A MECHANISM FOR CONDUCTION IN ELECTROLUMINESCENT SUBLIMATED THIN FILMS OF ZNS

The preparation of d.c. electroluminescent thin films of copper- and manganese-activated ZnS is described together with their electrical and luminescent characteristics. Films have been prepared from activated powders by sublimation in a horizontal two-zone vacuum furnace. Reproducible luminescent emission was obtained in the low-voltage operation range 10-20 V, and in a number of cases emission was observed at voltages as low as 7-8 V. Their electrical characteristics are governed by bulk conduction processes and show a strong dependence on deposition temperature. A theoretical model is proposed to explain the conduction mechanism in terms of bulk properties only. A relationship of the form V=A0+A1 ln I+A2I 1/2; was found to give good agreement with the experimental results.