Abstract
Electroluminescence, thermoluminescence, and thermoluminescence under an applied voltage have been studied in ZnS single crystals. For electroluminescent crystals, the application of a constant electric field during thermoluminescence generally increases the intensity of the emitted light over the sum of the intensities due to the thermoluminescence and to the electroluminescence separately. A similar effect was observed during phosphorescence and during infrared stimulation. No such effects were observed on non-electroluminescent crystals. It was also found that an electric field can fill electron traps, but field emptying of traps did not appear to be important.The current during the electroluminescence and during the thermoluminescence was measured simultaneously with the light emission. There was little correlation between current and thermoluminescence, but quite good correlation between current and the additional light resulting from a constant voltage during the thermoluminescence. These results suggest that some of the electrons released from traps contribute to the current and can cause impact excitation or ionization, but that others are not effective in this. Since both the current and the additional light are considerably higher during the high-temperature glow peak than during the low-temperature one, it appears that the electrons released from the deeper traps are more effective in these processes than those released from the shallower traps.
Published Version
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