Paul Scherrer Institute

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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

News


15 November 2018

Woman in Science

Congratulations to our former postdoc, Alexandra Palla-Papavlu (4th from the left), for winning the L’Oreal Prize for Woman in Science in the category Physics in Romania
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Upcoming Conference

November 2018

2018 MRS Fall Meeting & Exhibit

November 25-30, 2018
Boston, Massachusetts, USA
More Information


Upcoming Group Seminars

TBA
Speaker: Pascal Puphal
Date: Tuesday 18 December 2018 13:00
Room: OSGA/EG06, LMX

Scientific Highlight

25 October 2018

Rolling dopant and strain in Y-doped BiFeO3 epitaxial thin films for photoelectrochemical water splitting

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We report significant photoelectrochemical activity of Y-doped BiFeO3 (Y-BFO) epitaxial thin films deposited on Nb:SrTiO3 substrates. The Y-BFO photoanodes exhibit a strong dependence of the photocurrent values on the thickness of the films, and implicitly on the induced epitaxial strain. The peculiar crystalline structure of the Y-BFO thin films and the structural changes after the PEC experiments have been revealed by high resolution X-ray diffraction and transmission electron microscopy investigations. The crystalline coherence breaking due to the small ionic radius Y-addition was analyzed using Willliamson-Hall approach on the 2Θ-ω scans of the symmetric (00l) reflections and confirmed by high resolution TEM (HR-TEM) analysis. In the thinnest sample the lateral coherence length (L||) is preserved on larger nanoregions/nanodomains. For higher thickness values L|| is decreasing while domains tilt angles (αtilt) is increasing. The photocurrent value obtained for the thinnest sample was as high as Jph = 0.72 mA/cm2, at 1.4 V(vs. RHE). The potentiostatic scans of the Y-BFO photoanodes show the stability of photoresponse, irrespective of the film’s thickness. There is no clear cathodic photocurrent observation for the Y-BFO thin films confirming the n-type semiconductor behavior of the Y-BFO photoelectrodes.
Reference: F. Haydous et al, Scientific Reports 8, 15826 (2018)

Read full article: here


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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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.

Most recent Paper

Elisa Gilardi, Aline Fluri, Thomas Lippert, and Daniele Pergolesi;
Real-time monitoring of stress evolution during thin film growth by in situ substrate curvature measurement
Journal of Applied Physics 125, 082513 (2019)



6 December 2018

Real-time monitoring of stress evolution during thin film growth by in situ substrate curvature measurement

Abstract:
Schematic representation of the working principle of the multi-beam optical stress sensor. An n × m array of laser beams is reflected at the substrate surface toward a CCD camera. The mean differential spacing between the laser spots is recorded during the film deposition. This allows for monitoring the substrate curvature which is directly related to the stress.zoom
Schematic representation of the working principle of the multi-beam optical stress sensor. An n × m array of laser beams is reflected at the substrate surface toward a CCD camera. The mean differential spacing between the laser spots is recorded during the film deposition. This allows for monitoring the substrate curvature which is directly related to the stress.
Strain engineering is the art of inducing controlled lattice distortions in a material to modify specific physicochemical properties. Strain engineering is applied not only for basic fundamental studies of physics and chemistry of solids but also for device fabrication through the development of materials with new functionalities. Thin films are one of the most important tools for strain engineering. Thin films can in fact develop large strain due to the crystalline constraints at the interface with the substrate and/or as a result of specific morphological features that can be selected by an appropriate tuning of the deposition parameters. Within this context, the in situ measurement of the substrate curvature is a powerful diagnostic tool allowing real time monitoring of the stress state of the growing film. This paper reviews a few recent applications of this technique and presents new measurements that point out the great potentials of the substrate curvature measurement in strain engineering. Our study also shows how, due to the high sensitivity of the technique, the correct interpretation of the results can be in certain cases not trivial and require complementary characterizations and an accurate knowledge of the physicochemical properties of the materials under investigation.
Keywords: PLD; Thin Films; Strain; MOSS; XRD diffraction

Facility: Thin Films and Interfaces, LMX

Reference: E. Gilardi et al., Journal of Applied Physics 125, 082513 (2019)

Read full article: [here]
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