Pulsed measurements and circuit modeling of a new breakdown mechanism of MESFETs and HEMTs

We measured the on-state breakdown of HEMTs in a nondestructive way using the Transmission Line Pulse technique reaching very high values of gate current density (30 mA/mm). On the basis of the experimental observations, we developed a new model for on-state breakdown of HEMTs, suitable for SPICE simulations, which is capable of predicting the breakdown curves. We have shown that a parasitic bipolar action can give rise in HEMTs to a new form of breakdown, which is accurately modeled by the SPICE equivalent circuit. The model not only predicts I/sub G/, but consistently describes I/sub D/ up to breakdown levels.