Sulfur passivation of GaAs metal-semiconductor field-effect transistor

Abstract

A passivation technique consisting of a (NH4)2S dip followed by GaS deposition has been applied to a GaAs microwave-power metal–semiconductor field-effect transistor (MESFET). The breakdown characteristic of the MESFET is greatly improved upon the (NH4)2S treatment, and a stable passivation effect can be achieved by GaS film deposition. It is found that the FET current–voltage characteristics are closely related to variations in the pinning position of the GaAs surface Fermi level. With the surface passivated, a depletion layer can be properly formed and protected, which is of benefit to the control of the device parameters.