Investigation of Heavy-Ions-Induced Leakage Current Modes and Degradation Mechanism in SiC MOSFETs Under Complex Heavy Ion Conditions

A comprehensive investigation is conducted to explore the heavy-ions-induced leakage current (HIILC) modes and degradation mechanism in silicon carbide (SiC) MOSFET. The ions used in irradiation experiments had different linear energy transfer (LET) values, which aimed to simulate complex ion conditions in aerospace applications. The distinct HIILC degradation modes of SiC MOSFETs are observed first under heavy ion irradiation with different LET values. Under irradiation with low LET ions, the overall leakage current degradation is dominated by the degradation of the drain current. Conversely, gate current has a higher degradation rate under irradiation with high LET ions. The degradation mechanisms of leakage current are discussed by combining the defect analysis of irradiated samples and simulation results. We propose and verify for the first time that the generation of stacking faults (SFs) in SiC MOSFETs under heavy ion irradiation is the cause of drain current degradation regardless of LET values. Additionally, under high LET ion irradiation, damage caused by a high electric field in the gate oxide is presumed to be attributed to the rapid degradation in gate current. The proposed theory provides a foundation and guidance for reinforcing against HIILC degradation of SiC MOSFET by addressing the process and material characteristics of the SiC.