Regensburg 2025 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 2: Layer Deposition
DS 2.5: Vortrag
Montag, 17. März 2025, 10:30–10:45, H14
Role of point defects on the superconducting transition temperature in NbTIN thin films with positron annihilation spectroscopy — •Sebastian Klug1, Maik Butterling1, Maciej Oskar Liedke1, Eric Hirschmann1, Andreas Wagner1, Bharath Reddy Lakki Reddy Venkata2, Aleksandr Zubtsovskii2, and Xin Jiang2 — 1Institute of Radiation Physics, HZDR, Germany — 2Chair of Surface and Materials Technology, University of Siegen, Germany
Positron annihilation spectroscopy (PAS) is a non-destructive method for studying point defects in materials with high sensitivity. It can sense defect densities in the range of 1015 to 1019 cm−3 . The time for positrons to annihilate with electrons depends on the local electron density. Therefore, positrons can be trapped in neutral and negatively charged open-volume defects. Positrons are implanted into the studied material with a defined implantation energy. Changing of this energy allows for depth-resolved characterization. The user facility ELBE of HZDR provides the two main PAS techniques Doppler broadening spectroscopy (DBS) and positron annihilation lifetime spectroscopy (PALS) which allows for evaluation of the atomic environment of defects as well as defect size and density.
In this contribution the most recent results of magnetron sputtered NbTiN thin films as promising candidate for improving the characteristics of superconducting radio-frequency cavities (SRF cavities) will be discussed. The correlation between defect size and their concentration and the superconducting transition temperature will be highlighted.
Keywords: Superconductivity; Magnetron sputtering; Thin films; Positron annihilation spectroscopy; Point defects