Noise-induced current oscillations in superlattices:: from stationary to moving domains

We provide a detailed understanding of the transition between stationary and moving domains in semiconductor superlattices. We show that it corresponds to a global bifurcation (saddle-node infinite period bifurcation on a limit cycle or SNIPER). The dynamics close to such a bifurcation is moreover very sensitive to noise. We show that front motion, and hence current oscillations, can be induced by shot noise of the tunneling processes even if the deterministic system exhibits a stable stationary field domain.