Low-noise and high-power GaAs microwave field-effect transistors prepared by molecular beam epitaxy

The low-noise FET’s prepared on molecular-beam-epitaxial (MBE) layers have a noise figure of 1.9 dB with a corresponding gain of 11 dB at 6 GHz. The power FET’s can produce 1.3 W at 4.4 GHz (1-dB compression) with a gain of 10 dB and a power-added efficiency of 35%. The influence of substrate preparation on Hall mobility for very thin layers was also studied and there is no evidence of Cr diffusion from the substrate at the MBE growth temperature.