Papers by Author: Anant K. Agarwal

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Authors: Qing Chun Jon Zhang, Robert Callanan, Anant K. Agarwal, Albert A. Burk, Michael J. O'Loughlin, John W. Palmour, Charles Scozzie
Abstract: 4H-SiC Bipolar Junction Transistors (BJTs) and hybrid Darlington Transistors with 10 kV/10 A capability have been demonstrated for the first time. The SiC BJT (chip size: 0.75 cm2 with an active area of 0.336 cm2) conducts a collector current of 10 A (~ 30 A/cm2) with a forward voltage drop of 4.0 V (forced current gain βforced: 20) corresponding to a specific on-resistance of ~ 130 mΩ•cm2 at 25°C. The DC current gain, β, at a collector voltage of 15 V is measured to be 28 at a base current of 1 A. Both open emitter breakdown voltage (BVCBO) and open base breakdown voltage (BVCEO) of ~10 kV have been achieved. The 10 kV SiC Darlington transistor pair consists of a 10 A SiC BJT as the output device and a 1 A SiC BJT as the driver. The forward voltage drop of 4.5 V is measured at 10 A of collector current. The DC forced current gain at the collector voltage of 5.0 V was measured to be 440 at room temperature.
Authors: Sumi Krishnaswami, Anant K. Agarwal, Craig Capell, Jim Richmond, Sei Hyung Ryu, John W. Palmour, S. Balachandran, T. Paul Chow, Stephen Baynes, Bruce Geil, Kenneth A. Jones, Charles Scozzie
Abstract: 1000 V Bipolar Junction Transistor and integrated Darlington pairs with high current gain have been developed in 4H-SiC. The 3.38 mm x 3.38 mm BJT devices with an active area of 3 mm x 3 mm showed a forward on-current of 30 A, which corresponds to a current density of 333 A/cm2, at a forward voltage drop of 2 V. A common-emitter current gain of 40 was measured on these devices. A specific on-resistance of 6.0 mW-cm2 was observed at room temperature. The onresistance increases at higher temperatures, while the current gain decreases to 30 at 275°C. In addition, an integrated Darlington pair with an active area of 3 mm x 3 mm showed a collector current of 30 A at a forward drop of 4 V at room temperature. A current gain of 2400 was measured on these devices. A BVCEO of 1000 V was measured on both of these devices.
Authors: Q. Jon Zhang, Charlotte Jonas, Joseph J. Sumakeris, Anant K. Agarwal, John W. Palmour
Abstract: DC characteristics of 4H-SiC p-channel IGBTs capable of blocking -12 kV and conducting -0.4 A (-100 A/cm2) at a forward voltage of -5.2 V at 25°C are demonstrated for the first time. A record low differential on-resistance of 14 mW×cm2 was achieved with a gate bias of -20 V indicating a strong conductivity modulation in the p-type drift region. A moderately doped current enhancement layer grown on the lightly doped drift layer effectively reduces the JFET resistance while maintains a high carrier lifetime for conductivity modulation. A hole MOS channel mobility of 12.5 cm2/V-s at -20 V of gate bias was measured with a MOS threshold voltage of -5.8 V. The blocking voltage of -12 kV was achieved by Junction Termination Extension (JTE).
Authors: Q. Jon Zhang, Anant K. Agarwal, Craig Capell, L. Cheng, Michael J. O'Loughlin, Albert A. Burk, John W. Palmour, Sergey L. Rumyantsev, T. Saxena, Michael E. Levinshtein, A. Ogunniyi, Heather O'Brien, Charles Scozzie
Abstract: In this paper, for the first time, we report 12 kV, 1 cm2 SiC GTOs demonstrated with a novel negative bevel termination, which improves the breakdown voltage by >3.5 kV compared to the conventional multiple-zone Junction Termination Extension (JTE). The significant improvement in the blocking voltage was attributed to the elimination of the electrical field crowding in the periphery of the mesa with conventional JTE termination. This new termination has been used in both electrically and optically triggered SiC GTOs. An ultrafast turn-on speed of 70 ns has been measured on 12 kV, 1 cm2 SiC light triggered GTOs.
Authors: Anant K. Agarwal, Jeff B. Casady, L.B. Rowland, W.F. Valek, C.D. Brandt
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 Zhu, Mayura Shanbhag, T. Paul Chow, Kenneth A. Jones, Matthew H. Ervin, Pankaj B. Shah, Michael A. Derenge, R.D. Vispute, T. Venkatesan, Anant K. Agarwal
Authors: Anant K. Agarwal, Sei Hyung Ryu, Ranbir Singh, Olof Kordina, John W. Palmour
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: Q. Jon Zhang, Charlotte Jonas, Albert A. Burk, Craig Capell, Jonathan Young, Robert Callanan, Anant K. Agarwal, John W. Palmour, Bruce Geil, Charles Scozzie
Abstract: 4H-SiC BJTs with a common emitter current gain (b) of 108 at 25°C have been demonstrated. The high current gain was accomplished by using a base as thin as 0.25 μm. The current gain decreases at high temperatures but is still greater than 40 at 300°C. The device demonstrates an open emitter breakdown voltage (BVCBO) of 1150 V, and an open base breakdown voltage (BVCEO) of 250 V. A low specific on-resistance of 3.6 mW-cm2 at 25°C was achieved. The BJTs have shown blocking capabilities over a wide range of operating temperatures up to 300°C.
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