Atomic Level Studies of Se Electrodeposition on Au(111) and Au(110)

摘要

Studies of the electrodeposition of Se atomic layers of Au(111) and Au(110) arepresented. Three electrochemical methods of forming Se atomic layers were investigated: reductive deposition, oxidative stripping of bulk Se, and reductive stripping of bulk Se. The resulting Se atomic layers were studied using low energy electron diffraction (LEED), Auger electron spectroscopy (AES), and scanning tunneling microscopy (STM). LEED indicated the formation of Au(111) ( square root of 3 X square of 3)R30 deg-Se and Au(110)(2X3)-Se structures. STM analysis confirmed the presence of those structures along with several others. At low Se coverages on Au(111), a mosaic structure was formed, composed of a large number of small domains of a (square root of 3 X square root of 3)R30 deg-Se structure, separated by areas void of Se. At higher coverages, near 1/3, the (square root of 3 X square root of 3)R30 deg structure covered most of the surface, except for a number of linear phase boundaries. Commensurate with completion of the (square root of 3 X square root of 3)R30 deg structure, some domains of square Se8 rings were usually evident, as well. At still higher coverages, a heterogeneous surface was formed, composed of a complex network of rings, chains, clusters and pits. This heterogeneity appears to result from slow deposition kinetics, probably the result of both a low exchange current and Se surface mobility.