Indium phosphide: a semiconductor for microwave devices

Since 1970, InP has been developed as a material for microwave oscillators and amplifiers, with most interest to date being taken in transferred-electron devices. the physics of electron transport and of transferred-electron oscillators is reviewed; the features of greatest practical significance are the high potential oscillator efficiency set by the peak-to-valley ratio, which is approximately 3·5, of the velocity/field curve; studies of cathode-contact effects which have led to oscillator efficiencies over 20% and the observation of limited-space-charge-accumulation (l.s.a.) mode operation. Consideration is also given to other less developed InP microwave components, including transferred-electron small-signal amplifiers which have given noise measures of 8 dB at 15 GHz, and field-effect transistors for which encouraging preliminary results have been obtained.