On the identification of interface oxides and interface serration by ARXPS

Summary Oxidized surfaces show smeared out XPS lines which cannot be fitted by bulk compounds and by lateral growth. By simultaneously fitting XPS spectra obtained for take-off angles between 5 ° and 80 ° the resolution is enhanced. Thus small amounts (<0.5 nm) of interface oxides are identified in level shift, stoichiometry and spatial distribution, i.e., serration and protrusion of interfaces are revealed. The ARXPS-analysis of oxidized (<100 °C) NbN, NbC and Nb shows that the metal surface is serrated by metallic ( 1 nm) and dielectric ( 1 nm) interface oxides, where Nb₂O₅ forms the outermost layer. The serration is deeper for Nb than for NbN, because Nb is weaker and dissolves more O. In contrast, in high temperature oxidation (900 °C) of a clean Si single crystal (100) surface, less interface oxides (<1 nm) have been found which grow laterally.

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Über die Identifizierung von Interface-Oxiden und der Interface-Verzahnung durch ARXPS