Recent developments in heterostructure transistors

摘要

Heterostructure transistors, PMODFETs and HBTs are reviewed. The PMODFET, alleviates the DX center problem of the conventional MODFETs and provides an InGaAs chaennel with superior properties. A MODFET exhibited a power gain of 7.3 dB at 140 GHz and a noise level of 1.4 dB near 90 GHz. As for HBTSs, AlGaAs/GaAs, GaInP/GaAs, InP/InGaAs, AlInAs/InGaAs, and siGE/Si have been exploited. Current gaincut off, f_t, and maximum oscillation, f_(max), frequencies are about 100 GHz and 200 GHz, reespectively. SiGe HBTs exhibited f_t's in exess of 100 GHz with applications in Ad converters and PCS. Metal insulator semiconductor structures utilizing Si interface and Si_3N_4 dielectric la7ers exhibit inversion field effect transistors.