Investigation of argon ion bombarded Re x Si 1-x thin film composites by XPS, SEM and AES

Abstract

The electronic structure of argon ion bombarded RexSi1-x films (∼ 100 nm) were investigated by X-ray photoelectron spectroscopy. Argon ion bombardment leads to preferential sputtering of the silicon atoms and produces an subsurface rhenium enrichment. Changes in the core level binding energies and in the valence band structure have been studied as the rhenium concentration in the composites varies between 0 ≤ x ≤ 1 through the metal-semiconductor transition at x ≈ 0.32. The data of the multiplex spectra were subjected to factor analysis in order to determine the relevant components of the ion bombarded metal-silicon system. Four principal components are extracted and are proposed as the pure elements, a rhenium-rich phase and a component near the ReSi2 stoichiometry. Complementary investigations by SEM and AES provide further proof of the phase assignment in the rhenium-rich component. The silicon-rich component being in composition close to the metal-semiconductor transition can be correlated to the ReSi2 compound.