NUMERICAL-ANALYSIS OF THE LOOPING EFFECT IN GAAS-MESFETS

Abstract

The looping effect in the I(D)-V(D) characteristics of GaAs MESFET's on semi-insulating substrates has been studied using a two-dimensional numerical analysis. Both the transient and the steady-state behaviors of the looping phenomenon are simulated and discussed. Peak voltage- and frequency-dependent behaviors of the looping effect are analyzed. The I(D)-V(D) loop is due to the difference in the distribution of ionized EL2 concentration when the drain voltage rises and falls because of the trapping process of EL2's. The output conductance is also found to be frequency-dependent and is explained by the frequency-dependent modulation of the potential barrier height at the channel/substrate interface due to the drain-voltage variation.