ARXPS, SEM, and SAM studies of highly textured YBa/sub 2/Cu/sub 3/O/sub x/ films

Halbritter, J.; Häuser, B.; Keim, Enrico G.; Mathes, H.J.; Walk, Philipp; Rogalla, Horst

doi:10.1109/20.92775

Cited by 9 publications

(4 citation statements)

References 15 publications

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“…The relatively high barium concentration in the surface region is due to the formation of the thermodynamically stable BaO, [5], forming crystallites as shown in ref. 1 by the elemental Auger mappings. Furthermore, the build-up of barium is enhanced by the rapid barium diffusion in oxygen- deficient cuprate via the oxygen vacancies in the copper chains [6].…”

Section: Analysis Resultsmentioning

confidence: 99%

Scanning Auger microscopy as applied to the analysis of highly textured YBaCu3Ox thin films

Keim

Halbritter

Häuser

et al. 1989

Journal of the Less Common Metals

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SummaryScanning Auger electron spectroscopy and scanning electron microscopy have been used to investigate the local composition and structure of highly textured c^ axis oriented YBaCuO films with thicknesses in the range 0.4 -1 pm. The cuprate films were sputtered on MgO and sapphire (lOO)-oriented single-crystal substrates at room temperature followed by several anneal stages below or at 920 "C in pure oxygen. The YBaCuO/sapphire sample was examined again after an additional 750 "C air anneal for 24 h. By applying Auger line profiling on a freshly prepared cross-sectional surface of a thin cuprate film deposited on a sapphire substrate we have been able to show that barium aluminate segregation at grain boundaries is the main cause of the higher electrical resistance usually observed for cuprate films on A&O,. The (drastic) reduction in T, can be attributed to the substitution of aluminium in the cuprate at copper sites. Severe interdiffusion has been observed for the epitaxial c^ axis oriented YBaCu oxide films grown on an MgO substrate, which leads to a deterioration in the superconductivity.The main reason for reduced T, and quality of cuprate films on MgO is the copper loss into the substrate, the depth of penetration of copper extending more than 400 nm below the YBaCuO-MgO interface. From our experimental results it is evident that Auger line profiling is an important tool in the analysis of high T, superconducting thin films.

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Section: Analysis Resultsmentioning

confidence: 99%

Scanning Auger microscopy as applied to the analysis of highly textured YBaCu3Ox thin films

Keim

Halbritter

Häuser

et al. 1989

Journal of the Less Common Metals

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“…Wide scans and angle-resolved measurements show intrinsic peaks and reveal a 3-nm layer consisting mainly of BaCO 3 and CuO. Figure 3 shows two high-resolution spectra of the Ba 4d 3/2 and 5/2 doublet measured at a time interval of 4 months.…”

Section: Surface Analysis By Arxps On An Oxygenated Crystalmentioning

confidence: 97%

“…By spatially resolved tunneling spectroscopy the vortex lattice in a magnetic field of 4 T has been imaged. The inter-vortex distance amounts to 20 ± 2 nm.Scanning probe methods and angle resolved X-ray photoelectron spectroscopy (ARXPS) are well established tools for studying the surface properties of high-temperature superconductors [1][2][3][4]. Each of these methods probes specific qualities and depths of a material, allowing the reconstruction of a three-dimensionally resolved interface.…”

mentioning

confidence: 99%

YBa 2 Cu 3 O 7-δ single crystals revisited: Scanning probe data on very pure samples grown in BaZrO 3 crucibles

Hubler¹,

Jess²,

Lang³

et al. 1998

Applied Physics A: Materials Science & Processing

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We have studied very pure YBa 2 Cu 3 O 7−δ (YBCO) single crystals grown in BaZrO 3 crucibles by scanning and friction force microscopy (SFM, FFM) as well as by scanning tunneling microscopy (STM) and angle resolved X-ray photo-electron spectroscopy (ARXPS). By STM and SFM, clean stepped terraces are observed on as-grown crystals. Friction contrast, however, implies the presence of different materials, presumably traces of flux. After oxidation of the YBCO crystals, particles of 10 to 100 nm in size appear on the surface. Their number per unit area increases with time when the crystal is stored in air. Complementary information on such aged YBCO surfaces is provided by ARXPS. These data reveal 3 nm of mainly BaCO 3 and CuO on top of the YBCO matrix and suggest a very slow aging rate of the crystals, which is 20 times slower than for epitaxial thin films. The superconducting energy gap has been determined on fresh crystals by scanning tunneling spectroscopy (STS) at 4.6 K as 2∆ ≈ 30 meV. By spatially resolved tunneling spectroscopy the vortex lattice in a magnetic field of 4 T has been imaged. The inter-vortex distance amounts to 20 ± 2 nm.Scanning probe methods and angle resolved X-ray photoelectron spectroscopy (ARXPS) are well established tools for studying the surface properties of high-temperature superconductors [1][2][3][4]. Each of these methods probes specific qualities and depths of a material, allowing the reconstruction of a three-dimensionally resolved interface. Scanning tunneling microscopy (STM) and scanning force microscopy (SFM) not only allow investigations of the surface morphology on a nanometer to micrometer scale, but also provide material contrast by use of friction force microscopy (FFM). This yields valuable information on the purity of such surfaces. Complementary data on their chemical composition and aging process is provided by ARXPS. Furthermore, scanning tunneling spectroscopy (STS) probes the electronic density of states (DOS) near the Fermi level and allows the determination of the superconducting energy gap from current vs. voltage (I(V )) characteristics [5].Until recently, traces of residual flux on YBa 2 Cu 3 O 7−δ (YBCO) surfaces (mainly BaCuO 2 and CuO serving as flux solvents) as well as impurities originating from crucible materials (e.g. Al 2 O 3 , Au, MgO) constituted a major problem for crystal growers. Poor surface quality presents a problem especially when a surface-sensitive technique, such as STM or STS, is applied to probe electronic properties in the superconducting state. The short coherence length in YBCO, which is only of the order of a few Å in the [001] direction, means measurements are strongly affected even by thin contamination layers.These problems seem to have been overcome by using BaZrO 3 as the crucible material [6][7][8]. This material shows a sharp and non-reactive interface with the flux used in the YBCO growth process. Furthermore, Zr is unlikely to be incorporated into YBCO by substitution reactions, since its ion size does not fit in the structur...

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“…Scanning probe methods and angle resolved X-ray photoelectron spectroscopy (ARXPS) are well established tools for studying the surface properties of high-temperature superconductors [1][2][3][4]. Each of these methods probes specific qualities and depths of a material, allowing the reconstruction of a three-dimensionally resolved interface.…”

mentioning

confidence: 99%

YBa2Cu3O7-δ single crystals revisited: Scanning probe data on very pure samples grown in BaZrO3 crucibles

et al. 1998

View full text Add to dashboard Cite

ARXPS, SEM, and SAM studies of highly textured YBa/sub 2/Cu/sub 3/O/sub x/ films

Cited by 9 publications

References 15 publications

Scanning Auger microscopy as applied to the analysis of highly textured YBaCu3Ox thin films

Scanning Auger microscopy as applied to the analysis of highly textured YBaCu3Ox thin films

YBa 2 Cu 3 O 7-δ single crystals revisited: Scanning probe data on very pure samples grown in BaZrO 3 crucibles

YBa2Cu3O7-δ single crystals revisited: Scanning probe data on very pure samples grown in BaZrO3 crucibles

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