Quantitative analysis of X-ray photoemission spectra, acquired on c-axis oriented high-Tc superconducting YBa2Cu3O7−δ thin films

Abstract

Angle-resolved X-ray photoemission spectroscopy (ARXPS) was performed on c-axis oriented high-T~ superconducting YBa,Cu30 , ~ thin films. The layered structure of the YBa2Cu30 7 ~ films was used to develop a model for the quantitative analysis of the ARXPS experiments. Our XPS results may be compared to spectra taken on YBazCu30 7_~ single-crystal surfaces. On the spectra features are superposed that are assigned to a thin non-superconducting surface layer. For the first time. relative ARXPS measurements show that the interface between the superconducting YBa,Cu3OT_,~ film and the surface layer is formed by the atomic Y layer. The surface layer consists mainly of BaCO~ and C. A small volume fraction ( ~ 20%) contains Ba-and Cu-oxides. probably in the form of BaCuO 2. From absolute ARXPS measurements, the thickness of the surface layer was calculated to be 11.93 + 11.06 nm. It is shown that the surface roughness of our films is on the order of 0.6 rim. A good agreement between theory and experiment has been found in this report.