An UMOSFET integrated with graded semi-super-junction and 3C/4H–SiC hetero-crystalline freewheeling junction

Abstract

SiC trench metal-oxide-semiconductor field-effect transistor (UMOSFET) can play a promising candidate in high frequency and large power electronics. Herein, an UMOSFET inserted with n/p-/p/p-/n-type graded semi-super-junction (GSSJ) in drift region and 3C/4H–SiC hetero-crystalline freewheeling junction (HCFJ) connected to source electrode is proposed by the Silvaco TCAD, called as the 3C/4H–SiC-GSSJ-UMOSFET. The GSSJ can be regarded as two back-to-back n/p-type unilateral graded junctions to shrink the depletion zones in n-type pillars for reducing the specific on-resistance (Ron, sp) without degrading the breakdown voltage (VB), hence optimizes the trade-off between VB and Ron,sp. Further, the 3C/4H–SiC HCFJ can be conducted prior to the body junction (BJ) composed of 4H–SiC p-body and n-type current spreading layer, due to the turning-on voltage of HCFJ much lower than that of BJ, which benefits to freewheel the backward current while decrease the reverse recovery charges and time. Thus can improve the device performance.