Photoelectro-ionic processes in photoinduced surface deposition of metallic silver on a chalcogenide glass

To understand the mechanism of Ag+ migration in the phenomenon of photoinduced surface deposition (PSD) of metallic silver, the photoelectro-ionic properties of glasses showing the PSD phenomenon have been studied using Ag-rich Ag-As-S glasses. From the Dember and photovoltaic effects of the glasses, it is suggested that the glasses are p-type semiconductors and that the photoexcited electrons can be trapped by the Ag particles deposited by the PSD phenomenon, The depth profile of the Ag concentration after photodeposition was examined by electron-probe microanalysis to determine the consumption of Ag at the illuminated surface. The profile was found to be almost constant from the illuminated surface to the deep interior of the glass, suggesting that Ag+ ions deeper than 1 mu m can migrate in counterflow to the hole motion. Accordingly, Ag+ migration in the PSD phenomenon can be accounted for both by the Coulomb force induced by the trapped electrons and coupled ion-hole motions deep inside the glass.