Approaching the limit of switching loss reduction in Si-IGBTs

This paper reports on the reduction limit of switching loss in Si-IGBTs without increasing the on-state voltage. We focused on surge decrease and turn-off loss saturation with small gate resistance. It became clear that the surge decrease derives from a dynamic avalanche adjacent to the trench bottom and leads to the turn-off loss saturation. This avalanche phenomenon is suppressed by the reduction of the electric field and positive space charge near the trench bottom. A 20 % improvement in the trade-off relation with small gate resistance was realized by the suppression of the dynamic avalanche, which is close to the turn-off loss reduction limit.