Microwave oscillations in epitaxial layers of GaAs

Microwave oscillations of the type reported by Gunn have been observed in samples prepared from epitaxial layers of gallium arsenide. Descriptions of sample preparation and measuring techniques are included. The frequency of oscillation ranged from 7 to 14 GHz. The samples, which were prepared from 16.5 to 25µ thick layers, had cross sections that were 0.25 mm and 0.5 mm square. Peak output power ranged from 50 to 200 mW at the higher frequencies to 0.5 to 1.5 W at the lower frequencies. Typical efficiencies ranged from 4 percent to 6 percent.