Papers by Keyword: High-Temperature

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Authors: Martin Petrenec, Jaroslav Polák, Tomáš Šamořil, Jiří Dluhoš, Karel Obrtlík
Abstract: In-situ Low Cycle Fatigue test (LCF) at temperature 635 °C have been performed in SEM on flat specimen ofcast Inconel 713LC superalloy. The aim of the investigation was to studymechanisms of the fatigue damage during elastic-plastic cycling by theobservations of the characteristic surface relief evolution and theaccompanying internal dislocation structures. The selected locations on thesurface were systematically studied in-situ and documented by SEM and usingAFM. The surface relief in the first tensile half-cycle was formed by numerousslip steps on the primary slip planes (111). In the following compressionhalf-cycle additional opposite slip were formed. The relief was modified in thenext cycles but without forming additionally new slip traces in the primarysystem. The reorientation of two grains in the gauge area was measured usingEBSD. At the end of cyclic loading the relation between surface persistent slipmarkings and persistent slip bands in the interior of the material wasdocumented by TEM on lamella prepared by FIB. The early stages of extrusion andintrusion formation were documented. The damage mechanism evolution is closelyconnected with the cyclic strain localization to the persistent slip bands thatare also places of fatigue crack initiation.
Authors: Lin Cheng, Anant K. Agarwal, Craig Capell, Michael J. O'Loughlin, Khiem Lam, Jon Zhang, Jim Richmond, Al Burk, John W. Palmour, Aderinto Ogunniyi, Heather O’Brien, Charles Scozzie
Abstract: In this paper, we report our recently developed 1 cm2, 15 kV SiC p-GTO with an extremely low differential on-resistance (RON,diff) of 4.08 mΩ•cm2 at a high injection-current density (JAK) of 600 ~ 710 A/cm2. The 15 kV SiC p-GTO was built on a 120 μm, 2×1014/cm3 doped p-type SiC drift layer with a device active area of 0.521 cm2. Forward conduction of the 15 kV SiC p-GTO was characterized at 20°C and 200°C. Over this temperature range, the RON,diff at JAK of 600 ~ 710 A/cm2 decreased from 4.08 mΩ•cm2 at 20°C to 3.45 mΩ•cm2 at JAK of 600 ~ 680 A/cm2 at 200°C. The gate to cathode blocking voltage (VGK) was measured using a customized high-voltage test set-up. The leakage current at a VGK of 15 kV were measured 0.25 µA and 0.41 µA at 20°C and 200°C respectively.
Authors: Lin Cheng, Anant K. Agarwal, Michael J. O'Loughlin, Craig Capell, Khiem Lam, Charlotte Jonas, Jim Richmond, Al Burk, John W. Palmour, Aderinto Ogunniyi, Heather O’Brien, Charles Scozzie
Abstract: In this work, we report our recently developed 16 kV, 1 cm2, 4H-SiC PiN diode results. The SiC PiN diode was built on a 120 µm, 2×1014/cm3 doped n-type SiC drift layer with a device active area of 0.5175 cm2. Forward conduction of the PiN diode was characterized at temperatures from 20°C to 200°C. At high injection-current density (JF) of 350 ~ 400 A/cm2, the differential on-resistance (RON,diff) of the SiC PiN diode decreased from 6.08 mΩ·cm2 at 20°C to 5.12 mΩ·cm2 at 200°C, resulting in a very small average temperature coefficient of –5.33 µΩ·cm2/°C, while the forward voltage drop (VF) at 100 A/cm2 reduced from 4.77 V at 20°C to 4.17 V at 200°C. This is due to an increasing high-level carrier lifetime with an increase in temperature, resulting in reduced forward voltage drop. We also observed lower RON,diff at higher injection-current densities, suggesting that a higher carrier lifetime is needed in this lightly doped n-type SiC thick epi-layer in order to achieve full conductivity modulation. The anode to cathode reverse blocking leakage current was measured as 0.9 µA at 16 kV at room temperature.
Authors: Jian Hui Zhang, Jian Wu, Petre Alexandrov, Terry Burke, Kuang Sheng, Jian H. Zhao
Abstract: This paper reports recent progress in the development of high power 4H-SiC BJTs based on an improved device design and fabrication scheme. Near theoretical limit high blocking voltage of VCEO=1,836 V has been achieved for 4H-SiC BJTs based on a drift layer of only 12 μm, doped to 6.7x1015 cm-3. The collector current measured for a single cell BJT with an active area of 0.61 mm2 is up to IC=9.87 A (JC=1618 A/cm2). The collector current is 7.64 A (JC=1252 A/cm2) at VCE=5.9 V in the saturation region, corresponding to an absolute specific on-resistance (RSP_ON) of 4.7 m9·cm2. From VCE=2.4 V to VCE= 5.8 V, the BJT has a differential RSP_ON of only 3.9 m9·cm2. The current gain is about 8.8 at Ic=5.3 A (869 A/cm2). This 4H-SiC BJT shows a V2/RSP_ON of 717 MW/cm2, which is the highest value reported to date for high-voltage and high-current 4H-SiC BJTs. A verylarge area 4H-SiC BJT with an active area of 11.3 mm2 is also demonstrated.
Authors: Anant K. Agarwal, Sei Hyung Ryu, Ranbir Singh, Olof Kordina, John W. Palmour
Authors: E. Maset, Esteban Sanchis-Kilders, Pierre Brosselard, Xavier Jordá, Miquel Vellvehi, Phillippe Godignon
Abstract: Silicon Carbide 300V-5A Ni and W Schottky diodes with high temperature operation capability (up to 300°C) have been fabricated. This paper reports on the stability tests (ESA space mission to Mercury, BepiColombo requirements) performed on these diodes. A DC current stress of 5A has been applied to these diodes at 270°C for 800 hours. These reliability tests revealed both, degradation at the Schottky interface (forward voltage drift) and at the diode top surface due to Aluminum diffusion (bond pull strength degradation). The use of W as Schottky metal allows eliminating the forward voltage drift producing stable metal–semiconductor interface properties. Nevertheless, SEM observations of the top metallization still reveal metal degradation after stress. The bond pull strength of the wire bond is also significantly reduced.
Authors: Zachary Stum, Vinayak Tilak, Peter A. Losee, Emad A. Andarawis, Cheng Po Chen
Abstract: MOSFET-based integrated circuits were fabricated on silicon carbide (SiC) substrates. SiC devices can operate at much higher temperatures than current semiconductor devices. Simple circuit components including operational amplifiers and common source amplifiers were fabricated and tested at room temperature and at 300°C. The common source amplifier displayed gain of 7.6 at room temperature and 6.8 at 300°C. The operational amplifier was tested for small signal open loop gain at 1kHz, measuring 60 dB at room temperature and 57 dB at 300°C. Stability testing was also performed at 300°C, showing very little drift at over 100 hours for the individual MOSFETs and the common source amplifier.
Authors: Jim Richmond, Sei Hyung Ryu, Sumi Krishnaswami, Anant K. Agarwal, John W. Palmour, Bruce Geil, Dimos Katsis, Charles Scozzie
Abstract: This paper reports on a 400 watt boost converter using a SiC BJT and a SiC MOSFET as the switch and a 6 Amp and a 50 Amp SiC Schottky diode as the output rectifier. The converter was operated at 100 kHz with an input voltage of 200 volts DC and an output voltage of 400 volts DC. The efficiency was tested with an output loaded from 50 watts to 400 watts at baseplate temperatures of 25°C, 100°C, 150°C and 200°C. The results show the converter in all cases capable of operating at temperatures beyond the range possible with silicon power devices. While the converter efficiency was excellent in all cases, the SiC MOSFET and 6 Amp Schottky diode had the highest efficiency. Since the losses in a boost converter are dominated by the switching losses and the switching losses of the SiC devices are unaffected by temperature, the efficiency of the converter was effectively unchanged as a function of temperature.
Authors: Jeff B. Casady, Anant K. Agarwal, L.B. Rowland, R.R. Siergiej, S. Seshadri, S. Mani, J. Barrows, D. Piccone, P.A. Sanger, C.D. Brandt
Authors: Jean-Louis Robert, Sylvie Contreras, Jean Camassel, Julien Pernot, Sandrine Juillaguet, Lea Di Cioccio, Thierry Billon
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