In-Situ Processing of Epitaxial and Textured High Tc Superconducting Hoba2Cu3O7.X Thin Films By Pulsed Laser Evaporation Technique

1989 ◽  
Vol 169 ◽  
Author(s):  
C. B. Lee ◽  
R. Prasad ◽  
A. K. Singh ◽  
S. Sharan ◽  
R. K. Singh ◽  
...  
Keyword(s):  
Thin Films ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Laser Evaporation ◽  
High Tc ◽  
Zero Resistance ◽  
Evaporation Technique ◽  
Current Densities ◽  
Lattice Matched

AbstractExcellent quality epitaxial and textured superconducting HoBa2Cu307.x (Ho 123) thin films have been fabricated on lattice matched (100) KTaO3 and (100) LaAlO3, and lattice mismatched (100) MgO substrates by the pulsed laser evaporation (PLE) technique. A bulk Hol23 target was evaporated using nanosecond excimer laser pulses with the evaporating material depositing on a substrate maintained in the temperature range of 550‐650°C. The temperature for zero resistance for HoBa2Cu3O7_x films deposited on various substrates at 650°C varied between 85 to 89K. The epitaxial films deposited on (100) LaA103 substrates exhibited critical current densities greater than 3.5 x 106 Amps/cm2 at 77 K. The superconducting properties of the Ho 123 films were found to be similar to Y123 films.

Pulsed Laser Deposition of High Tc Superconducting Thin Films: Deposition Physics and in-Situ Processing

1989 ◽  
Vol 169 ◽  
Author(s):  
Rajiv K. Singh ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Laser Evaporation ◽  
Superconducting Thin Films ◽  
High Tc ◽  
Ion Channeling ◽  
In Situ Fabrication ◽  
Current Densities

AbstractThe pulsed laser evaporation (PLE) technique for deposition of thin films is characterized by a number of unique properties. Based on the experimental characteristics, a theoretical model is developed which considers the formation and anisotropic three dimensional expansion of the laser generated plasma. This model explains most of the experimental features observed in PLE. We have also employed the PLE technique for in-situ fabrication of YBa2Cu3O7 superconducting thin films on different substrates in the temperature range of 500–650°C. At temperatures below 600–C, a biased interposing ring between the substrate and the target was found to significantly improve the superconducting properties. The minimum ion channeling yields were between 3-3.5 % for films deposited on (100) SrTiO3 and (100) LaA1O3 substrates. The films exhibit very high critical current densities (Jc) with maximum values exceeding 6.5 x 106 amps/cm2 for silver doped YBa2Cu3O7 films on (100) LaA1O3 substrates, and the Jc also varies anisotropically with the magnetic field.

SUPERCONDUCTING Bi-Sr-Ca-Cu-O THIN FILMS PREPARED BY THE PULSED-LASER EVAPORATION

1988 ◽  
Vol 02 (08) ◽  
pp. 999-1003
Author(s):  
F.M. ZHANG ◽  
Y.C. ZHANG ◽  
S.J. GU ◽  
Y.L. ZHOU ◽  
Z.H. CHEN ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Nd:Yag Laser ◽  
Pulse Width ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Laser Evaporation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zero Resistance

We report here the preparation of the superconducting Bi-Sr-Ca-Cu-O thin films on SrTiO 3(100) substrates by a Nd:YAG laser, which provides laser pulses with wavelength of 1.06µm and pulse width of 200ns. After the heat treatment at 850°C for half an hour in oxygen flow, the samples exhibit superconductivity with the zero resistance at 66.8K and the onset temperature around 84K. X-ray diffraction analyses show that the samples have the preferred orientation with the c-axis perpendicular to the substrate.

In‐Situ Fabrication of YBa2Cu3O7‐x Superconducting Thin Films Directly on Silicon Substrates with Tc0 > 77K

1989 ◽  
Vol 169 ◽  
Author(s):  
C. B. Lee ◽  
R. K. Singh ◽  
S. Sharan ◽  
A. K. Singh ◽  
P. Tiwari ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Pulses ◽  
Superconducting Film ◽  
Laser Evaporation ◽  
Silicon Substrates ◽  
Superconducting Thin Films ◽  
Si Substrates ◽  
In Situ Fabrication ◽  
Substrate Temperatures

AbstractWe report in‐situ fabrication of c‐axis textured YBa2Cu3O7‐x superconducting thin films with Tco > 77K on unbuffered silicon substrates by the biased pulsed laser evaporation (PLE) technique in the temperature range of 550‐650°C. At substrate temperatures below 550°C, no c‐axis texturing of the superconducting film was observed. The YBa2Cu3O7‐x superconducting films were fabricated by ablating a bulk YBa2Cu3O7 target by a XeCl excimer laser (λ = 308 nm, τ = 45 × 10‐9 sec) in a chamber maintained at an oxygen pressure of 0.2 torr . The thickness of the films was varied from 0.3 to 0.5 nm depending on the number of laser pulses. Extensive diffusion was observed in thin films deposited at substrate temperatures above 550°C. However, microstructurally, with increase in the substrate temperature the films exhibited larger grain size and greater degree of c‐axis texturing (measured by the ratio of the (005) and (110) X‐ray diffraction peaks). This was found to give rise to better superconducting properties with Tco exceeding 77 K for YBa2Cu3O7‐x films deposited on Si substrates at 650°C.

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.

In-Situ Pulsed Laser Deposition of High-TC Yba2Cu3O7 Superconducting Thin Films on (100) LaAlO3 Substrates

1989 ◽  
Vol 169 ◽  
Author(s):  
P. Tiwari ◽  
S. Sharan ◽  
R. K. Singh ◽  
O. W. Holland ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Pulsed Laser ◽  
Zero Magnetic Field ◽  
Laser Evaporation ◽  
Superconducting Thin Films ◽  
Superconducting Transition ◽  
Ion Channeling ◽  
Lanthanum Aluminate ◽  
Evaporation Technique

AbstractThe formation of superconducting thin films on lanthanum aluminate substrates is very important for high‐frequency applications. In this paper, we discuss the fabrication of epitaxial superconducting YBa2Cu3O7 thin films on (100)LaAlO3 substrates, which exhibit excellent dielectric properties required for high frequency applications. The films were deposited by the biased pulsed laser evaporation technique (PLE) at substrate temperatures between 500‐650°C and exhibit excellent crystallinity with best minimum ion channeling yields corresponding to approximately 3%. The superconducting transition temperatures varied from 88‐92 K with critical current densities at 77K and zero magnetic field greater than 4 ‐ 5 x 106 Amps/cm2.

Growth of TiO2 Thin Films by Pulsed Laser Evaporation

1990 ◽  
Vol 191 ◽  
Author(s):  
Ming Y. Chen ◽  
P. Terrence Murray
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Grazing Incidence ◽  
Ex Situ ◽  
Laser Evaporation ◽  
Tio2 Thin Films ◽  
Film Properties ◽  
X Ray

ABSTRACTThin films of TiO2 have been grown by pulsed laser evaporation. The films were analyzed by in-situ Auger and x-ray photoelectron spectroscopy as well as by ex-situ grazing incidence xray diffraction. Films grown at room temperature and at a pressure of 5×10minus; 3 Torr were oxygen deficient. Films grown at 500°C and higher were found to be stoichiometric TiO2.The effect of substrate temperature and evaporation conditions on film properties will be discussed.

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