SRF2015 - List of Authors (Lukaszew, R.A.)

Paper	Title	Page
TUBA08	Growth and Characterization of Multi-Layer NbTiN Films	516
	A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin JLab, Newport News, Virginia, USA M.C. Burton, R.A. Lukaszew The College of William and Mary, Williamsburg, Virginia, USA
	Significant theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities. The technological challenges include realization of high quality superconductors with sharp, clean, transition to high quality dielectric materials and back to superconductor, with careful thickness control of each layer. Choosing NbTiN as the first candidate material, we have developed the tools and techniques that produce such SIS film structures and have begun their characterization. Using DC magnetron sputtering and HiPIMS, NbTiN and AlN can be deposited with nominal superconducting and dielectric parameters. Hc1 enhancement is observed for NbTiN layers with a Tc of 16.9 K for a thickness less than 150 nm. The optimization of the thickness of each type of layer to reach optimum SRF performance is underway. This talk describes this work and the rf performance characteristics observed to date.
	Slides TUBA08 [8.536 MB]
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TUPB037	Superconducting NbN-Based Multilayer and NbTiN Thin Films for the Enhancement of SRF Accelerator Cavities	638
	M.C. Burton, M. Beebe, R.A. Lukaszew, J.M. Riso The College of William and Mary, Williamsburg, Virginia, USA C.E. Reece, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	Funding: Funded by: Defense Threat Reduction Agency HDTRA1-10-1-0072 Current superconducting radio frequency (SRF) technology, used in various particle accelerator facilities is reliant upon bulk Nb. Due to technological advancements in the processing of bulk Nb cavities, the facilities have reached accelerating fields very close to material-dependent limits, i.e. ~50 MV/m for bulk Nb. One possible solution to overcome this limit proposed by A. Gurevich consists of the deposition of alternating thin layers of superconducting and insulating materials on the interior surface of the cavities which may prevent early field penetration and thus delay high field breakdown. Some candidate materials proposed for this scheme are NbN and NbTiN. Here we present experimental results correlating film microstructure and surface morphology with superconducting properties on coupon samples made with NbN and NbTiN. We have achieved thin films with close to bulk-like lattice parameters and transition temperatures, while achieving Hc1 values larger than bulk for films thinner than their London penetration depths. We compare results from samples grown utilizing NbTi targets with different stoichiometries and we will show RF measurements from 2” coupon samples. A. Gurevich, Appl. Phys. Lett. 88, 012511 (2006).
	Poster TUPB037 [0.989 MB]
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Paper

Title

Page

Growth and Characterization of Multi-Layer NbTiN Films

516

A-M. Valente-Feliciano, G.V. Eremeev, C.E. Reece, J.K. Spradlin
JLab, Newport News, Virginia, USA
M.C. Burton, R.A. Lukaszew
The College of William and Mary, Williamsburg, Virginia, USA

Significant theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities. The technological challenges include realization of high quality superconductors with sharp, clean, transition to high quality dielectric materials and back to superconductor, with careful thickness control of each layer. Choosing NbTiN as the first candidate material, we have developed the tools and techniques that produce such SIS film structures and have begun their characterization. Using DC magnetron sputtering and HiPIMS, NbTiN and AlN can be deposited with nominal superconducting and dielectric parameters. Hc1 enhancement is observed for NbTiN layers with a Tc of 16.9 K for a thickness less than 150 nm. The optimization of the thickness of each type of layer to reach optimum SRF performance is underway. This talk describes this work and the rf performance characteristics observed to date.

Slides TUBA08 [8.536 MB]

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUPB037

Superconducting NbN-Based Multilayer and NbTiN Thin Films for the Enhancement of SRF Accelerator Cavities

638

M.C. Burton, M. Beebe, R.A. Lukaszew, J.M. Riso
The College of William and Mary, Williamsburg, Virginia, USA
C.E. Reece, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: Funded by: Defense Threat Reduction Agency HDTRA1-10-1-0072
Current superconducting radio frequency (SRF) technology, used in various particle accelerator facilities is reliant upon bulk Nb. Due to technological advancements in the processing of bulk Nb cavities, the facilities have reached accelerating fields very close to material-dependent limits, i.e. ~50 MV/m for bulk Nb. One possible solution to overcome this limit proposed by A. Gurevich consists of the deposition of alternating thin layers of superconducting and insulating materials on the interior surface of the cavities which may prevent early field penetration and thus delay high field breakdown*. Some candidate materials proposed for this scheme are NbN and NbTiN. Here we present experimental results correlating film microstructure and surface morphology with superconducting properties on coupon samples made with NbN and NbTiN. We have achieved thin films with close to bulk-like lattice parameters and transition temperatures, while achieving Hc1 values larger than bulk for films thinner than their London penetration depths. We compare results from samples grown utilizing NbTi targets with different stoichiometries and we will show RF measurements from 2” coupon samples.
*A. Gurevich, Appl. Phys. Lett. 88, 012511 (2006).

Poster TUPB037 [0.989 MB]

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