Effect of stoichiometry on oxygen incorporation in MgB2 thin films

TL;DR

This study investigates how the stoichiometry of MgB2 thin films influences oxygen incorporation during exposure to various atmospheres and annealing conditions, revealing that Mg-rich films and humid environments lead to increased bulk oxygen content.

Contribution

It provides new insights into the relationship between film composition, environmental exposure, and oxygen uptake in MgB2 thin films.

Findings

Oxygen contamination is significant on the surface of all films.

Bulk oxygen increases mainly in Mg-rich films and humid conditions.

Stoichiometry strongly affects oxygen incorporation in MgB2 films.

Abstract

The amount of oxygen incorporated into MgB2 thin films upon exposure to atmospheric gasses is found to depend strongly on the material's stoichiometry. Rutherford backscattering spectroscopy was used to monitor changes in oxygen incorporation resulting from exposure to: (a) ambient atmosphere, (b) humid atmospheres, (c) anneals in air and (d) anneals in oxygen. The study investigated thin-film samples with compositions that were systematically varied from Mg0.9B2 to Mg1.1B2. A significant surface oxygen contamination was observed in all of these films. The oxygen content in the bulk of the film, on the other hand, increased significantly only in Mg rich films and in films exposed to humid atmospheres.