High performance low noise FETs operating from X-band through Ka-band

Electron beam defined 0.5 µ gate low noise FETs have been made using various types of GaAs channel layers in order to correlate the method of material preparation with device performance in the frequency range between 12 GHz and 30 GHz. The channel layers were made by vapor phase epitaxy (VPE), ion implanted liquid phase epitaxy (LPE) and direct ion implantation into boat grown (HB) Cr-doped and liquid encapsulated Czochralski (LEC) undoped substrates. The devices, which have a gate width of 300 µm, have demonstrated excellent high gain and low noise performance over a wide range of frequencies from 12 GHz through 30 GHz. Device fabricated on VPE delivered 6.2 dB gain across a 2.5 GHz bandwidth at 30 GHz. The latter result was obtained from a single stage 30 GHz Waveguide/Microstrip amplifier, This amplifier, although not optimized for noise, has demonstrated less than a 5 dB noise figure across its bandwidth, In this paper we will discuss the state-of-the-art high frequency device performance and the device characterization results as related to the method of channel layer fabrication.