Analysis of SiC MOSFET d I /d t and its temperature dependence

Abstract

A change regulation of variation in drain current (dI D /dt) of silicon carbide (SiC) metal-oxide-semiconductor fieldeffect transistors (MOSFETs) and their temperature dependencies are examined. Experimental results show that the magnitude of turn-off dI D /dt decreases with temperature and turn-on dI D /dt increases with increasing temperature. Further analysis shows that turn-on dI D /dt is better than turn-off dI D /dt in terms of temperature dependency and exhibits good linearity. This behaviour results from the positive temperature coefficient of the intrinsic carrier concentration and the negative temperature coefficient of the effective mobility of the electrons in the SiC MOSFET. Other factors that affect the temperature dependency of dI D /dt, such as supply voltage, load current, and gate resistance, are also discussed. A temperature-based analytical model of dI D /dt for the SiC MOSFET is derived using fundamental device physics equations. The calculations generally fit the measurements well. These results are beneficial since they provide a potential approach for junction temperature estimation in the SiC MOSFET. In SiC MOSFET-based practical applications, if turn-on dI D /dt is sensed, then the junction temperature can be derived from the relationship curve of turn-on dI D /dt versus temperature drawn experimentally in advance. 2 Temperature dependency characterisation of variation in drain current 2.1 Overview of the turn-on and turn-off process The typical structure of a 1200 V SiC MOSFET that consists of electrodes, gate oxide, junction field-effect transistor (JFET)

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“…Another source of error of the switching losses prediction methods is the temperature dependency of some parameters used in the models. The main temperature‐sensitive parameters are the on‐resistance, the device transconductance, both with a positive temperature coefficient, and the threshold voltage, which has a negative temperature coefficient [9, 45]. The behaviour of the aforementioned parameters according to the temperature are available in some devices datasheets, however, some manufacturers do no provide such curves, so that they must be obtained experimentally.…”

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