A New Heterojunction-Gate GaAs FET

Abstract

A new type of GaAs FET having a heterojunction gate is proposed. The structure involves a double epitaxial layer of n-GaAs for the channel and p-GaAlAs for the gate which can be easily formed by the self-alignment technology using an over-deposited titanium film. The potential advantage of the new structure over the conventional Schottky-barrier gate FET is that the fabrication process requires fewer masks due to the selective etching of p-GaAlAs and the self-aligned gate formation. In addition, the heterojunction gate is so endurable to high temperature heat-treatments that will be favourable for integration process. The proposed structure, the fabrication technology, and the dc characteristics of the new devices are described in full detail.