Papers by Author: Charles Scozzie

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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.
1025
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.
901
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.
1151
Authors: Victor Veliadis, Ty McNutt, Megan McCoy, Harold Hearne, Gregory De Salvo, Chris Clarke, Paul Potyraj, Charles Scozzie
Abstract: High-voltage normally-on VJFETs of 0.19 cm2 and 0.096 cm2 areas were manufactured in seven photolithographic levels with no epitaxial regrowth and a single ion implantation event. A self aligned guard ring structure provided edge termination. At a gate bias of -36 V the 0.096 cm2 VJFET blocks 1980 V, which corresponds to 91% of the 12 μm drift layer’s avalanche breakdown voltage limit. It outputs 25 A at a forward drain voltage drop of 2 V (368 A/cm2, 735 W/cm2) and a gate current of 4 mA. The specific on-resistance is 5.4 mΩ cm2. The 0.19 cm2 VJFET blocks 1200 V at a gate bias of -26 V. It outputs 54 A at a forward drain voltage drop of 2 V (378 A/cm2, 755 W/cm2) and a gate current of 12 mA, with a specific on-resistance of 5.6 mΩ cm2. The VJFETs demonstrated low gate-to-source leakage currents with sharp onsets of avalanche breakdown.
1047
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.
978
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.
895
Authors: Edward van Brunt, Lin Cheng, Michael J. O'Loughlin, Jim Richmond, Vipindas Pala, John Palmour, Charles W. Tipton, Charles Scozzie
Abstract: In this work, we report our recently developed 27 kV, 20 A 4H-SiC n-IGBTs. Blocking voltages exceeding 24 kV were achieved by utilizing thick (210 μm and 230 μm), lightly doped N-drift layers with an appropriate edge termination. Prior to the device fabrication, an ambipolar carrier lifetime of greater than 10 μs was measured on both drift regions by the microwave photoconductivity decay (μPCD) technique. The SiC n-IGBTs exhibit an on-state voltage of 11.8 V at a forward current of 20 A and a gate bias of 20 V at 25 °C. The devices have a chip size of 0.81 cm2 and an active conducting area of 0.28 cm2. Double-pulse switching measurements carried out at up to 16 kV and 20 A demonstrate the robust operation of the device under hard-switched conditions; coupled thermal analysis indicates that the devices can operate at a forward current of up to 10 A in a hard-switched environment at a frequency of more than 3 kHz and a bus voltage of 14 kV.
847
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.
1445
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.
1159
Authors: Victor Veliadis, Damian Urciuoli, Harold Hearne, H.C. Ha, R. Howell, Charles Scozzie
Abstract: Bi-directional solid-state-circuit-breakers (SSCBs) are highly desirable in power-electronic fault-protection applications due to their high actuation speed and repeated fault isolation capability. Normally-on SiC vertical-channel JFETs (VJFETs) are excellent candidates for high power/temperature scalable SSCB applications as majority carrier devices with low conduction losses and stable +300°C thermal characteristics. 600-V / 2-A bi-directional power flow was demonstrated using two VJFETs connected back-to-back with their sources in common. The low VJFET pre-breakdown leakage currents and sharp onset of breakdown are critical in enabling bi-directional power flow. 0.1-cm2 low conduction-loss VJFETs were designed for efficient and reliable SSCB applications.
1147
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