On the impedance associate with electron-hole recombination in the space charge layer of an illuminated semiconductor/electrolyte interface

The impedance associated with recombination of free electrons and free holes in the space charge layer has been calculated. It has been shown that this impedance corresponds to a parallel-equivalent circuit of a capacitance and a resistance in parallel with the space charge layer capacitance. It has been calculated that the recombination capacitance has almost the same voltage dependence as the space charge layer capacitance, and that the recombination resistance is inversely proportional to the recombination rate in the space charge layer. The impedance associated with recombination in the space charge layer has been compared with the surface recombination impedance and with experimental results obtained at illuminated GaAs electrodes.