Design and characteristics of strained InAs/InAlAs composite-channel heterostructure field-effect transistors

摘要

We report composite-channel heterostructure field-effect transistors (HFETs) with an InAs channel and an In_(0.9)Al_(0.1)As subchannel. The HFETs are grown on antimonide buffer layers. Two composite-channel structures with different planar Te doping schemes are designed, fabricated, and characterized. High radio-frequency transconductances of above 0.9 S/mm and ～55 GHz current gain cutoff frequencies are achieved in devices with 500 nm gates. Planar Te doping in the buffer layers reduces the high kink-effect currents otherwise found in InAs/AlSb HFETs, an effect which can be attributed to either increased breakdown field in the In_(0.9)Al_(0.1)As subchannel or to suppression of hole blocking in the buffer. The present limitations to device performance and suggested approaches for their elimination are discussed.