Epitaxial ZnS MπS Blue Light Emitting Diode Fabricated on n+-GaAs by Low-Pressure Metalorganic Vapor Phase Epitaxy

Au/π-ZnS/n+-ZnS (metal-π-semiconductor) light-emitting diodes have been fabricated on n+-GaAs substrates by metalorganic vapor phase epitaxy. Blue electroluminescence (EL) was observed at room temperature when the positive and negative bias voltage were applied to the Au contact. It has been found under the forward bias (Au:+) that EL is emitted near the interface between the n+-ZnS and GaAs substrate, while a fairly bright blue EL is observed near the Au contact under the reverse bias (Au:-). It has been shown that these emissions are caused by impact ionization of accelerated electrons in high a field.