Abstract: The monolithic integration of enhancement- and depletion-mode (E/D-mode) InGaP/AlGaAs/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) with a 1.0μm gate length is presented.Epilayers are grown on SI GaAs substrates using MBE.For this structure,a mobility of 5410cm2/(V·s) and a sheet density of 1.34e12cm-2 are achieved at room temperature.During the gate fabrication of E/D-mode PHEMTs,a novel two-step technology is applied.The devices with a gate dimension of 1μm×100μm exhibit good DC and RF performances.Threshold voltages of 0.2 and -0.4V,maximum drain current densities of 300 and 340mA/mm,and extrinsic transconductances of 350 and 300mS/mm for E- and D-mode PHEMTs are obtained,respectively.The reverse gate-drain breakdown voltage is -14V for both E- and D-mode.Current-gain cutoff frequencies of 103 and 124GHz and power-gain cutoff frequencies of 12.8 and 14.7GHz for E- and D-mode are reported,respectively.

Key words: pseudomorphic high electron mobility transistors, enhancement-mode, depletion-mode, threshold voltage, GaAs