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. Regim es of periodic, quasi-periodic, and stochastic self-oscillations are determ ined and mechanisms for their formation are discussed. It is shown that the self-oscillation spectra are many-valued functions of the external field a mplitude and the static field in them is either absent, weak, or fractional ly quantized. Previously predicted states of self-induced superlattice tran sparency and dynamic electron localization are destroyed as a result of the evolution of dissipative and parametric instabilities and can only be obse rved in transient processes whose duration decreases with increasing electr on concentration. (C) 2000 MAIK "Nauka/Interperiodica".