Photoluminescence at a semiconductor-electrolyte contact around and beyond the flat-band potential

Photoluminescence measurements have been performed to study CdSe-, CdS-, and GaP- electrolyte contacts under cathodic bias. A strong increase of the luminescence intensity has been found in those cases where an accumulation layer is formed at the interface. This potential dependence is interpreted in terms of aquenching of surface recombination by the repulsive field in the space charge region which impedes the minority carriers to reach the surface. A theoretical description based on the Stevenson-Keyes approach for recombination is derived by introducing an exponential potential dependence of the surface recombination rate into the calculations of the luminescence generation in the bulk of the semiconductor