TIME DEPENDENCE OF SPECTRAL COMPONENTS OF THE ELECTROLUMINESCENCE OF ZNS SINGLE CRYSTALS.
Part C of final rept.,
NATIONAL ELECTROTECHNICAL INST TURIN (ITALY)
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The paper discusses results of measurements about the time dependence of the monochromatic components of the light emitted by Electroluminescent ZnS single crystals, Cu activated, subjected to a sinusoidal voltage. The light was analyzed with a spectrometer and its time dependence was digitally recorded using a time-to-pulse height conversion technique. The light of two crystals, one labelled A exhibiting blue and green EL, the second labelled B exhibiting blue, very weak green and red EL, was analyzed at 77 degrees K. Both with respect to the exciting voltage and to each other the spectral components of crystals A and B appear nearly in phase, although small time lags, of the order of 0.1 period, different for each component, were actually measured. Between the alternances of the exciting voltage the light does not fall to zero, the relative importance of the continuous light pedestal being different for the various spectral bands. No obvious relationship, however, with the decay times has been found. These results are compared with the few data available from the literature and their relevance as to the mechanism of the EL is briefly discussed. Author