Sumi Krishnaswami

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In this paper, we report 4H-SiC power DMOSFETs capable of blocking 10 kV. The devices were scaled up to 5 A, which is a factor of 25 increase in device area compared to the previously reported value. The devices utilized 100 mum thick n-type epilayers with a doping concentration of 6 times 10<sup>14</sup> cm<sup>-3</sup> for drift layers, and a floating(More)
In this paper, static and switching characteristics of a 1200 V 4H-silicon carbide (SiC) bipolar junction transistor (BJT) at a bus voltage of 600 V are reported for the first time. Comparison was made between the SiC BJT and a 1200 V Si insulated gate bipolar transistor (IGBT). The experimental data show that the SiC BJT has much smaller conduction and(More)
SiC materials and device technology has entered a new era with the commercialization and acceptance of 600 V/10 A and 1200 V/10 A Schottky Barrier Diodes (SBDs) in the marketplace. These diodes are finding applications in the Power Factor Correction (PFC) stage of Switch Mode Power Supplies (SMPS). SiC power MOSFETs with ratings of 800-1200 V up to 10 A(More)
4 kV, 10 A bipolar junction transistors have been demonstrated in 4H-SiC. The device conducts 10 A of collector current with a current gain of 34 at room temperature. The current gain reduces to 21 at 300 degC. Under reverse bias, the device is capable of blocking 4.7 kV with 50 muA leakage current. Room temperature switching measurements show a turn-on(More)
This paper presents the development of 1000 V, 30A bipolar junction transistor (BJT) with high dc current gain in 4H-SiC. BJT devices with an active area of 3/spl times/3 mm/sup 2/ showed a forward on-current of 30 A, which corresponds to a current density of 333 A/cm/sup 2/, at a forward voltage drop of 2 V. A common-emitter current gain of 40, along with(More)
Due to the high critical field in 4H-SiC, the drain charge and switching loss densities in a SiC power device are approximately 10/spl times/ higher than that of a silicon device. However, for the same voltage and resistance ratings, the device area is much smaller for the 4H-SiC device. Therefore, the total drain charge and switching losses are much lower(More)
The paper presents the reliability of MOS-based 4H-SiC devices. Recent high temperature gate oxide breakdown measurements on MOS capacitors reveal that the gate oxides on an as-grown epi surface are more reliable than those grown on ion-implanted and activated surfaces. The reduction in the oxide reliability on implanted surfaces is primarily due to the(More)
For 1-kV 30-A 4H-SiC epitaxial emitter n-p-n bipolar junction transistors, the dependences of the common-emitter current gain /spl beta//sub CE/ on the collector current I/sub C/ were measured at elevated temperatures. The collector-emitter voltage was fixed (at 100 V) to provide an active operation mode at all collector currents varying in a wide range(More)
The compelling system benefits of using silicon carbide (SiC) Schottky diodes have resulted in rapid commercial adoption of this new technology by the power supply industry. Silicon carbide PiN diodes, MOSFET's, and BJT's, are approaching the point of development that they could be transitioned to volume production. This work reviews the characteristics of(More)
Silicon carbide (SiC) is a very attractive material for high temperature semiconductor devices because of its very wide bandgap (3.26 eV). Due to the wide bandgap, thermal carrier generation is very low in SiC, resulting in negligible junction leakage currents for temperatures up to 500 degC. Other advantage of SiC is high breakdown strength (10times that(More)