A new approach to the determination of gate length and other parameters of GaAs MESFETs and MODFETs

Abstract

In this paper, we present a new method for determining the major parameters for short-gate length GaAs MESFETs and MODFETs, such as the metallurgical gate length, parasitic pad capacitance, gate fringe capacitance and effective gate length. These are deduced from the zero bias low-frequency FET capacitance-voltage characteristics with different gate widths. The main assumption is that the measured FET gate capacitance can be represented as a sum of three components: gate-channel capacitance, fringe capacitance and pad capacitance. We assume that the gate-channel capacitance is proportional to the measured Schottky diode capacitance, and that the pad capacitance is independent of the gate voltage. The results obtained by applying this method to short-gate length devices are given.