Whole-ingot annealed semi-insulating GaAs substrates for low-noise microwave amplifiers

The quality of liquid-encapsulated Czochralski (LEC) grown GaAs substrates critically affects the final low-noise microwave device and circuit performance as evidenced by comparing Si-implanted undoped, In-alloyed, and whole-ingot annealed semi-insulating substrates. We investigated differences in Si-implant activation, electrical profiles, and uniformity of material, device, and circuit parameters. The best noise figure of 1.33 dB at 10 GHz was measured on a 0.5-µm low-noise FET fabricated on the high-pressure whole-ingot annealed LEC wafer. A noise figure of 2.0 dB with associated gain of 24 dB at 10 GHz was achieved for a monolithic two-stage low-noise amplifier (LNA) fabricated on the standard high-pressure LEC substrate.