Improved characteristics of metamorphic InAlAs/InGaAs high electron mobility transistor with symmetric graded InxGa1-xAs channel

A metamorphic high electron mobility transistor with symmetric graded InxGa1-xAs channel has been successfully grown by molecular beam epitaxy system. Due to the lower interface roughness scattering. the improved electron mobility as high as 9500 (30 600) cm(2)/V s at 300 (77) K is achieved. By using the self-consistent method, three subbands in the graded channel are found, which is matched to the Shubnikov-de Haas data. By using the graded channel, In0.425Al0.575As Schottky layer, and undoped InP setback layer, a high gate breakdown voltage of 24 V is obtained. Meanwhile, the measured current gain cutoff frequency f(T) and maximum oscillation frequency f(max) for a 1.5 mum gate device are 18.9 and 48.4 GHz, respectively. (C) 2004 American Vacuum Society.