Demonstration of thin film pair distribution function analysis (tfPDF) for the study of local structure in amorphous and crystalline thin films

• Published in: IUCrJ Vol. 2; no. Pt 5; pp. 481 - 489
• Main Authors: Jensen, Kirsten M Ø, Blichfeld, Anders B, Bauers, Sage R, Wood, Suzannah R, Dooryhée, Eric, Johnson, David C, Iversen, Bo B, Billinge, Simon J L
• Format: Journal Article
• Language: English
• Published: England International Union of Crystallography 01-09-2015
• Subjects: amorphous solids; Amorphous structure; Antimony; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Crystal structure; Crystallization; Crystals; Dielectric films; Distribution functions; framework-structured solids and amorphous materials; inorganic materials; materials modelling; nanostructure; pair distribution function analysis; Precursors; Properties; Research Papers; Scattering; Scattering (Physics); Structure; Thin films; total scattering; inorganic materials; materials modelling; pair distribution function analysis; framework-structured solids and amorphous materials; total scattering; nanostructure; amorphous solids; thin films
• ISSN: 2052-2525; 2052-2525
• DOI: 10.1107/s2052252515012221

By means of normal-incidence, high-flux and high-energy X-rays, total scattering data for pair distribution function (PDF) analysis have been obtained from thin films (tf), suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. The 'tfPDF' method is illustrated through studies of as-deposited (i.e. amorphous) and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows the prediction of whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films.