Repetitive Short Circuit Energy Dependent VTH Instability of 1.2kV SiC Power MOSFETs

Repetitive short circuit energy (E-SC) dependent threshold voltage (V-TH) instabilities of 1.2kV SiC power MOSFETs are characterized. A bidirectional V-TH shift behavior, i.e. negative shift at lower E-SC and positive shift at higher E-SC, was revealed. The V-TH shifts under repetitive SC tests are attributed to the SC pulse phase according to the results of high temperature reverse bias (HTRB) and dynamic high temperature gate bias (HTGB) tests. The underlying mechanisms of the complex V-TH shift behavior are explained in a unified framework by taking into account the junction temperature (T-j) increase with higher E-SC. TCAD device simulation is used to help analyze the mechanisms.