scholarly journals Development and Characterization of Nb3Sn/Al2O3 Superconducting Multilayers for High-performance Radio-Frequency Applications

2021 ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  
Keyword(s):  
Radio Frequency ◽  
High Performance ◽  
High Energy ◽  
Quality Factors ◽  
Critical Fields ◽  
Linear Accelerators ◽  
Cross Sectional ◽  
Low Field ◽  
Superconducting Radio Frequency

Abstract Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1-2 GHz and 2K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.

scholarly journals Development and characterization of Nb3Sn/Al2O3 superconducting multilayers for particle accelerators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul B. Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  
Keyword(s):  
High Performance ◽  
High Energy ◽  
Particle Accelerators ◽  
Quality Factors ◽  
Critical Fields ◽  
Linear Accelerators ◽  
Cross Sectional ◽  
Low Field ◽  
Superconducting Radio Frequency

AbstractSuperconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1–2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200–240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.

Development of High-Performance GaAs Solar Cells on Large-Grain Polycrystalline Ge Substrates

1995 ◽  
Vol 403 ◽  
Author(s):  
R. Venkatasubramanian ◽  
B. O'Quinn ◽  
J. S. Hills ◽  
M. L. Timmons ◽  
D. P. Malta
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Cross Sectional ◽  
Plan View ◽  
Electron Beam Induced Current ◽  
Induced Defects

AbstractThe characterization of MOCVD-grown GaAs-AlGaAs materials and GaAs p+n junctions on poly-Ge substrates is presented. Minority carrier lifetime in GaAs-AIGaAs double-hetero (DH) structures grown on these substrates and the variation of lifetimes across different grainstructures are discussed. Minority-carrier diffusion lengths in polycrystalline GaAs p+-n junctions were evaluated by cross-sectional electron-beam induced current (EBIC) scans. The junctions were also studied by plan-view EBIC imaging. Optimization studies of GaAs solar cell on poly-Ge are discussed briefly. The effect of various polycrystalline substrate-induced defects on performance of GaAs solar cells are presented.

Growth and Characterization of AlBN Polycrystalline Thin Film by Radio-Frequency Plasma-Assisted Molecular Beam Epitaxy

2006 ◽  
Vol 301 ◽  
pp. 95-98 ◽  
Author(s):  
Masashi Yamashita ◽  
Yukari Ishikawa ◽  
Hitoshi Ohsato ◽  
Noriyoshi Shibata
Keyword(s):  
Thin Film ◽  
Molecular Beam Epitaxy ◽  
Radio Frequency ◽  
Photoelectron Spectroscopy ◽  
Molecular Beam ◽  
High Energy ◽  
Radio Frequency Plasma ◽  
Group Iii ◽  
Frequency Plasma

An AlBN thin film with a boron content (B/(Al+B)) of 0.1 or 0.3 was obtained by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE) using EB-guns as group-III element sources and an RF radical source for nitrogen supply. We compared the characteristics of the film with those of AlN and BN films. By reflective high-energy electron diffraction (RHEED), we observed ring patterns in the AlBN film. The X-ray photoelectron spectroscopy (XPS) N1s peak of the AlBN film was observed at a binding energy between the peaks of AlN and BN. There was no evidence for phase separation in the film.

scholarly journals Dual-energy CT characterization of winter sports injuries

2020 ◽  
Vol 93 (1106) ◽  
pp. 20190620
Author(s):  
Jonathan Hickle ◽  
Frances Walstra ◽  
Peter Duggan ◽  
Hugue Ouellette ◽  
Peter Munk ◽  
...  
Keyword(s):  
High Speed ◽  
Sports Injuries ◽  
Imaging Modality ◽  
High Energy ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Cross Sectional ◽  
Winter Sports ◽  
Conventional Ct

CT is a readily available imaging modality for cross-sectional characterization of acute musculoskeletal injuries in trauma. Dual-energy CT provides several additional benefits over conventional CT, namely assessment for bone marrow edema, metal artifact reduction, and enhanced assessment of ligamentous injuries. Winter sports such as skiing, snowboarding, and skating can result in high speed and high energy injury mechanisms; dual-energy CT is well suited for the characterization of those injuries.

characterization of amorphization in Ni-Ti multilayers

1988 ◽  
Vol 46 ◽  
pp. 452-453
Author(s):  
K. B. Alexander ◽  
F. J. Walker ◽  
R. A. McKee ◽  
F. A. List
Keyword(s):  
Amorphous Film ◽  
High Energy ◽  
Film Deposition ◽  
Cross Sectional ◽  
Transmission Electron ◽  
20 Nm ◽  
Elemental Layer ◽  
Deposited Films

The formation of amorphous alloys through the solid-state reaction of crystalline multilayers has recently been studied by several groups. In each of these studies, the multilayers were entirely amorphous when there were less than 4-10 planes in each layer. Layer thicknesses larger than this resulted in crystalline layers, presumably separated by an amorphous film approximately 4-10 layers thick. Our intent was to measure the thickness of the amorphous film in Ni-Ti multilayer specimens with a wavelength (thickness of Ni + Ti layers) of 20 nm, or approximately 40 planes per elemental layer. In situ Reflection High Energy Electron Diffraction (RHEED) was performed during the film deposition and transmission electron microscopy of cross-sectional specimens was used to examine the as-deposited films.Nickel and titanium layers were sequentially deposited onto a 50 nm amorphous Ni-Ti codeposit on an unheated (001) silicon substrate in the ORNL Molecular Beam Epitaxy (MBE) facility with a vacuum < 10-9 torr.

Microstructure of silicon implanted with MeV gold ions

1991 ◽  
Vol 49 ◽  
pp. 876-877
Author(s):  
M.J. Kim ◽  
M. Catalano ◽  
T.P. Sjoreen ◽  
R.W. Carpenter
Keyword(s):  
Single Crystal ◽  
Ion Irradiation ◽  
Microstructural Characterization ◽  
High Energy ◽  
Ion Milling ◽  
Cross Sectional ◽  
Microstructural Investigation ◽  
Annealing Behavior ◽  
Different Doses

High-energy implantation of silicon is of great interest in recent years for microelectronics due to the formation of a buried damage or dopant layer away from the active region of the device. The damage nucleation and growth behavior is known to vary significantly along the ion's track for MeV irradiation. In this paper, a detailed characterization of the damage morphology produced by MeV gold ions for different doses into single crystal Si, as well as the associated annealing behavior, is presented.Single crystal n-type Czochralski silicon {001} wafers were implanted with Au++ ions from doses of 1x1015 to 3x1016 cm-2 at 2-3 MeV. Specimen temperatures for all implantations were 20 or 300°C. A measurement with an infrared pyrometer of the implanted surface indicated a slight temperature rise during ion irradiation. The compositional and damage profiles were determined by Rutherford backscattering/channeling spectroscopy (RBS). Cross-sectional TEM samples for microstructural characterization were prepared by mechanical polishing and ion milling. A Philips 400ST/FEG analytical microscope was used for nanoprobe experiments, at 100 kV. Microstructural investigation was performed using ISI-002B and JEM-2000FX microscopes, at 200 kV.

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