AlGaAs/InGaAs/GaAs heterostructures for pHEMT switching transistors

Abstract

The pHEMT heterostructures optimized in this work to improve the parameters of switching microwave transistors have a one-sided delta-doping at 6· 1012 cm-2 and an AlAs/GaAs spacer. Such heterostructures were used to fabricate the monolithic integrated circuits of single-pole double throw pHEMT switches with gate length and width of 0.5 μm and 100 μm, respectively. The resulting transistors had the following parameters: gmax=400 mS/mm, saturation current ID=380 mA/mm, ON-state resistance 1.0 Ω· mm, OFF-state capacitance 0.37 pF/mm. The switch parameters at 20 GHz are: insertion loss -2.2 dB, isolation -56 dB, return loss -11.7 dB, linearity P1 dB=21 dBm and IIP3=40 dBm. Keywords: Single-side doping, spacer design, maximal conductivity, pHEMT, switches.