Short Circuit Capability and Short Circuit Induced $V_{\mathrm{TH}}$ Instability of a 1.2-kV SiC Power MOSFET

The withstand capability and threshold voltage (VTH) instability of 1.2-kV silicon carbide (SiC) MOSFETs under repetitive short circuit (SC) tests are investigated. An SC test system is constructed to apply repetitive SC stress to SiC MOSFETs and measure the transfer I-V characteristics and gate-to-source leakage current (I
_GSS
) after each set of SC tests. To evaluate the SC capability, repetitive SC tests with different SC durations (t
_p
) are conducted until device failure. The SC withstand time (SCWT) at 1000 SC cycles is found to be ~3.3 μs. V
_TH
instability under repetitive SC tests prior to the device failure is characterized. A bidirectional V
_TH
shift behavior, i.e., negative shift at shorter t
_p
and positive shift at longer t
_p
, was revealed. The V
_TH
shifts under repetitive SC tests are attributed to the SC pulse process 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 longer t
_p
. TCAD device simulation is used to help analyze the mechanisms.