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.

In-Situ Preparation and Characterization of Superconducting Thin Films and Related Materials by Mocvd for the Development of Three Terminal Switching Devices

1989 ◽  
Vol 169 ◽  
Author(s):  
R. Singh ◽  
S. Sinha ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
High Temperature Superconductor ◽  
Chemical Vapor ◽  
Silicon Substrates ◽  
Superconducting Thin Films ◽  
In Situ Preparation ◽  
In Situ Deposition ◽  
Rapid Isothermal Processing

AbstractMetalorganic chemical vapor deposition (MOCVD) has the potential of emerging as a major technique for the fabrication of high temperature superconductor devices. In this paper, we present preliminary results of in-situ deposition of Y-Ba-Cu-0 thin films (Tc = 79K) by rapid isothermal processing assisted MOCVD on BaF2/silicon substrates.

Study of the Orientation of Y1Ba2cu/3O7−x Thin Films In-Situ Prepared by Reactive Coevaporation With RF Activated Oxygen-Ozone Plasma.

1991 ◽  
Vol 223 ◽  
Author(s):  
M. Nagata ◽  
H. Nojima ◽  
H. Shintaku ◽  
M. Koba
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Superconducting Films ◽  
Crystal Quality ◽  
Axis Orientation ◽  
Activated Oxygen ◽  
Zero Resistance ◽  
Plasma Crystal

ABSTRACTSuperconducting films of Y1Ba2Cu3O7−x have been prepared in-situ onto SrTiO3 (100) substrates by reactive coevaporation with rf activated oxygenozone plasma. Crystal quality and orientation of the films were evaluated as a function of substrate temperature(Ts). The films evaporated at Ta between 680°C, and 690°C had an a,b-axis orientation perpendicular to the substrate. The zero resistance temperature(Tc) of the film evaporated at Ts, of 690°C was 80K. The films evaporated at Ta above 700°C had c-axis orientation. The Ts of the film evaporated at a Ts, of 710°C was 90K.

Microstructure of In-Situ Grown YBa2Cu4O8 Thin Films Deposited by MOCVD

1992 ◽  
Vol 275 ◽  
Author(s):  
K. Uehara ◽  
H. Sakai ◽  
H. Hayashi ◽  
Y. Shiohara ◽  
S. Tanaka
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
Film Surface ◽  
Superconducting Thin Films ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTHigh-resolution transmission electron microscopy (HREM) has been used to study the microstructures of Y-Ba-Cu-0 superconducting thin films in which the YBa2Cu4O8 phase was the main phase. From cross-sectional observations, the c-normal 123 phase predominated in the film near the substrate surface, while the c-normal 124 phase occupied the region near the film surface. Another remarkable microstructure was that a-normal 123 variants overcame the c-normal 123 region, but the c-normal 124 phase surpassed the a-normal 123 phase in the upper part of the film.

In Situ Preparation of Y‐Ba‐Cu‐O Thin Films on Silicon Single Crystals

1989 ◽  
Vol 169 ◽  
Author(s):  
Hanns—Ulrich Habermeier ◽  
Gunter Wagner ◽  
Günter Mertens
Keyword(s):  
Thin Films ◽  
Single Phase ◽  
Critical Temperatures ◽  
Lithographic Patterning ◽  
Target Composition ◽  
In Situ Preparation ◽  
Crystalline Films ◽  
Zero Resistance ◽  
Post Deposition

AbstractSuperconducting Y—Ba—Cu—O thin films with critical temperatures exceeding 80 K are deposited on silicon single crystal substrates using the pulsed laser deposition technique. Deposition from a sintered Y1 Ba2Cu3O7‐ target in oxygen ambient of 0.1 — 5 mbar onto substrates kept at 700°C to 820°C results in crystalline films in which the target composition of the metallic constituents is preserved. No post deposition treatments are required to obtain high values for the zero resistance. X— ray analysis as well as Raman spectroscopy reveal that specimens prepared at optimum conditions are single phase c—axis oriented. In contrast to films prepared on LaAlO3 or SrTiO3 the surface morphology shows a granular structure. The films prepared by this technique are quite stable against chemicals used in conventional lithographic patterning, however, a strong correlation between film quality before patterning and some degradation after patterning is observed.

In‐Situ Patterning and Critical Current Density Measurements in Laser Deposited High‐Tc Superconducting Thin Films

1989 ◽  
Vol 169 ◽  
Author(s):  
R. K. Singh ◽  
C. B. Lee ◽  
P. Tiwari ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Deposition Process ◽  
Laser Deposition ◽  
Zero Magnetic Field ◽  
Transport Critical Current Density ◽  
Superconducting Thin Films

AbstractWe have performed transport critical current density, Jc, measurements on epitaxial superconducting thin films which were in‐situ patterned during the laser deposition process. Shadow masks of various dimensions were placed close to the substrate to generate different patterns. Epitaxial films of YBa2Cu3O7 on (100) SrTiO3, (100) YSZ, and (100) LaA1O3 substrates were fabricated at low processing temperatures (500‐650°Q by the biased laser deposition technique in an oxygen ambient of 200 mtorr. Excellent quality superconducting thin films were formed on patterned areas. The critical temperature of the films was found to be in the range of 88 to 90 K, and the best critical current density values (at 77K, and zero magnetic field) greater than 6.5 x106 Amps/cm2 were obtained for silver doped YBa2Cu3O7 films on (100)LaAlO3 substrates.

A New Hybrid Pvd/Omcvd Route to High‐Tc Superconducting Thin Films of Tl‐Ba‐Ca‐Cu‐O

1989 ◽  
Vol 169 ◽  
Author(s):  
D. S. Richeson ◽  
L. M. Tonge ◽  
X. K. Wang ◽  
H. O. Marcy ◽  
T. J. Marks ◽  
...  
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Water Vapor ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Electron Beam Evaporation ◽  
Hybrid Technique ◽  
Superconducting Thin Films ◽  
Zero Resistance ◽  
Oriented Parallel

AbstractSuperconducting thin films of Tl‐Ba‐Ca‐Cu‐0 have been prepared by a unique hybrid technique that combines electron beam evaporation with organometallic chemical vapor deposition (OMCVD). Multilayer thin films of Ba‐Ca‐Cu‐O are prepared by sequential electron beam evaporation of BaF2, CaF2, and Cu sources onto single crystal MgO (100) or yttria‐stabilized zirconia (YSZ) substrates followed by annealing in a water vapor‐saturated oxygen atmosphere. Thallium is then incorporated into these films in either of two ways: (1) via OMCVD using thallium(cyclopentadienide) as the source, or (2) rapid annealing of the Ba‐Ca‐Cu‐O film in the presence of bulk thallium superconductor. The resultant films primarily consist of single phase TlBa2Ca2Cu3Ox with the Cu‐O planes preferentially oriented parallel to the substrate surface. Resistivity measurements indicate superconducting onset temperatures above 120 K with zero resistance by 104 K. By eliminating the water vapor anneal, residual fluoride, originating from the sources, may be left in the film. This leads to formation of predominantly c‐axis oriented crystallites of the TlBa2CaCu2Ox phase.

Substrate bias effects during R-F sputtering of Y-Ba-Cu-O films

1990 ◽  
Vol 5 (4) ◽  
pp. 677-679 ◽  
Author(s):  
A. J. Drehman ◽  
M. W. Dumais
Keyword(s):  
Thin Films ◽  
Strontium Titanate ◽  
Reactive Sputtering ◽  
Negative Bias ◽  
Superconducting Thin Films ◽  
Substrate Bias ◽  
Composition Control ◽  
Zero Resistance

Y-Ba-Cu-O films were made by R-F diode sputtering using a single oxide target. It was found that if a small negative bias is applied to the substrate, the etching associated with reactive sputtering is significantly reduced. This results in better composition control and uniformity, which are quite important for the formation of superconducting thin films. Films deposited on strontium titanate, when annealed in oxygen, become superconducting with zero resistance at 89 K.

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