A Superjunction MOSFET with Ultralow Reverse Recovery Charge and Low Switching Losses

High reverse recovery charge (QRR) and high switching losses have become the main factors that constrain the performance and application area of a superjunction MOSFET (SJ-MOSFET). To reduce QRR and switching losses, an SJ-MOSFET with p-type Schottky diode and source field-plate is proposed and investigated. The p-type Schottky diode consists of Schottky contact and p-base, which is reverse series-connected with body p–n junction diode. The source field-plate is formed by implementing a polysilicon field-plate electrically coupled to the source, which is on the top of an n-pillar. During the reverse conduction state, the p-type Schottky diode is reverse biased, which dramatically suppresses minority carriers injecting into the drift region. Simultaneously, an electron accumulation layer formed under the source field-plate, which provides a path for the reverse current. Consequently, compared with the conventional SJ-MOSFET (Conv-SJ-MOSFET), the proposed SJ-MOSFET achieves an 84.0% lower QRR with almost no sacrifice in other characteristics. Moreover, with reduced gate area, the proposed device also exhibits 47.4% and 66.0% lower gate charge (QG) and gate to drain charge (QGD), respectively. The significantly reduced QG, QGD, and QRR contribute to an overall improvement in switching losses and result in a decrease of over 54.8% in total power losses with operation frequency higher than 50 kHz, demonstrating great potential of the proposed SJ-MOSFET used in power conversion systems.