A microscopic study of 0.1 μm recessed gate b-doped AlInAs/GaInAsHEMTs has been performed by using a semiclassical Monte Carlo devicesimulation. The geometry and layer structure of the simulated HEMT iscompletely realistic, including recessed gate and δ-dopingconfiguration. The usual T-gate technology is used to improve thedevice characteristics by reducing the gate resistance. For firsttime we take into account in the Monte Carlo simulations the effectof the T-gate and the dielectric used to passivate the devicesurface, which affects considerably the electric field distributioninside the device. The measured I_d-V_ds characteristics of a realdevice are favourably compared with the simulation results. Whencomparing the complete simulation with the case in which Poissonequation is solved only inside the semiconductor, we find that evenif the static I-V characteristics remain practically unchanged,important differences appear in the dynamic and noise behaviour,reflecting the influence of an additional capacitance.
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