Dortmund 2021 – wissenschaftliches Programm

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 3: Radiofrequency

AKBP 3.2: Vortrag

Dienstag, 16. März 2021, 14:15–14:30, AKBPb

ALD-Based NbTiN studies for SIS R&D — •isabel gonzález díaz-palacio¹, marc wenskat², wolfgang hillert², robert zierold¹, and robert blick¹ — ¹Center for Hybrid Nanostructures, Hamburg — ²Institute for Experimental Physics, Hamburg

Superconductor-Insulator-Superconductor multilayers (SIS structures) improve the performance of SRF cavities providing magnetic screening of the bulk cavity and lower surface resistance. In this framework NbTiN mixtures stand as a potential material of interest. One method which enables fine tuning of the stoichiometry and precise thickness control in sub-nm range is atomic layer deposition (ALD). ALD bases on a sequence of self-limiting gas-solid surface reactions and allows for uniform coating of complex geometries. In this talk, we report about NbTiN thin films deposited by plasma-enhanced ALD on insulating AlN buffer layer, which has been previously deposited in situ without vacuum break with the same technique. The deposition process has been optimized by studying the superconducting electrical properties of the films. Post-deposition thermal annealing studies with varying temperatures, annealing times, and gas atmospheres have been performed to further improve the thin film quality and the superconducting properties. Our experimental studies show an increase in Tc by 87.5% after thermal annealing and a maximum Tc of 13.9 K has been achieved for NbTiN of 23 nm thickness. Future steps include lattice characterization, using XRR/XRD/EBSD/PALS, and SRF measurements to obtain Hc1 and the superconducting gap Δ.