High-Performance In0.3Ga0.7As/In0.29Al0.71As/GaAs Metamorphic High-Electron-Mobility Transistor

A new high-electron-mobility transistor (HEMT) using InAlAs/InGaAs grown by molecular beam epitaxy on GaAs has been successfully realized. This device, having an In content close to 30%, presents several advantages over conventional pseudomorphic HEMTs on GaAs as well as over lattice matched HEMTs on InP. High electron mobility with high two-dimensional electron gas density ( 25000 cm2/V·s with 3×1012 cm-2 at 77 K) as well as high Schottky barrier quality (V b=0.68 V with η= 1.1) has been obtained for this material system. A 0.4-µm-gate-length device showed an intrinsic transconductance as high as 700 mS/mm with f t=45 GHz and f max =115 GHz while a minimum noise figure of N F min =1.1 dB at 18 GHz has been obtained with a 0.2 µm device. This performance is, to the authors' knowledge, the first reported for submicrometer-gate metamorphic InAlAs/InGaAs/GaAs HEMTs.