Ultrahigh-speed pseudomorphic InGaAs/InAlAs HEMTs with 400-GHz cutoff frequency

Abstract
An excellent cutoff frequency (f/sub t/) as high as 400 GHz was successfully realized in 45-nm-gate pseudomorphic InGaAs/InAlAs high electron mobility transistors (HEMTs). An additional vertical gate-recess suppressed short-channel effects, while keeping good pinchoff characteristics. Gate length (L/sub g/) dependence of electron transit time (/spl tau//sub transit/) implied an increased saturation velocity (/spl upsi//sub s/) of 3.6/spl times/10/sup 7/ cm/s in the developed pseudomorphic HEMTs. This f/sub t/ is the highest value ever reported for any transistors to date.