Validity of film-thickness estimates based on angle-resolved X-ray photoelectron spectroscopy using various inelastic mean-free-path formulae

Abstract

We investigated the thickness of Ag on a W(001) substrate and the native oxide on top of a Si0.8Ge0.2 alloy grown on Si(100) substrate. We used X-ray photoelectron spectroscopy to confirm the consistency of various inelastic mean-free-path formulae. Because the Ag/W(001) system is composed of four core levels (W 4f, W 4d, Ag 3d and Ag 3p(3/2)) and the O-2/Si0.8Ge0.2 on Si(100) system is composed of three core levels (Si 2p, Ge 2p(3/2) and Ge 3d), these systems are quite useful for checking the accuracy of various inelastic mean-free-path(IMFP) formulae with a variety of combinations between films and substrates. We found that the reported inelastic mean-free-path formulae were uncorrelated in our systems.