Silver-Silicon Bonding on Silica Surfaces

摘要

The properties of Ag films deposited on silica or silica-based glass substrates have been investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), ion scattering spectrometry (ISS), and secondary ion mass spectrometry (SIMS). Interfacial studies are reported for films prepared by decomposing organometallic Ag on glass, depositing Ag by the wet chemical electroless method onto glass and SiO sub 2 , and vacuum evaporating Ag onto SiO sub 2 . For organometallic Ag films on glass, depth profiles indicate that the interfacial regions are enriched in Si or depleted in O. For electroless films, Sn-Si bonds are formed after sensitization with tin chloride and Ag-Si bonds are formed after silvering without reducers. Silver is strongly bonded to Si via a set of Sn insertion reactions, but impurities were found at the interfaces and these probably contribute to the rapid degradation of mirrors in terrestrial environments. Particle bombardment of silica with He, Ne, Ar or electrons in the range of 0.25 to 8 keV results in reduction of the surface to form SiO/sub x/ (x 2). Although complete reduction was not observed, enrichment of the surface in Si prior to vacuum deposition of Ag improves the adhesion of the film. Angle resolved XPS and ISS on one monolayer of evaporated Ag and SiO sub 2 indicate that Si is preferentially masked by the Ag, suggesting that Ag is in an atop position over the Si atoms in silica. (ERA citation 11:000414)