Two dimensional numerical simulation of submicron GaAs MESFETs

A two-dimensional numerical simulation of a GaAs MESFET with 0.7-μm gate length is performed. The drift-diffusion model, which considers mobility as a function of local electric field, and the energy transport model, which considers mobility as a function of energy are investigated, and the results are compared and examined. The control-volume formulation is used as the discretization method, and, as a numerical scheme, the current hybrid scheme or upwind scheme is replaced by a power-law scheme. The I-V characteristic of the energy transport model is much larger than that of the drift-diffusion model; hence, the energy transport model is a good fit for the submicron GaAs MESFET device. The mechanisms of velocity saturation in the drift-diffusion model and velocity overshoot in the energy-transport model are described from the standpoints of velocity, energy, and electric field distribution at the bottom of the channel