Regensburg 2019 – scientific programme

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DS: Fachverband Dünne Schichten

DS 1: Optical Analysis of Thin Films I (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...

DS 1.3: Talk

Monday, April 1, 2019, 10:30–10:45, H32

Reflectance Anisotropy Spectroscopy as an analytical tool for phase transformation studies: order reactions in Cu-Au Thin Films — •Marco Volpi, Alla Sologubenko, Philipp Okle, and Ralph Spolenak — ETHZ, Zürich, Switzerland

Increasing interest of materials science in thin films is driven by a vast range of applications in many fields like mechanics, electronics and optics. Outstanding physical and mechanical properties originate from their morphology and microstructure, which are processing conditions dependent. Therefore, monitoring of film phase stabilities during their production is fundamental. In this work, we study thermally induced phase transformations of Cu-x at.% Au (x=15, 25, 50, 75) thin films produced with Plasma Assisted Physical Vapor Deposition (PAPVD) by combining transmission electron microscopy (TEM) and X-Ray diffraction (XRD). Information gained on the order reactions were used to validate the phase state sensitivity in Reflectance Anisotropy Spectroscopy (RAS) [1]. As-deposited Cu-Au thin films show a solid solution state that disagrees with the equilibrium phase configurations expected from the bulk phase diagram. However, thermal treatment triggers order reactions that lead to equilibrium. Both TEM and RAS revealed the formation of intermetallic phases in Cu-25 at.% Au and Cu-50 at.% Au upon annealing. Yet, only RAS could reveal a two-phase state that coexisted in the annealed Cu-25 at.% Au and Cu-50 at.% Au films. To conclude, RAS proves to be a very sensitive alternative to TEM that allows prompt and non-destructive phase analyses in films. [1] Cole R.J.et al., J Phys. D Appl. Phys., (2003), 36.