Surface engineering by Atomic Layer Deposition for SRF cavities

Surface engineering by Atomic Layer Deposition for SRF cavities Yasmine Kalboussi1, Claire Antoine1, Aurélien four1, Baptiste Delatte1, Frédérique Miserque2 , Diana Dragoe3, David Longuevergne4, Thierry pepin donat4, Sarra Bira5, Sandrine Tusseau-Nenez6, Yunlin Zheng7, David Hrabovsky8, Aurélie Gentils9, Stéphanie Jublot Leclerc9, Mohamed Belhaj10, Tobias Junginger11, Jocelyne Leroy12, Thomas Proslier1. WEIBA01SRF conference 2023 1IRFU, CEA Paris-Saclay University; 2LECA, CEA Paris-Saclay University; 3Plateforme ICMMO, Paris-Saclay University; 4IJCLab, CNRS, Paris-Saclay University, 5Jefferson laboratory; 6Plateforme DIFFRAX, Ecole Polytechnique; 7INSP, CNRS, Sorbonne University; 8Plateforme MPBT, Sorbonne University; 9Plateforme MOSAIC, IJClab Paris-Saclay University; 10 DPHY, ONERA; 11University of Victoria, 12LICSEN, CEA Paris-Saclay University; At CEA, we are trying to improve the performances of niobium cavities by tayloring their inner surface using the technique of atomic layer deposition: I. Changing the nature of oxide layer and studying their impact on high and low fied performances. 2 Outline Yasmine Kalboussi - SRF 2023 At CEA, we are trying to improve the performances of niobium cavities by tayloring their inner surface using the technique of atomic layer deposition: I. Changing the nature of oxide layer and studying their impact on high and low fied performances. II. Tuning the secondary emission yield of the surface. 3 Outline Yasmine Kalboussi - SRF 2023 At CEA, we are trying to improve the performances of niobium cavities by tayloring their inner surface using the technique of atomic layer deposition: I. Changing the nature of oxide layer and studying their impact on high and low fied performances. II. Tuning the secondary emission yield of the surface. III. Doping Niobium cavities. 4 Outline Yasmine Kalboussi - SRF 2023 At CEA, we are trying to improve the performances of niobium cavities by tayloring their inner surface using the technique of atomic layer deposition: I. Changing the nature of oxide layer and studying their impact on high and low fied performances. II. Tuning the secondary emission yield of the surface. III. Doping Niobium cavities. IV. Using a multilayer structure to screen the magnetic field seen by Niobium. 5 Outline Yasmine Kalboussi - SRF 2023 High vacuum oven: - 650°C – 10-6 mbar / 900°C 1bar N2 - Volume retort: Φ = 49 cm, L= 110 cm (1.3, 0.7 GHz cavities) ALD system: - 9 precursor lines (2 gases, 2 liquids, 4 solids, 1 Ultra high temp). - RGA synthesis monitoring. Interface and control: - Labview program of ALD system and Oven. - Automatic synthesis parameter control (overnight dep.) and monitoring. 6 Front Back New ALD system for cavity coating at CEA Yasmine Kalboussi - SRF 2023 High vacuum oven: - 650°C – 10-6 mbar / 900°C 1bar N2 - Volume retort: Φ = 49 cm, L= 110 cm (1.3 , 0.7 GHz cavities) 7 New ALD system for cavity coating at CEA Yasmine Kalboussi - SRF 2023 Part I: Enhancement of niobium superconductivity through the use of ALD-oxides To replace niobium native oxides with ALD-deposited protective layer [1] 1) Deposit ~ 10 nm oxide layer by ALD (Al2O3, Y2O3and MgO ) onto Niobium. 2) Perfom a subsequent thermal treatement to dissolve niobium native oxide underneath (vacuum levels 10-6 mbar) The oxide layer must be thermally stable and have low dielectric losses. 9 ALD-deposited oxide ALD-deposited oxide [1] T. Proslier et al . Improvement and protection of niobium surface superconductivity by atomic layer deposition and heat treatment. Applied Physics Letters, 93(19):192504, November 2008 Replacing niobium native oxides with ALD-deposited oxide layer Yasmine Kalboussi - SRF 2023 16 The quality factor is lower but the 1.5 nm ( 40 cycles ) thick TiN film is effective as a multipacting mitigation layer. T= 1.4 K RF test of the TiN thin film on 1.3 GHz Niobium cavitiy Yasmine Kalboussi - SRF 2023 Doping SRF cavities 17 Part III: ALD synthesis: NbN, TiN, ZrN, AlN, MgO, Al2O3, Y2O3… 1) Well controled and uniform quantity of dopant. 2) Induce O/N dopant in Nb but keep the metallic ions on the surface. 3) Avoid chemistry step ? 18 ALD approach for doping cavities We tested four nitrides layer: NbN, TiN, ZrN and AlN Doping for SRF cavities Yasmine Kalboussi - SRF 2023 Niobium nitride 19 No nitrogen detected by XPS at the surface. 5 nm of NbN + annealing 900°C3 Hrs - UHV XPS Profiling Yasmine Kalboussi - SRF 2023 Niobium nitride 20 Doping levels comparable to observed at Fermilab without electropolishing . TOF-SIMS Profiling 5 nm of NbN + annealing 900°C3 Hrs - UHV 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0,001 0,01 0,1 1 10 100 NbN-/NbSputter time [s] 5 nm-NbN film + annealing 900°C3 hours Fermilab doping levels Yasmine Kalboussi - SRF 2023 Test on 1.3 GHz Nb cavity The cavity was coated with 5 nm of NbN + annealing at 900°C-3 hours in vacuum. 21 The RBCS is lowered but the residual resistance increased. 0,2 0,3 0,4 0,5 0,6 0,7 10 100 1000 Rs [nW] 1/T [1/K] After doping Baseline Yasmine Kalboussi - SRF 2023 Test on 1.3 GHz Niobium cavity The cavity was coated with 5 nm of NbN + annealing at 900°C-3 hours. No electro-polishing have been preformed. 22 The quality factor is higher at 4.2 K but lower at 2 K . 0 5 10 15 20 25 30 10 8 10 9 10 10 10 11 After doping Baseline (EP) Q 0 E (MV/m) 0 1 2 3 4 5 2,0×10 8 4,0×10 8 6,0×10 8 8,0×10 8 1,0×10 9 Q0 E (MV/m) After doping Baseline T= 2 K T= 4.2 K Yasmine Kalboussi - SRF 2023 Zirconium nitride 23 XPS Profiling No nitrogen detected by XPS at the surface. 5 nm of ZrN + annealing 900°C3 Hrs - UHV Yasmine Kalboussi - SRF 2023 Zirconium nitride 24 The Nb is well passivated with a ZrO2 layer. 5 nm of ZrN + annealing 900°C3 Hrs - UHV Yasmine Kalboussi - SRF 2023 Part IV: ALD-depositied multilayer to improve the superconducting performances of SRF cavities More investigations are ongoing ( Q0vs T ) … 32 0 5 10 15 20 25 30 35 40 1E9 1E10 1E11 Baseline with multilayer-1 with multilayer-2 Q0 E Acc (MV/m) T = 1.4 K 0,2 0,3 0,4 0,5 0,6 0,7 10 100 1000 Baseline with multilayer-1 with multilayer-2 Rs (nW) 1/T (K -1 ) The Niobium cavity was coated with AlN (7 nm) – NbTiN (50 nm ) bilayer . First RF tests of NbTiN-AlN bilayer on 1.3 GHz Nb cavity 1. 4 K Yasmine Kalboussi - SRF 2023 Thermal treatment multilayer 2: IJClab Summary 33 We manage to deposit uniformly a thin film of Alumina and reduce drastically niobium native oxides. Significant improvement of the Q0under low Fields. Proof of multipacting mitigation in SRF cavity using ALD-deposited TiN film. Interesting results with N-doping using ALD-deposited NbN films as dopant source. First tests of S-I-S structure on 1.3 GHz Nb cavity. Yasmine Kalboussi. Nano hetero-structures for improving performances of superconductors under high fields. Materials Science [cond-mat.mtrl-sci]. Université Paris-Saclay, 2023. English. ⟨NNT : 2023UPASP029⟩ ⟨tel-04116992⟩ For more details Thank you for your attention 34 Questions ? Ackowledgements: RF measurements – M. Baudrier, L. Maurice; Cavity preparation: G. Jullien, F. Eozenou; Technical assistance: G. Monnereau, T. Vacher. 35 Back up An ALD cycle is composed of four steps: 36 O-Hterminated surface Atomic layer deposition Yasmine Kalboussi - SRF 2023 An ALD cycle is composed of four steps 1. Pulse of precursor 1, enabling the first gas surface reaction. 37 Atomic layer deposition Yasmine Kalboussi - SRF 2023 An ALD cycle is composed of four steps 1. Pulse of precursor 1, enabling the first gas surface reaction. 38 Atomic layer deposition Yasmine Kalboussi - SRF 2023 An ALD cycle is composed of four steps 1. Pulse of precursor 1, enabling the first gas surface reaction. 2. Purge of precursor 1, enabling the evacuation of the excess of precursor 1 and the by-products. 39 Atomic layer deposition Yasmine Kalboussi - SRF 2023 An ALD cycle is composed of four steps 1. Pulse of precursor 1, enabling the first gas surface reaction. 2. Purge of precursor 1, enabling the evacuation of the excess of precursor 1 and the by-products. 3. Pulse of precursor 2, enabling the second gas-surface reaction. 40 Atomic layer deposition Yasmine Kalboussi - SRF 2023 An ALD cycle is composed of four steps 1. Pulse of precursor 1, enabling the first gas surface reaction. 2. Purge of precursor 1, enabling the evacuation of the excess of precursor 1 and the by-products. 3. Pulse of precursor 2, enabling the second gas-surface reaction. 41 Atomic layer deposition Yasmine Kalboussi - SRF 2023