Study of thermal oxidation of LaSi x/Si(1 0 0) by grazing incidence electron-induced X-ray emission spectroscopy

Abstract

A new X-ray emission spectroscopy (XES) apparatus for analyzing nondestructively the chemical states of the inner regions of layered materials was constructed. Using electron excitation at grazing incidence, it also enables the analyzing depth to be confined to the surfaces of the materials. The apparatus was employed to the study of oxidation of a La silicide layer formed on a Si substrate. By comparing the Si Kβ emissions with results by XPS analysis, it was concluded that the Si Kβ emission band of the oxidized sample at the excitation energy of 3.0 keV represents the Si 3p density of states (DOS) of a LaSiO mixed oxide. The variations of the spectra at increasing electron beam energies were compared with probing depths calculated by an empirical model. This result indicates that we can analyze the chemical states of a mixed oxide layer of one to two tens angstroms in thickness, and nondestructively probe into the depth of about several tens angstroms.