Temperature modification of the Nb oxidation at the Nb/Al interface studied by reflEXAFS

We report on the modifications of the Nb oxidation in Nb/Al interfaces due to different thermal treatments. The samples were prepared by radio frequency (RF) ion sputtering and studied by X-ray absorption detected in total reflection mode (reflEXAFS). This technique combines the specific atomic sensitivity property of the extended X-ray absorption fine structure (EXAFS) with a surface sensitivity, due to the total reflection mode of the incident beam. We studied the niobium oxide revealed at the Nb/Al interface after different thermal treatments and on bare thick Nb film. Up to 200°C the increasing temperature does not modify appreciably the oxide layer, while higher temperature treatments (600°C) causes a further oxide formation. The study of the Nb K-edge absorption leads to the conclusion that no single phase Nb oxide is formed at the interfacial zone and no presence of NbAl alloy is observed.