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|Silicon Carbide "Super" Junction Transistors Operating at 500 ºC|
|Keywords: Silicon Carbide, High Temperature, High Voltage|
|SiC “Super” Junction Transistors (SJTs) are high current gain, majority carrier transport SiC NPN BJTs developed by GeneSiC in 1200 V -10 kV ratings. 1200 V-class, 3 mm2 active area SiC SJTs with current gains as high as 88, low on-resistance of 5.8 mΩ-cm2 and switching times of < 15 ns were recently reported. This paper is focused on the 500 °C operation of the SiC SJTs after packaging the devices in special test coupons. After fabrication, selected SJT die were attached to DBC alumina substrates with off-eutectic AuSn die-attach, which is capable of operation up to 600 °C for short durations. The die were then wire bonded using thick 10 mil Au wire bonds. Output characteristics of the packaged die were measured up to 500 °C. At temperatures ≤ 300 °C, the I-V curves show a distinct lack of a quasi-saturation region, which indicate unipolar operation mode of the SiC SJT. However, in the temperature range of 400 – 500 °C, clearly demarcated saturation and quasi-saturation regions appear in the I-V characteristics, implying a shift in operation from unipolar mode to bipolar mode. Due to an increase in ionization of the p-type acceptors in the base region, the current gain shows a negative temperature co-efficient up to 300 °C. However at > 300 °C temperatures, the current gain increases with temperature, due to an increase in carrier lifetime with temperature. Blocking voltage measurements have been performed on packaged SJT die up to 325 °C and the leakage currents at 1200 V remain below 100 µA, even at 325 °C. Switching measurements performed on the SJTs indicate temperature-independent switching transients up to 300 °C, with switching times within 20 ns. Blocking voltage and switching measurements on the SiC SJTs up to 500 °C will be presented in the full paper.|