V subthreshold hysteresis technology and temperature dependence in commercial 4H-SiC MOSFETs

Abstract

V TH subthreshold hysteresis measured in commercially available 4H-SiC MOSFET is more pronounced in trench than in planar ones. All planar devices from different manufacturers exhibit an inverse temperature dependence, with the hysteresis amplitude reducing as the temperature increases, whereas all trench devices from different manufacturers exhibit the opposite behaviour. A physical interpretation is proposed, based on experimental evidence, which demonstrates that temperature dependence of the V TH subthreshold hysteresis is related to the technology. The findings are relevant to the ongoing discussion on SiC bespoke validation standards development and contribute important new insight.

SiC power MOSFETs Threshold-voltage hysteresis and its impact on Short Circuit operation

“…Some of the difficulties that prevent WBG devices from becoming mainstream are related to concerns such as reliability and specific driver needs. The reliability of SiC MOSFETs is actually plagued by NBTI [1,[4][5][6][7][8] caused mainly by hole trapping in the oxide [2]. This phenomenon affects the operation of the device by shifting its V TH either permanently or in a recoverable manner.…”

“…It has been observed that the drain leakage current SiC MOSFETs depends on the OFF-state voltage applied on the gate [1,3]. When a negative gate bias is applied for a short time in the OFF-state, the drain current leakage is enhanced for as long as the applied bias is kept under the threshold voltage.…”

“…In literature, it is stated that the V TH subthreshold hysteresis is erased for gate biases beyond the V TH [1,3,4], but it seems that it is the case only for static measurements, where the equilibrium is achieved. Almost Short Circuit tests, with gate bias just above the threshold voltage, show that hysteresis is still present and has a great impact on the device performance [10].…”

“…In this paper we show that the hysteresis affects the short circuit operation of commercially available SiC MOSFETs even for real application bias conditions. A comparative study between commercially available SiC MOSFETs from different manufacturers has shown that hysteresis depends on technology (planar and trench) and operating temperature [1]. Such a comparative study on Short Circuit operation can be of great interest when it comes to the reliability of SiC MOSFETs as it can shed some light on the role of the hysteresis in dynamic events and its reliability related issues.…”

VTH-Hysteresis and Interface States Characterisation in SiC Power MOSFETs with Planar and Trench Gate

“…Recent investigations have targeted a benchmark of commercially available devices, based in particular on differences in their gate terminal technology [11]. For illustration, Fig.…”