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 HEMTs has been performed by using a semiclassical, Monte Carlo device simulation. The geometry and laver structure of the simulated MERIT is completely realistic, including recessed gate and delta-doping configuration. The usual T-gate technology is used to improve the device characteristics by reducing the gate resistance. For first time we take into account in the Monte Carlo simulations the effect of the T-gate and the dielectric used to passivate the device surface, which affects considerably the electric field distribution inside the device. The measured I-d-V-ds characteristics of a real device 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 characteristics remain practically unchanged, important differences appear in the dynamic and noise behaviour, reflecting the influence of an additional capacitance.