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|Development of Low RON,Diff, 12 kV, 4H-SiC GTOs for High-Power and High-Temperature Applications|
|Keywords: 4H-SiC GTOs, Low differential on-resistance, High-Power and High-Temperature|
|The development of high-voltage power devices based on wide bandgap semiconductor such as silicon carbide (SiC) has attracted great attention due to its superior material properties over silicon for high-temperature applications. Among the high-voltage SiC power devices, the 4H-SiC gate turn-off thyristor (GTO) offers excellent current handling, very high voltage blocking, and fast turn-off capabilities. The 4H-SiC GTO also exhibits lower forward voltage drop than the IGBT-based switch, resulting in lower losses during normal operation. In this paper, for the first time, to our knowledge, we report our recently developed 1 x 1 cm^2, 12 kV SiC GTOs with a very low differential on-resistance (RON,Diff) of 4 mOhm-cm^2 with respect to the device active area at high injection current of 100 A or higher, which is more than 40% reduction from our previously reported work. This significant reduction in the on-resistance was attributed to an improvement of carrier lifetime in the SiC bulk region. The SiC GTO was wire-bonded and attached to a high-voltage package before the high-temperature measurement. The forward characteristics of the device were then measured using a Tektronics 371 curve tracer from room temperature (20°C) up to 400°C. Over this temperature range, the RON,Diff of the device increased modestly from 4 mOhm-cm^2 at 20°C to 4.7 mOhm-cm^2 at 400°C, while the forward voltage drop at 100 A decreased slightly from 3.97 V at 20°C to 3.6 V at 400°C. The gate to cathode blocking voltage (VGK) was measured using a customized high-voltage test set-up. The leakage current of < 1 uA was measured at a VGK of 12 kV at 20°C. A high-temperature set-up is being developed for high-voltage measurement. The blocking characteristics of the 4H-SiC GTO at high temperatures will be presented and discussed in the full paper.|
|Lin Cheng, Power Device Scientist