Radio frequency transistor amplifiers having widened and/or asymmetric source/drain regions for improved on-resistance performance

Abstract

A gallium nitride-based RF transistor amplifier comprises a semiconductor layer structure comprising a barrier layer on a channel layer, first and second source/drain regions in the semiconductor layer structure, first and second source/drain contacts on the respective first and second source/drain regions, and a longitudinally-extending gate finger that is between the first and second source/drain contacts. The first and second source/drain contacts each has an inner sidewall that faces the gate finger and an opposed outer sidewall. The first source/drain region extends a first distance from a lower edge of the inner sidewall of the first source/drain contact towards the second source/drain region along a transverse axis that extends parallel to a plane defined by the upper surface of the semiconductor layer structure, and extends a second, smaller distance from a lower edge of the outer sidewall of the first source/drain contact away from the second source/drain region.