The transport of photogenerated electrons through porous n-GaP electrodes has been investigated with Intensity Modulated Photocurrent Spectroscopy. Porous layers with a thickness of between 1 and 200 pm were formed on GaP substrates by anodic etching of crystalline n-GaP electrodes. They consist of a network of crystalline GaP interpenetrated with the electrolyte. It is shown that the transit time of photogenerated electrons through the depleted porous network is larger than the RC response time. Hence, IMPS performed in the frequency window below (RC)-' directly probes the transient photocurrent flow in the depleted porous network. The relatively long transit times observed with IMPS are attributed to strongly meandering paths of the photogenerated electrons through the crystalline network, probably determined by the potential distribution in the depleted network.

It has been found that porous GaP photoanodes show considerable photocurrent when illuminated with sub‐bandgap light, in contrast to flat electrodes. The origin of this enhanced response to sub‐bandgap light was investigated. Due to the morphology of the porous structure, photons are more effectively absorbed. Light absorption by surface electronic levels is found to be an important source of sub‐bandgap photocurrent.

An interpenetrating GaP and gold nanometer‐scale network system has been formed by electrochemical deposition of the metal on a nanoporous n‐type semiconductor GaP network. The electrical characteristics of the system–in particular capacitance and current–voltage measurements–indicate that a semiconductor/metal Schottky barrier junction with a huge internal contact area is produced, which could find applications in solid‐state electronic devices.

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Cadmium telluride (CdTe) has been etched for the first time in a 2M H2SO4 solution in the presence of Ce4+. The etching rates have been obtained by means of step measurements. They are proportional to the Ce4+ concentration and to the dipping time and are close to etching rates obtained for III-V compounds under the same conditions. The etching rates show no decrease with time in the concentration range studied ( 10-4 M-10-1 M) even for large steps (several µ m). Etching rates up to 0.1 µ m/min have been obtained, which can be increased by a factor of about 10 by ultrasonication. The evolution of composition of the sample surface has been investigated by means of X-ray photoelectron spectroscopy (XPS) analysis. Elemental tellurium-rich, oxide-free surfaces are obtained after etching in the presence of Ce4+.