Abstract
In this paper we present a methodology to use drift diffusion (DD) simulations in the design of short channel heterojunction FETs (HFETs) with well pronounced velocity overshoot. In the DD simulations the velocity overshoot in the channel is emulated by forcing the saturation velocity in the field dependent mobility model to values corresponding to the average velocity in the channel obtained from Monte Carlo (MC) simulation. To illustrate our approach we compare enhanced DD and MC simulation results for a pseudomorphic HEMTs with 0.12 μm channel length, which are in good agreement. The usefulness of the described methodology is illustrated in a simulation example of self aligned gamma gate pseudomorphic HEMTs. The effect of the gamma gate shape and the self aligned contacts on the overall device performance has been investigated.