Characteristic Electroluminescence at the Semiconductor/Electrolyte Interface

Abstract

Electroluminescence (EL) of an n-type semiconductor can be observed when a hole, which is injected into the valence band by a strong oxidizing agent, and an electron recombine radiatively. The study of this EL is a valuable tool in the characterization of processes occurring at the semiconductor/electrolyte interface. The use of dopant ions, whose spectral properties are known, can provide extra information. An example is the characteristic Tb³⁺-emission in thin Ta₂0₅ films. Photoluminescence measurements indicate that the Tb³⁺-ion acts as a recombination center. The spatial origin of the EL can then be deduced from the decay time of the Tb³⁺-emission and from the relative intensity of the various 4f–4f transitions.