Conceptual Study of Sub-600 V IGBTs

Very low voltage, 60-600 V insulated-gate bipolar transistors (IGBTs) were compared to power mosfet s with conventional and superjunction drift layers of identical voltage classes using mixed-mode numerical device simulation. This study was done in the light of forthcoming 400 V class IGBTs for use in electric vehicle/hybrid electric vehicle: the 600 V borderline, which previously separated the bulk of power mosfet from IGBT applications, has become fragile recently. We find that the 400 V class must not represent a lower limit for IGBTs based on silicon: in fact, LV IGBTs could offer lower losses down to the 60-100 V level. Most importantly, low-voltage IGBTs may outperform power mosfets not only with respect to on-state voltage drop but also regarding switching offering up to 30% lower turn-off losses. This paper presents physics-based arguments focusing on the device transconductance to augment these projections. LV IGBTs or hybrid devices (monolithic integration of mosfet plus IGBT) could become lower cost, high performance alternatives to SJ power mosfets thanks to short development cycles common in mature silicon technologies.