Nature of luminescence transition in low-resistivity n-type ZnS single crystals

The cathodoluminescence spectra of low-resistivity n-type ZnS single crystals were recorded. The emission peak energy shifted towards higher energies with a corresponding decrease in the half-width of the emission band as the temperature was decreased. Time-resolved emission spectra and the decay of luminescence were measured at 77 K, in which the energy of the emission band at its maximum shifted to lower energies during decay. The decay of luminescence was found to be non-exponential. These studies gave experimental evidence that the blue self-activated emission of low-resistivity n-type ZnS crystals is of the donoracceptor pair transition nature, and thereby the difference of emission peak energy for emitting ZnS diodes with different Schottky contacts was interpreted.