Document Details
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Document Type |
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Thesis |
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Document Title |
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Study and Characterization of Noble Metal Contacts to High-Tc Superconducting Films دراسة وتوصيف اتصال معدن نبيل بأغشية رقيقة فائقة التوصيل |
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Subject |
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physics department |
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Document Language |
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Arabic |
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Abstract |
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The high temperature superconductivity is an important topic in solid state physics and it’s still active area of research due to the potential for application in electronic devices. This class of material has attracted the attention of researchers in solid state physics and electronics engineering. Moreover, there are many questions remain unanswered up to this moment related to theory of superconductivity.
YB2C3O7-δ thin films are significant capabilities in a large variety of superconducting devices, such as microwave cavities and filters, superconducting bolometers, MRI scanners, fault current limiters, and DC and RF superconducting quantum interference devices (SQUIDs).
In this work, the high temperature superconducting films were deposited by thermal reactive co-evaporation were prepared by THEVA GmbH. The YB2C3O7-δ films were made of 330 nm thickness deposited on 2"×0.43 mm, r-cut sapphire (Al2O3) circular wafer, buffered by CeO2 of 40 nm thickness, is introduced between YB2C3O7-δ film and sapphire substrate, to prevent interdiffusion from Aluminum (in sapphire) into YBCO film, the critical temperature and critical current density are Tc ≈ 89 K, and Jc = 3.1×106 A/cm2 (at 77 K), respectively. The ErB2C3O7-δ film was fabricated using the same method of YBCO film and same thickness, but only differ in shape of sapphire substrate (20×20×0.5 mm), which is rectangular wafer, the critical temperature is Tc ≈ 90 K , and its critical current density is Jc = 3.5×106 A/cm2 (at 77 K).
After obtaining YBCO & ErBCO thin films, we studied the structural and electrical characteristics in detail by employing scanning electron microscope (SEM) to analyze the surface and morphology, and x-ray diffraction (XRD) is used for provide information on unit cell dimensions. The electrical measurements were performed by four-point probe method (include resistivity dependence on temperature or R-T Curve, and current–voltage characteristic or I–V curve), additionally, 50 nm of noble metal (gold, Au) were deposited ex-situ (on clean surface of film) using thermal evaporation technique (AUTO 306 Vacuum Coater, Edward) to make good contact with the superconductor thin film and obtain low-resistance contact. The other part of measurements were performed by two-point probe method using LCR-meter (HIOKI 3532-50 LCR HiTESTER) to examine the frequency dependent dielectric properties of superconductor films such as dielectric constants (εr/ /εr//), loss tangent |tanδ|, and AC-conductivity (σac) and it have been investigated in terms of capacitance (C) and conductance (G) of HTS films with frequency (f) in the range of 50 KHz to 5 MHz at different temperatures. The results for this experiment procedure are summarized and comparative study between YBCO & ErBCO thin films will be reported.
The next aim of our experimental investigation is preparation of YB2C3O7-δ powders by Coprecipitation process as solution-based technique i.e. solution used to produce powders. In this technique, from solutions the cations are generally precipitated either as hydroxides or carbonates, oxalate formate, acetate, etc. we have successfully fabricated YBCO (123) powder and then we compressed to make sample pellet. Its structural characteristic was examined using x-ray diffraction (XRD) and scanning electron microscope (SEM), and DC electrical characteristic were performed by using temperature dependent of resistance measurements. Finally, our results were compared to literature and explained similarities. |
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Supervisor |
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Dr. Mohammed Hafez Elfeky |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1434 AH
2013 AD |
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Co-Supervisor |
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Dr. Saeed Saad Alameer |
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Added Date |
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Saturday, March 9, 2013 |
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Researchers
| باسم صالح عركوك | Arkook, Bassim Saleh | Researcher | Master | |
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