The Experts below are selected from a list of 5187 Experts worldwide ranked by ideXlab platform
Farah Mohammadi - One of the best experts on this subject based on the ideXlab platform.
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Conical Swiss Roll Metamaterial Application for Slow-Light Waveguides
Canadian Journal of Electrical and Computer Engineering, 2020Co-Authors: Somayeh Komeylian, Farah MohammadiAbstract:The framework for designing and fabricating a slow-light waveguide structure with conical Swiss Roll metamaterial core at Terahertz frequencies has been carried out in this article. In the earliest work, theoretical backgrounds based on Maxwell’s equations have been developed for anisotropic single-negative permeability slab waveguides and anisotropic metamaterial slab waveguides. Subsequently, simulation results fulfilled by the MATLAB programming tool verify extremely low group velocities in the aforementioned slab waveguides in the Terahertz regime frequency. A volumetric conical Swiss Roll metamaterial has been proposed as a practical achievement for slow-light waveguides. Dispersion characteristics of the electromagnetic waves in the proposed conical Swiss Roll metamaterial have been investigated using the CST simulation tool in Terahertz frequencies. Furthermore, a 2-D dispersion diagram fulfilled by CST and MATLAB validates highly electromagnetic field concentration as well as the presence of backward waves in the conical Swiss Roll Configuration.
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CCECE - Conical Swiss Roll Metamaterial Application for Slow-light Waveguides
2019 IEEE Canadian Conference of Electrical and Computer Engineering (CCECE), 2019Co-Authors: Somayeh Komeylian, Farah MohammadiAbstract:The framework for designing a slow-light waveguide structure with Conical Swiss Roll Metamaterial at THz frequencies have been carried out. In the earliest work, theoretical backgrounds based on Maxwell’s equations have been developed for anisotropic single-negative permeability slab waveguides and anisotropic Metamaterial slab waveguides. Subsequently, simulation results fulfilled by MATLAB programming tool verify extremely-low group velocities in the aforementioned slab waveguides in THz regime frequency. A volumetric Conical Swiss Roll Metamaterial has been proposed as a practical achievement for slow-light waveguides. Dispersion characteristics of the electromagnetic waves in the proposed Conical Swiss Roll Metamaterial have been investigated using CST simulation tool in THz frequencies. Furthermore, two-dimensional dispersion diagram drawn by CST and MATLAB validates highlyelectromagnetics field concentration as well as the presence of backward waves in the Conical Swiss Roll Configuration.
Zhiquan Huang - One of the best experts on this subject based on the ideXlab platform.
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High-Speed Imaging/Mapping Spectroscopic Ellipsometry for In-Line Analysis of Roll-to-Roll Thin-Film Photovoltaics
IEEE Journal of Photovoltaics, 2014Co-Authors: Ambalanath Shan, Miklós Fried, György Juhász, Csaba Major, Olivér Polgár, Ágoston Németh, Péter Petrik, Lila R. Dahal, Jie Chen, Zhiquan HuangAbstract:An expanded-beam spectroscopic ellipsometer has been developed and applied toward in situ high-speed imaging/mapping analysis of large area spatial uniformity for multilayer coated substrates in Roll-to-Roll thin-film photovoltaics (PV). Slower speed instrumentation available in such analyses applies a 1-D detector array for spectroscopic mapping and involves width-wise translation of the ellipsometer optics over the moving coated substrate surface, measuring point-by-point in a time-consuming process. The expanded-beam instrument employs instead a 2-D detector array with no moving optics, exploiting one array index for spectroscopy and the second array index for line imaging across the width of a large area sample. Thus, the instrument enables imaging width-wise and mapping length-wise for uniformity evaluation at the high linear substrate speeds required for real-time, in situ, and online analysis in Roll-to-Roll thin-film PV. In this investigation, we employ the expanded beam technique to characterize the uniformity of the Ag, ZnO, and n-type hydrogenated amorphous silicon (a-Si:H) layers of an a-Si:H n-i-p structure deposited on a flexible polyimide substrate in the Roll-to-Roll Configuration. Spectroscopic ellipsometry data across a line image were collected as the substrate was translated by a Roll-to-Roll mechanism. Coated areas as large as 12 cm × 45 cm were analyzed in this study for layer thickness and optical properties by applying the appropriate analytical models for the complex dielectric functions of the Ag, ZnO, and n-type a-Si:H layers.
Somayeh Komeylian - One of the best experts on this subject based on the ideXlab platform.
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Conical Swiss Roll Metamaterial Application for Slow-Light Waveguides
Canadian Journal of Electrical and Computer Engineering, 2020Co-Authors: Somayeh Komeylian, Farah MohammadiAbstract:The framework for designing and fabricating a slow-light waveguide structure with conical Swiss Roll metamaterial core at Terahertz frequencies has been carried out in this article. In the earliest work, theoretical backgrounds based on Maxwell’s equations have been developed for anisotropic single-negative permeability slab waveguides and anisotropic metamaterial slab waveguides. Subsequently, simulation results fulfilled by the MATLAB programming tool verify extremely low group velocities in the aforementioned slab waveguides in the Terahertz regime frequency. A volumetric conical Swiss Roll metamaterial has been proposed as a practical achievement for slow-light waveguides. Dispersion characteristics of the electromagnetic waves in the proposed conical Swiss Roll metamaterial have been investigated using the CST simulation tool in Terahertz frequencies. Furthermore, a 2-D dispersion diagram fulfilled by CST and MATLAB validates highly electromagnetic field concentration as well as the presence of backward waves in the conical Swiss Roll Configuration.
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CCECE - Conical Swiss Roll Metamaterial Application for Slow-light Waveguides
2019 IEEE Canadian Conference of Electrical and Computer Engineering (CCECE), 2019Co-Authors: Somayeh Komeylian, Farah MohammadiAbstract:The framework for designing a slow-light waveguide structure with Conical Swiss Roll Metamaterial at THz frequencies have been carried out. In the earliest work, theoretical backgrounds based on Maxwell’s equations have been developed for anisotropic single-negative permeability slab waveguides and anisotropic Metamaterial slab waveguides. Subsequently, simulation results fulfilled by MATLAB programming tool verify extremely-low group velocities in the aforementioned slab waveguides in THz regime frequency. A volumetric Conical Swiss Roll Metamaterial has been proposed as a practical achievement for slow-light waveguides. Dispersion characteristics of the electromagnetic waves in the proposed Conical Swiss Roll Metamaterial have been investigated using CST simulation tool in THz frequencies. Furthermore, two-dimensional dispersion diagram drawn by CST and MATLAB validates highlyelectromagnetics field concentration as well as the presence of backward waves in the Conical Swiss Roll Configuration.
Ambalanath Shan - One of the best experts on this subject based on the ideXlab platform.
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High-Speed Imaging/Mapping Spectroscopic Ellipsometry for In-Line Analysis of Roll-to-Roll Thin-Film Photovoltaics
IEEE Journal of Photovoltaics, 2014Co-Authors: Ambalanath Shan, Miklós Fried, György Juhász, Csaba Major, Olivér Polgár, Ágoston Németh, Péter Petrik, Lila R. Dahal, Jie Chen, Zhiquan HuangAbstract:An expanded-beam spectroscopic ellipsometer has been developed and applied toward in situ high-speed imaging/mapping analysis of large area spatial uniformity for multilayer coated substrates in Roll-to-Roll thin-film photovoltaics (PV). Slower speed instrumentation available in such analyses applies a 1-D detector array for spectroscopic mapping and involves width-wise translation of the ellipsometer optics over the moving coated substrate surface, measuring point-by-point in a time-consuming process. The expanded-beam instrument employs instead a 2-D detector array with no moving optics, exploiting one array index for spectroscopy and the second array index for line imaging across the width of a large area sample. Thus, the instrument enables imaging width-wise and mapping length-wise for uniformity evaluation at the high linear substrate speeds required for real-time, in situ, and online analysis in Roll-to-Roll thin-film PV. In this investigation, we employ the expanded beam technique to characterize the uniformity of the Ag, ZnO, and n-type hydrogenated amorphous silicon (a-Si:H) layers of an a-Si:H n-i-p structure deposited on a flexible polyimide substrate in the Roll-to-Roll Configuration. Spectroscopic ellipsometry data across a line image were collected as the substrate was translated by a Roll-to-Roll mechanism. Coated areas as large as 12 cm × 45 cm were analyzed in this study for layer thickness and optical properties by applying the appropriate analytical models for the complex dielectric functions of the Ag, ZnO, and n-type a-Si:H layers.
Robert W. Birkmire - One of the best experts on this subject based on the ideXlab platform.
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Scaleup of Cu(InGa)Se2 Thin Film Coevaporative Physical Vapor Deposition Process, 1. Evaporation Source Model Development
Industrial & Engineering Chemistry Research, 2009Co-Authors: Kapil Mukati, Erten Eser, Shannon Fields, Babatunde A. Ogunnaike, Robert W. BirkmireAbstract:Even though rapid advances have been made in improving Cu(InGa)Se2 thin-film-based solar cell efficiencies, the breakthroughs have been limited to the laboratory scale. Most commercially viable thin-film technologies reside at the premanufacturing development stage and scaleup has proven to be much more difficult than expected. Elemental in-line evaporation on flexible substrates in a Roll-to-Roll Configuration is a commercially attractive process for the manufacture of large-area CuInSe2-based photovoltaics. At the University of Delaware’s Institute of Energy Conversion (IEC), such a process is being investigated, at the pilot scale, for a polyimide web substrate. The process works well for 6-in.-wide substrates and for short deposition runtimes. However, a commercially viable process is required to produce large-area, high-quality films at a much-higher throughput. Specifically, the desired film thickness (∼2 μm) and composition uniformity must be achieved continuously and reproducibly on large-area (12...
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Critical Issues for Cu(InGa)Se2 Solar Cells on Flexible Polymer Web
2007Co-Authors: Erten Eser, Shannon Fields, William N. Shafarman, Robert W. BirkmireAbstract:Elemental in-line evaporation on glass substrates has been a viable process for the large-area manufacture of CuInSe2-based photovoltaics, with module efficiencies as high as 12.7% [1]. However, lightweight, flexible CuInSe2-based modules are attractive in a number of applications, such as space power sources. In addition, flexible substrates have an inherent advantage in manufacturability in that they can be deposited in a Roll-to-Roll Configuration allowing continuous, high yield, and ultimately lower cost production. As a result, high-temperature polymers have been used as substrates in depositing CuInSe2 films [2]. Recently, efficiency of 14.1% has been reported for a Cu(InGa)Se2-based solar cell on a polyimide substrate [3]. Both metal foil and polymer webs have been used as substrates for Cu(InGa)Se2-based photovoltaics in a Roll-to-Roll Configuration with reasonable success [4,5]. Both of these substrates do not allow, readily, the incorporation of Na into the Cu(InGa)Se2 film which is necessary for high efficiency devices [3]. In addition, polymer substrates, can not be used at temperatures that are optimum for Cu(InGa)Se2 deposition. However, unlike metal foils, they are electrically insulating, simplifying monolithically-integrated module fabrication and are not a source of impurities diffusing into the growing film. The Institute of Energy Conversion (IEC) has modified its in-line evaporation system [6] from deposition onto glass substrates to Roll-to-Roll deposition onto polyimide (PI) film in order to investigate key issues in the deposition of large-area Cu(InGa)Se2 films on flexible polymer substrates. This transition presented unexpected challenges that had to be resolved. In this paper, two major problems, spitting from the Cu source and the cracking of Mo back contact film, will be discussed and the solution to each will be presented.
