AlGaAs/InGaAs/GaAs heterostructures for pHEMT switching transistors

The pHEMT heterostructures optimized in this work to improve the parameters of switching microwave transistors have a one-sided $\delta$-doping at 6 $\cdot$ 10$^{12}$ 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 $\mu$m and 100 $\mu$m, respectively. The resulting transistors had the following parameters: $g_{\mathrm{max}}$ = 400 mS/mm, saturation current $I_D$ = 380 mA/mm, ON-state resistance 1.0 $\Omega$ $\cdot$ 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 $P_{1\mathrm{dB}}$ = 21 dBm and II$P_3$ = 40 dBm.