Solitary current-density patterns in thin ZnS : Mn films

We experimentally investigate pattern formation phenomena in the electrolum inescence of ac-driven ZnS:Mn thin films. Under suitable driving conditions , certain samples show a broad spectrum of patterns, which ranges from stat ionary filamentary distributions to traveling fronts and pulses. We present a survey of the bifurcation scenarios, choosing the frequency and amplitud e of the driving voltage as bifurcation parameters. Moreover, we investigat e the influence of the temperature an the dissipative current and pattern f ormation. The experimental results are used to identify activating and inhi biting processes, and a pattern formation mechanism based on autocatalysis and lateral inhibition is suggested.