XPS spectral fitting analysis of Si-intercalated buffer layer/SiC(0001) using expectation-conditional maximization algorithm

Abstract

X-ray photoelectron spectroscopy (XPS) spectral fitting provides a powerful approach for resolving complex surface chemical states, particularly when combined with automated optimization algorithms. In this study, the expectation-conditional maximization (ECM) algorithm was used to fit the component peaks of the C1s core-level spectra obtained from the as grown buffer layer on SiC(0001) and the Si-intercalated sample. The ECM algorithm, an iterative optimization method, was used to determine the parameters that best describe the spectral components. The results indicate that the buffer layer becomes partially decoupled from the substrate following the intercalation of four monolayers (ML) of Si atoms, as evidenced by the increased intensity of the graphene-related signal. A comparative analysis with a 1.3 ML Si-intercalated graphene sample further supports these findings, highlighting the effectiveness of ECM-based spectral fitting in capturing subtle interfacial modifications.