Photocurrent multiplication at p-type semiconductor electrodes

A review is presented of photoelectrochemical systems which at p-type semiconductor electrodes give a quantum efficiency greater than one. The use of intensity modulated photocurrent spectroscopy (IMPS) for studying such systems is considered. Special attention is devoted to the mechanism of current-doubling at p-GaAs caused by oxidizing agents which also etch the semiconductor chemically. New data are presented for the photocathodic reduction of iodate in alkaline solution at p-GaAs. At low light intensity this system gives a quantum efficiency ( Q) close to 6.