 were measured by time domain thermoreflectance, with the thinnest films exhibiting the lowest conductivity. The structural analysis suggests that the ultralow thermal conductivity is a consequence of rotational disorder, which increases the separation between MoSe2 layers. The bonding environment of the Se atoms also becomes significantly distorted from C3v symmetry due to the rotational disorder between layers. This structural disorder efficiently reduces the group velocity of the transverse phonon modes but not that of longitudinal modes. Since rotational disorder between adjacent layers in heterostructures is expected if the constituents have incommensurate lattices, this study indicates that these heterostructures will have very low cross-plane thermal conductivity.
关键词： rotational disorder,heterostructure,TMDs,turbostratic disorder,thermal conductivity,molybdenum diselenide
更新于2025-09-23 15:22:29
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Phasea??Controlled Synthesis of Monolayer W <sub/>1a??</sub><i> <sub/>x</sub></i> Re <i> <sub/>x</sub></i> S <sub/>2</sub> Alloy with Improved Photoresponse Performance
摘要： Tuning bandgap and phases in the ternary 2D transition metal dichalcogenides (TMDs) alloys has opened up unexpected opportunities to engineer optoelectronic properties and explore potential applications. In this work, a salt-assisted chemical deposition vapor (CVD) growth strategy is reported for the creation of high-quality monolayer W1?xRexS2 alloys to fulfill a readily phase control from 1H to DT by changing the ratio of Re and W precursors. The structures and chemical compositions of doping alloys are confirmed by combining atomic resolution scanning transmission electron microscopy-annular dark field imaging with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy, matching well with the calculated results. The field-effect transistors (FETs) devices fabricated based on 1H-W0.9Re0.1S2 monolayer exhibit a n-type semiconducting behavior with the mobility of 0.4 cm2 V?1 s?1. More importantly, the FETs show high-performance responsivity with a value of 17 μA W?1 in air, which is superior to that of monolayer CVD-grown WS2. This work paves the way toward synthesizing monolayer ternary alloys with controlled phases for potential optoelectronic applications.
关键词： W1?xRexS2 alloys,phase transition,ternary TMDs,chemical vapor deposition,photoresponsivity
更新于2025-09-23 15:19:57
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PbE (E = S, Se) Colloidal Quantum Dot-Layered 2D Material Hybrid Photodetectors
摘要： Hybrid lead chalcogenide (PbE) (E = S, Se) quantum dot (QD)-layered 2D systems are an emerging class of photodetectors with unique potential to expand the range of current technologies and easily integrate into current complementary metal-oxide-semiconductor (CMOS)-compatible architectures. Herein, we review recent advancements in hybrid PbE QD-layered 2D photodetectors and place them in the context of key findings from studies of charge transport in layered 2D materials and QD films that provide lessons to be applied to the hybrid system. Photodetectors utilizing a range of layered 2D materials including graphene and transition metal dichalcogenides sensitized with PbE QDs in various device architectures are presented. Figures of merit such as responsivity (R) and detectivity (D*) are reviewed for a multitude of devices in order to compare detector performance. Finally, a look to the future considers possible avenues for future device development, including potential new materials and device treatment/fabrication options.
关键词： photodetectors,phosphorene,infrared,PbS,graphene,layered 2D materials,TMDs,colloidal quantum dots,PbSe
更新于2025-09-19 17:13:59
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Visible to Near-Infrared Photodetector Based on Graphene-MoTe2-Graphere Heterostructure
摘要： Graphene and transition metal dichalcogenides (TMDs) are widely investigated two dimensional materials in recent years. As a member of the TMDs family, MoTe2 possesses a suitable bandgap of ~1.0 eV for near infrared (NIR) photodetection. Here we stacked the MoTe2 flake with two graphene flakes of high carrier mobility to form a graphene-MoTe2-graphene heterostructure. It exhibits high photo-response to a broad spectrum range from 500 nm to 1300 nm. The photoresponsivity was calculated to be 1.6 A/W for the 750 nm light under 2 V/0 V drain-source/gate bias, and 154 mA/W for the 1100 nm light under 0.5 V/60 V drain-source/gate bias. Besides, the polarity of the photocurrent under zero Vds can be efficiently tuned by the back gate voltage to satisfy different applications. Finally, we fabricated a vertical graphene-MoTe2-graphene heterostructure photodetector which showed improved photoresponsivity of 3.3 A/W toward visible light.
关键词： photodetector,graphene,TMDs,van der Waals heterostructure,two-dimensional materials
更新于2025-09-19 17:13:59
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Spatially Controlled Fabrication and Mechanisms of Atomically Thin Nanowell Patterns in Bilayer WS <sub/>2</sub> Using <i>in Situ</i> High Temperature Electron Microscopy
摘要： We show controlled production of atomically thin nanowells in bilayer WS2 using an in situ heating holder combined with a focused electron beam in a scanning transmission electron microscope (STEM). We systematically study the formation and evolvement mechanism involved in removing a single layer of WS2 within a bilayer region with 2 nm accuracy in location and without punching through to the other layer to create a hole. Best results are found when using a high temperature of 800 °C, because it enables thermally activated atomic migration and eliminates the interference from surface carbon contamination. We demonstrate precise control over spatial distributions with 5 nm accuracy of patterning and the width of nanowells adjustable by dose-dependent parameters. The mechanism of removing a monolayer of WS2 within a bilayer region is different than removing equivalent sections in a monolayer film due to the van der Waals interaction of the underlying remaining layer in the bilayer system that stabilizes the excess W atom stoichiometry within the edges of the nanowell structure and facilitates expansion. This study offers insights for the nanoengineering of nanowells in two-dimensional (2D) transitional metal dichalcogenides (TMDs), which could hold potential as selective traps to localize 2D reactions in molecules and ions, underpinning the broader utilization of 2D material membranes.
关键词： bilayer TMDs,nanowells,in situ STEM,nanopores,2D materials
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Nonlinear Refraction and Nonlinear Absorption in Layered Transition Metals Dichalcogenides
摘要： The unique thickness- and composition-dependent properties of two-dimensional Transition Metal Dichalcogenides (TMDs) afford opportunities to a wide range of applications, as reviewed in [1]. Among the diverse methods to fabricate TMDs, redox exfoliation offers features critical to composite, coating and ink technologies, including low cost, low-energy, and a general framework for exfoliating TMDs from Groups IV, V, VI, and VII. Nonlinear (NL) optical absorption is a relevant effect in TMDs with potential applications in multiphoton microscopy, fluorescence imaging and optical limiting. For instance, two-photon absorption (TPA) saturation in MoS2 was reported in [2]. On the other hand, NL refraction may be exploited for all-optical switching and optical processing. In this communication, we describe the NL optical behavior of MoS2, WS2, NbS2 and ZrTe2 in the femtosecond regime. Details of the redox exfoliation and morphological characterization of the TMDs are given in [3]. For the experiments, the TMDs were suspended in acetonitrile with concentrations of (cid:26)(cid:19)(cid:3)(cid:541)(cid:74)(cid:18)(cid:80)(cid:79) (MoS2)(cid:15)(cid:3)(cid:23)(cid:19)(cid:3)(cid:541)(cid:74)(cid:18)(cid:80)(cid:79) (WS2), (cid:20)(cid:19)(cid:19)(cid:3) (cid:541)(cid:74)(cid:18)(cid:80)(cid:79)(cid:3) (NbS2) (cid:68)(cid:81)(cid:71)(cid:3) (cid:20)(cid:19)(cid:19)(cid:3) (cid:541)(cid:74)(cid:18)(cid:80)(cid:79) (ZrTe2). The mean lateral flakes’ sizes varied from 84 nm to 325 nm and thicknesses from 2.0±1.1 nm to 3.8±1.7 nm. Fig.1(a) shows the linear extinction spectra of the four samples. The effective NL refractive index (nNL) and effective NL absorption coefficient ((cid:68)NL) were measured. In principle, both parameters include contributions from NL susceptibilities and NL light scattering. The light source used was a Ti:Sapphire based regenerative amplifier (800 nm, 1 kHz, 100 fs). The beam was focused with a 15 cm focal length lens onto a 1 mm quartz cuvette. The peak intensity was varied up to (cid:1835) =120 GW/cm2. Z-scan measurements were also performed for pure acetonitrile which showed third-order refractive index equal to +1.9×10-17cm2/W. Fig.1(b) shows the ratio between the peak-to-valley Z-scan curve and the laser intensity (|(cid:959)(cid:1846)|/(cid:1835)) versus (cid:1835) that indicates an effective fifth-order nonlinearity of MoS2 - the values of the third- and fifth-order effective refractive indices are +(4.5±0.3)×10-16 cm2/W and - (7.1±0.2) × 10-25 cm4/W2, respectively. Fig. 1(c) shows that in the case of WS2 only the third-order nonlinearity is observed and nNL=+(3.4±0.2) ×10-16 cm2/W. Fig. 1(d), for NbS2, shows a change in the nNL sign from negative to positive as the intensity increases. Finally, Fig.1(e) for the novel ZrTe2 material shows third-order response with nNL=+(4.2±0.3)×10-16 cm2/W. NL absorption was only observed for NbS2 which presented the effective TPA changing to saturated absorption as the intensity is increased. The results were analyzed considering the sample’s characteristics and applying the Z-scan procedure as described in [4]. To fit the NL absorption curves of NbS2 we assumed homogeneous broadening relaxation and the saturation intensities obtained were 33 GW/cm2 for 1-photon and 39 GW/cm2 for 2-photon absorption. The effective TPA coefficient was 0.21 cm/GW for intensities below saturation.
关键词： Transition Metals Dichalcogenides,TMDs,redox exfoliation,Nonlinear Absorption,Nonlinear Refraction,femtosecond regime
更新于2025-09-12 10:27:22
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Rhenium Diselenide (ReSe <sub/>2</sub> ) Near‐Infrared Photodetector: Performance Enhancement by Selective p‐Doping Technique
摘要： In this study, a near-infrared photodetector featuring a high photoresponsivity and a short photoresponse time is demonstrated, which is fabricated on rhenium diselenide (ReSe2) with a relatively narrow bandgap (0.9–1.0 eV) compared to conventional transition-metal dichalcogenides (TMDs). The excellent photo and temporal responses, which generally show a trade-off relation, are achieved simultaneously by applying a p-doping technique based on hydrochloric acid (HCl) to a selected ReSe2 region. Because the p-doping of ReSe2 originates from the charge transfer from un-ionized Cl molecules in the HCl to the ReSe2 surface, by adjusting the concentration of the HCl solution from 0.1 to 10 m, the doping concentration of the ReSe2 is controlled between 3.64 × 1010 and 3.61 × 1011 cm?2. Especially, the application of the selective HCl doping technique to the ReSe2 photodetector increases the photoresponsivity from 79.99 to 1.93 × 103 A W?1, and it also enhances the rise and decay times from 10.5 to 1.4 ms and from 291 to 3.1 ms, respectively, compared with the undoped ReSe2 device. The proposed selective p-doping technique and its fundamental analysis will provide a scientific foundation for implementing high-performance TMD-based electronic and optoelectronic devices.
关键词： photodetector,transition-metal dichalcogenides (TMDs),p-doping,selective doping,HCl doping,ReSe2,transistor
更新于2025-09-11 14:15:04
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Flakes Size-Dependent Optical and Electrochemical Properties of MoS2
摘要： Background: Molybdenum disulfide (MoS2) is a transition metal dichalcogenides and has some interesting and promising properties. MoS2 has direct and indirect band gaps depending on its crystalline structure. In addition, its sheets morphology makes it a good candidate for supercapacitor applications. Objective: The aim of this work is to study the effect of MoS2 flakes size on its optical and electrochemical properties. Method: MoS2 with different flakes sizes were prepared by exfoliation method. The exfoliation was performed by sonication of MoS2 powder in N,N-Dimethylformamide followed by different centrifugation speeds. UV-Vis spectra illustrated the optical energy gap was inversely proportional to the MoS2 flakes size. Results: Absorption coefficient values indicated that the exfoliation reduced the number of layers. Symmetric supercapacitor was made from two MoS2 electrodes and tested in 6 M KOH electrolyte. The specific capacitance was found to be dramatically increased with decreasing flakes size (9.5 and 4.5 mF/cm2 for 0.26 and 0.98 μm flakes size, respectively). Conclusion: These findings recommend that MoS2 can be the excellent electrode material for supercapacitor.
关键词： nanoflakes,cyclic voltammetry,supercapacitors,Transition Metal Dichalcogenides (TMDs),optical band gap,Molybdenum disulfide
更新于2025-09-10 09:29:36
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Valley coherent exciton-polaritons in a monolayer semiconductor
摘要： Two-dimensional transition metal dichalcogenides (TMDs) provide a unique possibility to generate and read-out excitonic valley coherence using linearly polarized light, opening the way to valley information transfer between distant systems. However, these excitons have short lifetimes (ps) and efficiently lose their valley coherence via the electron-hole exchange interaction. Here, we show that control of these processes can be gained by embedding a monolayer of WSe2 in an optical microcavity, forming part-light-part-matter exciton-polaritons. We demonstrate optical initialization of valley coherent polariton populations, exhibiting luminescence with a linear polarization degree up to 3 times higher than displayed by bare excitons. We utilize an external magnetic field alongside selective exciton-cavity-mode detuning to control the polariton valley pseudospin vector rotation, which reaches 45° at B = 8 T. This work provides unique insight into the decoherence mechanisms in TMDs and demonstrates the potential for engineering the valley pseudospin dynamics in monolayer semiconductors embedded in photonic structures.
关键词： Exciton-polaritons,Valley pseudospin dynamics,TMDs,Microcavity,Valley coherence
更新于2025-09-10 09:29:36