Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 49: Poster Nanostructures at Surfaces

O 49.9: Poster

Tuesday, March 18, 2025, 18:00–20:00, P2

Investigation of onset field variations in annealed and as-deposited NbTiN samples through field emission scanning microscopy — •Frederic Braun¹, Isabel Díaz-Palacio², Lea Preece², Florian Brockner¹, Robert Zierold², Marc Wenskat², Wolfgang Hillert², and Dirk Lützenkirchen-Hecht¹ — ¹Bergische Universtiät Wuppertal — ²Universität Hamburg

Current superconducting radio frequency (SRF) cavities are predominantly constructed from high purity Niobium which is pushed to its theoretical limit. To enhance future cavity performance by minimizing operational power losses and increasing accelerating field strength, the focus of research must shift to alternative cavity materials. An effective strategy involves depositing superconducting thin films like NbTiN or Nb3Sn on the cavity inner walls. Heat treating NbTiN may further optimize film properties. In this study various samples, including as deposited NbTiN and annealed NbTiN are analyzed via a Field Emission Scanning Microscopy (FESM). Current-voltage-curves allow the determination of onset-fields for parasitic field emission . Mapping these fields at e.g., 1 nA reveals lateral variations due to thin film inhomogeneities, defects or surface contaminations Additionally, assessing long term surface stability through constant current measurements over an extended period is crucial for practical cavity applications.

Keywords: FESM; NbTiN; Thin films