Well-balanced 4H-SiC JBSFET: Integrating JBS diode and VDMOSFET characteristics for reliable 1700V applications

Abstract

SiC power devices are suitable for high voltage and temperature applications due to their higher breakdown electrical field and thermal conductivity. Recently, many SiC SBDs and VDMOSFETs have been commercially produced. In comparison to Si-IGBT devices, the inherent body diode of SiC VDMOSFETs can also be used as the freewheeling diode in inductive switching power circuits, eliminating the need for an additional packaged diode. This can save costs and reduce the footprint of the total package. However, the bipolar carrier conduction and minority carrier injection mechanism on the body diode of SiC VDMOSFETs result in a higher turn-on knee voltage and longer reverse recovery time when used as a freewheeling diode. In fact, SiC SBDs are often utilized to replace the body diode, aiming to enhance the knee voltage and reverse recovery speed. To harness both the benefits of SiC VDMOSFETs and SBDs, it is worthwhile to integrate these two types of power devices into a single monolithic chip. In this study, we fabricated integrated JBS diodes into VDMOSFETs (JBSFETs) targeting 1700 V applications. Well-behaved JBSFETs with a threshold voltage (V_th) of 1.9 V, specific on-resistance (R_on,sp) of 5.2 mΩ-cm², and acceptable blocking voltage (BV) of 2373 V have been achieved. The temperature dependence of the JBSFET device characteristics was also investigated. These results represent significant progress in implementing high-performance JBSFETs in power electronics.