Spectral Investigation of Acoustoelectric Domains in n -GaAs by Microwave Emission Studies

Microwave emission from n-GaAs crystals, under conditions of current instability with propagating acoustoelectric domains, was detected and analyzed for various stages of the total acoustic flux level in such domains. Frequency range covered extended from 0.2 to 4.5 GHz. Diagnostic experiments indicate that the emission is due to the electromechanical conversion of the acoustic flux as the propagating domain hits the anode. The frequency spectrum of the emission shows various peaks that can be identified as sub-harmonics and sum frequencies. The experimental result is consistent with the theory of parametric conversions.