Effect of Orientation of Crystal Face of Silver and its Alloying with Gold on Properties of Thin Anodic Ag(I) Oxide Films: II. Photopotential

D. A. Kudryashov, S. N. Grushevskaya, O. Olalekan, N. V. Kukhareva, and A. V. Vvedenskii

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received September 5, 2008

Abstract — The current efficiency of the formation of anodic oxide on polycrystalline silver is shown to decrease with an increase in the concentration of KOH solutions, while the rate-limiting stage remains the solid-phase mass transfer. Photopotential in nano-size Ag(I) oxide films anodically formed on polycrystalline silver is independent of the OH^–  ion concentration, which means that a photoresponse is generated in the bulk oxide. The n-type conductivity of oxide films on silver, Ag–Au alloys, and low-index silver crystal faces, which was determined previously when measuring photocurrent, is confirmed. Replacing polycrystalline silver with its monocrystals results in a substantial decrease in  the photopotential amplitude due to the decrease in the deviation from a stoichiometric composition. The electron mobility and the partial electronic photoconductivity in the anodic Ag(I) oxide depend on the orientatinon of the crystal face in silver and the gold content. At E = 0.56 V, a series of changes in these characteristics correlates to the changes in other structure-dependent parameters of Ag₂O oxide (the optical absorption coefficient , the concentration of donor defects N_D, the width of the spatial charge region W, and the Debye screening lengthL_D).