Enhanced Reverse Recovery Performance in Superjunction MOSFET with Reduced Hole-Barrier

High reverse recovery charge (Q RR ) and resultant high switching losses have become the main factors that constrain the performance and application area of superjunction MOSFET (SJ-MOSFET). To reduce Q RR , an SJ-MOSFET with reduced hole-barrier is proposed and demonstrated. By introducing a Schottky contact on the bottom of the n-pillar at the drain side, the barrier for the hole carrier is dramatically reduced in the reverse conduction state. As a result, the hole carrier in the drift region is significantly reduced, which results in a low Q RR and enhanced reverse recovery performance. Compared with the conventional SJ-MOSFET (Conv-SJ-MOSFET), the proposed device achieves 64.6% lower Q RR with almost no sacrifice in other characteristics. The attenuated Q RR accounts for a 19.6% ∼ 46.8% reduction in total power losses with operation frequency at 5 ∼ 200 kHz, demonstrating the great potential of the proposed SJ-MOSFET used in power conversion systems.