Failure Mechanisms in Wideband Semiconductor Power Devices
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Silicon carbide (SiC), as one of the wide bandgap semiconductors, is a promising material for next-generation power devices due to its high critical electric field, high thermal conductivity, and high saturated electron drift velocity properties. Extensive studies have been focused their electrical characterizations. Failure mechanisms of SiC devices, however, have not been fully explored. In this work the failure mechanisms of SiC power devices, including Schottky diodes, power MOSFETs and IGBTs, are investigated. The characteristics of SiC Schottky diodes have been investigated and simulated based on the drift-diffusion model. Interface state degradation has been identified as the mechanism responsible for the non-catastrophic failure happened in Schottky diode. Experimental and simulation results are provided to support this conclusion. Single-event burnout (SEB) and single-event gate rupture (SEGR) failure mechanisms have been investigated for SiC power MOSFETS in details in this work since power MOSFETs have been used in very critical applications. The features of SiC power MOSFET SEB and SEGR failures have been simulated successfully and compared to those of Si power MOSFETs. The much better robustness of SiC power MOSFES against SEB failures has been demonstrated by the simulation results. At last the latch-up failure mechanism has been investigated for SiC IGBTs. Compared to Si IGBTs, the results show that SiC IGBTs have a stronger capability against the latch-up failure. The design and application guideline for SiC power devices can be made base on the results obtained in this work.