ABSTRACT
We have developed a recess gate process to fabricate high electron mobility transistors (HEMTs) of enhancement and depletion type on two inch GaAs wafers. The vertical HEMT structure is grown by molecular beam epitaxy (MBE). The gates are written by e-beam lithography and are recessed by dry etching. Mushroom shaped gates of dimension of 0.4 µm for Lg = 0.1 μm are used to reduce the gate resistance. The average threshold voltage for D- and E-type FETs is −500 mV and 100 mV respectively with a standard deviation of ≤ 20 mV over a 2″ Wafer with Lg = 0.3 μm.
