Interface between a III–VI intercalation compound and a solid electrolyte: XPS and RHEED study

An X-ray Photoelectron Spectroscopy (XPS) and Reflection High Energy Electron Diffraction (RHEED) study of interfaces between B2O3–0.5Na2O and InSe has been performed as a function of the thickness of the InSe film. From RHEED and XPS, the InSe film grows mainly in a two-dimensional mode along the smooth polished borate substrate and the interface between InSe and borate glass can be considered as abrupt. The RHEED patterns indicate an in-plane misorientation of the domains. The semi-quantitative analysis of the intensities of photoelectron peaks leads to substrate attenuation and deposit uptake curves. They follow mainly an exponential law and allow an estimation of the escape depth of the photoelectrons in agreement with the calculated ones and with the flux determined from interferometry measurements although a good definition and determination of the monolayer thickness is required. Nevertheless, the phenomenological average `monolayerʹ defined by Seah and Dench agrees with the experimental estimation of the escape depth, even in the case of these strong anisotropic materials. We suggest that a sodium insertion in the layered compound is plausible.