Dissertations / Theses on the topic 'Wide bandgap device'
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Sathyanarayanan, Arvind Shanmuganaathan. "Analysis of Reflected Wave Phenomenon on Wide Bandgap Device Switching Performance." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu149273424426787.
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Shao, Ye. "Study of wide bandgap semiconductor nanowire field effect transistor and resonant tunneling device." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448230793.
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Mahadik, Nadeemullah A. "Non-destructive x-ray characterization of wide-bandgap semiconductor materials and device structures." Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3404.
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Thesis (Ph.D.)--George Mason University, 2008.Vita: p. 104. Thesis director: Mulpuri V. Rao. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering. Title from PDF t.p. (viewed Mar. 17, 2009). Includes bibliographical references (p. 99-103). Also issued in print.
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Deshpande, Amol Rajendrakumar. "Design of A Silicon and Wide-Bandgap Device Based Hybrid Switch for Power Electronics Converter." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461238625.
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Hontz, Michael Robert. "Next Generation Integrated Behavioral and Physics-based Modeling of Wide Bandgap Semiconductor Devices for Power Electronics." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1556718365514067.
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Swenberg, Johanes F. N. McGill T. C. McGill T. C. "Development of wide-bandgap II-VI semiconductor light-emitting device technology based on the graded injector design /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-10122007-142152.
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Rafique, Subrina. "Growth, Characterization and Device Demonstration of Ultra-Wide Bandgap ß-Ga2O3 by Low Pressure Chemical Vapor Deposition." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512652677980762.
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Allen, Noah Patrick. "Electrical Characterization of Gallium Nitride Drift Layers and Schottky Diodes." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/102924.
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Interest in wide bandgap semiconductors such as silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga 2 O 3 ) and diamond has increased due to their ability to deliver high power, high switching frequency and low loss electronic devices for power conversion applications. To meet these requirements, semiconductor material defects, introduced during growth and fabrication, must be minimized. Otherwise, theoretical limits of operation cannot be achieved. In this dissertation, the non-ideal current- voltage (IV) behavior of GaN-based Schottky diodes is discussed first. Here, a new model is developed to explain better the temperature dependent performance typically associated with a multi-Gaussian distribution of barrier heights at the metal-semiconductor interface [Section 3.1]. Application of this model gives researches a means of understanding not only the effective barrier distribution at the MS interface but also its voltage dependence. With this information, the consequence that material growth and device fabrication methods have on the electrical characteristics can be better understood. To show its applicability, the new model is applied to Ru/GaN Schottky diodes annealed at increasing temperature under normal laboratory air, revealing that the origin of excess reverse leakage current is attributed to the low-side inhomogeneous barrier distribution tail [Section 3.2]. Secondly, challenges encountered during MOCVD growth of low-doped GaN drift layers for high-voltage operation are discussed with focus given to ongoing research characterizing deep-level defect incorporation by deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) [Section 3.3 and 3.4]. It is shown that simply increasing TMGa so that high growth rates (>4 µm/hr) can be achieved will cause the free carrier concentration and the electron mobilities in grown drift layers to decrease. Upon examination of the deep-level defect concentrations, it is found that this is likely caused by an increase in 4 deep level defects states located at E C - 2.30, 2.70, 2.90 and 3.20 eV. Finally, samples where the ammonia molar flow rate is increased while ensuring growth rate is kept at 2 µm/hr, the concentrations of the deep levels located at 0.62, 2.60, and 2.82 eV below the conduction band can be effectively lowered. This accomplishment marks an exciting new means by which the intrinsic impurity concentration in MOCVD-grown GaN films can be reduced so that >20 kV capable devices could be achieved.Doctor of Philosophy
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Allen, Noah P. "Electrical Characterization of Gallium Nitride Drift Layers and Schottky Diodes." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102924.
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Interest in wide bandgap semiconductors such as silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga 2 O 3 ) and diamond has increased due to their ability to deliver high power, high switching frequency and low loss electronic devices for power conversion applications. To meet these requirements, semiconductor material defects, introduced during growth and fabrication, must be minimized. Otherwise, theoretical limits of operation cannot be achieved. In this dissertation, the non-ideal current- voltage (IV) behavior of GaN-based Schottky diodes is discussed first. Here, a new model is developed to explain better the temperature dependent performance typically associated with a multi-Gaussian distribution of barrier heights at the metal-semiconductor interface [Section 3.1]. Application of this model gives researches a means of understanding not only the effective barrier distribution at the MS interface but also its voltage dependence. With this information, the consequence that material growth and device fabrication methods have on the electrical characteristics can be better understood. To show its applicability, the new model is applied to Ru/GaN Schottky diodes annealed at increasing temperature under normal laboratory air, revealing that the origin of excess reverse leakage current is attributed to the low-side inhomogeneous barrier distribution tail [Section 3.2]. Secondly, challenges encountered during MOCVD growth of low-doped GaN drift layers for high-voltage operation are discussed with focus given to ongoing research characterizing deep-level defect incorporation by deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) [Section 3.3 and 3.4]. It is shown that simply increasing TMGa so that high growth rates (>4 µm/hr) can be achieved will cause the free carrier concentration and the electron mobilities in grown drift layers to decrease. Upon examination of the deep-level defect concentrations, it is found that this is likely caused by an increase in 4 deep level defects states located at E C - 2.30, 2.70, 2.90 and 3.20 eV. Finally, samples where the ammonia molar flow rate is increased while ensuring growth rate is kept at 2 µm/hr, the concentrations of the deep levels located at 0.62, 2.60, and 2.82 eV below the conduction band can be effectively lowered. This accomplishment marks an exciting new means by which the intrinsic impurity concentration in MOCVD-grown GaN films can be reduced so that >20 kV capable devices could be achieved.Doctor of Philosophy
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Xia, Zhanbo. "Materials and Device Engineering for High Performance β-Ga2O3-based Electronics." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587688595358557.
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Elf, Patric. "Radiation effects on wide bandgap semiconductor devices." Thesis, KTH, Tillämpad fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-283320.
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Gallium nitride (GaN) based high-electron-mobility transistors (HEMTs) are used in a wide variety of areas, such as 5G, automotive, aeronautics/astronautics and sensing elds ranging from chemical, mechanical, biological to optical applications. Owing superior material properties, the GaN based HEMTs are especially useful in harsh operation environments e.g. in the combustion engine, exhaust, space, and medical instruments where the reliability and resilience are highly demanded. In this thesis the e ect of proton irradiation on the GaN HEMTs as well as the possible incorporation of them in biomedicine and diagnostics are investigated. The thesis includes mainly two parts: one is on theoretic background of GaN HEMTs, and another presents the experiment/simulation details of the devices before and after proton radiation. In the background section, the HEMTs function, manufacture technique and defect formation mechanism in the device under di erent proton radiation conditions are introduced. Then, the characterizations of the HEMT devices and related test structures before and after the proton radiation with dose range from 1011 to 1015 protons=cm2 are emphasized, as well as the comparison with simulation results obtained using SRIM/TRIM program. In addition, the biocompatibility of GaN devices and their biomedicine applications in proton radiation scenarios are also described and discussed in this thesis.Gallium Nitrid (GaN) baserade high electron mobility transistors (HEMTs) används inom många olika områden, såsom 5G, bil-industrin, yg/rymd och i sensorer fö kemiska, mekaniska, biologiska och optiska applikationer. Tack vare dess goda materialegenskaper GaN baserade HEMTs särskilt användbara i harda miljöer, som till exempel i förbränningsmotorer, avgaser, i rymden, samt till medicinska instrument där pålitlighet och tålighet är eftersträvat. I det här examensarbetet sa undersöks e ekten av protonbestrålning pa GaN HEMTs samt möjligheten till användning av dem inom biomedicin och diagnostik. Arbetet är uppdelat i två delar: den ena behandlar den teoretiska bakgrunden av GaN HEMTs och den andra presenterar de experiment/simuleringar som utförts för att se efekterna på komponenterna före och efter protonbestrålning. I bakgrunds-sektionen så beskrivs hur HEMTs fungerar, tillverkningstekniker och mekanismerna för hur defekter uppkommer under olika former av protonbestrålning. Därefter sa karaktäriseras HEMT komponenterna och relaterade teststrukturer före och efter protonbestralning, med ett fokus på doser mellan 1011 to 1015 protoner=cm2, samt en jämförelse med resultat som fatts fran simuleringar med SRIM/TRIM-program. Utöver detta sa beskrivs och diskuteras även biokompatibiliteten och applikationer inom biomedicin av GaN komponenter vid protonbestralnings-scenarion i arbetet.
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Grummel, Brian. "HIGH TEMPERATURE PACKAGING FOR WIDE BANDGAP SEMICONDUCTOR DEVICES." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3200.
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Currently, wide bandgap semiconductor devices feature increased efficiency, higher current handling capabilities, and higher reverse blocking voltages than silicon devices while recent fabrication advances have them drawing near to the marketplace. However these new semiconductors are in need of new packaging that will allow for their application in several important uses including hybrid electrical vehicles, new and existing energy sources, and increased efficiency in multiple new and existing technologies. Also, current power module designs for silicon devices are rife with problems that must be enhanced to improve reliability. This thesis introduces new packaging that is thermally resilient and has reduced mechanical stress from temperature rise that also provides increased circuit lifetime and greater reliability for continued use to 300°C which is within operation ratings of these new semiconductors. The new module is also without problematic wirebonds that lead to a majority of traditional module failures which also introduce parasitic inductance and increase thermal resistance. Resultantly, the module also features a severely reduced form factor in mass and volume.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
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Buzzo, Marco. "Dopant imaging and profiling of wide bandgap semiconductor devices /." Konstanz : Hartung-Gorre, 2007. http://www.loc.gov/catdir/toc/fy0715/2007427206.html.
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Dhakal, Shankar. "Circuit Level Reliability Considerations in Wide Bandgap Semiconductor Devices." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1532703747534188.
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Kozak, Joseph Peter. "Hard Switched Robustness of Wide Bandgap Power Semiconductor Devices." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104874.
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As power conversion technology is being integrated further into high-reliability environments such as aerospace and electric vehicle applications, a full analysis and understanding of the system's robustness under operating conditions inside and outside the safe-operating-area is necessary. The robustness of power semiconductor devices, a primary component of power converters, has been traditionally evaluated through qualification tests that were developed for legacy silicon (Si) technologies. However, new devices have been commercialized using wide bandgap (WBG) semiconductors including silicon carbide (SiC) and gallium nitride (GaN). These new devices promise enhanced capabilities (e.g., higher switching speed, smaller die size, lower junction capacitances, and higher thermal conductance) over legacy Si devices, thus making the traditional qualification experiments ineffective.
This work begins by introducing a new methodology for evaluating the switching robustness of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). Recent static acceleration tests have revealed that SiC MOSFETs can safely operate for thousands of hours at a blocking voltage higher than the rated voltage and near the avalanche boundary. This work evaluates the robustness of SiC MOSFETs under continuous, hard-switched, turn-off stresses with a dc-bias higher than the device rated voltage. Under these conditions, SiC MOSFETs show degradation in merely tens of hours at 25si{textdegree}C and tens of minutes at 100si{textdegree}C. Two independent degradation and failure mechanisms are unveiled, one present in the gate-oxide and the other in the bulk-semiconductor regions, detected by the increase in gate leakage current and drain leakage current, respectively. The second degradation mechanism has not been previously reported in the literature; it is found to be related to the electron hopping along the defects in semiconductors generated in the switching tests. The comparison with the static acceleration tests reveals that both degradation mechanisms correlate to the high-bias switching transients rather than the high-bias blocking states.
The GaN high-electron-mobility transistor (HEMT) is a newer WBG device that is being increasingly adopted at an unprecedented rate. Different from SiC MOSFETs, GaN HEMTs have no avalanche capability and withstand the surge energy through capacitive charging, which often causes significant voltage overshoot up to their catastrophic limit. As a result, the dynamic breakdown voltage (BV) and transient overvoltage margin of GaN devices must be studied to fully evaluate the switching ruggedness of devices. This work characterizes the transient overvoltage capability and failure mechanisms of GaN HEMTs under hard-switched turn-off conditions at increasing temperatures, by using a clamped inductive switching circuit with a variable parasitic inductance. This test method allows flexible control over both the magnitude and the dV/dt of the transient overvoltage. The overvoltage robustness of two commercial enhancement-mode (E-mode) p-gate HEMTs was extensively studied: a hybrid drain gate injection transistor (HD-GIT) with an Ohmic-type gate and a Schottky p-Gate HEMT (SP-HEMT). The overvoltage failure of the two devices was found to be determined by the overvoltage magnitude rather than the dV/dt. The HD-GIT and the SP-HEMT were found to fail at a voltage overshoot magnitude that is higher than the breakdown voltage in the static current-voltage measurement. These single event failure tests were repeated at increasing temperatures (100si{textdegree}C and 150si{textdegree}C), and the failures of both devices were consistent with room temperature results. The two types of devices show different failure behaviors, and the underlying mechanisms (electron trapping) have been revealed by physics-based device simulations.
Once this single-event overvoltage failure was established, the device's robustness under repetitive overvoltage and surge-energy events remained unclear; therefore, the switching robustness was evaluated for both the HD-GIT and SP-HEMT in a clamped, inductive switching circuit with a 400 V dc bias. A parasitic inductance was used to generate the overvoltage stress events with different overvoltage magnitude up to 95% of the device's destructive limit, different switching periods from 10 ms to 0.33 ms, different temperatures up to 150si{textdegree}C, and different negative gate biases. The electrical parameters of these devices were measured before and after 1 million stress cycles under varying conditions. The HD-GITs showed no failure or permanent degradation after 1-million overvoltage events at different switching periods, or elevated temperatures. The SP-HEMTs showed more pronounced parametric shifts after the 1 million cycles in the threshold voltage, on-resistance, and saturation drain current. Different shifts were also observed from stresses under different overvoltage magnitudes and are attributable to the trapping of the holes produced in impact ionization. All shifts were found to be recoverable after a relaxation period.
Overall, the results from these switching-oriented robustness tests have shown that SiC MOSFETs show a tremendous lifetime under static dc-bias experiments, but when excited by hard-switching turn-off events, the failure mechanisms are accelerated. These results suggest the insufficient robustness of SiC MOSFETs under high bias, hard switching conditions, and the significance of using switching-based tests to evaluate the device robustness. These inspired the GaN-based hard-switching turn-off robustness experiments, which further demonstrated the dynamic breakdown voltage phenomena. Ultimately these results suggest that the breakdown voltage and overvoltage margin of GaN HEMTs in practical power switching can be significantly underestimated using the static breakdown voltage. Both sets of experiments provide further evidence for the need for switching-oriented robustness experiments to be implemented by both device vendors and users, to fully qualify and evaluate new power semiconductor transistors.Doctor of Philosophy
Power conversion technology is being integrated into industrial and commercial applications with the increased use of laptops, server centers, electric vehicles, and solar and wind energy generation. Each of these converters requires the power semiconductor devices to convert energy reliably and safely. textcolor{black}{Silicon has been the primary material for these devices; however,} new devices have been commercialized from both silicon carbide (SiC) and gallium nitride (GaN) materials. Although these devices are required to undergo qualification testing, the standards were developed for silicon technology. The performance of these new devices offers many additional benefits such as physically smaller dimensions, greater power conversion efficiency, and higher thermal operating capabilities. To facilitate the increased integration of these devices into industrial applications, greater robustness and reliability analyses are required to supplement the traditional tests. The work presented here provides two new experimental methodologies to test the robustness of both SiC and GaN power transistors. These methodologies are oriented around hard-switching environments where both high voltage biases and high conduction current exist and stress the intrinsic semiconductor properties. Experimental evaluations were conducted of both material technologies where the electrical properties were monitored over time to identify any degradation effects. Additional analyses were conducted to determine the physics-oriented failure mechanisms. This work provides insight into the limitations of these semiconductor devices for both device designers and manufacturers as well as power electronic system designers.
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Rashid, Suhail Jeremy. "High voltage packaging technology for wide bandgap power semiconductor devices." Thesis, University of Cambridge, 2008. https://www.repository.cam.ac.uk/handle/1810/252098.
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Alexakis, Petros. "Reliability of wide bandgap semiconductor devices under unconventional mode conduction." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/105611/.
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The use of power electronics is increasing in an exponential form. The need of power devices to be faster, block higher voltages and reduce their losses is leading to a fundamental change in the device architecture and choice of material. Gallium nitride and Silicon carbide are the materials of choice and commercial devices are available. Diamond and gallium oxide are materials that are considered for the future and they will push the boundaries of power electronics even further. There are well developed tools that can simulate the behavior of a power device is a very accurate way and they can calculate losses, turn on and turn off times and the over behavior of the device during switching. These tools are usually very complex and difficult to learn. They also cannot provide very quick results and they heavily depend on the amount of computational power that is available to the user. Due to their complexity they can only calculate a few maybe a couple of switching events before they run out of computational memory. This thesis is trying to solve this problem by using simple state space analysis and using a lot simpler equations and computational methods to predict the behaviour of the device. The simplicity of these calculations can give faster results that is very helpful in a lot of cases. Also tools that calculate the temperature of the power devices have been created again using simpler mathematical equations that can evaluate the device temperature. So a fast, reliable and simple way of estimating the device behavior has been created. Another aspect that has been covered in this thesis is the reliability of power devices under unconventional conduction. A number of devices have been tested under avalanche mode conduction and an extensive comparison has been made between device architecture, MOSFET vs IGBT, Si vs SiC, Repetitive vs single avalanche events. Also these tests have been conducted in different ambient temperatures so the effect of temperature has been investigated thoroughly as well.
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Wei, Yu. "A Novel Auxiliary Resonant Snubber Inverter Using Wide Bandgap Devices." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83238.
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In the application of power inverters, power density has become a key design specification where it has stringent requirements on system size and weight. Achieving high power density need to combine lasted wide bandgap (WBG) device technology and high switching frequency to reduce passive filter size thus further shrink overall space. While still maintaining decent power conversion efficiency and low electromagnetic interference (EMI) with higher switching frequency, soft-switching needs to be implemented.
A novel auxiliary resonant snubber is introduced. The design and operation are carried out, in which this snubber circuitry enables main Gallium Nitride (GaN) switches operating under zero voltage switching (ZVS) condition, and auxiliary Silicon Carbide (SiC) diodes switching under zero current switching (ZCS) condition. Besides, the auxiliary snubber circuitry gating algorithm is also optimized which allows reduction of the switching and conduction loss in auxiliary GaN switches to obtain higher system efficiency and better thermal performance. Here, this novel auxiliary resonant snubber circuitry is applied to a traditional full bridge inverter with flexible modulation suitability. This proposed inverter can be applied to a wide range of potential applications, such as string solar inverter, renewable energy combined distributed generation, dc-ac part of bi-directional electrical vehicle (EV) on-board charger, and uninterruptible power supply (UPS), etc.Master of Science
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Ghin, Raymond. "Avalanche multiplication and breakdown in wide bandgap semiconductors." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301673.
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Lades, Martin. "Modeling and simulation of wide bandgap semiconductor devices 4H/6H-SiC /." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962057827.
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Razzak, Towhidur. "Design and Fabrication of High Performance Ultra-Wide Bandgap AlGaN Devices." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619031091410235.
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Koganti, Naga Babu. "Modeling and Characterization of Circuit Level Transients in Wide Bandgap Devices." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo153311831687909.
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Grummel, Brian. "Design and Characterization of High Temperature Packaging for Wide-Bandgap Semiconductor Devices." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5231.
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Advances in wide-bandgap semiconductor devices have increased the allowable operating temperature of power electronic systems. High-temperature devices can benefit applications such as renewable energy, electric vehicles, and space-based power electronics that currently require bulky cooling systems for silicon power devices. Cooling systems can typically be reduced in size or removed by adopting wide-bandgap semiconductor devices, such as silicon carbide. However, to do this, semiconductor device packaging with high reliability at high temperatures is necessary. Transient liquid phase (TLP) die-attach has shown in literature to be a promising bonding technique for this packaging need. In this work TLP has been comprehensively investigated and characterized to assess its viability for high-temperature power electronics applications. The reliability and durability of TLP die-attach was extensively investigated utilizing electrical resistivity measurement as an indicator of material diffusion in gold-indium TLP samples. Criteria of ensuring diffusive stability were also developed. Samples were fabricated by material deposition on glass substrates with variant Au–In compositions but identical barrier layers. They were stressed with thermal cycling to simulate their operating conditions then characterized and compared. Excess indium content in the die-attach was shown to have poor reliability due to material diffusion through barrier layers while samples containing suitable indium content proved reliable throughout the thermal cycling process. This was confirmed by electrical resistivity measurement, EDS, FIB, and SEM characterization. Thermal and mechanical characterization of TLP die-attached samples was also performed to gain a newfound understanding of the relationship between TLP design parameters and die-attach properties. Samples with a SiC diode chip TLP bonded to a copper metalized silicon nitride substrate were made using several different values of fabrication parameters such as gold and indium thickness, Au–In ratio, and bonding pressure. The TLP bonds were then characterized for die-attach voiding, shear strength, and thermal impedance. It was found that TLP die-attach offers high average shear force strength of 22.0 kgf and a low average thermal impedance of 0.35 K/W from the device junction to the substrate. The influence of various fabrication parameters on the bond characteristics were also compared, providing information necessary for implementing TLP die-attach into power electronic modules for high-temperature applications. The outcome of the investigation on TLP bonding techniques was incorporated into a new power module design utilizing TLP bonding. A full half-bridge inverter power module for low-power space applications has been designed and analyzed with extensive finite element thermo-mechanical modeling. In summary, TLP die-attach has investigated to confirm its reliability and to understand how to design effective TLP bonds, this information has been used to design a new high-temperature power electronic module.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Montañez, Huamán Liz Margarita. "Synthesis and characterization of wide bandgap semiconductors doped with terbium for electroluminescent devices." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6999.
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In this work, stoichiometric, structural and light emission properties of amorphous wide bandgap
semiconductor materials doped with terbium are presented. The amorphous nature of the thin
films was confirmed by X-ray diffraction under grazing incidence. Fourier transform infrared
spectroscopy spectra exhibit the formation of oxygen bonded elements and X-ray photoelectron
spectroscopy reveals the formation of aluminum oxynitride and silicon oxycarbide as host
matrices. The thin films were annealed at temperatures ranging from 300 °C to 1000 °C using a
rapid thermal processing furnace. The highest light emission intensity for the case of aluminum
oxynitride was obtained for terbium concentrations higher than 1 at% and for the annealing
temperature at around 400 °C. Additionally, using the characterized films as active layer first
electroluminescence devices were designed and investigated.En el presente trabajo de investigación se ha estudiado propiedades estequiometrias, estructurales y de emisión de luz de semiconductor de amplio ancho de banda dopados con terbio. La difracción de rayos-X en ángulo rasante confirma el estado amorfo de las películas. Los espectros de absorción infrarroja muestran la formación de óxidos en las películas y la espectroscopia de foto-electrones de rayos-X revela la formación de oxinitruro de aluminio y oxicarburo de silicio. Las películas han sido calentadas a temperaturas en el rango de 300 °C a 1000 °C en un horno de rápido procesamiento térmico. De acuerdo con el análisis de las medidas de fotoluminiscencia, la intensidad más alta de emisión de luz del terbio es para películas que tengan concentraciones de terbio mayores al 1at% y a una temperatura de tratamiento térmico de alrededor de 400 °C. Adicionalmente, las películas analizadas han sido usado como capas activas para el diseño de dispositivos electroluminiscentes
Tesis
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Li, Ke. "Wide bandgap (SiC/GaN) power devices characterization and modeling : application to HF power converters." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10080/document.
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Les matériaux semi-conducteurs à grand gap tels que le carbure de silicium (SiC) et le nitrure de gallium (GaN) sont utilisés pour fabriquer des composants semi-conducteurs de puissance, qui vont jouer un rôle très important dans le développement des futurs systèmes de conversion d'énergie. L'objectif est de réaliser des convertisseurs avec de meilleurs rendements énergétiques et fonctionnant à haute température. Pour atteindre cet objectif, il est donc nécessaire de bien connaître les caractéristiques de ces nouveaux composants afin de développer des modèles qui seront utilisés lors de la conception des convertisseurs. Cette thèse est donc dédiée à la caractérisation et la modélisation des composants à grand gap, mais également l'étude des dispositifs de mesure des courants des commutations des composants rapides. Afin de déterminer les caractéristiques statiques des composants semi-conducteurs, une méthode de mesure en mode pulsé est présentée. Dans le cadre de cette étude, une diode SiC et un JFET SiC "normally-off" sont caractérisés à l'aide de cette méthode. Afin de mesurer les capacités inter-électrodes de ces composants, une nouvelle méthode basée sur l'utilisation des pinces de courant est proposée. Des modèles comportementaux d'une diode Si et d'un JFET SiC sont proposés en utilisant les résultats de caractérisation. Le modèle de la diode obtenu est validé par des mesures des courants au blocage (recouvrement inverse) dans différentes conditions de commutation. Pour valider le modèle du JFET SiC, une méthode de mesure utilisant une pince de courant de surface est proposéeCompared to traditional silicon (Si) semiconductor material, wide bandgap (WBG) materials like silicon carbide (SiC) and gallium nitride are gradually applied to fabricate power semiconductor devices, which are used in power converters to achieve high power efficiency, high operation temperature and high switching frequency. As those power devices are relatively new, their characterization and modeling are important to better understand their characteristics for better use. This dissertation is mainly focused on those WBG power semiconductor devices characterization, modeling and fast switching currents measurement. In order to measure their static characteristics, a single-pulse method is presented. A SiC diode and a "normally-off" SiC JFET is characterized by this method from ambient temperature to their maximal junction temperature with the maximal power dissipation around kilowatt. Afterwards, in order to determine power device inter-electrode capacitances, a measurement method based on the use of multiple current probes is proposed and validated by measuring inter-electrode capacitances of power devices of different technologies. Behavioral models of a Si diode and the SiC JFET are built by using the results of the above characterization methods, by which the evolution of the inter-electrode capacitances for different operating conditions are included in the models. Power diode models are validated with the measurements, in which the current is measured by a proposed current surface probe
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Devarapally, Rahul Reddy. "Survey of applications of WBG devices in power electronics." Kansas State University, 2016. http://hdl.handle.net/2097/32665.
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Master of ScienceDepartment of Electrical and Computer Engineering
Behrooz Mirafzal
Wide bandgap devices have gained increasing attention in the market of power electronics for their ability to perform even in harsh environments. The high voltage blocking and high temperature withstanding capabilities make them outperform existing Silicon devices. They are expected to find places in future traction systems, electric vehicles, LED lightning and renewable energy engineering systems. In spite of several other advantages later mentioned in this paper, WBG devices also face a few challenges which need to be addressed before they can be applied in large scale in industries. Electromagnetic interference and new requirements in packaging methods are some of the challenges being faced by WBG devices. After the commercialization of these devices, many experiments are being carried out to understand and validate their abilities and drawbacks. This paper summarizes the experimental results of various applications of mainly Silicon Carbide (SiC) and Gallium Nitride (GaN) power devices and also includes a section explaining the current challenges for their employment and improvements being made to overcome them.
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Lyu, Xintong. "Power Module Design and Protection for Medium Voltage Silicon Carbide Devices." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu160856011259485.
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Li, Cong. "High Frequency High Boost Ratio Dc-dc Converters with Wide Bandgap Devices for PV System Applications." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1411858489.
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Nakagawara, Tanner A. "Optical Spectroscopy of Wide Bandgap Semiconductor Heterostructures and Group-IV Alloy Quantum Dots." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5195.
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Efficient and robust blue InGaN multiple quantum well (MQW) light emitters have become ubiquitous; however, they still have unattained theoretical potential. It is widely accepted that “localization” of carriers due to indium fluctuations theoretically enhance their efficiency by moderating defect-associated nonradiative recombination. To help develop a complete understanding of localization effects on carrier dynamics, this thesis explores degree of localization in InGaN MQWs and its dependence on well thickness and number of wells, through temperature and power dependent photoluminescence measurements. Additionally, silicon-compatible, nontoxic, colloidally synthesizable 2-5 nm Ge1-xSnx alloy quantum-dots (QDs) are explored for potential visible to near-IR optoelectronic applications. While bulk Ge is an indirect gap material, QD confinement allows enhanced direct transitions, and alloying with Sn improves transition oscillator strengths. Temperature dependent steady-state and time-resolved photoluminescence reveal relaxation pathways involving bright/dark excitons and surface states in Ge1-xSnx QDs, showing their great potential for future use.
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Alsolami, Mohammed Faham. "Wide Bandgap (WBG) Devices Based Switched Capacitor Multiport Multilevel SinglePhase AC/DC/AC Converter for UPS Applications." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461327268.
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Zhao, Xiaonan. "High-Efficiency and High-Power Density DC-DC Power Conversion Using Wide Bandgap Devices for Modular Photovoltaic Applications." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89025.
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With the development of solar energy, power conversion systems responsible for energy delivering from photovoltaic (PV) modules to ac or dc grid attract wide attentions and have significantly increased installations worldwide. Modular power conversion system has the highest efficiency of maximum power point tacking (MPPT), which can transfer more solar power to electricity. However, this system suffers the drawbacks of low power conversion efficiency and high cost due to a large number of power electronics converters. High-power density can provide potentials to reduce cost through the reduction of components and potting materials. Nowadays, the power electronics converters with the conventional silicon (Si) based power semiconductor devices are developed maturely and have limited improvements regarding in power conversion efficiency and power density. With the availability of wide bandgap devices, the power electronics converters have extended opportunities to achieve higher efficiency and higher power density due to the desirable features of wide bandgap devices, such as low on-state resistance, small junction capacitance and high switching speed.
This dissertation focuses on the application of wide bandgap devices to the dc-dc power conversion for the modular PV applications in an effort to improve the power conversion efficiency and power density.
Firstly, the structure of gallium-nitride (GaN) device is studied theoretically and characteristics of GaN device are evaluated under testing with both hard-switching and soft-switching conditions. The device performance during steady-state and transitions are explored under different power level conditions and compared with Si based devices.
Secondly, an isolated high-efficiency GaN-based dc-dc converter with capability of wide range regulation is proposed for modular PV applications. The circuit configuration of secondary side is a proposed active-boost-rectifier, which merges a Boost circuit and a voltage-doubler rectifier. With implementation of the proposed double-pulse duty cycle modulation method, the active-boost-rectifier can not only serve for synchronous rectification but also achieve the voltage boost function. The proposed converter can achieve zero-voltage-switching (ZVS) of primary side switches and zero-current-switching (ZCS) of secondary side switches regardless of the input voltages or output power levels. Therefore, the proposed converter not only keeps the benefits of highly-efficient series resonant converter (SRC) but also achieves a higher voltage gain than SRC and a wide range regulation ability without adding additional switches while operating under the fixed-frequency condition. GaN devices are utilized in both primary and secondary sides. A 300-W hardware prototype is built to achieve a peak efficiency of 98.9% and a California Energy Commission (CEC) weighted efficiency of 98.7% under nominal input voltage condition.
Finally, the proposed converter is designed and optimized at 1-MHz switching frequency to pursue the feature of high-power density. Considering the ac effects under high frequency, the magnetic components and PCB structure are optimized with finite element method (FEM) simulations. Compared with 140-kHz design, the volume of 1-MHz design can reduce more than 70%, while the CEC efficiency only drops 0.8% at nominal input voltage condition. There are also key findings on circuit design techniques to reduce parasitic effects. The parasitic inductances induced from PCB layout of primary side circuit can cause the unbalanced resonant current between positive and negative half cycles if the power loops of two half cycles have asymmetrical parasitic inductances. Moreover, these parasitic inductances reflecting to secondary side should be considered into the design of resonant inductance. The parasitic capacitances of secondary side could affect ZVS transitions and increase the required magnetizing current. Because of large parasitic capacitances, the dead-time period occupies a large percentage of entire switching period in MHz operations, which should be taken into consideration when designing the resonant frequency of resonant network.Doctor of Philosophy
Solar energy is one of the most promising renewable energies to replace the conventional fossils. Power electronics converters are necessary to transfer power from solar panels to dc or ac grid. Since the output of solar panel is low voltage with a wide range and the grid side is high voltage, this power converter should meet the basic requirements of high step up and wide range regulation. Additionally, high power conversion efficiency is an important design purpose in order to save energy. The existing solutions have limitations of narrow regulating range, low efficiency or complicated circuit structure. Recently, the third-generation power semiconductors attract more and more attentions who can help to reduce the power loss. They are named as wide band gap devices. This dissertation proposed a wide band gap devices based power converter with ability of wide regulating range, high power conversion efficiency and simple circuit structure. Moreover, this proposed converter is further designed for high power density, which reduces more than 70% of volume. In this way, small power converter can merge into the junction box of solar panel, which can reduce cost and be convenient for installations.
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Koné, Sodjan. "Développement de briques technologiques pour la réalisation des composants de puissance en diamant monocristallin." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0048/document.
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A mesure que les demandes dans le domaine de l'électronique de puissance tendent vers des conditions de plus en plus extrêmes (forte densité de puissance, haute fréquence, haute température,…), l'évolution des systèmes de traitement de l'énergie électrique se heurte aux limites physiques du silicium. Une nouvelle approche basée sur l'utilisation des matériaux semi-conducteurs grand gap permettra de lever ces limites. Parmi ces matériaux, le diamant possède les propriétés les plus intéressantes pour l'électronique de puissance: champ de rupture et conductivité thermique exceptionnels, grandes mobilités des porteurs électriques, possibilité de fonctionnement à haute température… Les récents progrès dans la synthèse du diamant par des méthodes de dépôt en phase vapeur (CVD) permettent d'obtenir des substrats de caractéristiques cristallographiques compatibles avec l'exploitation de ces propriétés en électronique de puissance. Cependant, l'utilisation du diamant en tant que matériau électronique reste toutefois délicate à ce jour du fait de la grande difficulté de trouver des dopants convenables (en particulier les donneurs) dans le diamant. En outre, certaines propriétés du diamant telles que sa dureté extrême et son inertie chimique, faisant de lui un matériau unique, posent aussi des difficultés dans son utilisation technologique. L'objectif de ces travaux de thèse a été dans un premier temps d'évaluer les bénéfices que pourrait apporter le diamant en électronique de puissance ainsi que l'état de l'art de sa synthèse par dépôt en phase vapeur. Ensuite, différentes étapes technologiques nécessaires à la fabrication de composants sur diamant ont été étudiées: Gravure RIE, dépôt de contacts électriques. Enfin, ces travaux ont été illustrés par la réalisation et la caractérisation de diodes Schottky, dispositifs élémentaires de l'électronique de puissance. Les résultats obtenus permettent d'établir un bilan des verrous scientifiques et technologiques qu'il reste à relever pour une exploitation industrielle de la filière diamantAs applications in the field of power electronics tend toward more extreme conditions (high power density, high frequency, high temperature ...), evolution of electric power treatment systems comes up against physical limits of silicon, the main semiconductor material used in electronic industry for over 50 years. A new approach based on the use of wide bandgap semiconductor materials will permit to overcome those limits. Among these materials, diamond is a very attractive material for power electronics switch devices due to its exceptional properties: high electric breakdown field, high carriers mobilities, exceptional thermal conductivity, high temperature operating possibility... However, the use of diamond as an electronic material is still very problematic due to the difficulty in the synthesis of high electronic grade CVD diamond and to find suitable dopants (in particular donors) in diamond. Besides, some of the unique properties of diamond, such as its extreme hardness and chemical inertness that make it an attractive material also cause difficulties in its application. Nevertheless, recent progress in the field of chemical vapor deposition (CVD) synthesis of diamond allow the study of the technological steps (RIE etching, ohmic and Schottky contacts, passivation,...) necessary for future diamond power devices processing. This is the aim of this thesis. In a first section, the uniqueness of diamond, the promise it bears as a potential material for specific electronic devices and the difficulties related to its application were reviewed. Then, the different technological steps required for power switching devices processing were studied: RIE etching, Ohmic and Schottky contacts. Finally, these works were illustrated by carrying out and electrical characterizations of Schottky Barrier Diodes. The achieved results allow us to make a summary of scientific and technological locks that remain for an industrial exploitation of diamond in power electronic switch devices field
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Chmielewski, Daniel Joseph. "III-V Metamorphic Materials and Devices for Multijunction Solar Cells Grown via MBE and MOCVD." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534707692114982.
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Gabrysch, Markus. "Charge Transport in Single-crystalline CVD Diamond." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122794.
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Diamond is a semiconductor with many superior material properties such as high breakdown field, high saturation velocity, high carrier mobilities and the highest thermal conductivity of all materials. These extreme properties, as compared to other (wide bandgap) semiconductors, make it desirable to develop single-crystalline epitaxial diamond films for electronic device and detector applications. Future diamond devices, such as power diodes, photoconductive switches and high-frequency field effect transistors, could in principle deliver outstanding performance due to diamond's excellent intrinsic properties. However, such electronic applications put severe demands on the crystalline quality of the material. Many fundamental electronic properties of diamond are still poorly understood, which severely holds back diamond-based electronic device and detector development. This problem is largely due to incomplete knowledge of the defects in the material and due to a lack of understanding of how these defects influence transport properties. Since diamond lacks a shallow dopant that is fully thermally activated at room temperature, the conventional silicon semiconductor technology cannot be transferred to diamond devices; instead, new concepts have to be developed. Some of the more promising device concepts contain thin delta-doped layers with a very high dopant concentration, which are fully activated in conjunction with undoped (intrinsic) layers where charges are transported. Thus, it is crucial to better understand transport in high-quality undoped layers with high carrier mobilities. The focus of this doctoral thesis is therefore the study of charge transport and related electronic properties of single-crystalline plasma-deposited (SC-CVD) diamond samples, in order to improve knowledge on charge creation and transport mechanisms. Fundamental characteristics such as drift mobilities, compensation ratios and average pair-creation energy were measured. Comparing them with theoretical predictions from simulations allows for verification of these models and improvement of the diamond deposition process.
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Paredes, Camacho Alejandro. "Active gate drivers for high-frequency application of SiC MOSFETs." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669291.
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The trend in the development of power converters is focused on efficient systems with high power density, reliability and low cost. The challenges to cover the new power converters requirements are mainly concentered on the use of new switching-device technologies such as silicon carbide MOSFETs (SiC). SiC MOSFETs have better characteristics than their silicon counterparts; they have low conduction resistance, can work at higher switching speeds and can operate at higher temperature and voltage levels. Despite the advantages of SiC transistors, operating at high switching frequencies, with these devices, reveal new challenges. The fast switching speeds of SiC MOSFETs can cause over-voltages and over-currents that lead to electromagnetic interference (EMI) problems.
For this reason, gate drivers (GD) development is a fundamental stage in SiC MOSFETs circuitry design. The reduction of the problems at high switching frequencies, thus increasing their performance, will allow to take advantage of these devices and achieve more efficient and high power density systems.
This Thesis consists of a study, design and development of active gate drivers (AGDs) aimed to improve the switching performance of SiC MOSFETs applied to high-frequency power converters. Every developed stage regarding the GDs is validated through tests and experimental studies. In addition, the developed GDs are applied to converters for wireless charging systems of electric vehicle batteries. The results show the effectiveness of the proposed GDs and their viability in power converters based on SiC MOSFET devices.La tendencia en el diseño y desarrollo de convertidores de potencia está enfocada en realizar sistemas eficientes con alta densidad de potencia, fiabilidad y bajo costo. Los retos para cubrir esta tendencia están centrados principalmente en el uso de nuevas tecnologías de dispositivos de conmutación tales como, MOSFETs de carburo de silicio (SiC). Los MOSFETs de SiC presentan mejores características que sus homólogos de silicio; tienen baja resistencia de conducción, pueden trabajar a mayores velocidades de conmutación y pueden operar a mayores niveles de temperatura y tensión. A pesar de las ventajas de los transistores de SiC, existen problemas que se manifiestan cuando estos dispositivos operan a altas frecuencias de conmutación. Las rápidas velocidades de conmutación de los MOSFETs de SiC pueden provocar sobre-voltajes y sobre-corrientes que conllevan a problemas de interferencia electromagnética (EMI). Por tal motivo, el desarrollo de controladores de puertas es una etapa fundamental en los MOSFETs de SiC para eliminar los problemas a altas frecuencias de conmutación y aumentar su rendimiento. En consecuencia, aprovechar las ventajas de estos dispositivos y lograr sistemas más eficientes y con alta densidad de potencia. En esta tesis, se realiza un estudio, diseño y desarrollo de controladores activos de puerta para mejorar el rendimiento de conmutación de los MOSFETs de SiC aplicados a convertidores de potencia de alta frecuencia. Los controladores son validados a través de pruebas y estudios experimentales. Además, los controladores de puerta desarrollados son aplicados en convertidores para sistemas de carga inalámbrica de baterías de vehículos eléctricos. Los resultados muestran la importancia de los controladores de compuerta propuestos y su viabilidad en convertidores de potencia basados en carburo de silicio.
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Lashway, Christopher R. "Resilient and Real-time Control for the Optimum Management of Hybrid Energy Storage Systems with Distributed Dynamic Demands." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3515.
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A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides the capability to individually monitor and control a wide range of different ES, enabling the extraction of an ES module within a series array to charge or conduct maintenance, while remaining storage can still function to serve a demand. Enhancements and testing of the ESMC are explored in not only interfacing of multiple ES and HESS, but also as a platform to improve management algorithms. There is an imperative need to provide a bridge between the depth of the electrochemical physics of the battery and the power engineering sector, a feat which was accomplished over the course of this work. First, the ESMC was tested on a lead acid battery array to verify its capabilities. Next, physics-based models of lead acid and lithium ion batteries lead to the improvement of both online battery management and established multiple metrics to assess their lifetime, or state of health. Three unique HESS were then tested and evaluated for different applications and purposes. First, a hybrid battery and SC HESS was designed and tested for shipboard power systems. Next, a lithium ion battery and SC HESS was utilized for an electric vehicle application, with the goal to reduce cycling on the battery. Finally, a lead acid battery and flywheel ES HESS was analyzed for how the inclusion of a battery can provide a dramatic improvement in the power quality versus flywheel ES alone.
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"Robust Control of Wide Bandgap Power Electronics Device Enabled Smart Grid." Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46215.
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abstract: In recent years, wide bandgap (WBG) devices enable power converters with higher power density and higher efficiency. On the other hand, smart grid technologies are getting mature due to new battery technology and computer technology. In the near future, the two technologies will form the next generation of smart grid enabled by WBG devices. This dissertation deals with two applications: silicon carbide (SiC) device used for medium voltage level interface (7.2 kV to 240 V) and gallium nitride (GaN) device used for low voltage level interface (240 V/120 V). A 20 kW solid state transformer (SST) is designed with 6 kHz switching frequency SiC rectifier. Then three robust control design methods are proposed for each of its smart grid operation modes. In grid connected mode, a new LCL filter design method is proposed considering grid voltage THD, grid current THD and current regulation loop robust stability with respect to the grid impedance change. In grid islanded mode, µ synthesis method combined with variable structure control is used to design a robust controller for grid voltage regulation. For grid emergency mode, multivariable controller designed using H infinity synthesis method is proposed for accurate power sharing. Controller-hardware-in-the-loop (CHIL) testbed considering 7-SST system is setup with Real Time Digital Simulator (RTDS). The real TMS320F28335 DSP and Spartan 6 FPGA control board is used to interface a switching model SST in RTDS. And the proposed control methods are tested. For low voltage level application, a 3.3 kW smart grid hardware is built with 3 GaN inverters. The inverters are designed with the GaN device characterized using the proposed multi-function double pulse tester. The inverter is controlled by onboard TMS320F28379D dual core DSP with 200 kHz sampling frequency. Each inverter is tested to process 2.2 kW power with overall efficiency of 96.5 % at room temperature. The smart grid monitor system and fault interrupt devices (FID) based on Arduino Mega2560 are built and tested. The smart grid cooperates with GaN inverters through CAN bus communication. At last, the three GaN inverters smart grid achieved the function of grid connected to islanded mode smooth transitionDissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017
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Wang, Yi-An, and 王翊安. "Design and Implementation of Analog Controlled Power Factor Corrector with Wide Bandgap Device." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6wsfv7.
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碩士國立臺北科技大學
電力電子產業研發碩士專班
105
The objective of this thesis is to design and implement an analog controlled power factor corrector with wide bandgap devices. By employing the benefits of wide gap devices, including high carrier mobility, high saturation velocity, and low turn-on resistance, the whole system can operate in high frequency, which means the volume of passive elements can be reduced, and the power density can be improved. The prototype of this thesis is designed to work in discontinuous conduction mode even under full load condition. Due to the special feature of discontinuous conduction mode, the current sensor is not required, so, the traces of the PCB board can be shortened. This topology is suitable for the low-power application of the power factor corrector. The specification of this thesis is described as follow: input voltage is 110 Vac/60Hz, output voltage is 400V, switching frequency is 300 kHz, and the controller is TI UC3525A. According to the experimental results, when the input voltage is 110 Vac, full load, the efficiency is 88.9%, and the PF is 0.98.
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Chiu, Ya-chi, and 邱雅琦. "Realization of a High-Efficiency Phase-Shift Full-Bridge DC-DC Converter with Wide-Bandgap Device." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60722524739664418591.
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碩士國立臺灣科技大學
電子工程系
101
A phase-shift full-bridge converter with zero-voltage-switching (ZVS) features can reduce the switching losses and high-frequency noises. Thus, the conversion efficiency can be effectively improved and the switching frequency can be raised to reduce the sizes of magnetic components. Since the output specifications of the studied converter are low voltage and high current, synchronous rectifiers are used instead of the Schottky diodes on the secondary side to reduce the conduction losses. In addition, the effects of the primary-side clamp diodes are analyzed. And wide-bandgap GaN FETs are applied for the lagging leg to achieve ZVS at light load. The operating principles and design considerations of the proposed converter are discussed in detail. A prototype phase-shift full-bridge converter has been implemented. The input voltage is 390 V, the output voltage is 12 V and the output current is 54 A. Theoretical analyses are verified with the experimental results.
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Ou, Jehn, and 歐震. "Growths and Characterizations of Wide-Bandgap III-Antimonide and III-Nitride Epilayers and Their Device Structures." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/74590427695931909661.
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博士國立交通大學
電子物理系
87
We have carried out systematic studies on the epitaxial growth of AlAs1-xSbx, GaN and InxGa1-xN compounds using metalorganic vapor phase epitaxy technique. Experimental data indicate that the solid composition of AlAsSb depends strongly on the input reactant flow rates and the growth temperature. A high Sb concentration of AlAsSb alloy can only be obtained at a V/III ratio close to 1, whereas too high the Sb flow rates and too low the V/III ratio will lead to the formation of Sb droplets and Al metal platelets, respectively. For AlAsSb prepared at high growth temperatures, the side reaction of TBAs, b-elimination, is believed to response for the result in a decrease of the As solid concentration. By employing a thermodynamic analysis, a novel phase diagram for AlAsSb with simpler solid-vapor distribution relationship was obtained, according to which the As solid concentration can be directly determined by the input As/Al mole flow rate ratio. The AlAs1-xSbx alloy was also used to fabricate two novel diodes, the enhanced InP Schottky diode and the In0.53Ga0.47As/AlAs0.44Sb0.56/In0.53Ga0.47As single barrier tunneling diode. By introducing AlAsSb into the conventional Schottky structure, the InP Schottky barrier height was improved greatly from 0.45eV to 0.76eV. For single-barrier tunneling diode, a negative differential resistance characteristic was successfully observed at 100 and 300K. A high peak-to-valley current ratio of 4.2 is obtained at 100K, which is the best value ever reported for such type of device. For GaN, the film quality appears to be very sensitive to the buffer layer property and the growth temperature. The optimized buffer layer thickness, temperature ramping rate and growth temperature are found to be around 100~300A, 75~100℃/min, and 1,000~1,050℃, respectively. A phase transition from hexagonal to cubic structure for GaN has been evidenced at a growth temperature around 750℃. The best quality of our GaN films in terms of FWHMs of x-ray and 300K-PL are as narrow as only 160 arcsec and 28meV, respectively. The corresponding electron mobility and carrier concentration also exhibit superior values of 330 cm^2/V and 1.1x10^17 cm^-3, respectively. Regarding to the InGaN growth, our experimental results indicate that the solid composition and characteristic of InGaN are determined not only by the growth temperature, but also by the TMGa and TMIn flow rates. The films with the good structural and optical properties can only be obtained at temperatures above 750℃. For the solid distribution, we found that too high the TMIn flow rate and too low the TMGa flow rate will both bring a decrease of In concentration solid, unfavorable to the high-In content InGaN growth. Besides, the thermodynamic analysis was also performed in our InGaN study. By introducing an empirical high-temperature factor in our modified InGaN growth model, we can successfully predict the solid-vapor distribution in InGaN and the appearance of In-droplets during growth. Based on thermodynamic arguments, the maximum allowed In solid concentration for a single phase InGaN is constrained primarily by the high temperature effect, such as In desorption, and the In saturation vapor pressure. By optimizing the growth conditions, we can obtain high quality InGaN epilayers with the narrow FWHMs of 150 arcsec and 92 meV for (0002) x-ray diffraction and 300K-PL peaks, respectively.
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Swenberg, Johanes F. N. "Development of wide-bandgap II-VI semiconductor light-emitting device technology based on the graded injector design." Thesis, 1995. https://thesis.library.caltech.edu/4058/1/Swenberg_jfn_1995.pdf.
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This thesis describes the technical development of a novel semiconductor device design aimed at realizing short wavelength visible light emitters. The device structure, called the graded injector, achieves minority carrier injection in a heterojunction system with unfavorable type-II band alignment. Band edge engineering with an alloy graded intermediary layer effectively reduces the conduction band offset and allows for efficient minority carrier injection. The basic device structure consists of a n-CdSe/Mg[subscript x]Cd[subscript 1-x]Se/p-ZnTe heterojunction, where the Mg[subscript x]Cd[subscript 1-x]Se region is graded.
The device design, materials growth, and characterization of II-VI green LEDs based on this structure are presented. Simulations demonstrate the operating principle of the graded injector. Early device development had been hindered by the lack of a p-type dopant for MBE ZnTe and the unavailability of high quality substrates. These restrictions have been overcome with the development of efficient nitrogen p-type doping of ZnTe and the growth capability of high quality heteroepitaxy on GaSb substrates. The materials characterization of the Mg-chalcogenides has enabled more accurate band edge engineering necessary for an operating device.
The advances in growth technology and materials characterization have been incorporated to grow and fabricate working graded injector LEDs. The operating characteristics of these devices unequivocally demonstrate the diode-like operation and efficient minority carrier injection. The electrical and optical performance of these devices will be presented and analyzed.
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Parvez, Mohammad. "Analysis, Modelling, Design, and Control of DC-DC Converter for Renewable Power Generation Systems." Thesis, 2021. https://hdl.handle.net/2440/135635.
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Global energy demand is rapidly growing and therefore meeting the future energy demand is becoming a major concern worldwide. To meet the energy demand, fossil fuels are still used as the primary energy source. However, these hydrocarbonbased fuels produce greenhouse gases that adversely affect environment and human health. Therefore, alternative renewable energy sources such as solar, wind, hydro, biomass and geothermal are getting very popular. Currently, development of power converters for these renewable energy sources is becoming more and more essential for converting this energy to appropriate voltage levels or feeding it to electrical power distribution networks. This research study is focused on the DC-DC boost converter analysis, design, modelling, and using current control techniques for singlephase uninterruptible power supply (UPS) inverter systems. The major contributions of the presented work can be categorized into two parts: Firstly, a comprehensive analysis of classical and advanced DC-DC converter topologies for renewable power applications. DC-DC power converters have attracted significant attention due to their increased use in a number of applications from aerospace to biomedical devices. The interest in wide bandgap (WBG) power semiconductor devices stems from outstanding features of WBG materials and power device operation at higher temperatures, larger breakdown voltages and sustaining larger switching transients than silicon (Si) devices. As a result, recent progress and development of WBG power devices based converter topologies are well-established for power conversion applications in which classical Si based power devices show limited performance. Currently, WBG devices such as silicon carbide (SiC) and gallium nitride (GaN) are the most promising semiconductor materials that are being considered for new generation of power devices because of their high voltage operation, high current switching capabilities, very low ON resistance, good thermal conductivity, etc. Secondly, a cost effective design of Gallium nitride (GaN)-based high-frequency, high efficiency DC-DC boost converter owing to preferred soft-switching features. The use of new power semiconductor devices such as GaN high electron mobility transistors (GaN HEMTs) are able to minimize switching losses, allowing high switching frequencies (from kHz to MHz) for realizing compact and fully integrated power converters. Finally, PI and PR control parameters are optimally tuned, and experimentally tested for single-phase UPS inverters to obtain very low total harmonic distortion (THD), zero steady-state error, and fast response. This research presents detailed analysis and mathematical models of PI and PR controllers in single-phase UPS inverter applications. In order to realize the importance of PR control features over conventional PI controllers, a PI controller is implemented in the same UPS inverter and mathematically analyzed. The performance of these controllers is analyzed in terms of steady-state is and transient responses and current harmonics level. The experimental result shows that the PR controller achieves zero steady-state error, improved transient response and reduced low-order harmonics distortion of the output current compared to PI controller. The performances of the implemented controllers are simulated and compared using the MATLAB/Simulink modeling environment. The main significance of this work is the design and development of a DC-DC boost converter, and optimization of controller parameters for high power application such as Electric Vehicle (EV) charging, aerospace, renewable power generation, etc.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2022
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Lai, Ying-Yu, and 賴映佑. "Study of wide-bandgap semiconductor planar microcavity laser devices." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/73068859300140660100.
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博士國立交通大學
光電工程研究所
103
In planar microcavities (MCs), beside the vertical-cavity surface-emitting laser (VCSEL) action, another low threshold laser could be generated by the Bose-Einstein condensation of cavity-polaritons, named polariton laser. Wide-bandgap materials including ZnO and GaN have a high potential on making VCSELs and polariton lasers due to their high exciton binding energies. In this thesis, we report an electrically injected GaN-based VCSEL and an optically pumped ZnO polariton laser. Through simulation, we found that transparent conducting layer and lateral confinement aperture play important roles on reducing lasing threshold of the GaN VCSEL. We also proposed a new low index aperture design for GaN VCSEL and observed a transverse mode lasing behavior by an optical pumping experiment. For the electrically pumped VCSELs, the proposed low-index SiO2 aperture can confine both the current and optical mode simultaneously, which reveals its confinement capability. For the ZnO-based MC, a clear formation of cavity polariton has been observed. And the corresponding poalriton relaxation and bottleneck effect were also verified. A low threshold polariton laser can be achieved by polariton self-interaction at room temperature. Besides, the polariton laser with a lower threshold can be achieved by assistant of longitudinal optical phonon-polariton scattering. These results provide a clear map for future designing of low threshold ZnO MC polarton lasers.
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Kao, Chi-Joe, and 高治舟. "The application of surface insulating layer on wide-bandgap semiconductor devices." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26482128824848849878.
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博士國立中央大學
物理研究所
93
Abstracts In this dissertation, the applications of insulators/oxides on GaN-based MSM photodectors or GaN-, ZnO-based FETs are performed. Several application cases and theories of insulator on GaN- and ZnO-based devices are introduced here: GaN-based MSM UV photodetectors with a low-temperature grown GaN (LT-GaN) layer is demonstrated first. It was found that we could achieve a two-order of magnitude smaller, dark-current of GaN MSM photodetector by employing a LT-GaN surface insulating layer. This result could be attributed to the larger Schottky-barrier height between the Ni/Au metal contact and the LT-GaN surface insulating layer. It was also found that photodetectors with the LT-GaN layer could provide a larger photocurrent to dark-current contrast ratio and a larger UV-to-visible rejection ratio. The maximum responsivity was found to be 3.3 A/W and 0.13 A/W when the biases were at 5 V and 1 V, respectively. The performance of AlGaN/GaN heterostructure field-effect transistors (HFETs) with either uncapped free surface or with LT-GaN, SiO2, Si3N4 as gate insulators is examined second. LT-GaN, SiO2 and Si3N4 surface high-resistivity layer disposed on the AlGaN/GaN heterostructures resulted in an increase of sheet carrier concentrations. These observations could be attributed from the passivation effect to passivate the surface states, thereby having a different, maybe lower, electronic density of states compared to the AlGaN free surface. To clarify the effect of these surface insulating layers on the AlGaN/GaN HFET structures, Hall measurement were performed here. The sheet carrier concentrations of AlGaN/GaN HFETs with any of these surface insulating layers are similar to each other and about 100% higher than that in an AlGaN/GaN HFET structure with a free surface. Due to the better lattice match with the AlGaN surface layer, the HFET with a LT-GaN layer as the gate insulating layer shows the best DC and RF device performance, demonstrating that this material is an effective insulator for nitrides. Comparison of ZnO MOSFETs and MESFETs fabricated on the same wafers using either sapphire or glass substrate is report finally. ZnO thin film field effect transistors with 1.5-20um gate width were fabricated using either a metal gate (metal-semiconductor field-effect transistor, MESFET) or a metal-oxide-semiconductor (MOS) gate. In both cases we found that use of a thick (around 0.8~0.9µm) ZnO buffer was necessary on the sapphire or glass substrate prior to growing the active layers in order to reduce gate leakage current. The MOS structure with a 50-nm-(Ce,Tb)MgAl11O19 gate dielectric showed an order of magnitude lower gate leakage current than the MESFET, due to the relatively high barrier height of MOS structure. Good drain-source current characteristics were obtained from MOS gate structures using phosphorus-doped ZnO channels, whereas the metal structures showed very poor modulation. For the general speaking form this dissertation, surface insulating layer could provide device high Schottky barrier height, low metal/semiconductor leakage current, low surface state density and highly stable device performance. One may use surface insulating layer to achieve more stable, even higher, performance of semiconductor device easily.
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Bandić, Zvonimir Z. "Novel devices employing epitaxial wide bandgap semiconductors : physics, electronics and materials characterization." Thesis, 2000. https://thesis.library.caltech.edu/6096/2/Bandic_zz_2000.pdf.
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This thesis describes the developments of novel semiconductor devices based on epitaxial wide bandgap semiconductors GaN and ZnS. The number of interesting and exciting results in physics, electronics and materials science of these systems were found in studies motivated by these devices. This thesis consists of three major topics, structural characterization and kinetic growth modeling of the GaNAs/GaAs superlattices, structural and optical characterization and solid phase recrystallization of ZnS thin films grown on GaN and sapphire substrates, and design and fabrication of GaN high power devices as well as measurement of fundamental electronic properties of GaN, such as minority carrier diffusion lengths and lifetimes and critical field for electric breakdown.
The set of GaNAs/GaAs superlattices grown by molecular beam epitaxy was analyzed by high resolution X-ray diffraction and cross—sectional transmission electron microscopy. The nitrogen incorporation and GaNAs/GaAs interface sharpness were experimentally found to strongly depend on growth temperature. The activation energies for nitrogen desorption and nitrogen to arsenic segregation were found through simple kinetic model, which is in fine agreement with experimentally obtained results. These fundamental studies provide important insights into growth of GaN on GaAs substrates, which is of significant practical importance for all electronic GaN devices.
Zinc sulfide/Gallium nitride heterostructures are potentially interesting system for light emitters in blue and green part of visible spectrum, with DC low power consumption electroluminescent displays being one attractive application of these diodes. Zinc sulfide thin films grown on GaN (0001), GaAs (001) and sapphire (0001) substrates by MBE were characterized by variable temperature photoluminescence and high resolution X-ray diffraction. The structural properties of the films suffered from the large lattice mismatch between ZnS and various substrates which were used. The optical properties of the ZnS films were found to be in direct correlation with structural properties of the films. The ZnS films doped with Al and Ag grown on n and p-type GaN, and sapphire were characterized by low temperature photoluminescence and displayed bright blue luminescence. Fabricated N-ZnS/p-GaN heterostructures were characterized by current-voltage and electroluminescence. Electroluminescence was found to be centered around 390 nm, corresponding to high energy silver band, and it shifted to higher energies with increase in device voltage. Since as grown films suffered from crystalline imperfections, the ZnS thin films on sapphire were recrystallized, by annealing at temperatures above 900 °C at sulfur overpressure of 10 atm. The structural properties of samples significantly improved, indicating more than 10-fold reduction in tilting and excellent crystallinity. The role of sulfur was discussed, and it was found that sulfur is important in preventing film evaporation, increasing boundary migration and providing compliancy to sapphire substrate.
The minority carrier diffusion lengths and lifetimes were measured for electrons and holes in unintentionally doped, n and p-type GaN samples grown by several different growth techniques. The experimentally observed diffusion lengths were in the 0.2 — 0.3 µm range for Metal-Organic Chemical Vapor Deposition (MOCVD) and Molecular Beam Epitaxy (MBE) grown samples, and 1 — 2 µm in the case of Halide Vapor Phase Epitaxy (HVPE) grown sample. In the case of MOCVD grown samples, the hole lifetime was estimated to approximately 7 ns, and electron lifetime to approximately 0.1 ns. The same samples were structurally characterized by AFM, and the size of the defect-free regions surrounded by linear dislocations is found to be of the order of measured diffusion length, in qualitative agreement with minority carrier recombination at linear dislocations. A simple model is presented which explains an increase in minority carrier lifetime and diffusion length with a decrease in the dislocation density or increase in the size of defect-free grains. A model which explains why linear dislocations might act as recombination sites is also presented.
The important advantage of nitrides and other wide band gap materials for high power devices is a smaller standoff layer thickness for the same standoff voltage, giving smaller ON-state voltage and resistance, smaller power dissipation and larger maximum current density, allowing physically smaller devices for the same power rating. The design rules for nitride based Schottky rectifiers and thyristors are presented. The critical field for electric breakdown and minority carrier recombination lifetimes are found to be important design parameters. Using modeling parameters which are well in the range currently available with GaN, and measured from fabricated devices, design results indicate the possibility of 18 µm thick GaN Schottky rectifiers and 12 µm thick A1GaN thyristors supporting 5 kV standoff voltage. The critical field for electric breakdown was found to be 5 MV/cm from the theoretical studies. The maximum current density for 5 kV thyristors is in the 200 — 400 A/cm^2 range depending on the hole lifetime, and is limited by thermal breakdown. The maximum operating frequency of 5 kV thyristors is in the 1-2 MHz range and also depends on the hole lifetime.
Two-terminal GaN Schottky rectifiers were fabricated. The Schottky rectifiers were fabricated on thick GaN layers grown by HVPE and had a standoff voltages in the 450 V to 750 V range, depending on the thickness of the GaN film and contact geometry. Best devices were characterized with reverse current density of 10^(-5)A/cm^2 at reverse bias of 100 V, and 4.2 V ON-state voltage at a forward current density of 100 A/cm^2. Various contact geometries were investigated. It was found that mesa geometry improves ON-state voltage, but causes increase in reverse current density, while that metal field plate geometry significantly reduces reverse current density. The measured critical field for electric breakdown in GaN was found to be (2.5 ± 0.5) MV/cm and it approaches the theoretical estimate of 5 MV/cm. The measured values of critical field are only a lower limit since the reverse breakdown voltage was limited by premature corner and edge breakdown.
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Lades, Martin [Verfasser]. "Modeling and simulation of wide bandgap semiconductor devices : 4H/6H-SiC / Martin Lades." 2000. http://d-nb.info/962057827/34.
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Li-ChiPeng and 彭立琪. "Wide Bandgap III-Nitride-based Optoelectronic Devices Grown by Metalorganic Vapor Phase Epitaxy." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/84978359794927842251.
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博士國立成功大學
光電科學與工程學系
100
In this dissertation, growth and fabrication of III-nitride-based optoelectronic devices by MOVPE have been studied. Several methods used to improve output power efficiency of GaN-based blue light emitting diodes (LEDs) have been studied. GaN-based blue LEDs with textured sidewalls and micro-scale pillars around mesa region could enhance light efficiency about 26% by reducing the total internal reflection of light inside the LED structure. Furthermore, comparison of conventional LEDs, the LEDs combining with textured sidewalls, GaN micro-pillars around the mesa region, patterned sapphire substrate (PSS), and highly reflective p-/n-type Ag/Cr/Au electrode pads could further improve around 80% in wall-plug efficiency (WPE). The embedded multilayers of GaN/AlxGa1-xN microlens-like structure on GaN template with micro-pillars pattern could enhance the LEDs output power by more than 30% due to the enhanced guided-light scattering efficiency, resulting from the difference in refractive index of GaN and AlGaN layer. Moreover, owing to the difference in lateral and vertical growth rate of homoepitaxial GaN grown on GaN template with micro-pillars pattern, the similar epitaxial lateral overgrowth model have be demonstrated and could further improve the crystal quality of epilayer. A single AlGaN layer with two different Al contents by grown on the GaN template with micro-pillars structure has been demonstrated. The strains-induced Al incorporation efficiency and difference in lateral and vertical growth rate of AlGaN grown on the sidewalls, top and valley surfaces of the pillars lead to form the different Al contents in the single AlGaN layer. The Schottky-type photodetectors (PDs) were also demonstrated for double Al contents of deposited AlGaN on GaN μ-pillar templates, exhibiting the three steps of responses occurred at about 326, 346, and 356 nm. The cutoff wavelength of the Schottky PDs at 326 and 346 nm should be contributed by the AlGaN layer on the sidewall of cone shaped pillars and the rest of the area of the AlGaN, respectively.
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Liao, Long-De, and 廖隆德. "Design and Implementation of Digital Controlled Interleaved Power Factor Corrector with Wide Bandgap Devices." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6a8ms2.
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碩士國立臺北科技大學
電機工程系電力電子產業研發碩士專班
105
The objective of this thesis is to design and implement an interleaved power factor corrector with wide bandgap devices. Compared with traditional silicon power devices, the gallium nitride power devices have the advantages of high electron mobility, high saturable velocity, high electrical field strength and low on-resistance. The switching frequency can be increased without increasing the excessive switching loss in order to reduce the magnetic components size and increase power density. The design specifications include: output power rating of 750 W, input AC voltage 115 Vac and 230 Vac, output DC voltage of 400 Vdc and switching frequency of 300 kHz. Experimental results show that the efficiency is up to 93%, power factor is greater than 0.996 in low line voltage and full load condition. The efficiency is up to 95%, power factor is greater than 0.94 in high line voltage and full load condition.
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Lin, Jia-Hong, and 林佳鴻. "Design and Implementation of a Semi-Bridgeless Power Factor Corrector with Wide Bandgap Devices." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dmvb8n.
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碩士國立臺北科技大學
電機工程系電力電子產業碩士專班
107
The main purpose of this thesis is to design and implement a semi-bridgeless power factor corrector (PFC) by using wide bandgap device. The characteristics of wide bandgap device is utilized to increase the switching frequency and the volume of the required inductor is reduced. This thesis uses the average current control method to make the source current can trace source voltage to improve the power factor and stabilize the output voltage. Compared to the traditional power factor correctors, the number of the semiconductor components in the current path of the semi-bridgeless PFC is less, therefore the circuit efficiency can be improved, and it is more suitable for high power applications. In addition, the semi-bridgeless PFC has lower common mode noise feature. In this thesis, the microcontroller TMS320F28035 produced by Texas Instruments is used as the control core to achieve power factor correction by the average current control method, and associated with the implemented power stage circuit to verify the proposed circuit design theory. The experimental specifications include the input source voltage range changes from AC 110V to AC 220V, the output voltage is DC 400V, the maximum output power is 600W and the switching frequency is 200kHz. In experiments, the maximum efficiency is up to 98.6%, the power factor is up to 0.99 at full load condition, and the harmonic currents meet IEC61000-3-2 Class D standard.
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Liao, Bo-Wei, and 廖博偉. "Design and Implementation of Digital Controlled Bridgeless Power Factor Corrector with Wide Bandgap Devices." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dqb44m.
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碩士國立臺北科技大學
電機工程系電力電子產業碩士專班
106
The objective of this thesis is to design and implement a bridgeless power factor corrector with wide bandgap devices. Compared with traditional silicon power devices, the gallium nitride power devices have the advantages of low on-resistance, high electron mobility, high saturable velocity and high electrical field strength. The switching frequency can be increased without increasing the excessive switching loss in order to reduce the magnetic component sizes and increase power density. The implemented bridgeless power factor corrector has specifications that the output power is 500 W, the input voltage is 110 Vac/ 60 Hz, and the switching frequency is 200 kHz. The experimental results show that under full load, the efficiency can reach 96.6% and the power factor can reach 0.997.