Papers by Keyword: Reverse Recovery

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Authors: Lin Lin Liu, Ting Gang Zhu, Michael Murphy, Marek Pabisz, Milan Pophristic, Boris Peres, Tom Hierl
Abstract: The first commercially viable high voltage (>600V) gallium nitride (GaN) Schottky barrier devices are reported. Though GaN does not have any “micropipe” defects, which commonly exists in SiC material, defects like dislocations due to lattice mismatch hamper the material development of GaN high power devices. Improvements in the nitride epitaxial film growth have led to significant reduction of conductive dislocations. Conductive Atomic Force Microscope (CAFM) analysis of conductive dislocations shows only on the order of 103 cm-2 density of conductive dislocations, which are believed to be responsible for the undesired leakage current. GaN diodes compare to SiC or Si devices demonstrate a significant advantage in the thermal resistance. The insulating properties of Sapphire substrates allow fabrication of the devices in TO220 packages with insulating frame and thermal resistance better than 1.8°C/W compare to 3°C/W of SiC or Si devices with insulating frame. Performance of GaN, SiC and Si devices in the switch mode power supplies is compared.
Authors: Won Suk Choi, Sung Mo Young, Richard L. Woodin, A.W. Witt, J. Shovlin
Abstract: SuperFETTM MOSFETs and silicon carbide (SiC) Schottky diodes are applied to continuous conduction mode active power factor correction pre-regulators. SuperFETTM MOSFETs can reduce power losses dramatically with their extremely low RDS(ON) and fast switching. The SiC Schottky diode has virtually zero reverse recovery current and high thermal conductivity, and is close to an ideal diode for a CCM PFC circuit. Due to these outstanding switching characteristics, frequency can be increased. In this paper, the SiC Schottky diode’s and SuperFETTM MOSFET’s performance have been verified in a CCM PFC boost converter. These products can reduce the total power losses and enhance the system efficiency.
Authors: Satoshi Tanimoto, Kenichi Ueoka, Takaya Fujita, Sawa Araki, Kazu Kojima, Toshiharu Makino, Satoshi Yamasaki
Abstract: A new rectifier, called SPND or SNPD (Schottky-PN or -NP junction diode) and inherently showing low on-resistance and unipolar operation, was experimentally demonstrated for the first time on 4H-SiC. It is structured with an n or a p region of very low doping that is sandwiched and completely depleted between a Schottky junction and a one-sided PN junction. Either electrons or holes, but not both, contribute to the current conduction process. Clear and sharp rectifying properties are observed over the entire range of applied voltage.
Authors: A. Marikkannan, B.V. Manikandan, S. Jeyanthi
Abstract: The interest toward the application of fuel cells is increasing in the last years mainly due to the possibility of highly efficient decentralized clean energy generation. The output voltage of fuel-cell stacks is generally below 50 V. Consequently, low-power applications with high output voltage require a high gain for proper operation. A zero-voltage-switching (ZVS) dc–dc converter with high voltage gain is proposed for fuel cell as a front-end converter. It consists of a ZVS boost converter stage and a ZVS half-bridge converter stage and two stages are merged into a single stage. The ZVS boost converter stage provides a continuous input current and ZVS operation of the power switches. The ZVS half-bridge converter stage provides a high voltage gain. The principle of operation and system analysis are presented. Theoretical analysis and simulation result of the proposed converter were verified.
Authors: Jeffery B. Fedison, Z. Li, V. Khemka, Nudjarin Ramungul, T. Paul Chow, Mario Ghezzo, James W. Kretchmer, Ahmed Elasser
Authors: Nudjarin Ramungul, V. Khemka, T. Paul Chow, Mario Ghezzo, James W. Kretchmer
Authors: Tsuyoshi Funaki, Kazuya Kodama, Hitoshi Umezawa, Shinichi Shikata
Abstract: Wide band gap semiconductors have been attracted as the material for fabricating power switching devices to obtain lower power conversion loss in high voltage circuit, and to operate harsh environment of high temperature. This paper focuses on diamond as the wide band gap semiconductor material and elucidates the dynamic characteristics in switching operation. To this end, Schottky barrier diode (SBD) is fabricated with p type diamond semiconductor and static I-V characteristics is evaluated. Then, the switching operation of diamond SBD is demonstrated, and forward current dependency of the recovery phenomena is characterized. The diamond SBDs show superior fast switching capability with low reverse recovery current, which is inherent in uni-polar switching device.
Authors: Rudolf Elpelt, Bernd Zippelius, Daniel Domes
Abstract: In switching applications with half-bridge like configurations the load current is commutated to the so-called reverse or body-diode of a switching device once each switching cycle. The bipolar charge generated in the switch in principle leads to a reverse recovery current and to additional losses. Though it is well known, that in silicon carbide these reverse recovery losses are very low compared to e.g. silicon devices, it turns out that depending on device structure and switching conditions the reverse recovery charge for the JFET may become larger than can be explainable by the stored bipolar charge. In this paper therefore we focus on a simulation study comparing the body-diode operation of common lateral channel silicon carbide JFET and MOSFET devices in a so-called double pulse measurement. It is shown, that the MOSFET body-diode operation still remains uncritical under very fast switching conditions, while the JFET body-diode exhibits a pronounced recovery current peak originating from a partial channel turn-on, and thus higher losses.
Authors: Uwe Zimmermann, Martin Domeij, Anders Hallén, Mikael Östling
Authors: Sergey A. Reshanov, Gerhard Pensl
Abstract: Minority carrier (hole) lifetime investigations are conducted on identical 6H-SiC p+-n structures by electrical (reverse recovery, open circuit voltage decay) and optical (time-resolved photoluminescence) techniques. The p+-n diodes are fabricated by Al implantation. Depending on the particular analysis technique, the lifetime is determined either electrically in different regions of the p+-n diode or optically in the n-type 6H-SiC epilayer and results, therefore, in different values ranging from ≈10 ns to 2.5 µs.
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