Problems and prospects of compound semiconductor field‐effect transistors

The application of binary, ternary, and quaternary semiconducting III– V compounds for high frequency field‐effect transistors (FETs) and microwave integrated circuits (ICs) presents hitherto unavailable options and challenging problems which arise from the inherent bulk and surface properties of these materials and of the interfaces between them and metal or dielectric overlayers. Although the depletion‐mode (normally‐on) Schottky barrier gate GaAs transistor is the older and, at this stage, more advanced technology, alternative approaches based primarily on insulated gate FETs and other materials such as InP, InxGa1−xAs, and InxGa1−xAsyP1−y have been demonstrated to have important advantages for enhancement type (normally‐off) as well as depletion‐ and inversion‐mode insulated gate FETs, a potential high frequency analog of the lower frequency silicon MOS technology. The problems and prospects of such devices and structures as well as those of a variety of Schottky barrier gate and heterojunction gate t...