Work-function variation with alloy composition: Ag-Au

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Abstract
Auger electron spectroscopy has been used in situ to characterize the surfaces of evaporated silver-gold alloy films grown epitaxially on heated mica [(111) orientation]. The films were shown to be free of any detectable surface impurities. The known energy dependence of the electron escape depth in these metals was used to show that the alloy films had the same surface and bulk composition. The surface composition was determined by comparing Auger signals from the alloys with signals from pure metal reference standards evaporated simultaneously with the alloys. An electron-beam retarding potential method using the electron gun of the Auger spectrometer was used to determine the difference in work function between the alloys and the references. The measurements showed that the work functions of these alloys fall significantly below a linear interpolation between the values for the two pure materials. The change in work function with oxygen adsorption was found to be not linear in surface composition.