The structure and stability of β-Ta thin films

• Published in: Thin solid films 2005-05, Vol.479 (1), p.166-173
• Main Authors: Jiang, Aiqin, Tyson, Trevor A., Axe, Lisa, Gladczuk, Leszek, Sosnowski, Marek, Cote, Paul
• Format: Article
• Language: English
• Subjects: Clusters; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular dynamics; Physics; Space group; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; X-ray diffraction; β-tantalum; σ-type Frank–Kasper structure
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2004.12.006

Ta films with tetragonal crystalline structure (β-phase), deposited by magnetron sputtering on different substrates (steel, silicon, and silicon dioxide), have been studied. In all cases, very highly preferred (001) orientation was observed in X-ray diffraction measurements. All diffraction data revealed two weak reflections corresponding to d-spacing of 0.5272 and 0.1777 nm. The presence of the two peaks, attributed to (001) and (003) reflections, indicates that β-Ta films exhibit a high preference for the space group of P-42 1 m over P4 2 /mnm, previously proposed for β-Ta. Differences in relative intensities of (00 l) reflections, calculated for single crystal β-Ta σ-type Frank–Kasper structure and those measured in the films, are attributed to defects in the films. Molecular dynamics simulations performed on tantalum clusters with six different initial configurations using the embedded-atom-method potential revealed the stability of β-Ta, which might explain its growth on many substrates under various deposition conditions.