002903423 001__ 2903423
002903423 003__ SzGeCERN
002903423 005__ 20240909171905.0
002903423 0247_ $$2DOI$$9Elsevier Ltd$$a10.1016/j.vacuum.2024.113354$$qpublication
002903423 0248_ $$aoai:cds.cern.ch:2903423$$pcerncds:FULLTEXT$$pcerncds:CERN:FULLTEXT$$pcerncds:CERN
002903423 035__ $$9https://inspirehep.net/api/oai2d$$aoai:inspirehep.net:2797978$$d2024-07-04T12:12:22Z$$h2024-07-05T05:21:15Z$$mmarcxml
002903423 035__ $$9Inspire$$a2797978
002903423 041__ $$aeng
002903423 100__ $$aCarlos, Carlota P [email protected]$$uCERN$$uU. Geneva (main)$$vDepartment of Quantum Matter Physics, University of Geneva, Geneva, Switzerland
002903423 245__ $$9Elsevier Ltd$$aPlanar deposition of Nb thin films by HiPIMS for superconducting radiofrequency applications
002903423 260__ $$c2024
002903423 300__ $$a12 p
002903423 520__ $$9Elsevier Ltd$$aCost efficiency and sustainability are critical challenges for future accelerator machines. Nb-coated Cu (Nb/Cu) superconducting radiofrequency (SRF) accelerating cavities, while requiring R&D; to meet high acceleration gradient performance standards, show potential for addressing these challenges. Defects in the Nb layer responsible for the deterioration of cavity performance have been linked to the underlying Cu substrate. This study investigates a novel optimization method by mitigating the substrate surface’s impact on deposited Nb, using High Power Impulse Magnetron Sputtering alongside a DC substrate bias (from −50 to −300 V). Trenched silicon substrates are chosen to emulate substrates with exceptionally rugged surface characteristics. Film deposition is investigated both experimentally and through kinetic Monte Carlo simulations. Higher DC voltages are shown to eliminate self-shadowing during the coating process via improved incident ionic flux directionality, enhanced adatom mobility and increased re-sputtering rates, ultimately yielding flat and densely-packed films. The influence of the substrate’s shape on the film’s surface was found to decrease exponentially with increasing ion bombardment energies. Films sputtered under high DC bias conditions (−300 V) exhibited complete planarization with a 30% re-sputtering rate. Strategies for applying this technique to Nb/Cu SRF cavities, enhancing their viability for future particle accelerators, are also discussed. •Simulation and Nb thin film deposition by HiPIMS at different ion bombardment energies.•Film planarization on trenched Si substrates achieved with high ion bombardment energies.•Experimental confirmation of simulated planarization effect by ion bombardment.•Elimination of the influence of the substrate’s surface morphology on films deposited at higher energies.•Potential mitigation of Q-slope phenomenon on Nb/Cu SRF cavities and improved energy efficiency of accelerators.
002903423 540__ $$3publication$$aCC BY 4.0$$fCERN-RP: Elsevier$$uhttp://creativecommons.org/licenses/by/4.0/
002903423 542__ $$3publication$$dThe Authors$$g2024
002903423 65017 $$2SzGeCERN$$aAccelerators and Storage Rings
002903423 6531_ $$9Elsevier Ltd$$aSuperconducting radiofrequency cavities
002903423 6531_ $$9Elsevier Ltd$$aNiobium thin film
002903423 6531_ $$9Elsevier Ltd$$aHiPIMS
002903423 6531_ $$9Elsevier Ltd$$aIon Bombardment
002903423 6531_ $$9Elsevier Ltd$$aKinetic Monte Carlo simulations
002903423 6531_ $$9Elsevier Ltd$$aPlanarization
002903423 690C_ $$aARTICLE
002903423 690C_ $$aCERN
002903423 700__ $$aLeith, Stewart$$uCERN
002903423 700__ $$aRosaz, Guillaume$$uCERN
002903423 700__ $$aPfeiffer, Stephan$$uCERN
002903423 700__ $$aSenatore, Carmine$$uU. Geneva (main)
002903423 773__ $$c113354$$mpublication$$pVacuum$$v227$$y2024
002903423 8564_ $$82542774$$s4421485$$uhttps://cds.cern.ch/record/2903423/files/Publication.pdf$$yFulltext
002903423 960__ $$a13
002903423 980__ $$aARTICLE