Self-oscillations in semiconductor superlattices

An investigation is made of nonlinear oscillations of the field and current in semiconductor superlattices driven by strong terahertz radiation. Regimes of periodic, quasi-periodic, and stochastic self-oscillations are determined and mechanisms for their formation are discussed. It is shown that the self-oscillation spectra are many-valued functions of the external field amplitude and the static field in them is either absent, weak, or fractionally quantized. Previously predicted states of self-induced superlattice transparency and dynamic electron localization are destroyed as a result of the evolution of dissipative and parametric instabilities and can only be observed in transient processes whose duration decreases with increasing electron concentration.