Fabrication of high Tc Superconducting Films with Diffusion Barriers

1987 ◽  
Vol 99 ◽  
Author(s):  
C. T. Ghien ◽  
Gang Xiao ◽  
M. Z. Cieplak ◽  
A. Bakhshai ◽  
A. Gavrin ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Meissner Effect ◽  
Superconducting Films ◽  
Diffusion Barriers ◽  
Buffer Layers ◽  
High Temperature Annealing ◽  
Superconducting Properties ◽  
High Tc ◽  
Effective Current ◽  
High Transition

Superconducting YBa2Cu3O; thin films have been prepared by magnetron sputtering onto [100] single crystal MgO with and without an Au buffer layer. All samples show high transition temperatures (82–87 K). The use of an Au buffer layer significantly improves the superconducting properties, particularly the Meissner effect and critical current density (3.3×106A/cm2 at 2 K and 3.5×104A/cm2 at T=77 K). The Au buffer layers remain metallic after high temperature annealing in an oxygen atmosphere, and may thus serve as effective current shunts.

Microstructural analysis of the compatibility of solution deposited buffer layers with the TFA process for YBCO

2000 ◽  
Vol 659 ◽  
Author(s):  
K. Salama ◽  
S. Sathyamurthy ◽  
M. Mironova
Keyword(s):  
Buffer Layer ◽  
Critical Current ◽  
Strontium Titanate ◽  
Surface Defects ◽  
Microstructural Analysis ◽  
Buffer Layers ◽  
Barium Zirconate ◽  
Chemical Compatibility ◽  
Superconducting Properties ◽  
Current Densities

ABSTRACTIn this paper, the feasibility of applying solution deposition processes for the fabrication of coated conductors has been explored. The crystal and chemical compatibility of the buffer layers processed using metalorganic decomposition with the Y123 deposition using the trifluoroacetate process has been studied. Two buffer layer materials have been used, namely, barium zirconate and strontium titanate. The measured superconducting properties of these conductors were correlated with the microstructure observed on these samples using SEM and cross-sectional TEM. In case of barium zirconate buffer layers, though there exists a very good structural and chemical compatibility between the buffer layer and the Y123, the presence of surface defects in the buffer layer causes compositional heterogeneity and randomly oriented grains in the Y123 film. This leads to poor superconducting properties. In case of strontium titanate buffer layers, due to the excellent crystal and chemical compatibility, and the absence of surface defects, high critical current densities (of the order of 106A/cm2 at 77K and self field) were obtained. However, TEM cross section studies reveals the presence of a significant portions of a-oriented Y123 crystallites which could lead to lower critical current densities. Further studies of the TFA process is required to eliminate the occurrence of a-oriented Y123 in the microstructure. This could lead to further improvements in the properties.

Epitaxial Relationships of the a-Axis Oriented YBa2Cu3O7-x Thin Films on the PrBa2Cu3O7-xTx Buffered SrTiO3(100) by two Step PLD

1994 ◽  
Vol 341 ◽  
Author(s):  
Gun Yong Sung ◽  
Jeong Dae Suh ◽  
Sahn Nahm
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Volume Fraction ◽  
Buffer Layers ◽  
Laser Deposition ◽  
Superconducting Properties ◽  
Ybco Thin Film ◽  
Axis Orientation ◽  
Ybco Thin Films ◽  
Zero Resistance

AbstractAn a-axis oriented YBa2Cu3O7-x (YBCO) thin film exhibiting zero resistance at 83 K and critical current density of 7.9x103 A/cm2 at 62 K was obtained on an 180 nm - thick PrBa2Cu3 O7-xx(PBCO) buffered SrTiO3(100) substrate by two step pulsed laser deposition (PLD). The volume fraction of a-axis orientation and the crystallinity(Xmin) of the 150 nm-thick YBCO thin films were increased with increasing the thickness of PBCO buffer layer, which was varied friom 0 nm to 180 nm. It is concluded that the thickness of PBCO buffer layer is one of the important parameters to control the structural and superconducting properties of the a-axis oriented YBCO thin films using the PBCO buffer layers.

High TC Superconducting Films from Metallo-Organic Precursors

1987 ◽  
Vol 99 ◽  
Author(s):  
W. W. Davison ◽  
S. G. Shyu ◽  
R. C. Buchanan
Keyword(s):  
Precursor Solution ◽  
Superconducting Films ◽  
Superconducting Properties ◽  
High Tc ◽  
Casting Technique ◽  
Spin Casting ◽  
Molar Ratios ◽  
High Boiling Point ◽  
Organic Precursors ◽  
Metal Soaps

ABSTRACTHigh Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O7−x, using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1–1.0μm were achieved after heat treatment at 550°-850°C ≤4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction and superconducting properties.

PREPARATION OF BUFFER LAYERS ON SAPPHIRE FOR HIGH Tc SUPERCONDUCTING THIN FILMS

1991 ◽  
Vol 05 (19) ◽  
pp. 1267-1273 ◽  
Author(s):  
X. D. WU ◽  
R. E. MUENCHAUSEN
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Dielectric Constants ◽  
Buffer Layers ◽  
Processing Temperature ◽  
Superconducting Thin Films ◽  
Superconducting Properties ◽  
Stabilized Zirconia ◽  
Low Loss ◽  
High Tc

Sapphire is a preferred substrate for high frequency applications where small dielectric constants and low loss tangents are required. It is also much cheaper than other oxide subsrates such as SrTiO 3, LaAlO 3, NdGaO 3, MgO, and yttria-stabilized zirconia (YSZ) for high T c superconducting thin films. Unfortunately, sapphire is not chemically compatible with the high T c superconductors at the processing temperature required to obtained good superconducting properties. As a result, an appropriate buffer layer on sapphire is required.

Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation

1988 ◽  
Vol 46 ◽  
pp. 866-867
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
L. G. Turner ◽  
N. Lewis
Keyword(s):  
Thin Film ◽  
Thin Film Deposition ◽  
Superconducting Films ◽  
Electron Beam Evaporation ◽  
Film Deposition ◽  
Silicon Substrates ◽  
Superconducting Properties ◽  
Sequential Electron ◽  
Thin Superconducting Films

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.

In-Situ Study of NiO Growth on Textured Nickel Tape Using Environmental Scanning Electron Microscope (ESEM) and Hot Stage

2001 ◽  
Vol 7 (S2) ◽  
pp. 1276-1277
Author(s):  
Y. Akin ◽  
R.E. Goddard ◽  
W. Sigmund ◽  
Y.S. Hascicek
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Dip Coating ◽  
Buffer Layers ◽  
Superconducting Film ◽  
Environmental Scanning ◽  
Cold Rolling And Annealing

Deposition of highly textured ReBa2Cu3O7−δ (RBCO) films on metallic substrates requires a buffer layer to prevent chemical reactions, reduce lattice mismatch between metallic substrate and superconducting film layer, and to prevent diffusion of metal atoms into the superconductor film. Nickel tapes are bi-axially textured by cold rolling and annealing at appropriate temperature (RABiTS) for epitaxial growth of YBa2Cu3O7−δ (YBCO) films. As buffer layers, several oxide thin films and then YBCO were coated on bi-axially textured nickel tapes by dip coating sol-gel process. Biaxially oriented NiO on the cube-textured nickel tape by a process named Surface-Oxidation- Epitaxy (SEO) has been introduced as an alternative buffer layer. in this work we have studied in situ growth of nickel oxide by ESEM and hot stage.Representative cold rolled nickel tape (99.999%) was annealed in an electric furnace under 4% hydrogen-96% argon gas mixture at 1050°C to get bi-axially textured nickel tape.

Noise of high-Tc superconducting films and bolometers

1998 ◽  
Vol 08 (PR3) ◽  
pp. Pr3-293-Pr3-296
Author(s):  
I. A. Khrebtov ◽  
V. N. Leonov ◽  
A. D. Tkachenko ◽  
P. V. Bratukhin ◽  
A. A. Ivanov ◽  
...  
Keyword(s):  
Superconducting Films ◽  
High Tc

Effects of the Sputtering Time of AlN Buffer Layer on the Quality of ZnO Thin Films

2014 ◽  
Vol 881-883 ◽  
pp. 1117-1121 ◽  
Author(s):  
Xiang Min Zhao
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Rf Magnetron Sputtering ◽  
Buffer Layers ◽  
Zno Thin Films ◽  
Zno Films ◽  
Si Substrates ◽  
Atomic Force ◽  
Structure Morphology ◽  
Aln Buffer

ZnO thin films with different thickness (the sputtering time of AlN buffer layers was 0 min, 30 min,60 min, and 90 min, respectively) were prepared on Si substrates using radio frequency (RF) magnetron sputtering system.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO thin films with different sputtering time of AlN buffer layer,and for the better growth of ZnO films, the optimal sputtering time is 60 min.

The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ewa Dumiszewska ◽  
Wlodek Strupinski ◽  
Piotr Caban ◽  
Marek Wesolowski ◽  
Dariusz Lenkiewicz ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Oxygen Concentration ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Temperature Growth ◽  
Gan Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

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