Surface reactions and long time stability of YBCO thin films

Behner, H.; Rührnschopf, K.; Wedler, G.; Rauch, Walter

doi:10.1016/0921-4534(93)90216-d

Cited by 25 publications

(14 citation statements)

References 10 publications

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“…This degradation layer is characterized by a broad multiplet absorption in the Y(3d) region, the BaCO 3 signature in the Ba(3d5/2) region (i.e., the lower energy humps on the main peaks), and a CO 3 2- signature in the O(1s) region (i.e., ∼527 eV). These spectral signatures supports the presence of a degradation layer, in good agreement with the prior literature for similarly treated samples. − Quite interestingly, treatment of the “dirty” YBa 2 Cu 3 O 7 samples with a 2 mM solution of octadecylamine, butylamine, or hexylamine for 12 h leads to a dramatic improvement in the XPS signature for the cuprate powder, film, and pellet samples (Figure , solid curves). The presence of a clean exterior is noted by the doublet-like feature in the Y(3d) region, matching closely the pristine case that was prepared and evaluated in situ. − In addition, the amine exposure serves, for the most part, to eliminate the BaCO 3 surface layers, as evidenced by the clean Ba(3d5/2), Ba(3d3/2), and O(1s) transitions.…”

supporting

confidence: 86%

“…These spectral signatures supports the presence of a degradation layer, in good agreement with the prior literature for similarly treated samples. − Quite interestingly, treatment of the “dirty” YBa 2 Cu 3 O 7 samples with a 2 mM solution of octadecylamine, butylamine, or hexylamine for 12 h leads to a dramatic improvement in the XPS signature for the cuprate powder, film, and pellet samples (Figure , solid curves). The presence of a clean exterior is noted by the doublet-like feature in the Y(3d) region, matching closely the pristine case that was prepared and evaluated in situ. − In addition, the amine exposure serves, for the most part, to eliminate the BaCO 3 surface layers, as evidenced by the clean Ba(3d5/2), Ba(3d3/2), and O(1s) transitions. Finally, the XPS signature of the adsorbed amine reagent is found in the N(1s) region of the spectra that was absent in the untreated samples.…”

supporting

confidence: 86%

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Surface Cleaning and Adsorbate Layer Formation: Dual Role of Alkylamines in the Formation of Self-Assembled Monolayers on Cuprate Superconductors

et al. 1999

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supporting

confidence: 86%

supporting

confidence: 86%

Surface Cleaning and Adsorbate Layer Formation: Dual Role of Alkylamines in the Formation of Self-Assembled Monolayers on Cuprate Superconductors

et al. 1999

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“…The shaded area is subtracted background quality as well as a very slow aging rate. The formation of an insulating overlayer of thickness d is ≈ 20 times slower than for epitaxial films [17], i.e.…”

Section: Surface Analysis By Arxps On An Oxygenated Crystalmentioning

confidence: 99%

“…surface layers, and the 90-eV component from Ba−CO 3 /(OH). The Ba 4d 5/2 line at 87 eV is an excellent indicator of the superconducting YBCO surface [17], since aging is reflected in a decay of the bulk component. In Fig.…”

Section: Surface Analysis By Arxps On An Oxygenated Crystalmentioning

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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“…It can be seen that slight variations in the doping density and temperature can change the entire material property from superconducting to Mott insulating phase. Certain thin films of HTS can also degrade with time, for example, by losing oxygen doping . Thus, for device applications with thin films, it is extremely important to carefully choose the deposition method and conditions, substrate, fabrication procedure, and device packaging for reliable device operation.…”

Section: Introductionmentioning

confidence: 99%

Thin‐Film‐Based Integrated High‐Transition‐Temperature Superconductor Devices

Balasubramanian

Xing

Strugo

et al. 2019

Adv Funct Materials

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Since the discovery of superconductivity at temperatures above the technologically promising liquid nitrogen temperatures, applications based on superconductors have expanded and are being put to commercial use. However, superconductivity at higher temperatures typically occurs in complex materials requiring stringent material and environmental constraints. Such restraints make the realization and integration of these materials with normal materials a nontrivial aspect. In this progress report, unique features of these superconductors in terms of their synthesis, physical properties determining interface electrical transport, and their applications are discussed. A detailed progress report on these applications with remarks on efforts taken to integrate these devices with traditional platforms and semiconducting materials is provided.

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Surface reactions and long time stability of YBCO thin films

Cited by 25 publications

References 10 publications

Surface Cleaning and Adsorbate Layer Formation: Dual Role of Alkylamines in the Formation of Self-Assembled Monolayers on Cuprate Superconductors

Surface Cleaning and Adsorbate Layer Formation: Dual Role of Alkylamines in the Formation of Self-Assembled Monolayers on Cuprate Superconductors

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

Thin‐Film‐Based Integrated High‐Transition‐Temperature Superconductor Devices

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