Photo-depolarization spectroscopy, and the voltage dependence of transferred charge, were used to study the energy depth of defect states in Mn-doped electroluminescent structures. This revealed a hysteresis of the charge-voltage and luminance-voltage characteristics. The hysteresis effects were associated with the formation of self-organized patterns. It was shown that there was a correlation between the concentration and the energy depth of the defects in the film, on the one hand, and the hysteresis width (as well as the patterns observed), on the other hand.

Energy Levels of Defects in Electroluminescent ZnS:Mn Thin Films Exhibiting Hysteresis and Self-Organized Patterns. N.A.Vlasenko, Z.L.Denisova, L.I.Veligura, S.Zuccaro, F.J.Niedernostheide, H.G.Purwins: Journal of Crystal Growth, 2000, 214-215, 944-9