Analysis of the Influence of Temperature on Turn-Off Stress Waves in SiC MOSFET Using Laser Doppler Vibrometry

Due to the effects of electromagnetic stress and thermoelastic effect, mechanical stress waves are generated in power semiconductor devices (PSDs) during turn-off moment. The characteristics of these turn-off stress waves vary when PSDs are subjected to different temperature environments. Measuring these turn-off stress waves is beneficial for analyzing the influence of temperature on the physical properties of PSDs. As a traditional contact-based mechanical stress wave detection method, acoustic emission testing (AET) is inevitably influenced by temperature, affecting the sensor’s measurement performance. This study employs noncontact laser Doppler vibrometry (LDV) to measure turn-off stress waves in silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) at different temperatures. By comparing the signals measured using AET, it has been demonstrated that the signals measured using LDV more effectively reflect the temperature-dependent variations in turn-off stress waves of SiC MOSFET. This research not only broadens the application scope of condition monitoring technology based on mechanical stress wave parameters for PSDs but also demonstrates the unique advantages of LDV in condition monitoring of PSDs in different temperature environments.