Analysis and Modeling of Vth Shift in 4H-SiC MOSFETs at Room and Cryogenic-Temperature

We investigate and model the threshold voltage instabilities of 4H-SiC power MOSFETs at room and cryogenic temperatures, based on wide time range (from µs to ks) PBTI analysis. We show that for T > 200 K a stretched (log-like) de-trapping transient dominates the recovery kinetics, while at lower temperatures (down to 80 K) a fast exponential component is also visible. The charge de-trapping process is modeled as a distribution of traps spread over the midgap, that causes the threshold instability. Results indicate: i) one narrow gaussian energy distribution at the interface, visible at low temperature, which explains the exponential transient behavior for T < 200 K; ii) a broader distribution deeper in energy, that is considered to take into account the logarithmic de-trapping kinetics at higher temperatures and the threshold static shift with temperature. The proposed modeling framework can accurately reproduce the experimental results.

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