GaAs ICs for Digital Applications

Abstract

GaAs integrated circuits (ICs) are used for digital circuits because they feature high-speed operation, low power dissipation, and good radiation hardness. GaAs IC chips consist of circuit elements and interconnections on a semi-insulating substrate. High-speed IC chips have to be mounted in low-capacitance packages for low-distortion waveform transmission. The most significant element of an IC is the switching transistor, which determines the intrinsic switching speed of the IC. This chapter describes MESFETs (metal—semiconductor field-effect transistors) and MIS/SIS FETs (metal-insulator-semiconductor and/or semiconductorinsulator-semiconductor FETs) as switching transistors in ICs. Self-aligned FET structures and process technologies for low-resistance source and drain n + layers are essential to obtain very high speed operation, which is considered the role for GaAs ICs, especially in Japan.