Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
2 results
Search Results
Master Thesis Fabrication and Characterizarion of Superconductor Ybco Josephson Junctions(Izmir Institute of Technology, 2008) Algül, Berrin Pınar; Abukay, Doğan; Abukay, DoğanA well-controlled, high-yield Josephson junction production process forms the basis of superconducting electronic device and circuit technology. In order to use the Josephson junctions effectively and fabricate them reproducibly, their structural and electrical characterization should be performed.This study concentrates on the fabrication and characterization of high temperature bicrystal grain boundary Josephson junctions fabricated onto 24-dand 30-degree SrTiO3 bicrystal substrates using high quality YBa2Cu3O7-. (YBCO) thin-films.200 nm thick YBCO thin films were deposited using a dc Inverted Cylindrical Magnetron Sputtering technique by investigating the thin film deposition conditions in order to obtain device quality films. The superconducting properties of the thin films were determined by electrical characterizations, consisting of resistance versus temperature and magnetic susceptibility versus temperature measurements. Structural properties were analyzed by Atomic Force Microscope, Scanning Electron Microscope and X-Ray Diffraction.Prepared thin film samples were patterned as bicrystal grain boundary Josephson junctions by standard photolithography and chemical etching processes. The current-voltage characteristics of the Josephson junctions were performed at 77 K under zero and non-zero applied field in magnetically shielded environment. The critical current values (Ic), normal resistance (Rn) and IcRn product of the output signals were determined, and the values were discussed as function of the film growth conditions. The optimization of the Josephson junctions was performed in order to improve both the signal performance and the stability of our devices against thermal cycling.Master Thesis Fabrication of Ybco Thin Flims by Pulsed Laser Deposiyion Technique and Their Charcterization(Izmir Institute of Technology, 2010) Tozan, Şerife; Abukay, DoğanThis thesis focuses on pulsed laser deposition (PLD) system, fabrication of high temperature superconducting YBCO thin films and their characterization. In this study, the electrical and structural studies performed on laser deposited YBCO films have shown that films produced by PLD. The thin films were characterized in detail by employing structural XRD, SEM, EDX and AFM and electrical ( R-T) measurements. During this work, pulsed laser deposition system used to grow superconducting thin film on MgO single crystal substrate. Firstly PLD system was carried out by using different growth parameters. Deposited films was cooled down in situ under an oxygen atmosphere at a given pressure. The deposition tecnique has emerged as a very powerful method to make composition and microstructure controlled superconducting YBCO films.Thanks to rapid heating and evaporation of the target and interaction of the laser beam with evaporated materials leading to formation of a high temperature plasma PLD system is different from other thin film growth system.However, major problem was particulates emmission which was shown SEM,we solved this problem by chaning distance between target and substrate, and laser power. Furthermore Electron Dispersive X-Ray Spectroscopy (EDX) method was used to identify the chemical contents of the films.The relation between critical temperature and oxygen deficieny was investigated by means of electrical resistance R(T) and x-ray diffraction measurements.Finally, our results were compared to literature and explanied similarites.