Determination of the Thicknesses of Single-Layer Coatings Exposed to Ion Bombardment by X-Ray Photoelectron Spectroscopy

Abstract

Samples of single-crystal silicon coated with gold nanolayers are investigated. The samples are obtained by two methods, namely, gold sputtering using a Xe⁺ beam with an initial energy of 7 keV and the method of thermal deposition. The preliminary analysis of samples based on deciphering the energy spectra of reflected protons with an initial energy of 25 keV is performed. By the methods of angle-resolved X-ray photoelectron spectroscopy (ARXPS), the thicknesses of the gold coatings on silicon are determined. Analysis of the samples using X-ray photoelectron spectroscopy is performed by comparing the intensities of the Au 4 f and Si 2p maxima measured at different angles of photoelectron detection. The calculations carried out by traditional methods indicate a marked dependence of the calculated gold-coating thickness on the angle of sight for the case of single-layer- and subsingle-layer coatings. It is shown that such a discrepancy is possible if gold is deposited onto silicon in the form of clusters forming islands rather than in the form of a continuous homogeneous coating. The possibility of gold islands moving relative to silicon in upper silicon layers subjected to proton bombardment at grazing angles to the surface is discussed.