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Sputtering yields of compounds using argon ions.

Seah, M P; Nunney, T S* (2010) Sputtering yields of compounds using argon ions. J. Phys. D, Appl. Phys., 43 (25). 253001

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An analysis is made of published sputtering yield data for compounds using argon primary ions at normal incidence to evaluate the validity of simple predictive equations. First, two archetypal compounds are analysed: GaAs with constituent elements of similar atomic number and weak preferential sputtering, and Ta2O5 with constituent elements of widely separate atomic number and strong preferential sputtering. The agreement of the sputtering yields predicted by the semi-empirical linear cascade theory is excellent when the appropriate parameters are interpolated, rather than using an average atomic number. The effect of preferential sputtering is included within the framework of the simple pair-bond theory. The average ratios of the data to the initial predictions for GaAs and Ta2O5 are 1.01 ± 0.06 and 1.00 ± 0.07, respectively. Extension of this analysis to a range of oxides shows that the heat of reaction of the oxidation process needs inclusion. It is here that the effect of preferential sputtering can lead to an expansion of the uncertainties. SiO2 is often used as a reference material and so the published yield data are analysed in detail. These show an extremely broad scatter and so new data are measured. These new results are in the upper range of previous data and correlate with the semi-empirical theory with a scatter of only 9%. These correlations show that the semi-empirical linear cascade theory is excellent for predicting the energy dependence of the yield and can be excellent for absolute yields where the compound heat of formation is low.

Item Type: Article
Keywords: Argon ions, GaAs, SiO2, Sputtering yields, Ta2O5
Subjects: Nanoscience
Nanoscience > Surface and Nanoanalysis
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4671

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