Silver layers on oxide surfaces: morphology and optical properties

Trends in the wetting of oxide substrates by silver are tested by surface differential reflectance via the determination of the aspect ratio of the silver clusters: (i) the wetting of α-Al2O3(0 0 0 1) substrates by silver, which is quite poor, is strongly improved by titanium predeposition, provided that the titanium is metallic; (in particular, the exposure of the silver/titanium/alumina system to oxygen leads to a dewetting of the silver layer;) (ii) On a less insulating substrate than alumina (8.9 eV band gap), the ZnO(0 0 0 1̄)–O surface (3.3 eV band gap), silver forms clusters with much higher aspect ratio (diameter/height) than on alumina. However, in all cases, silver films growth in a Volmer–Weber mode.