Two-dimensional simulation of submicrometer GaAs MESFETs: surface effects and optimization of recessed gate structures

The surface potential effect in GaAs MESFETs causes a depleted zone to form not only between the source and gate, but also between the gate and drain. The consequences of this phenomenon on the device behavior, the DC and AC characteristics, and the expected performance are studied. For this purpose, a two-dimensional resolution of the basic semiconductor equations is used. This model takes into account relaxation effects by including an energy relaxation equation. The dependence of MESFET characteristics such as transconductance, output conductance, and capacitance on the dimensions of the zone where surface potential effects occur is given. Some interesting conclusions concerning the optimization of recessed-gate structures are drawn