Dynamic Monte Carlo study of isolated-gate InAs/AlSb HEMTs

In this work, by means of Monte Carlo simulations, the static and dynamic behavior of isolated-gate InAs/AlSb high electron mobility transistors (Sb-HEMTs) has been studied and compared with experimental results. The influence of the existence of a native oxide under the gate, the value of the surface charges in the gate recess and the possible variation of electron sheet carrier density, ns, has been studied. A decrease in the gate-source capacitance, transconductance and intrinsic cut-off frequency is observed because of the presence of the native oxide, while changes in the value of the surface charges in the recess only introduce a threshold voltage shift. The increase of ns shifts the maximum of the transconductance and intrinsic cut-off frequency to higher values of drain current and improves the agreement with the experimental results.