0.03-μm gate-length enhancement-mode InAlAs/InGaAs/InP MODFET's with 300 GHz f_T and 2 S/mm extrinsic transconductance

We have developed high-performance enhancement-mode InP-based modulation-doped field-effect transistors with 0.03-μm gate-length. A record high current gain cutoff frequency exceeding 300 GHz has been achieved, and the maximum extrinsic transconductance is as high as 2 S/mm with an associated drain current of 0.5 A/mm at a drain bias of 1 V. This high performance is a result of the reduction of gate length, the use of the high barrier metal Pt as gate electrodes, and most importantly, the employment of the well-developed wet-etching technology that allows the formation of a very deep gate groove while retaining small side etching. The excellent E-MODFET performance opens up the possibility of implementing ever faster high-speed circuits based on direct-coupled FET logic.