Effect of the T-gate on the performance of recessed HEMTs. A Monte Carlo analysis

A microscopic study of 0.1 mu m recessed gate delta-doped AlInAs/GaInAs HEM Ts has been performed by using a semiclassical, Monte Carlo device simulati on. The geometry and laver structure of the simulated MERIT is completely r ealistic, including recessed gate and delta-doping configuration. The usual T-gate technology is used to improve the device characteristics by reducin g the gate resistance. For first time we take into account in the Monte Car lo simulations the effect of the T-gate and the dielectric used to passivat e the device surface, which affects considerably the electric field distrib ution inside the device. The measured I-d-V-ds characteristics of a real de vice an favourably compared with the simulation results. When comparing the complete simulation with the case in which Poisson equation is solved only inside the semiconductor, we find that even if the static I-V characterist ics remain practically unchanged, important differences appear in the dynam ic and noise behaviour, reflecting the influence of an additional capacitan ce.