Influence of a passivation layer on strain relaxation and lattice disorder in thin nano-crystalline Pt films during in-situ annealing

In this work we compared the relaxation of strain and lattice disorder in thin nano-crystalline Pt films for samples covered with a Si₃N₄ layer and samples without a cover layer, respectively. We measured thickness and interplanar distance of the Pt film by X-ray reflectometry and X-ray diffractometry during in-situ annealing using synchrotron radiation. The results show that strain and lattice disorder relaxation are impeded if the Pt film is sealed with a cover layer to suppress the creation of vacancies at the Pt surface. This emphasizes the postulated important role of the generation of vacancies at the free surface of thin metal films for strain relaxation during isothermal annealing. - Highlights: • Strain relaxation in nano-crystalline platinum films was investigated. • XRR and XRD measurements were carried out using synchrotron radiation. • In-situ annealing was performed at 130 °C and 210 °C. • Magnetron sputtered Pt films with and without a Si₃N₄-cover layer are compared. • Strain relaxation is slower and lattice disorder is higher for the covered samples