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Artigos de revistas sobre o assunto "Quasi-vertical devices"
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Evans, Jon, Jash Patel, Ahmed Ben Khaial, Nicholas Burridge, Rhonda Hyndman, Finn Monaghan, Mike Jennings, Huma Ashraf, Rob Harper e Matthew Elwin. "Fabrication of Quasi-Vertical GaN-On-SiC Trench MOSFETs". Key Engineering Materials 945 (19 de maio de 2023): 61–66. http://dx.doi.org/10.4028/p-97g365.
Texto completo da fonteResumo:
We demonstrate quasi-vertical GaN MOSFETs fabricated on SiC substrates. The GaN epitaxial layers were grown via MOCVD on 100 mm 4H-SiC wafers, with the device structure consisting of a 2.5 μm drift layer and a Mg doped p-GaN body. The fabricated transistors exhibit normally-off characteristics, with low off-state leakage behavior and an on/off ratio of over . The specific on-resistance was measured to be which compares favorably to devices fabricated on other foreign substrates. Our results demonstrate an alternative substrate for realizing vertical GaN devices, which potentially offers better material quality and thermal properties compared with other foreign substrate choices.
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Weikle, Robert M., S. Nadri, C. M. Moore, N. D. Sauber, L. Xie, M. E. Cyberey, N. Scott Barker, A. W. Lichtenberger e M. Zebarjadi. "Thermal Characterization of Quasi-Vertical GaAs Schottky Diodes Integrated on Silicon Using Thermoreflectance and Electrical Transient Measurements". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2019, DPC (1 de janeiro de 2019): 001293–310. http://dx.doi.org/10.4071/2380-4491-2019-dpc-presentation_tha3_009.
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Thermal management and design have been understood, for many years, as critical factors in the implementation of submillimeter-wave Schottky-diode-based circuits and instruments. Removal of heat is particularly important for frequency multipliers, as these circuits generally exhibit low-to-modest conversion efficiencies, and are usually driven with high-power sources to achieve usable output power in the submillimeter-wave region of the spectrum. Elevated diode junction temperature due to inadequate heat sinking is known to degrade performance, accelerate aging effects (for example, due to electromigration, ohmic contact deterioration, or thermally-induced stress), and can ultimately lead to device failure. The relatively-low thermal conductivity of GaAs (the predominant material technology for submillimeter-wave diodes), coupled with restrictions on diode anode size and geometry needed to minimize parasitics and achieve the device impedances required for high-frequency operation, present significant challenges and trade-offs between electrical and thermal designs of these devices. Recognition that heating is a major factor limiting efficiency and output power has prompted a number of approaches to mitigate excessive temperature rise in the junction of planar Schottky diodes, including the use of AlN or diamond as low-loss substrates that act as heat spreaders. A new diode topology, based on a quasi-vertical geometry that is realized through heterogeneous integration of GaAs with high-resistivity silicon, was recently developed at the University of Virginia for submillimeter-wave applications. Unlike planar diodes, the device structure of the quasi-vertical diode consists of a metal contact that underlies the diode's anode and epitaxial mesa, thus providing a large-area ohmic cathode contact that also serves as an integrated heat sink. Measurement of high-efficiency multipliers based on this technology suggest the quasi-vertical architecture provides an effective approach for heat removal and thermal management in Schottky diodes. This paper presents the first results reporting thermal performances of terahertz quasi-vertical GaAs Schottky diodes integrated on silicon. The devices are characterized using a thermoreflectance measurement technique, a method based on the change in refractive index, and therefore surface reflectivity, with changes in temperature. Heating and cooling temperature profiles and 2-D temperature maps are obtained for 3.5 micron and 5.5 micron diameter diodes. From these measurements, the device thermal resistances, junction temperatures, and thermal time-constants are extracted. Equivalent thermal circuit and finite element models are developed to study the device geometry, and extract material thermal parameters. The devices are also characterized using an electrical transient method, and the temperature and cooling transients found from this technique are found to be comparable to those obtained from thermoreflectance measurements. The quasi-vertical diodes studied in this work are shown to demonstrate a faster transient thermal response compared to flip-chip bonded terahertz diodes reported in the literature.
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Zhu, Xiaoxiao, Wei Lu, Jing Ning, Jincheng Zhang, Dong Wang, Chi Zhang, Yanbo Wang et al. "A high-performance quasi-vertical MoSe2 photodiode with ultra-low dark current". Applied Physics Letters 121, n.º 14 (3 de outubro de 2022): 141103. http://dx.doi.org/10.1063/5.0104664.
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Van der Waals heterostructure based on 2D materials is a promising technology for high-performance optoelectronic devices because of its tunable bandgaps and optical properties. However, photodetectors with a low dark current and a fast response speed commonly lose their photoresponsivity. The recovery current induced by the Schottky barrier height variation cancels out the device's reverse bias current in this paper, resulting in a quasi-vertical MoSe2 photodiode with ultralow dark current (<1 pA). Simultaneously, rapid electron–hole pair separation occurs at the interface due to the large heterojunction area and the strong interlayer coupling of MoSe2/graphene heterojunction, resulting in a fast response time of 1.5 ms and a high photoresponsivity of 19.72 A/W. Furthermore, the Au/MoSe2 forms a Schottky contact, which is asymmetrical to the Ohmic contact formed by the MoSe2/graphene, enabling the proposed device to achieve high-performance self-powered photodetection. Our work shows an alternative approach to improve the performance of future electronic and optoelectronic applications.
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Liu, Cheng, Ming Li, Zhang Wen, Zhao-Yuan Gu, Ming-Chao Yang, Wei-Hua Liu, Chuan-Yu Han, Yong Zhang, Li Geng e Yue Hao. "Establishment of composite leakage model and design of GaN Schottky barrier diode with stepped field plate". Acta Physica Sinica 71, n.º 5 (2022): 057301. http://dx.doi.org/10.7498/aps.71.20211917.
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Quasi-vertical GaN barrier Schottky diodes have attracted much attention due to their low cost and high current transfer capability. The main problem is that the reverse characteristics of the devices may not be well estimated, which affects the design of the diodes. In this paper, the defects of GaN materials and the leakage related tunneling mechanisms accompanied with other mechanisms are considered. Based on the established composite device models, the reverse leakage current is simulated which is well consistent with the recent experimental result. With the assistance of the proposed models, several field plate structures are discussed and simulated to obtain a quasi-vertical GaN barrier Schottky diode with high breakdown voltage. The major leakage mechanisms are also analyzed according to the relation among leakage current, temperature and electric field at various reverse voltages. High BFOM up to 73.81 MW/cm<sup>2</sup> is achieved by adopting the proposed stepped field plate structure.
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Khan, Sahanowaj, Aritra Acharyya, Hiroshi Inokawa, Hiroaki Satoh, Arindam Biswas, Rudra Sankar Dhar, Amit Banerjee e Alexey Y. Seteikin. "Terahertz Radiation from High Electron Mobility Avalanche Transit Time Sources Prospective for Biomedical Spectroscopy". Photonics 10, n.º 7 (10 de julho de 2023): 800. http://dx.doi.org/10.3390/photonics10070800.
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A Schottky barrier high-electron-mobility avalanche transit time (HEM-ATT) structure is proposed for terahertz (THz) wave generation. The structure is laterally oriented and based on AlGaN/GaN two-dimensional electron gas (2-DEG). Trenches are introduced at different positions of the top AlGaN barrier layer for realizing different sheet carrier density profiles at the 2-DEG channel; the resulting devices are equivalent to high–low, low–high and low-high–low quasi-Read structures. The DC, large-signal and noise simulations of the HEM-ATTs were carried out using the Silvaco ATLAS platform, non-sinusoidal-voltage-excited large-signal and double-iterative field-maximum small-signal simulation models, respectively. The breakdown voltages of the devices estimated via simulation were validated by using experimental measurements; they were found to be around 17–18 V. Under large-signal conditions, the series resistance of the device is estimated to be around 20 Ω. The large-signal simulation shows that the HEM-ATT source is capable of delivering nearly 300 mW of continuous-wave peak power with 11% conversion efficiency at 1.0 THz, which is a significant improvement over the achievable THz power output and efficiency from the conventional vertical GaN double-drift region (DDR) IMPATT THz source. The noise performance of the THz source was found to be significantly improved by using the quasi-Read HEM-ATT structures compared to the conventional vertical Schottky barrier IMPATT structure. These devices are compatible with the state-of-the-art medium-scale semiconductor device fabrication processes, with scope for further miniaturization, and may have significant potential for application in compact biomedical spectroscopy systems as THz solid-state sources.
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Yadav, Sugandha, Poornima Mittal e Shubham Negi. "An In-Depth Analysis of Variation in Characteristic Performance of OLED with Respect to Position of Charge Generation Layer". ECS Journal of Solid State Science and Technology 12, n.º 10 (1 de outubro de 2023): 106001. http://dx.doi.org/10.1149/2162-8777/acfd5f.
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In this paper, a high performance blue organic light emitting diode having a charge generation layer (CGL) is proposed and compared with the other five CGL and non-CGL based devices. The utilized CGL layer in the different structure consists of two materials; HAT-CN (hexaazatriphenylene-hexacarbonitrile) and TAPC (1,1-bis[(di-4-tolyamino)phenyl)]cyclohexane,) for electrons and holes generation, correspondingly. In the proposed novel structure, the CGL layer is incorporated outside of the emissive layer (EML) which significantly enhances the device performance in terms of current and luminescence. The device exhibits luminescence and current values as 3636.3 cd m−2 and 0.44 A, respectively. Furthermore, this paper represents in-depth internal analysis of the six devices (D1-D6). This analysis is provided by drawing horizontal and vertical cutlines inside the devices. The proposed device is analysed and compared with other mentioned devices in terms of several parameters such as Langevin recombination rate, electron concentration, hole concentration, band energy, total current density, electron affinity, hole QFL (quasi-Fermi level), conduction current density, potential distribution and electron/hole mobility. In comparison with D1, D2, D3, D4 and D5, the current of the proposed device (D6) is about 16.9, 2.2, 1.7, 3 and 1.6 times improved, correspondingly. Moreover, structural analysis is also included to understand the performance of the devices more precisely.
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Briskin, E. S., L. D. Smirnaya e K. S. Artemyev. "On the Control of Traction Characteristics and Resistance to Movement of Mobile Robots with Walking Propulsion Devices". Mekhatronika, Avtomatizatsiya, Upravlenie 24, n.º 2 (6 de fevereiro de 2023): 101–6. http://dx.doi.org/10.17587/mau.24.101-106.
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The problem of increasing the traction and dynamic properties of mobile robots with walking propulsion devices is considered. The interdependence of the traction forces developed by the propulsion devices and the forces of resistance to the movement of robots, due to their interaction with the environment, is analyzed. A mathematical model is proposed based on the quasi-static nature of the robot’s movement and taking into account the static uncertainty of the problem. Static indeterminacy is due to the presence of propulsion devices on each of the sides and interacting with the supporting surface in the amount of more than two. A feature of the solution is also taking into account the gait and schedule of the robot’s movement, which characterize the time sequence of the propulsion devices being in the phase of interaction with the supporting surface and in the phase of transfer to a new position. The gait is also characterized by the mode coefficient, which is the ratio of the time the propulsion device is in the stance phase to the total time of the cycle of its movement. An optimality criterion is introduced on the basis of which the design perfection of the propulsion devices and the place of their installation on the robot is evaluated. The optimality criterion consists of two indicators: the value of the maximum traction force and the average force of resistance to movement. The tractive force is assumed to be proportional to the sum of the maximum normal loads acting on each propulsion device unit, and the resistance force to the squares of the same loads. Simulation modeling has been carried out, proving the dependence of the magnitude of traction properties and the forces of resistance to movement on the location of the propulsion devices. Two systems of vertical arrangement of the points of suspension of propulsion devices were compared. It has been established that a sufficiently small change in the vertical coordinate of the suspension point of even one propulsion devices has a noticeable change in the maximum traction forces and movement resistance forces. It is concluded that by adjusting the vertical position of the propulsion devices foot relative to the robot body, it is possible to control the traction properties and movement resistance, as well as the importance of the positioning accuracy of the foot of the propulsion devices walking mechanism during movement.
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Cristoloveanu, Sorin, Joris Lacord, Sébastien Martinie, Carlos Navarro, Francisco Gamiz, Jing Wan, Hassan Dirani, Kyunghwa Lee e Alexander Zaslavsky. "A Review of Sharp-Switching Band-Modulation Devices". Micromachines 12, n.º 12 (11 de dezembro de 2021): 1540. http://dx.doi.org/10.3390/mi12121540.
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This paper reviews the recently-developed class of band-modulation devices, born from the recent progress in fully-depleted silicon-on-insulator (FD-SOI) and other ultrathin-body technologies, which have enabled the concept of gate-controlled electrostatic doping. In a lateral PIN diode, two additional gates can construct a reconfigurable PNPN structure with unrivalled sharp-switching capability. We describe the implementation, operation, and various applications of these band-modulation devices. Physical and compact models are presented to explain the output and transfer characteristics in both steady-state and transient modes. Not only can band-modulation devices be used for quasi-vertical current switching, but they also show promise for compact capacitorless memories, electrostatic discharge (ESD) protection, sensing, and reconfigurable circuits, while retaining full compatibility with modern silicon processing and standard room-temperature low-voltage operation.
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Eyvazian, Arameh, Hozhabr Mozafari, Faris Tarlochan e Abdel Magid S. Hamouda. "Numerical and Experimental Investigation on Corrugation Geometry for Metallic Tubes under Lateral Loading". Materials Science Forum 916 (março de 2018): 226–31. http://dx.doi.org/10.4028/www.scientific.net/msf.916.226.
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Energy absorption devices are being used to protect structures from severe damages and reduce injury to occupants during accidents. The integrated characteristics of crash absorption devices can be classified as high energy absorption capacity, light-weight, and cost-effective. One of the thin-walled structures which has drawn the attention of scientists is corrugated tube structure. In this paper, the effect of corrugation geometry on the crushing parameters of an aluminum corrugated tube is investigated. In this regard, different elliptical corrugation shapes were deemed and the compression response was numerically evaluated under lateral quasi-static loading. Finally, the crashworthiness parameters were extracted and compared to determine the influence of corrugation shape on the crashworthy response. Our results showed that using vertical elliptical corrugation decrease the densification point. Moreover, there is a gradual enhancement of mean crushing load by moving from the horizontal elliptical corrugations to the vertical ones. Also, by modifying of corrugation shape, the stress variation pattern changes, significantly.
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Salgado, Ruben, Amirmahdi Mohammadzadeh, Fariborz Kargar, Adane Geremew, Chun-Yu Huang, Matthew A. Bloodgood, Sergey Rumyantsev, Tina T. Salguero e Alexander A. Balandin. "Low-frequency noise spectroscopy of charge-density-wave phase transitions in vertical quasi-2D 1T-TaS2 devices". Applied Physics Express 12, n.º 3 (15 de fevereiro de 2019): 037001. http://dx.doi.org/10.7567/1882-0786/ab0397.
Texto completo da fonteTeses / dissertações sobre o assunto "Quasi-vertical devices"
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Kaltsounis, Thomas. "Épitaxie localisée de GaN sur silicium pour une nouvelle génération de transistors de puissance". Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5072.
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Les composants à haute puissance et en particulier haute tension sont essentiels pour la conversion et le stockage de l'énergie électrique pour des applications comme les systèmes photovoltaïques et les voitures électriques. Actuellement, les composants à base de silicium (Si) dominent le secteur de l'électronique de puissance. Les semiconducteurs à large bande interdite comme le nitrure de gallium (GaN) sont d'excellents candidats pour remplacer le silicium. Les propriétés électriques du GaN permettent d'obtenir des composants plus efficaces que ceux à base de Si et de dissiper moins d'énergie est durant leur fonctionnement. Cependant, les substrats natifs de GaN sont de taille et de disponibilité limitées. L'épitaxie de GaN sur des plaques de Si de diamètre 200 mm est une alternative intéressante à cause de leur faible cout et de leur compatibilité avec les lignes de fabrication CMOS. Cependant, les désaccords de paramètre de maille et de coefficient de dilatation thermique entre GaN et Si génèrent une grande contrainte en tension dans la couche de GaN et limitent l'épaisseur des couches qui peuvent être obtenue sur des plaques de Si sans fissures. Enfin, la configuration verticale améliore la fiabilité des composants, comme le maximum de champ électrique est loin de la surface et il est localisé dans la masse des composants. Alors, les effets de piégeage sont réduits et la résistance dynamique diminue. En plus, la gestion thermique des composants verticaux est plus facile que celle des composants latéraux. Cette thèse explore l'épitaxie localisée de GaN par EPVOM comme une solution pour gérer la relaxation de cette contrainte dans la couche de GaN et pour déposer des couches de grande épaisseur avec une faible concentration de dopage afin de fabriquer de composants de haute puissance. Quatre points principaux sont explorés avec des résultats cruciaux pour la poursuite de la recherche dans ce domaine : - Pour commencer, le matériau approprié pour servir de masque pour l'épitaxie localisée a été identifié en étudiant la concentration de dopage involontaire dans la couche de GaN, issu de la réaction des atomes de Ga avec le masque et de l'incorporation des atomes de dopant du masque - De plus, les techniques de caractérisation usuelles atteignent leurs limites pour mesurer de faibles concentrations de dopage. La microscopie de résistance et la microscopie de capacité réalisées au moyen d'un microscope à force atomique sur des sections transversales obtenues par gravure par faisceaux d'ions sont validées et pour la première fois une telle faible concentration de dopage est mesurée.- Un masque créé spécifiquement pour l'épitaxie localisée a permis l'investigation de la taille des structures qui peuvent être générées sans fissures, sous des conditions de croissance déjà validées.- Des diodes Schottky et des diodes p-n quasi-verticales ont été fabriquées et leur comportement a été étudié au moyen de mesures I-V. Les diodes p-n ont une résistance relativement faible, vu que le masque n'est pas optimisé et la résistance d'accès est grand. Pour la première fois, une tension de claquage de 700 V a été mesurée sur une diode p-n sans protection périphérique. Cette thèse présente des résultats qui n'ont jamais rapportés dans la littérature et elle montre le grand potentiel de l'épitaxie localisée de GaN sur des plaques de Si pour des composants verticaux de haute puissanceHigh-power devices and especially high-voltage ones are essential for the conversion and storage of electrical energy in applications such as photovoltaic systems and electric cars. Nowadays, silicon (Si)-based devices dominate the field of power electronics. Wide-bandgap semiconductors, such as Gallium Nitride (GaN), are excellent candidates to replace Si. Due to the excellent electrical properties of GaN, devices based on this semiconductor are more efficient than their Si-based counterparts and the energy lost occurring during conversion operation is much less. However, native GaN substrates have limited size and availability. The growth of GaN on 200 mm-diameter Si wafers is an attractive alternative because of their low cost and compatibility with a CMOS fabrication line. However, the lattice and coefficient thermal mismatch between GaN and Si generate a large tensile stress and limit the thickness of full-wafer GaN layers grown on Si wafers without cracking. Finally, the vertical configuration enhances the reliability of the devices by moving the maximum of the electric field away from the surface into the bulk of the devices. Thus, the trapping effects are reduced and the dynamic on-resistance decreases. The thermal management of the vertical devices is easier than that for the lateral ones.This dissertation explores the localized epitaxy of GaN as a solution to relax this stress in the regrown GaN layer and to grow thick layers with low net doping concentration required for the fabrication of high-power devices. There are four main points that are explored and crucial results are provided for the continuation of the research on the project: - First, a suitable mask material for the localized epitaxy with MOVPE is identified by investigating the unintentional doping concentration in the regrown layer, induced by the reaction of Ga atoms with the mask and the incorporation of dopant atoms from the mask.- Second, characterization techniques are pushed to the limits of measuring low doping concentrations. Scanning spreading resistance microscopy and scanning capacitance microscopy, combined with the ion-beam cross-section preparation technique are validated and for the first time are able to examine such low doping concentrations.- Third, through a mask designed specifically for the localized epitaxy, the scaling of crack-free structures that can be regrown is investigated, under growth conditions that have been already validated.- Fourth, quasi-vertical Schottky and p-n diodes are fabricated and their forward and reverse bias I-V behavior is investigated. The p-n diodes show relatively low on-resistance (Ron), considering that the mask is not optimized and the access resistance is large, and for the first time a 700 V breakdown voltage is measured on a p-n diode with no periphery protection.The current thesis shows remarkable results that have not been reported before in the literature and demonstrates the great potential that the localized epitaxy of GaN on Si wafers offers for high-power vertical devices
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Chang, Meng-Sheng, e 張盟昇. "The Design and Analysis of Quasi-Vertical Devices for High Voltage ESD Protection Circuits". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89866408640434861071.
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碩士國立清華大學
電子工程研究所
97
In this thesis, a novel quasi-vertical insulated gate bipolar transistor (VIGBT) and a quasi-vertical silicon controlled rectifier(VSCR) structure have been designed and fabricated for high voltage ESD protection circuit applications. In addition, a comparison is made among quasi-vertical MOSFETs, quasi-vertical IGBT and quasi-vertical SCR. The device characteristics are simulated using a semiconductor device simulator, MEDICI, to study the effects of device dimensions, then the devices were fabricated in a commercially available 0.5μm 100V process. Devices were then measured and analyzed. Measurement results indicate that, under the same condition, for the devices with 100μm channel width, VIGBT (2Sinker-1Channel)、(1Sikner -2Channel) can handle It2 of 7.22 amps and 9.48 amps. This is larger than It2 of 5.94 amps and 3.18 amps observed in VDMOS(2Sinker- 1Channel)、(1Sinker-2Channel). VIGBT outperforms VDMOS in the aspect of ESD current sustaining capability. For the devices with 200μm channel width, VSCR and VIGBT(1Sinker-2Channel) can handle It2 of 9.58 amps and 9.75 amps. This is larger than It2 of 6.13 amps achieved by VDMOS(1Sinker-2Channel). These results confirm that, due to the parasite PNPN structure, the ESD current sustaining capacity of VSCR and VIGBT is superior than VDMOS.
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Liu, Chung-Min, e 劉中民. "Analysis of the Quasi-Saturation Behavior in the Power Vertical Double-Diffused Metal-Oxide-Semiconductor(DMOS) Devices". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/80708280417525581150.
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博士國立臺灣大學
電機工程學系
85
In this thesis, the analytical model for the quasi-saturation behavior of aDMOS device by taking the cryogenic effects and the thermal effects into account, and the analyses of the capacitance characteristics and the transientbehavior for the DMOS device from the two-dimensional numerical simulation aredescribed. In Chapter 2, a simulation study on the 77K versus 300K operation in terms of the quasi-saturation behavior of a DMOS device usinglow-temperature PISCES is described. From the analysis, a closed-formanalytical quasi-saturation model for DMOS devices is derived. In Chapter 3,the analytical lattice temperature model and the quasi- saturation currentmodel considering heat flow for a DMOS device are derived. As verified by thePISCES results, a good prediction of the much worse quasi-saturation behavior due to the elevated lattice temperature can be observed. In Chapter 4, a simulation study on the capacitance overshoot behavior of a DMOS device operating in the quasi-saturation region is described. In this chapter, both of the incremental-charge-partitioning approach and the small- signal acadmittance matrix analysis are adopted for analyzing the DMOS capacitance. In addition, the turn-off transient analysis of a DMOS device considering the quasi-saturation behavior is also described.
Capítulos de livros sobre o assunto "Quasi-vertical devices"
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Warrick, Arthur W. "One-Dimensional Absorption". In Soil Water Dynamics. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195126051.003.0009.
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In this chapter we address one-dimensional absorption. Absorption denotes movement of water (or other liquid) into a soil under the influence of capillarity without the effects of gravity. Although important for horizontal flow conditions, there is more interest in the results and principles relevant to the early stage of infiltration and in general relationships descriptive of the physical principles for all unsaturated systems. At the outset, two simplified systems will be considered. Included is the classical problem of linear diffusion into a semi-infinite domain. Then the Boltzmann similarity transform will be applied, confirming results from the simplified solutions and leading to methods for finding soil-water diffusivity and Philip’s quasi-analytical solution. Finally, simultaneous water flow will be considered as a two-phase process. Figure 4-1 shows water introduced into a horizontal column of soil at a matric potential hwet. The value of hwet is maintained as zero or negative by the “mariotte” device to the left. The initial condition is that the matric potential is hdry with hdry < hwet ≤ 0. A porous plate at x = 0 allows water to come into the system but prevents air from flowing from the soil back into the water supply. The right-hand end allows air to freely escape the system as the water displaces the air. Vertical movement in the soil column is ignored. We make key simplifying assumptions that the conductivity is a constant K = Kwet in the wet part of the column and K = 0 for the dry part. Furthermore, we assume a sharp division between the wet and dry part at xf. On the supply side of the column (0 < x < xf), the water content is a constant (θ = θwet) and, to the dry side, the initial value is maintained (θ = θdry). These are equivalent to the “Green–Ampt” assumptions used in chapter 5, when gravity will be included as a driving force.
Trabalhos de conferências sobre o assunto "Quasi-vertical devices"
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Michel, Ancy, Binola K. Jebalin I.V, Navin M. George, Angelin Delighta A e D. Nirmal. "Quasi Vertical FinFET with Step Graded Doping for Obtaining 0.037 mΩ.cm2 ON Resistance". In 2024 IEEE International Conference of Electron Devices Society Kolkata Chapter (EDKCON), 353–57. IEEE, 2024. https://doi.org/10.1109/edkcon62339.2024.10870763.
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Pan, Zeyu, Harish Subbaraman, Yi Zou, Xingyu Zhang, Cheng Zhang, Qiaochu Li, L. Jay Guo e Ray T. Chen. "High optical coupling efficiency quasi-vertical taper for polymer waveguide devices". In SPIE OPTO, editado por Henning Schröder e Ray T. Chen. SPIE, 2015. http://dx.doi.org/10.1117/12.2078560.
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Liu, Chao, Riyaz Abdul Khadar e Elison Matioli. "645 V quasi-vertical GaN power transistors on silicon substrates". In 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD). IEEE, 2018. http://dx.doi.org/10.1109/ispsd.2018.8393647.
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Yoder, P. D., E. J. Flynn e S. Sridharan. "Vertical-illumination InGaAs/InP quasi-unipolar photodetector with high bandwidth, quantum efficiency, and resistance to bandwidth collapse". In Integrated Optoelectronic Devices 2007, editado por Marek Osinski, Fritz Henneberger e Yasuhiko Arakawa. SPIE, 2007. http://dx.doi.org/10.1117/12.699707.
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Tsai, Ying-Chieh, Jeng Gong, W. C. Chan, S. Y. Wu e C. H. Lien. "Design and analysis of a double RESURF 700V LIGBT with quasi-vertical DMOSFET in junction isolation technology". In 2014 IEEE 26th International Symposium on Power Semiconductor Devices & IC's (ISPSD). IEEE, 2014. http://dx.doi.org/10.1109/ispsd.2014.6855997.
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Zhou, Feng, Weizong Xu, Fangfang Ren, Dunjun Chen, Rong Zhang, Youdou Zheng, Tinggang Zhu e Hai Lu. "High Performance Quasi-Vertical GaN Junction Barrier Schottky Diode with Zero Reverse Recovery and Rugged Avalanche Capability". In 2021 33rd International Symposium on Power Semiconductor Devices and ICs (ISPSD). IEEE, 2021. http://dx.doi.org/10.23919/ispsd50666.2021.9452308.
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Wu, Tuanzhuang, Jiaxing Wei, Weidong Wang, Xiaonan Lin, Jie Ma, Sheng Li, Ran Ye et al. "Influence of Structure Parameters on the RoN, sp of Quasi- Vertical Power DMOS Compatible with 0.18μm BCD Process". In 2024 36th International Symposium on Power Semiconductor Devices and ICs (ISPSD). IEEE, 2024. http://dx.doi.org/10.1109/ispsd59661.2024.10579557.
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Chen, Jiabo, Zhihong Liu, Zhaoke Bian, Haiyong Wang, Xiaoling Duan, Jing Ning, Jincheng Zhang e Yue Hao. "Nearly ideal quasi-vertical GaN Schottky barrier diode with 1010 high on/off ratio and ultralow turn on voltage via post anode annealing". In 2021 5th IEEE Electron Devices Technology & Manufacturing Conference (EDTM). IEEE, 2021. http://dx.doi.org/10.1109/edtm50988.2021.9421063.
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Festa, Oscar, Susan Gourvenec e Adam Sobey. "Analytical Model of Non-Linear Load Reduction Devices for Catenary Moorings". In ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/omae2023-100845.
Texto completo da fonteResumo:
Abstract Load reduction devices are extensible components installed along mooring lines to provide peak and mean mooring load reduction, and are of articular interest for floating offshore wind. Various concepts exist, including ballasted pendulums, thermoplastic springs and hydraulic dampers, all of which provide compliance to environmental loads. This enables lighter mooring lines, smaller anchors and increased fatigue life of mooring lines — contributing to higher reliability and lower cost. Load reduction devices are designed to exhibit a non-linear load-extension behaviour: lower stiffness in the operational strain range to reduce loads, and higher stiffness at high strain. These devices are becoming an increasingly common consideration for FOWTs, and are pushing traditional analysis/design to readily incorporate nonlinearity. Well-established static catenary equations, used to define mooring tension-offset profiles, only account for linear elasticity such that capturing non-linear response typically requires finite element modelling. This paper presents an alternative through parameterising equations for three different non-linear load-extension curves and incorporating them into the existing catenary equations. For a given non-linear load-extension curve and length of load reduction device, the resulting analytical model can be solved quasi-instantaneously using Newton-Raphson or Newton-Krylov iterations to give vertical and horizontal mooring line tensions and thus strain of the device. Results from the new analytical model are compared with finite element predictions showing agreement to within 1%. The analytical model can be solved for any two unknowns, such that optimal load reduction device length and stiffness can be determined instantaneously given maximum environmental load and allowable surge. The new analytical equations are implemented into a graphical app, which allows the user to input any load reduction device parameters and visualise the resulting mooring system’s geometry and tension-offset profile.
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Sefat, Sina Mirzaei, e Antonio Carlos Fernandes. "Stability Analysis Hinged Vertical Flat Plate Rotation in a Uniform Flow". In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84020.
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The free falling of objects is a phenomenon that has been observed in the nature. The Pendulous Installation Method (PIM) of heavy devices is an example of free falling which occurs in the installation of heavy offshore devices on sea bed. Hence, the motivation of the present research is to study the fluttering and tumbling (autorotation) motions that may occur during the free fall of object. The fluttering is a periodic or chaotic oscillation of body about a vertical axis. On the other hand, the tumbling is end-over-end rotation of body. In order to access the main physical aspects, the present work decided to attack a more fundamental problem and describes the investigations on fluttering and autorotation motions of the interaction of uniform current and freely rotating plate about a fixed vertical axis. A quasi-steady model is suggested to model the trajectories of flow induced rotation phenomenon and a stability analysis performed to gain insight into the nature of the bifurcation from fluttering to autorotation. At first, the fixed points for different models of motion is obtained and each point analyzed by using the linearized equation. Secondly, the phase diagrams as a function of angular velocity and angle of rotation have been presented for different dynamic models.
Relatórios de organizações sobre o assunto "Quasi-vertical devices"
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Wu, Yingjie, Selim Gunay e Khalid Mosalam. Hybrid Simulations for the Seismic Evaluation of Resilient Highway Bridge Systems. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, novembro de 2020. http://dx.doi.org/10.55461/ytgv8834.
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Bridges often serve as key links in local and national transportation networks. Bridge closures can result in severe costs, not only in the form of repair or replacement, but also in the form of economic losses related to medium- and long-term interruption of businesses and disruption to surrounding communities. In addition, continuous functionality of bridges is very important after any seismic event for emergency response and recovery purposes. Considering the importance of these structures, the associated structural design philosophy is shifting from collapse prevention to maintaining functionality in the aftermath of moderate to strong earthquakes, referred to as “resiliency” in earthquake engineering research. Moreover, the associated construction philosophy is being modernized with the utilization of accelerated bridge construction (ABC) techniques, which strive to reduce the impact of construction on traffic, society, economy and on-site safety. This report presents two bridge systems that target the aforementioned issues. A study that combined numerical and experimental research was undertaken to characterize the seismic performance of these bridge systems. The first part of the study focuses on the structural system-level response of highway bridges that incorporate a class of innovative connecting devices called the “V-connector,”, which can be used to connect two components in a structural system, e.g., the column and the bridge deck, or the column and its foundation. This device, designed by ACII, Inc., results in an isolation surface at the connection plane via a connector rod placed in a V-shaped tube that is embedded into the concrete. Energy dissipation is provided by friction between a special washer located around the V-shaped tube and a top plate. Because of the period elongation due to the isolation layer and the limited amount of force transferred by the relatively flexible connector rod, bridge columns are protected from experiencing damage, thus leading to improved seismic behavior. The V-connector system also facilitates the ABC by allowing on-site assembly of prefabricated structural parts including those of the V-connector. A single-column, two-span highway bridge located in Northern California was used for the proof-of-concept of the proposed V-connector protective system. The V-connector was designed to result in an elastic bridge response based on nonlinear dynamic analyses of the bridge model with the V-connector. Accordingly, a one-third scale V-connector was fabricated based on a set of selected design parameters. A quasi-static cyclic test was first conducted to characterize the force-displacement relationship of the V-connector, followed by a hybrid simulation (HS) test in the longitudinal direction of the bridge to verify the intended linear elastic response of the bridge system. In the HS test, all bridge components were analytically modeled except for the V-connector, which was simulated as the experimental substructure in a specially designed and constructed test setup. Linear elastic bridge response was confirmed according to the HS results. The response of the bridge with the V-connector was compared against that of the as-built bridge without the V-connector, which experienced significant column damage. These results justified the effectiveness of this innovative device. The second part of the study presents the HS test conducted on a one-third scale two-column bridge bent with self-centering columns (broadly defined as “resilient columns” in this study) to reduce (or ultimately eliminate) any residual drifts. The comparison of the HS test with a previously conducted shaking table test on an identical bridge bent is one of the highlights of this study. The concept of resiliency was incorporated in the design of the bridge bent columns characterized by a well-balanced combination of self-centering, rocking, and energy-dissipating mechanisms. This combination is expected to lead to minimum damage and low levels of residual drifts. The ABC is achieved by utilizing precast columns and end members (cap beam and foundation) through an innovative socket connection. In order to conduct the HS test, a new hybrid simulation system (HSS) was developed, utilizing commonly available software and hardware components in most structural laboratories including: a computational platform using Matlab/Simulink [MathWorks 2015], an interface hardware/software platform dSPACE [2017], and MTS controllers and data acquisition (DAQ) system for the utilized actuators and sensors. Proper operation of the HSS was verified using a trial run without the test specimen before the actual HS test. In the conducted HS test, the two-column bridge bent was simulated as the experimental substructure while modeling the horizontal and vertical inertia masses and corresponding mass proportional damping in the computer. The same ground motions from the shaking table test, consisting of one horizontal component and the vertical component, were applied as input excitations to the equations of motion in the HS. Good matching was obtained between the shaking table and the HS test results, demonstrating the appropriateness of the defined governing equations of motion and the employed damping model, in addition to the reliability of the developed HSS with minimum simulation errors. The small residual drifts and the minimum level of structural damage at large peak drift levels demonstrated the superior seismic response of the innovative design of the bridge bent with self-centering columns. The reliability of the developed HS approach motivated performing a follow-up HS study focusing on the transverse direction of the bridge, where the entire two-span bridge deck and its abutments represented the computational substructure, while the two-column bridge bent was the physical substructure. This investigation was effective in shedding light on the system-level performance of the entire bridge system that incorporated innovative bridge bent design beyond what can be achieved via shaking table tests, which are usually limited by large-scale bridge system testing capacities.