Investigation of the Temperature Sensitivity and the Sensing Voltage Drift of the Body Diode of SiC Power MOSFET

This paper presents an experimental methodology to precisely estimate the junction temperature of commercial SiC power MOSFETs. To achieve this, the current-voltage characteristics and forward voltage drift of body diode were measured for various gate biases coupled with various ambient temperatures by using in-house test equipment. From those experimental data, we estimated the effect of the gate bias and sensing time on the sensitivity and the sensing voltage drift of SiC power MOSFETs. These results show that the sensitivity and sensing voltage drift exhibited different aspects with respect to gate bias (VGS). It is also found that the sensitivity was decreased with increasing the sensing current (ISENS) for VGS ≤ 5 V whereas increased for VGS > 5 V. However, the sensing voltage drift is found to be monotonically increased with ISENS for all the cases of the gate bias. We believe that this is attributed to a higher trap density at the SiC/SiO₂ interface.