Flash Evaporation as an Attempt for Preparation of YBCO Superconductor Thin Films | ||||
| Egyptian Journal of Solids | ||||
| Article 6, Volume 23, Issue 1, 2000, Page 59-69 PDF (70.94 K) | ||||
| DOI: 10.21608/ejs.2000.151475 | ||||
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| Abstract | ||||
| A home-made flash evaporation attachment was used to prepare YBCO superconductor in the form of thin film on Si wafer substrate. Structural study was achieved by XRD analysis and electric resistance was measured by linear four-probe method down to 77 K. The whole-pattern fitting of Rietveld method was applied to verify the presence of the orthorhombic YBCO phase in the prepared bulk sample used as a source for thin film deposition. Thin films deposited onto Si(111) wafer showed crystalline phase in case of substrate temperature ≥ 450 oC and post annealing at temperature ≥ 850 oC. The best and unexpected characteristics (Tc = 125 K, ΔT = 0.5 K) were obtained at critical thickness of 85 nm for films deposited at substrate temperature of 500 oC and subjected to post annealing in oxygen at 950 oC. This was attributed to the preferred orientation (c-axis normal to the substrate) and to the optimum Si concentration by interdiffusion under the proposed preparation condition. Increasing the film thickness than 100 nm deteriorates the superconducting behaviour. On the other hand, films of thickness less than 80 nm did not show superconducting behaviour. | ||||
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