Evolution of surface oxides and impurities in high vacuum heat treated Nb: A TEM and TOF-SIMS in-situ study, mechanism and repercussions on SRF cavity applications

AbstractAg/Cu multilayers are deposited onto a thin Si(100) cantilevered substrate in ultra high vacuum. During deposition, the force per unit width (F/w) in the multilayers is measured continuously from the substrate curvature by a laser scanning technique. Mechanical stability and sample temperature are monitored continuously. The evolution of stress in the film during a layer deposition depends on the thicknesses of the layers beneath it. During deposition of thicker layers of either Cu or Ag, we observe increasing tensile F/w at the start of each layer. The F/w increases up to a few N/m at ∼20 nm layer thickness, and then decreases. When the thickness of each layer is less than 30 nm, the tensile stress sometimes continues to decrease even after a new interface is created. This result does not support a model for the origin of compressive stress that is based on coherent propagation of compressive strain.

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In-Situ Study of the Oxide Mediated Epitaxy of CoSi2 on Si

MRS Proceedings ◽

10.1557/proc-564-135 ◽

1999 ◽

Vol 564 ◽

Author(s):

M. W. Kleinschmit ◽

M. Yeadon ◽

J. M. Gibson

Keyword(s):

Silicon Surface ◽

High Vacuum ◽

High Energy ◽

Ultra High Vacuum ◽

High Energy Electron ◽

In Situ Study ◽

Intermediate Phases ◽

Transmission Electron ◽

Combined Imaging

AbstractOxide Mediated Epitaxy (OME) shows promise as a method to form good quality, thin epitaxial CoSi2 films on most Si surfaces. We have performed an in-situ study of the OME of CoSi2, on the Si (001) surface. Our work was carried out with our specially modified ultra-high vacuum transmission electron microscope (UHV TEM) SHEBA (Surface High Energy Electron Beam Apparatus). With SHEBA we were able to monitor the diffraction pattern and therefore the phase formation throughout the anneal. Our results confirm the suppression of intermediate phases during CoSi2 formation in the OME process. We also see a difference in the as deposited Co film when the oxide coated silicon surface is used rather than a clean substrate. From combined imaging and diffraction studies we will shed some light on the mechanism behind the success of OME.

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In-situ study of multi-phase indium nanoparticle growth on/into CuPcF4 organic thin film in ultra-high vacuum conditions

Applied Surface Science ◽

10.1016/j.apsusc.2021.149136 ◽

2021 ◽

Vol 546 ◽

pp. 149136

Author(s):

O.V. Molodtsova ◽

I.M. Aristova ◽

D.V. Potorochin ◽

I.I. Khodos ◽

A.N. Chaika ◽

...

Keyword(s):

Thin Film ◽

High Vacuum ◽

Ultra High Vacuum ◽

Organic Thin Film ◽

Nanoparticle Growth ◽

In Situ Study ◽

Multi Phase

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In Situ Study of Nb Oxide and Hydride for SRF Cavity Applications Using Aberration-Corrected STEM and Electron Energy Loss Spectroscopy

IEEE Transactions on Applied Superconductivity ◽

10.1109/tasc.2012.2236380 ◽

2013 ◽

Vol 23 (3) ◽

pp. 7100703-7100703

Author(s):

R. Tao ◽

R. F. Klie

Keyword(s):

Energy Loss ◽

Electron Energy ◽

Electron Energy Loss Spectroscopy ◽

In Situ Study ◽

Aberration Corrected Stem ◽

Electron Energy Loss ◽

Srf Cavity ◽

Aberration Corrected

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SAM/EDX analysis of Cu(Nb) alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133539 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1780-1781

Author(s):

Albert J. Bevolo

Keyword(s):

Pure Copper ◽

High Vacuum ◽

Copper Matrix ◽

Ultra High Vacuum ◽

Ex Situ ◽

Static Vacuum ◽

Heat Treated ◽

Cast Alloys ◽

Edx Analyses

For several years our laboratory has investigated the properties of copper based alloys with transition metals such as Cu80Nb20. When heavily drawn these alloys retain the thermal conductivity of pure copper but acquire strengths usually associated with steels. Niobium dendrites, that are immiscible in the copper matrix in the as-cast form, become very fine, thermally stable filaments when heavily drawn. When heat treated in a diffusion pumped static vacuum chamber the surface unexpectedly acquires a silvery coloration rather than the reddish color expected from the dominant copper constituent. If a flow of inert gas is maintained then the surface becomes reddish. Experiments involving SAM and EDX analyses of cast alloys ex situ and in situ treated in ultra high vacuum (UHV) were performed to investigate this behavior.Auger depth profiles of the ex situ silver colored alloys showed from the Nb (167) Auger transition lineshape that the dominant phase was metallic NbO.

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In-situ study of Nb hydride for SRF cavity applications using aberration-corrected STEM and electron energy loss spectroscopy

Microscopy and Microanalysis ◽

10.1017/s1431927613005023 ◽

2013 ◽

Vol 19 (S2) ◽

pp. 606-607

Author(s):

R. Tao ◽

R.F. Klie ◽

L. Cooley ◽

A. Romanenko

Keyword(s):

Energy Loss ◽

Electron Energy ◽

Electron Energy Loss Spectroscopy ◽

In Situ Study ◽

Aberration Corrected Stem ◽

Electron Energy Loss ◽

Srf Cavity ◽

Aberration Corrected

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

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Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069272 ◽

1970 ◽

Vol 28 ◽

pp. 456-457

Author(s):

L. E. Murr ◽

G. Wong

Keyword(s):

Single Crystal ◽

High Vacuum ◽

Ultra High Vacuum ◽

High Rate ◽

Flash Evaporation ◽

Optimum Load ◽

Single Crystal Films ◽

Crystal Films ◽

A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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Hetero-Epitaxy of Group Va Metals on Sapphire

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095716 ◽

1972 ◽

Vol 30 ◽

pp. 492-493

Author(s):

J. E. O'Neal ◽

J. J. Bellina ◽

B. B. Rath

Keyword(s):

Thermal Contact ◽

High Vacuum ◽

Electron Beam Evaporation ◽

Ultra High Vacuum ◽

Backing Plate ◽

Sapphire Substrates ◽

Deposition Parameters ◽

Polishing Damage ◽

Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

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Formation Mechanisms for Multiply Twinned Particles During Nucleation in the Au/MICA System

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114049 ◽

1975 ◽

Vol 33 ◽

pp. 84-85

Author(s):

Eal H. Lee ◽

Helmut Poppa

Keyword(s):

Deposition Time ◽

High Vacuum ◽

Dark Field ◽

Ultra High Vacuum ◽

Formation Mechanisms ◽

Heat Treated ◽

Cluster Density ◽

Diffraction Patterns ◽

Crystal Particle ◽

Multiply Twinned Particles

The formation of thin films of gold on mica has been studied in ultra-high vacuum (5xl0-10 torr) . The mica substrates were heat-treated for 24 hours at 375°C, cleaved, and annealed for 15 minutes at the deposition temperature of 300°C prior to deposition. An impingement flux of 3x1013 atoms cm-2 sec-1 was used. These conditions were found to give high number densities of multiple twin particles and are based on a systematic series of nucleation experiments described elsewhere. Individual deposits of varying deposition time were made and examined by bright and dark field TEM after "cleavage preparation" of highly transparent specimens. In the early stages of growth, the films generally consist of small particles which are either single crystals or multiply twinned; a strong preference for multiply twinned particles was found whenever the particle number densities were high. Fig. 1 shows the stable cluster density ns and the variation with deposition time of multiple twin particle and single crystal particle densities, respectively. Corresponding micrographs and diffraction patterns are shown in Fig. 2.

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