Reliability of WBG semiconductor devices for automotive applications

Power electronics play a crucial role in modern electric vehicles, ensuring efficient energy conversion and distribution across various systems, such as motor drives, chargers, inverters, and other powertrain components. A key factor in the reliability and efficiency of these systems is the use of wide bandgap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN). These materials possess unique properties that make them highly suitable for automotive applications, including the ability to operate at high temperature, high voltages, and high frequencies, which reduce the weight and volume of the system while improving energy conversion efficiency. In this study, various methods for testing positive bias temperature instability (PBTI) in SiC MOSFETs were examined. Charge trapping mechanisms related to both pre-existing defects and the formation of new defects in the oxide region were identified and characterized. The effects of these defects on device characteristics were further confirmed through modeling using the Technology Computer-Aided Design (TCAD) simulator. The reliability study of GaN HEMTs included the investigation of time-dependent gate breakdown (TDGB) and transistor behavior during short circuits. The TDGB analysis provided deeper insights into breakdown mechanisms caused by prolonged gate stress, leading to degradation and device failure. Additionally, an experimental setup was developed and presented for testing the short-circuit behavior of GaN HEMTs, as such conditions may arise due to various failures in automotive systems. GaN HEMTs were subjected to short circuits with different durations and voltage levels, enabling an assessment of their resilience and the identification of conditions under which degradation occurs. The results of this study aim to optimize operating conditions and enhance the reliability of these devices, which is critical for the effective integration of WBG materials into automotive systems and for ensuring reliable electric vehicle operation under real-world conditions.