Photoelectrochemistry of Doped and Undoped Semiconductors: A Comparison

Abstract

Recently, an experimental method was introduced which allows photoelectrochemical studies of nearly intrinsic semiconductors. In this simple technique, subbandgap illumination is used to make the bulk material photoconductive. A corresponding model explains this behavior in terms of a potential distribution which is similar to that one of a doped semiconductor. The method allows one to predict whether the time consuming process of chemical doping, for applications such as photoelectrolysis, is worth undertaking. The model proposed relies heavily on the photoconductivity of the insulator. We have now been able to observe the effect even on a number of very poor photoconductors, such as layered chalcogenides , , . In the case of , we can compare the photoelectrochemical studies of undoped semiconductors with chemically doped semiconductors. Furthermore, we find that the response at high photon energies caused by the subbandgap illumination scales indeed with the photoconductivity of the high resistivity semiconductors, lending additional support for the model.