In0.52Al0.48As/InAs/InxAl1-xAs pseudomorphic HEMT's on InP

Abstract

The dc and microwave performance of an InAs channel HEMT is reported. Room-temperature electron mobility as high as 20 200 cm(2)/Vs is measured, with a high carrier concentration of 2.7x10(12) cm(-2). DC extrinsic transconductance of 714 mS/mm is measured and a unity-current-gain cut-off frequency of 50 GHz is obtained for a 1.1-mu m gate length HEMT. The success of achieving superior Hall mobility and device performance is strongly dependent on the InxAl1-xAs buffer layer design that changes the lattice constant from lattice-matched In0.52Al0.48As to In0.75Al0.25As. The multiple In0.52Al0.48As/InAs monolayer superlattices buffer achieves the best performance as compared to the step-graded InxAl1-xAs and the uniform In0.75Al0.25As buffer.