Fabrication of high breakdown pseudomorphic 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 0.3micrometer gatelength modulation doped field-effect transistors (MODFETs ) having a brakdown voltage up to 20 Volts. This technology uses mmolecular beam epitaxy (MBE) to grow the InGaAs/AlGaAs/GaAs heterostructure with two pulse doping layers on 3 inch semiisolating GaAs wafers. A mix and match lithography was applied using an i-line stepper and an eledtron beam diect write process to define the mushroom shaped gates (T-gates). The breakdown enhancement is achieved by a self aligned selective double dry etched gate recess using AlGaAs etch stop layers. We investigated the heterostructure doping and influence of the gate recess process to the device performance.