Influence of the kink effect on the dynamic performance of short-channel InAlAs/InGaAs high electron mobility transistors

Abstract

A semiclassical two-dimensional ensemble Monte Carlo simulator is used to perform a microscopic study of the influence of the kink effect on the dynamic behaviour of short-channel InAlAs/InGaAs lattice-matched high electron mobility transistors (HEMTs). To this end, the transient behaviour of the kink onset and the degradation introduced in some elements of the small signal equivalent circuit are analysed. According to our results, the pile-up of holes (generated by impact ionization) which is at the origin of the kink effect, jointly with the higher electron density in the channel, causes an increase of the gate–source capacitance. The drain conductance also increases because the accumulated hole density depends significantly on the drain–source voltage. In addition, the frequency dependence of the drain conductance reflects the influence of the hole recombination processes taking place in the accumulation zone.