Use of two-dimensional process and device modeling to solve somereal problems in GaAs MESFET design and analysis

摘要

A new, easy-to-use two-dimensional Poisson solver, GATES-2d, isdescribed. The program is used to address two problems that only atwo-dimensional simulator can answer: the problem of simultaneouslyminimizing short-channel effects, source resistances, and fringecapacitances in self-aligned MESFET technology, and analyzing parasiticcapacitances in recess-etched technology. Poisson's equation is solvedfor the electron concentration n(x,y)(assumed to obey Boltzmann statistics) in the presence of shallow donorsand acceptors and deep donors (EL2) and acceptors (Cr). 2D piezoelectricand surface-potential effects are included. With the results, analyticalcalculations are made of sheet resistances and saturated current atevery vertical slice. The total capacitance is computed by integratingthe electron concentration over the region simulated, and taking twicethe (half-FET) change with gate voltage