Die Bestimmung des Frequenzfaktors und der Haftstellentiefe aus der Temperaturabh�ngigkeit der Elektrolumineszenz von ZnS-Phosphoren

Abstract

The temperature dependence of the a.c. electroluminescence of ZnS-phosphors shows characteristic features which are closely related to the energetic distribution of traps. Measurements over a wide range of exciting field frequencies are used to determine frequency factors and trap depths with high accuracy. The order of magnitude of the obtained frequency factors agrees with theoretical values and results of other authors, who investigated CdS single crystals by different methods. The trap depths resulting from electroluminescence measurements are lower than those estimated from glow curves. This deviation can be explained by considering multiple retrapping and a low quantum efficiency of the thermoluminescence. An expression for the trap depth in dependence of the temperature of a glow maximum is derived, which is valid for all kinetics of thermoluminescence.