Solitary current-density patterns in thin ZnS:Mn films.

We experimentally investigate pattern formation phenomena in the electroluminescence of ac-driven ZnS:Mn thin films. Under suitable driving conditions, certain samples show a broad spectrum of patterns, which ranges from stationary filamentary distributions to traveling fronts and pulses. We present a survey of the bifurcation scenarios, choosing the frequency and amplitude of the driving voltage as bifurcation parameters.