Thin film deposition by pulsed laser deposition (PLD) is on the verge or is already an established tool for industry, e.g. for X-ray mirrors and high Tc superconducting tapes, but for a wider application several shortcomings must be overcome. These problems, e.g. differences in composition between targets and thin films, non-homogenous composition of the thin films, and deviation of the film thickness for substrates greater than around 1 cm2, are most likely related to the ablation plume. A detailed study of the ablation plume can therefore help to understand whether and how these problems can be overcome. We apply space-, angle-, and energy-resolved plasma mass spectrometry, space- and angle-resolved ion probe measurements, and spectral- and time-resolved plasma imaging in the same PLD chamber, that is equipped with a special designed substrate system to analyse the thin films composition for various deposition angles. To analyse the influence of the applied elements, a variety of different target compositions are utilized. We would like to highlight here some of the most important findings related to the film composition, while the thickness related variations are mostly related to the well-known forward peaked nature of the ablation plume.
A fundamental understanding of material properties and reactions in energy materials can often be achieved through advanced large-facility techniques, such as those available at synchrotrons or neutron sources. These techniques provide unique insights but often require well-defined samples with controlled properties, including crystallinity, surface roughness, and interface quality. Such requirements are frequently met by using thin films. To this end, we employ Pulsed Laser Deposition (PLD) to fabricate thin films, enabling the application of complementary methods ranging from neutron reflectometry (NR) to grazing incidence X-ray absorption spectroscopy (GIXAS).
One material system we study involves Li-containing materials for Li-ion batteries, with the ultimate goal of developing a thin-film battery entirely fabricated by PLD. A major challenge in this approach is identifying a suitable solid electrolyte that retains its properties in thin-film form. Many oxide electrolytes, such as LLZO (Li7La3Zr2O12) or LLTO (Li3xLa(2/3-x)TiO3), do not meet these criteria. Additionally, it is essential to identify oxide-based electrode materials (anode and cathode) that are compatible with the solid electrolyte, particularly in terms of deposition conditions and interfacial properties.
Another key area of our work focuses on oxynitrides, which are used as photoanodes for photo-electrochemical (PEC) water splitting. Despite their promise, this material class suffers from rapid activity decay during the initial electrochemical cycles and a gradual long-term decline. The long-term decay is likely linked to material degradation, such as nitrogen loss. However, the fast decay remains poorly understood, hindering the development of strategies to address it. By utilizing thin films as model systems, we studied the mechanisms behind the fast decay.