Modified TCAD simulation approach for 4H-SiC JBS diode to investigate electron trapping effects

Abstract

A modified TCAD approach is developed for 4H-SiC junction barrier Schottky (JBS) diode by placing distinct contacts to the Schottky barrier diode (SBD) and PN junction regions. Like reality, if a common metal contact with work function is specified for top electrode, TCAD model simulates back-to-back serially connected metal/p⁺-type Schottky and PN junction characteristics at the PN regions. Hence, the conventional contact definition simulates only the SBD characteristics with the reduced active area, while PN junctions remain inactive. Using modified contact strategy, the simulated forward I-V is matched with the measurements, and the SBD and PN diode current components are disassociated. The peak electric field occurs at the PN junction during reverse bias; however, reverse current is entirely caused by SBD tunneling current, thereby realizing the typical JBS diode operation. Trap-assisted tunneling (TAT) current induced by omnipresent electron traps (E_C – 0.19 eV, E_C – 0.65 eV, and E_C – 1.65 eV) in 4H-SiC is explored for JBS diodes. The reverse I-V is eventually validated using non-local tunneling model. The TCAD simulations are extended to investigate the electron trapping effects on the I-V properties with increasing trap concentrations. Consequently, the trapping-induced changes in the internal device parameters are probed to correlate with the macroscopic variation in the diode characteristics.