On avalanche processes in electroluminescence of single ZnS-Cu crystals

The electrical, photoelectrical and luminescent properties of single crystals (30 to 50 microns in size) of commercial ZnS-Cu electroluminophore with green emission have been investigated. The dependencies of dark current, photocurrent and luminescence brightness on the applied voltage have been found to reveal a greater complexity than those obtained for polycrystal samples.When the d.c. voltage applied to the crystal rose above 4 volts the dark and photo electrons were observed to multiply, this being accompanied by emission. The observed dependence of the multiplication coefficient on the applied voltage resembles in shape the curves obtained for other substances (Ge, Si, ZnO).