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The Thin Films and Interfaces Group

Thin films are nowadays utilized in many applications, ranging from semiconductor devices to optical coatings and are even present in pharmaceuticals (polymers). This wide-spread application of films with thicknesses from atomic monolayers to microns is due to the developments of thin film deposition techniques. Thin films are also important for studies of materials with new and unique properties due to the possibility of tuning their crystallographic and morphological properties. The thin film approach, i.e. the presence of interfaces (to a substrate or the film surface) adds more degrees of freedom for influencing the properties of materials, e.g. by lattice strain or surface functionalization. For these fundamental studies of material properties large research facilities such as synchrotron radiation or neutron spallation sources are one of the keys that the Paul Scherrer Institute (PSI) provides. Read more Top

PhD projects at the Thin Films and Interfaces Group

At present, we do not have open PhD positions available. As soon as we have details will be posted at our open position page. Other open positions are always published on the PSI Open Positions page.

News

Upcoming Group Seminars

TBA
Speaker: Y. Xiang
Date: Tuesday 19 December 2017 16:30
Room: OFLG/401

TBA
Speaker: G. Bimashofer
Date: Monday 8 January 2018 16:00
Room: OFLG/402


Special interview with Prof. Thomas Lippert (PSI and Principle Investigator at I2CNER, Kyushu University) and Prof. Tatsumi Ishihara (Associate Director I2CNER, Kyushu University) on Current and Future Energy Research and Development in Europe: Perspectives from Switzerland, Germany and Japan. The interview is being published in the August 2017 issue of the Energy Outlook of the International Institut for Carbon-Neutral Energy Research, I2CNER.
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Most recent Paper

Stela Canulescu, Max Döbeli, Xiang Yao, Thomas Lippert, Salvatore Amoruso, and Jørgen Schou
Nonstoichiometric transfer during laser ablation of metal alloys
Physical Review Materials 1, 073402 (2017)


26 October 2017

Nonstoichiometric transfer during laser ablation of metal alloys

Abstract:
Large angular variations in film composition have been found for ablation of a metallic AuCu alloy (Au/Cu ratio ∼1) in vacuum and background gases of Ne and Xe. The AuCu films grown in vacuum at a laser fluence of 5Jcm−2 exhibit a large loss in the Cu content, with the Au/Cu ratio ∼2.4 at angles close to normal incidence. At this fluence, a distortion of the plume front is observed followed by the appearance of a secondary emission at the substrate, suggesting that resputtering of the film by energetic ions and reflection of ions/atoms at the substrate can lead to a nonstoichiometric transfer in pulsed laser deposition. Further, we have found that depending on the mass of the background gas employed during growth (Ne or Xe), the ratio of elements in the film can vary significantly over a wide range of angles of deposition. In the presence of the light gas Ne, the degree of nonstoichiometric transfer is gradually reduced with increasing background pressure, resulting in a nearly stoichiometric AuCu films at a Ne pressure of 2 mbar. The behavior in the heavy gas Xe is more complex, and both theoretical and experimental data indicate that the loss of Cu in the deposits is caused by the preferential scattering, as well as by backscattering of the light Cu atoms in the plume upon collisions with the background gas.
Keywords: pulsed laser deposition; plasma spectroscopy; thin films; thin film composition; angular dependence of composition

Facility: Thin Films and Interfaces, LMX, ETHZ, Technical University of Denmark, University of Naples

Reference: S. Canulescu et al., Physical Review Materials 1, 073402 (2017)

Read full article: [here]