Photoelectrochemical Effects of Surface Modification of n‐Type Si with Porous Layer

Effects of semiconductor surface modification on the photoelectrochemical properties have been studied experimentally and in detail for a porous Si layer (PSL) formed on n‐type Si substrates. The behavior of this electrode is characterized by the fact that the photoanodic current in aqueous electrolytes shows a considerable increase at the initial stage of operation. From the results of the interfacial impedance measurements, a model is proposed that may account for this behavior. According to the model, the initial increase in the photocurrent is due to the penetration of electrolyte into the PSL accompanied by photoanodic oxidation. Characteristics of the PSL oxidized prior to operation and those of the PSL operated in a nonaqueous electrolyte are consistent with this model.