LOW-FREQUENCY OSCILLATIONS IN GAAS-MESFETS

Two types of oscillations have been distinguished in the properties of the active channel of a GaAs MESFET, substrate voltage dependent and voltage independent oscillations. They have been shown to originate in the channel-substrate current. The various experimental evidence of the substrate origin of the oscillations is supported by a model in which the drain current is modulated by the substrate current through the variation of the width of the channel-substrate depletion region. The complex spectrum of the oscillations has been explained by a simple microscopic mechanism in which the oscillation of the occupation of the EL2 trap is modulated by the occupation of other traps.