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.

Preparation of Yba2Cu3O7-X. Superconducting Thin Films by Means of Single Target Rf-Sputtering+

1989 ◽  
Vol 169 ◽  
Author(s):  
Herman D.L. Weyten ◽  
R. De Batist ◽  
P. Nagels ◽  
J. Cornelis
Keyword(s):  
Thin Films ◽  
Rf Sputtering ◽  
Buffer Layers ◽  
Superconducting Thin Films ◽  
High Tc ◽  
Resistivity Measurements ◽  
Single Target ◽  
Deposited Films ◽  
Post Deposition

AbstractHigh Tc superconducting thin films have been deposited on sapphire by means of RF‐sputtering from a single stoichiometric target of YBa2Cu3O7‐x composition. The YBa2Cu3O7‐x films were deposited in an argon‐oxygen atmosphere on a substrate which reached a temperature of s 400°C during deposition. The study of stoichiometry and homogeneity of the as‐deposited films, by means of electromicroprobe analysis (EMPA), was used to optimize the sputtering parameters of the system. To achieve superconductivity, with an onset of s 90 K, a high‐temperature, post‐deposition thermal treatment in oxygen was necessary. Resistivity measurements show that, with respect to the bulk samples, zero resistivity is lowered as a result of substrate interaction. The use of buffer layers can improve the quality of the superconducting thin films.

scholarly journals Measurement of Electrical Properties of Superconducting YBCO Thin Films in the VHF Range

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3360
Author(s):  
Yakir Dahan ◽  
Eldad Holdengreber ◽  
Elichai Glassner ◽  
Oz Sorkin ◽  
Shmuel E. Schacham ◽  
...  
Keyword(s):  
Thin Films ◽  
Theoretical Model ◽  
Quality Factor ◽  
High Frequency ◽  
Unit Length ◽  
Superconducting Thin Films ◽  
Electrical Parameters ◽  
Very High Frequency ◽  
Production Constraints ◽  
Very High

A new measurement technique of electrical parameters of superconducting thin films at the Very High Frequency (VHF) range is described, based on resonators with microstrip (MS) structures. The design of an optimal resonator was achieved, based on a thorough theoretical analysis, which is required for derivation of the exact configuration of the MS. A theoretical model is presented, from which an expression for the attenuation of a MS line can be derived. Accordingly, simulations were performed, and an optimal resonator for the VHF range was designed and implemented. Production constraints of YBa2Cu3O7 (YBCO) limited the diameter of the sapphire substrate to 3″. Therefore, a meander configuration was formed to fit the long λ/4 MS line on the wafer. By measuring the complex input reflection coefficients of a λ/4 resonator, we extracted the quality factor, which is mainly affected by the dielectric and conductor attenuations. The experimental results are well fitted by the theoretical model. The dielectric attenuation was calculated using the quasi-static analysis of the MS line. An identical copper resonator was produced and measured to compare the properties of the YBCO resonator in reference to the copper one. A quality factor of ~6·105 was calculated for the YBCO resonator, three orders of magnitude larger than that of the copper resonator. The attenuation per unit length of the YBCO layer was smaller by more than five orders of magnitude than that of the copper.

X-Ray Diffraction Analysis of High Tc Superconducting Thin Films

1989 ◽  
pp. 269-278
Author(s):  
T. C. Huang ◽  
A. Segmüller ◽  
W. Lee ◽  
V. Lee ◽  
D. Bullock ◽  
...  
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Superconducting Thin Films ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray

LOW LOSS DIELECTRIC MATERIALS FOR HIGH FREQUENCY APPLICATIONS

2009 ◽  
Vol 23 (17) ◽  
pp. 3649-3654 ◽  
Author(s):  
MOHAN V. JACOB
Keyword(s):  
High Frequency ◽  
Room Temperature ◽  
Low Cost ◽  
Dielectric Materials ◽  
Dielectric Constants ◽  
Transmission Losses ◽  
Low Loss ◽  
Microwave Characterization ◽  
Materials Used ◽  
Low Temperature Electronics

The microwave properties of some of the low cost materials which can be used in high frequency applications with low transmission losses are investigated in this paper. One of the most accurate microwave characterization techniques, Split Post Dielectric Resonator technique (SPDR) is used for the experimental investigation. The dielectric constants of the 3 materials scrutinized at room temperature and at 10K are 3.65, 2.42, 3.61 and 3.58, 2.48, 3.59 respectively. The corresponding loss tangent values are 0.00370, 0.0015, 0.0042 and 0.0025, 0.0009, 0.0025. The high frequency transmission losses are comparable with many of the conventional materials used in low temperature electronics and hence these materials could be implemented in such applications.

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