- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Multi-layered Parallel Plate Waveguide with Electrically and Magnetically Biased Graphene Walls
摘要： This paper focuses on the fault detection problem of 2-D systems described by the Roesser model. To detect faults effectively in the presence of disturbances, a fault detection ?lter is designed to satisfy a ?nite-frequency H? index and a ?nite-frequency H∞ index simultaneously. The corresponding ?nite-frequency performance analysis conditions are obtained by the aid of the generalized Kalman–Yakubovich–Popov lemma. Then, convex ?lter design conditions are derived by constructing a hyperplane tangent combined with linear matrix inequality techniques. An algorithm is proposed to construct a desired fault detection ?lter. Finally, a numerical example is given to show the effectiveness of the proposed method.
关键词： Fault detection,two-dimensional systems,?nite frequency,Roesser model
更新于2025-09-19 17:13:59
-
Plasmonic Pt Superstructures with Boosted Near‐Infrared Absorption and Photothermal Conversion Efficiency in the Second Biowindow for Cancer Therapy
摘要： Defects are commonly found in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials. Such defects usually dictate the optical and electrical properties of TMDs. It is thus important to develop techniques to characterize the defects directly with good spatial resolution, specificity, and throughput. Herein, we demonstrate that Kelvin probe force microscopy (KPFM) is a versatile technique for this task. It is able to unveil defect heterogeneity of 2D materials with a spatial resolution of 10 nm and energy sensitivity better than 10 meV. KPFM mappings of monolayer WS2 exhibit interesting work function variances that are associated with defects distribution. This finding is verified by aberration-corrected scanning transmission electron microscopy and density functional theory calculations. In particular, a strong correlation among the work function, electrical and optical responses to the defects is revealed. Our findings demonstrate the potential of KPFM as an effective tool for exploring the intrinsic defects in TMDs.
关键词： transition-metal dichalcogenides,density functional theory,defects,Kelvin probe force microscopy,scanning transmission electron microscopy,work function,two-dimensional materials
更新于2025-09-19 17:13:59
-
Plasmonically enabled two-dimensional material-based optoelectronic devices
摘要： Two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides, black phosphorus and hexagonal boron nitride, have been intensively investigated as building blocks for optoelectronic devices in the past few years. Very recently, significant efforts have been devoted to the improvement of the optoelectronic performances of 2D materials, which are restricted by their intrinsically low light absorption due to the ultrathin thickness. Making use of the plasmonic effects of metal nanostructures as well as intrinsic plasmon excitation in graphene has been shown to be one of the promising strategies. In this minireview, recent progresses in 2D material-based optoelectronics enabled by the plasmonic effects are highlighted. A perspective on more possibilities in plasmon-assisted 2D material-based optoelectronic applications will also be provided.
关键词： Transition metal dichalcogenides,Plasmonic effects,Two-dimensional materials,Black phosphorus,Hexagonal boron nitride,Graphene,Optoelectronic devices
更新于2025-09-19 17:13:59
-
Surface-Controlled Crystal Alignment of Naphthyl End-Capped Oligothiophene on Graphene: Thin-Film Growth Studied by <i>In Situ</i> X-ray Diffraction
摘要： We report on the microstructure, morphology, and growth of 5,5′-bis(naphth-2-yl)-2,2′-bithiophene (NaT2) thin films deposited on graphene, characterized by grazing-incidence X-ray diffraction (GIXRD) and complemented by atomic force microscopy (AFM) measurements. NaT2 is deposited on two types of graphene surfaces: custom-made samples where CVD-grown graphene layers are transferred onto a Si/SiO2 substrate by us and common commercially transferred CVD graphene on Si/SiO2. Pristine Si/SiO2 substrates are used as a reference. The NaT2 crystal structure and orientation depend strongly on the underlying surface, with the molecules predominantly lying-down on the graphene surface (face-on orientation) and standing nearly out-of-plane (edge-on orientation) on the Si/SiO2 reference surface. Post growth GIXRD and AFM measurements reveal that the crystalline structure and grain morphology differ depending on whether there is polymer residue left on the graphene surface. In situ GIXRD measurements show that the thickness dependence of the intensity of the (111) reflection from the crystalline edge-on phase does not intersect zero at the beginning of the deposition process, suggesting that an initial wetting layer, corresponding to 1-2 molecular layers, is formed at the surface-film interface. By contrast, the (111) reflection intensity from the crystalline face-on phase grows at a constant rate as a function of film thickness during the entire deposition.
关键词： surface-controlled alignment,molecular orientation,conjugated oligomers,GIXRD,small π-conjugated molecules,two-dimensional materials
更新于2025-09-19 17:13:59
-
Controlled polymer crystal/two-dimensional material heterostructures for high-performance photoelectronic applications
摘要： Controlled polymer crystal/two-dimensional material heterostructures for high-performance photoelectronic applications
关键词： epitaxy,epitaxial interaction,semiconducting polymer,graphene,crystal interaction,transition-metal dichalcogenide,ferroelectric polymer,two-dimensional materials
更新于2025-09-19 17:13:59
-
[IEEE 2019 22nd International Multitopic Conference (INMIC) - Islamabad, Pakistan (2019.11.29-2019.11.30)] 2019 22nd International Multitopic Conference (INMIC) - Neuro based Integral Terminal Sliding Mode Nonlinear MPPT Control Paradigms for Stand-Alone Photovoltaic System
摘要： This paper focuses on the fault detection problem of 2-D systems described by the Roesser model. To detect faults effectively in the presence of disturbances, a fault detection ?lter is designed to satisfy a ?nite-frequency H? index and a ?nite-frequency H∞ index simultaneously. The corresponding ?nite-frequency performance analysis conditions are obtained by the aid of the generalized Kalman–Yakubovich–Popov lemma. Then, convex ?lter design conditions are derived by constructing a hyperplane tangent combined with linear matrix inequality techniques. An algorithm is proposed to construct a desired fault detection ?lter. Finally, a numerical example is given to show the effectiveness of the proposed method.
关键词： Fault detection,two-dimensional systems,?nite frequency,Roesser model
更新于2025-09-19 17:13:59
-
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
-
Junctions between two-dimensional plasmonic waveguides in the presence of retardation
摘要： Plasmons in two-dimensional (2D) waveguides are traditionally analysed within the electrostatic approximation, which assumes that the plasmon phase velocity is much smaller than the velocity of light. However, novel effects have recently been demonstrated for plasmons whose velocity is comparable to the velocity of light. In this retardation regime, electrostatic models are inaccurate. For a junction between two plasmonic waveguides, we present an analytical and a numerical model both valid in the retardation regime and compare them to an electrostatic model. We quantify the re?ected and transmitted powers and the radiation loss in several scenarios. We found that power is radiated from a junction at the expense of the power of the re?ected plasmon, but retardation has little effect on the phases of the re?ected and transmitted plasmons. The radiation loss is typically below several percent when the plasmon velocities are ?ve or more times below the light velocity. However, radiation still persists for slower plasmon velocities for a junction between a 2D waveguide and a perfectly conducting sheet. As a result, retardation is expected to degrade the quality factors of plasmonic resonators without affecting their eigenfrequencies.
关键词： waveguide junctions,plasmonic waveguides,two-dimensional materials,plasmon
更新于2025-09-19 17:13:59
-
Strongly interfacial-coupled 2D-2D TiO2/g-C3N4 heterostructure for enhanced visible-light induced synthesis and conversion
摘要： Two-dimensional (2D) nanosheet-based nanocomposites have attracted intensive interest owing to the unique electronic and optical properties from their constituent phases and the synergistic effect from the heterojunctions. In this study, an interfacial coupled TiO2/g-C3N4 2D-2D heterostructure has been prepared via in situ growth of ultrathin 2D-TiO2 on dispersed g-C3N4 nanosheets. This strongly coupled 2D-2D TiO2/g-C3N4, different from the weakly bonded 2D-TiO2/g-C3N4 heterostructures produced by mechanical mixing, has unique electronic structures and chemical states due to strong interlayer charge transfer, confirmed by both experimental and theoretical analyses. Significantly enhanced visible-light responses have been observed, indicating a great potential for visible-light induced photosynthesis and photocatalysis. For benzylamine coupling reactions under visible-light irradiation, 80% yield rate has been achieved, superior to ~30% yield rate when adopting either 2D-TiO2 or g-C3N4 structure. The enhanced photocatalytic activity can be attributed to the adequate separation of photo-generated electrons at the strongly coupled 2D-2D heterojunction interfaces.
关键词： 2D-2D heterostructure,Two-dimensional nanosheet,Strongly coupled,Photocatalysis
更新于2025-09-19 17:13:59
-
A 20-GHz-band 64×64 Hollow Waveguide Two-Dimensional Butler Matrix
摘要： In this paper, a 20-GHz-band 64×64 hollow waveguide Butler matrix is proposed. By using two-plane short slot couplers and a modified diagram, a short-axis two dimensional Butler matrix is realized. The design method of the diagram and components is presented. The Butler matrix is composed of two plane hybrids, cross couplers and phase shifters. The designed Butler matrix is fabricated by milling and screwing together nine aluminum plates. The dimensions and weight are 86.40 mm × 74.19 mm × 396.34 mm and 7.0 kg, respectively. Transmission characteristics as a beam switching circuit are characterized by measurements, with a low insertion loss of less than 1.8 dB and an excitation error of 4-dB and 40-deg. standard deviation. Radiation characteristics as a 64-beam antenna are measured, and a wide coverage area of 40% of the hemisphere and high directivity of more than 18.7 dBi were determined by measurements.
关键词： two-plane short slot coupler,Butler matrix,two dimensional beam switching,Hollow waveguide
更新于2025-09-16 10:30:52