Epitaxial Growth and Superconducting Properties of Yba2Cu3O7 Thin Films and Yba2Cu3O7/Dy(Pr)Yba2Cu3O7 Superlattices

1989 ◽  
Vol 169 ◽  
Author(s):  
J.-M. Triscone ◽  
M.G. Karkut ◽  
O. Brunner ◽  
L. Antognazza ◽  
A.D. Kent ◽  
...  
Keyword(s):  
Thin Films ◽  
Residual Resistivity ◽  
Unit Cell ◽  
Superconducting Properties ◽  
Single Target ◽  
Planar Magnetron ◽  
Zero Resistance ◽  
Superconducting Fluctuations ◽  
Modulation Wavelength

AbstractWe have prepared in situ REBa2Cu3O7 (REBCO) (RE= Y, Pr, Dy) thin films and YBC0/Dy(Pr)BC0 superlattices by single target dc planar magnetron sputtering. YBCO/DyBCO superlattices have been realized with modulation wavelength as short as 24Å, i.e., a unit cell of YBCO alternates with a unit cell of DyBCO, on average. The superconducting properties of such superlattices are indistinguishable from those of single layers. Tco's (zero resistance) are between 85 and 89K, and the residual resistivity ratios are between 2.5 and 3. In contrast to these results, when YBCO is layered with PrBCO, which is insulating, a dramatic change in the superconducting properties is observed. We have been able to artificially vary the coupling between single 12Å unit cell of YBCO by interposing insulating planes of PrBCO. As the YBCO layer separation increases, T is reduced and the transition broadens showing evidence of 2‐D superconducting fluctuations.

In‐Situ Growth of Superconducting Bi‐Sr‐Ca‐Cu‐O Thin Films by Activated Reactive Co‐evaporation

1989 ◽  
Vol 169 ◽  
Author(s):  
K. Yoshikawa ◽  
T. Satoh ◽  
N. Sasaki ◽  
M. Nakano
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Transition Temperature ◽  
Smooth Surface ◽  
Oxygen Plasma ◽  
In Situ Growth ◽  
Superconducting Properties ◽  
Cooling Conditions ◽  
Zero Resistance

AbstractThe effect of in‐situ cooling conditions on surface roughness and superconducting properties have been studied. Bi‐Sr‐Ca‐Cu‐0 thin films were grown in‐situ on (100) MgO substrates at 700°C by activated reactive co‐evaporation. The films cool‐down in 760 Torr oxygen showed a transition temperature (Tc(onset)) of 100 K and zero resistance temperature (Tc (zero)) of 65 K. Smooth surface was obtained for the sample cooled‐down in oxygen plasma.

Synthesis and Properties of Ultra-Thin YBa2Cu3O7 and YBa2Cu3O7/La2-xSrxCuO4 Multilayers

1989 ◽  
Vol 169 ◽  
Author(s):  
C.B. Eom ◽  
S.K. Streiffer ◽  
J.Z. Sun ◽  
K. Yamamoto ◽  
S.S. Laderman ◽  
...  
Keyword(s):  
Single Layer ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Superconducting Thin Film ◽  
Cross Sectional ◽  
X Ray ◽  
Single Target ◽  
Modulation Wavelength

AbstractUsing our standard single target off-axis sputter deposition procedure[1], ultra-thin YBa2Cu3O7 superconducting films were made in-situ. We have studied the thickness dependence of superconducting properties (Tc, Jc) from 20 to 5000Å. Tc starts degrading below 125Å and falls to 50 K for the 30 Å film. Jc drops linearly with decreasing thickness below l000Å. We have grown YBa2Cu3O7/La2-xSrxCuO4 superconducting thin film multilayers in-situ by the same process. The modulation wavelength of the multilayers ranged from 45Å to 2000Å. X-ray diffraction and cross sectional TEM confirm the superlattice periodicity. The superconducting transition temperature drops in much the same way as the single layer ultra-thin films. Both the critical current density and its magnetic field dependence decrease as the modulation wavelength decreases.

Epitaxy and texture analysis of Bi-Sr-Ca-Cu-O thin films on (100) MgO using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 68-69
Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Critical Currents ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Cell Axis ◽  
Transmission Electron ◽  
Synthesis Procedure

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).

Large Area Uniform Deposition of YBa2Cu3O7 Thin Films by a 90° Off-axis Sputtering Technique

1995 ◽  
Vol 401 ◽  
Author(s):  
R. A. Rao ◽  
Q. Gan ◽  
C. B. Eom
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Uniform Thickness ◽  
Superconducting Properties ◽  
Large Area ◽  
Substrate Rotation ◽  
Single Target ◽  
High Transition ◽  
Substrate Position ◽  
Uniform Deposition

AbstractLarge area uniform deposition of Yba2Cu3O7 (YBCO) thin films on 8 inch diameter wafers, using a 3 inch diameter sputtering target and optimized substrate rotation in a single target 90° off-axis sputtering technique, is reported. The variation in thickness, composition and superconducting properties was studied as a function of substrate position on stationary and rotating substrates. The films deposited from a 3” target on rotating substrates displayed uniform thickness (< ±5% variation) and composition (< 2.3% deviation from target stoichiometry) and a consistently high transition temperature ( Tc > 88.3°K) over an 8” diameter area.

In-Situ Laser Processing and Microstructural Characteristics of YBa2Cu3O7−δ Thin Films on Si with TiN Buffer Layer

1992 ◽  
Vol 285 ◽  
Author(s):  
P. Tiwari ◽  
T. Zheleva ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transition Temperature ◽  
Buffer Layer ◽  
Processing Parameters ◽  
Superconducting Transition ◽  
Epitaxial Relationship ◽  
Ybco Thin Films ◽  
Zero Resistance

ABSTRACTWe have prepared high-quality superconducting YBa2Cu3O7−δ (YBCO) thin films on Si(100) with TiN as a buffer layer using in-situ multitarget deposition system. Both TiN and YBCO thin films were deposited sequentially by KrF excitner laser ( λ = 248 nm ) at substrate temperature of 650°C. Thin films were characterized using X-ray diffraction (XRD), four-point-probe ac resistivity, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Rutherford backscattering (RBS). The TiN buffer layer was epitaxial and the epitaxial relationship was found to be cube on cube with <100> TiN // <100> Si. YBCO thin films on Si with TiN buffer layer showed the transition temperature of 90–92K with Tco (zero resistance temperature) of ∼84K. We have found that the quality of the buffer layer is very important in determining the superconducting transition temperature of the thin film. The effects of processing parameters and the correlation of microstructural features with superconducting properties are discussed indetail.

IN-SITU PREPARATION OF YBa2Cu3O7 SUPERCONDUCTING THIN FILMS BY PULSED Nd:YAG LASER DEPOSITION

1992 ◽  
Vol 06 (08) ◽  
pp. 477-483 ◽  
Author(s):  
QINGXIN SU ◽  
SHIFA XU ◽  
DAFU CUI ◽  
HUIBIN LU ◽  
YONGJUN TIAN ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Nd:Yag Laser ◽  
Ac Susceptibility ◽  
Substrate Surface ◽  
Zero Magnetic Field ◽  
Superconducting Thin Films ◽  
In Situ Preparation ◽  
Zero Resistance

High-T c superconducting thin films of YBa 2 Cu 3 O 7 were grown in-situ on (100) SrTiO 3 substrates by Nedymium:yttrium aluminum garnet [Nd:YAG] laser ablation. The effects of the substrate temperature on the transition temperature, microcrystalline structure and surface morphology of the films were discussed. Best results were obtained in the 730°–770°C range. X-ray diffraction analysis showed that these films were highly c-oriented with the c-axis perpendicular to the substrate surface. At the optimum substrate temperature, a very smooth morphology with only a few small particles were observed by scanning electron microscopy. The zero resistance temperature of these films were ≥ 90 K with a narrow transition width and the ac susceptibility measurement also gave the same result. The highest critical current density obtained at 77 K and zero magnetic field was 3.8 × 106 A/cm 2.

EPITAXIAL YBa2Cu3O7 and GdBa2Cu3O7 THIN FILMS GROWN IN-SITU BY SINGLE TARGET D.C. SPUTTERING

1990 ◽  
pp. 336-343
Author(s):  
M.G. KARKUT ◽  
M. GUILLOUX-VIRY ◽  
A. PERRIN ◽  
O. PENA ◽  
J. PADIOU ◽  
...  
Keyword(s):  
Thin Films ◽  
Single Target

Atomic Layer and Unit-Cell Layer Growth of (Ca,Sr)CuO2 and Bi2Sr2Can-1CunO2n+4 Thin Films by Laser Molecular Bean Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
Masaki Kanai ◽  
Tomoji Kawai ◽  
Takuya Matsumoto ◽  
Shichio Kawai
Keyword(s):  
Thin Films ◽  
Diffraction Pattern ◽  
Cell Layer ◽  
Atomic Layer ◽  
High Energy ◽  
Layer Growth ◽  
Unit Cell ◽  
Layer By Layer ◽  
Diffraction Intensity

ABSTRACTThin films of (Ca,Sr)CuO2 and Bi2Sr2Can-1CunO2n+4 are formed by laser molecular beam epitaxy with in-situ reflection high energy electron diffraction observation. The diffraction pattern shows that these materials are formed with layer-by-layer growth. The change of the diffraction intensity as well as the analysis of the total diffraction pattern makes It possible to control the grown of the atomic layer or the unit-cell layer.

Comparison of Several CU(I) and CU(II) Precursors for the Sol-Gel Preparation of High TC Superconducting Metal Oxides

1988 ◽  
Vol 121 ◽  
Author(s):  
Mariquita A. Accibal ◽  
Jonathan W. Draxton ◽  
Allen H. Gabor ◽  
Wayne L. Gladfelter ◽  
Beth Anne Hassler ◽  
...  
Keyword(s):  
Thin Films ◽  
Metal Oxides ◽  
Coordination Compounds ◽  
Sol Gel ◽  
High Tc ◽  
Superconducting Metal ◽  
Zero Resistance ◽  
Gel Preparation ◽  
Sol Gel Synthesis

ABSTRACTA comparison of the use of three different coordination compounds of copper as precursors for the sol-gel synthesis of YBa2Cu3O7-δ has been made. For yttrium, the tris(isopropoxide) was used exclusively, while the use of both Ba(O-i-Pr)2 and Ba(OCH2CH2OEt)2 (prepared in situ from Ba metal) as sources for Ba were studied. After dissolving Y(O-i-pr)3, a Ba source, and the copper(I) alkoxide, [Cu(O-i-Bu)]4, hydrolysis led immediately to an orange gelatinous solid which yielded YBa2Cu3O7-δ upon firing in oxygen. Copper(II) acetate was found to give heterogeneous mixtures under our conditions and was not further studied. Copper(II) acac (acac = acetylacetonate) yielded the best results. Partially hydrolyzed solutions of Cu(acac)2, Ba(OCH2CH2OEt)2, and Y(O-i-pr)3 were spin coated on SrTi03 (100) and fired under oxygen to give oriented (b axis normal to the surface) thin films of YBa2Cu3O7-δ. The onset of superconductivity for the films was 92 K, but they did not reach zero resistance until much lower temperatures.

Superconducting properties of two-step in situ annealed MgB2 thin films

2004 ◽  
Vol 412-414 ◽  
pp. 1371-1375 ◽  
Author(s):  
Zon Mori ◽  
Toshiya Doi ◽  
Yuichiro Ishizaki ◽  
Hitoshi Kitaguchi ◽  
Michiya Okada ◽  
...  
Keyword(s):  
Thin Films ◽  
Superconducting Properties ◽  
Mgb2 Thin Films
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