Superconducting and Insulating Nitride Based Thin Films Deposited

Superconducting and Insulating Nitride. Based Thin Films Deposited by Plasma Enhanced ALD Isabel González Díaz-Palacio, 1 Robert H. Blick, 1 Robert Zierold 1, Marc Wenskat, 3 Wolfgang Hillert, 3 1. Institute of Nanostructure and Solid State Physics & Center for Hybrid Nanostructures, Universität Hamburg 2. Advanced Ceramics, Hamburg University of Technology 3. Institute of Experimental Physics, Universität Hamburg University of Hamburg 19. 06. 2020 SIS Multilayer Structures for Applications in SRF Technology (SMART)

ALD Processes System Precurso r Aim Plasma Al. N as insulator TMA Supercycle ALD Ti. N TDMAT Arradiance GEMStar XT-P located in CHy. N cleanroom dry pump (Ebara A 10 s) Pbase = 4 E-2 mbar TBTDEN Ar (6. 0) purge gas Tix. Nb 1 -x. N N 2/H 2 -Plasma Nb. N Chamber temp. 250 °C, TMA pulse 21 ms @ RT, Plasma on at 300 W for 10 s, N 2/H 2 10/30 sccm Plasma on at 300 W for 60 s, N 2/H 2 20/45 sccm, TDMAT pulse 500 ms @ 70 °C,

Supercycle ALD Approach for Tix. Nb 1 -x. N Aim: Tuning the superconducting properties of the deposited thin by varying ratio of Nb. N to Ti. N Static (DC) field @ 1. 8 K TDMAT TBTDEN N 2/H 2 -Plasma Increasing Nb-content in thin films and Hc Superconductivity measurements increase in Tc

Further Magneto-Transport Characterization Resistance minimum in temperature disordered superconductor. Transition from a 3 D to a 2 D electronic system when thermal coherence length equals the film thickness. Postolova et al. , Sci. Rep. , 7 (2017) 1718 Increasing the Nb. N /Ti. N ratio Parameters Ti. N: Chamber temp. 250 °C, TDMAT pulse 500 ms @ 70 °C, Plasma on at 300 W for 120 s, N 2/H 2 20/45 sccm.

EDX Composition Analysis GPCNb. N ≈ 0. 6 Å/cycle Growth per cycle

Additionally Topics Ø EP Nb Samples Solution (2 L) 1: 9 48%HF: 96% H 2 SO 4 2 h @ 14 V Ø Annealing of Al 2 O 3 and Al. N thin films deposited by atomic layer deposition Ø Technical Drawings for adapting thermal ALD system for the QPR sample SIS Multilayer Structures for Applications in SRF Technology (SMART)

Future Work Ø Further Nb. Ti. N depositions varying the Nb. N / Ti. N ratio and their characterization Ø Nb Annealing @800 °C ≤ 10 -5 mbar Ø SEM analysis of the insulator layers after the termal treatment SIS Multilayer Structures for Applications in SRF Technology (SMART)

Thank you very much for your attention! SIS Multilayer Structures for Applications in SRF Technology (SMART)