Low temperature grown GaAs lossy dielectric heterostructure FET

Abstract

A lossy dielectric FET has been realized and evaluated for the first time by employing /spl sigma/-LT-GaAs. 3.5 W/mm RF power capability extracted from the DC output characteristics give evidence for a field redistribution which overcomes the power limitation of Schottky gate FET devices. 60 GHz f/sub max/ values have been obtained for 1 /spl mu/m devices. Gate-drain breakdown voltages above 30 V have been identified at 2 GHz in conjunction with a channel sheet charge of 5/spl middot/10/sup 12/ cm/sup -2/. Parasitics, specific to the lossy dielectric have been widely eliminated. However limitations specific to the /spl sigma/-LT-GaAs material need still to be overcome, which is discussed.