Fabrication and noise performance of high-power GaAs IMPATTS

Schottky-barrier GaAs IMPATT diodes have been fabrirated in a double epitaxial layer structure on low-etch-pit density substrates. The resulting low defect density in the active region permits high power outputs and low noise measure. Mounted on copper studs and a 20°C heat sink, such diodes have given a maximum CW power output of 2.94 W at 6.1 GHz with 13.8 percent efficiency. The small-signal amplifier noise measure was 25dB. Operated as injection-locked oscillators, the noise measure was 32 dB at an output of 1 W. These results show that in a suitable structure, GaAs can surpass the efficiency and noise performance of other materials, and demonstrate the capability of high power output in this frequency band.