VISIBLE-LIGHT EMISSION FROM A POROUS SILICON SOLUTION DIODE

Reduction of S2O82- ions at the interface between an n-type porous Si electrode and an aqueous solution gives rise to electroluminescence showing evidence of quantization effects. A broad emission band with a maximum at 670 nm is observed similar to the photoluminescence spectrum of the same layers. The results suggest that holes are "injected " into the valence band of the porous semiconductor from an intermediate of the reduction reaction, the SO4-. radical ion. The resulting electron-hole recombination is responsible for the visible light emission.