Direct correlation between impact ionization and the kink effect in InAlAs/InGaAs HEMTs

We present new, unmistakable experimental evidence directly linking the kink effect with impact ionization in the channel of InAlAs-InGaAs HEMTs on InP. Through the use of a sidegate structure, we confirm that the impact ionization coefficient obeys the classic exponential dependence on the inverse electric field at the drain end of the gate, and that the onset of the kink strongly coincides with the onset of impact ionization in the devices we consider. These measurements illuminate the functional relationship between the kink and impact ionization, and therefore will allow assessment of the numerous impact-ionization related kink mechanisms that have recently been suggested in the literature.