Dynamics of the kink effect in InAlAs/InGaAs HEMTs

We have carried out pulsed measurements of the kink effect in InAlAs/InGaAs HEMT's on InP with nanosecond resolution. Our measurements show that the kink's characteristic time constant is strongly dependent on V/sub DS/, i.e., it drops by more than three decades, from 100 μs down to 50 ns, between low and high values of V/sub DS/. This suggests that the kink should not be operational for frequencies in the microwave and millimeter wave regimes. We also find that the kink turn-on dynamics correlate with impact ionization. In particular, the inverse of the kink's characteristic time constant follows a classical impact ionization behavior.