FABRICATION OF HIGH BREAKDOWN PSEUDOMORPHIC MODULATION-DOPED FIELD-EFFECT TRANSISTORS USING DOUBLE DRY-ETCHED GATE RECESS TECHNOLOGY IN COMBINATION WITH E-BEAM T-GATE LITHOGRAPHY

We have developed a technology to fabricate pseudomorphic 0.3 mu m gat elength modulation doped field-effect transistors (MODFETs) having a b reakdown voltage up to 20 Volts, This technology uses molecular beam e pitaxy (MBE) to grow the InGaAs/AlGaAs/GaAs heterostructure with two p ulse doping layers on 3 inch semiisolating GaAs wafers. A mix and matc h lithography was applied using an i-line stepper and an electron beam direct write process to define the mushroom shaped gates (T-gates). T he breakdown enhancement is achieved by a self aligned selective doubl e dry etched gate recess using AlGaAs etch stop layers, We investigate d the heterostructure doping and the influence of the gate recess proc ess to the device performance.