Injection electroluminescence in forward-biased ZnS metal–semiconductor diodes

Electroluminescence, electrical and noise properties are investigated of ZnS metal-semiconductor light-emitting diodes which exhibit blue emission under forward voltage bias U ⪆ ⪆ 1.8 V; the external efficiency of such diodes attains 0.1%. A conclusion is drawn that such electroluminescence may be due to the injection of holes excited in the contact by Auger processes into the semiconductor. It is found that the forward current and, as a result, the electroluminescence intensity are limited by effect of surface levels being filled with electrons in the course of forward current passing.