A temperature (T) rise from 20 up to 80 °C results in some decrease of the threshold voltage and slope of the voltage (V) dependences of the luminance and the transferred charge of the electron‐beam evaporated ZnS:Mn ac thin film electroluminescent structures (ac TFELS) showing different patterns or no patterns in the emission. Such a heating leads to an improvement of the dynamics of all the patterns, to a narrowing and acceleration of the autowave (AW) front. However, the dynamic patterns are not formed by such a heat treatment if they are absent at any frequency of V and T = 20 °C. Although AWs more often take place at 70–80 °C, they have also been observed at T ≤ 40 °C in some samples. It has been concluded that heating is not a sufficient condition for the formation of patterns. It enhances the generation of initial free electrons at a given V, promotes a lateral spreading of the non‐equilibrium charge carriers, but decreases the rate of all processes responsible for the bistability of the TFELS and the self‐organization in them.
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. Moreover, we investigate the influence of the temperature on the dissipative current and pattern formation. The experimental results are used to identify activating and inhibiting processes, and a pattern formation mechanism based on autocatalysis and lateral inhibition is suggested.
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