Performance of quarter-micron GaAs metal-semiconductor field-effect transistors on Si substrates

Abstract

Metal-semiconductor field-effect transistors (MESFET’s) having quarter-micron gate lengths were fabricated in GaAs films grown directly on 〈100〉 silicon tilted towards 〈110〉 by 4°. Following the growth of 2 μm undoped GaAs buffer layer a 3 μm GaAs doped with Si to a level of 3×1017 cm−3 was grown all by molecular beam epitaxy. Devices showed good dc characteristics with extrinsic transconductances as high as 360 mS/mm. Extrapolation of the short-circuit current gain calculated from scattering parameters measured up to 20 GHz indicated a current gain cut-off frequency of 55 GHz, which is comparable to the best MESFET on GaAs substrates. The noise figure measured at 18 GHz was 2.8 dB, which is about 1.4 dB higher than that on GaAs substrates.