Parametric interaction of space-charge waves in asymmetric thin-film n-GaAs structures

Abstract

Based on a theory developed previously, parametric interaction between space-charge waves in thin-film semiconductor structures with negative differential conductivity is analyzed. The analysis is carried out in the approximation that the drift flux of charge carriers has a rigid boundary and under the assumption that the frequency of low-frequency pumping equals the cutoff frequency fc of waves being amplified (fc roughly equals 30 GHz in our case). For asymmetric structures, a general multimode set of coupled equations is reduced to a pair of differential equations for the excitation amplitudes of the fundamental space-charge mode at the signal frequency ωs and idler frequency ωi=ωs−ωp. The equations are solved numerically for n-GaAs-based structures, and the solution obtained is discussed.