Charge to Breakdown Testing of MOSFETs for Reliability Analysis in Electric Vehicles

Abstract

With a ban on fossil-fuel vehicles coming into place in 2030, the window for developing electric vehicles (EVs) with reliable performance is rapidly closing. Investigating the reliability of emerging materials, specifically silicon carbide (SiC) metal-oxide-semiconductor field-effect-transistors (MOSFETs) and gallium nitride (GaN) cascode silicon (Si) MOSFETs, this thesis uses a charge to breakdown (QBD) technique to test the reliability in electric vehicle (EV) power electronics. While traditional Si insulated gate bipolar transistors (IGBTs) have been widely studied, SiC devices offer enhanced thermal and electrical properties, making them a more efficient alternative for EV applications. However, their long-term reliability under high-voltage and high-temperature conditions remains a critical area of study.During this research, an accelerated age testing setup was designed to assess the breakdown behavior of SiC and Si MOSFETs through QBD testing, in which the results revealed distinct differences in oxide reliability between the two materials. The SiC MOSFETs exhibited QBD values of 0.134C and 0.174C, however, the Si MOSFETs did not exhibit breakdown, highlighting the need for further investigation into their failure mechanisms and performance limitations in EV applications. By focusing on SiC MOSFETs and Si MOSFETs, this study offers insights into the importance of gate oxide reliability in maintaining MOSFET performance and therefore the reliability of EV power electronics, as well as the potential of QBD testing for future innovations of EV technology