Comparison of 80 nm-200 nm gate length Al/sub 0.25/GaAs/GaAs/Al/sub 0.25/GaAs, Al/sub 0.3/GaAs/In/sub 0.15/GaAs/GaAs and In/sub 0.52/AlAs/In/sub 0.65/GaAs/InP HEMTs

Abstract

This paper describes a comparative analysis of the high frequency performance of 80-200 nm gate length high electron mobility transistors (HEMTs) fabricated on three material structures having different 2 dimensional electron gas (2DEG) transport properties. The higher effective velocity of carriers in the channel of pseudomorphic InGaAs/InP devices resulted in 80 nm gate length devices with f/sub T/'s of 275 GHz. Device output resistance was found to be strongly material dependent. At the shortest gate lengths, the device f/sub max/ was limited primarily by the gate resistance. Additionally however, f/sub max/ was significantly affected by both the contribution of the gate drain capacitance to the total gate capacitance and the magnitude of the output resistance.<>