Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Electrical Characterization of Vanadium Dioxide (vo₂) Thin Films Grown by Magnetron Sputtering Technique(01. Izmir Institute of Technology, 2024) Akyürek, Bora; Aygün, Gülnur; Özyüzer, Gülnur Aygün; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe aim of this thesis is to determine the parameters required for the production of pure VO₂ thin films and to evaluate the usability of these films by calculating their MIT ratios. Vanadium dioxide (VO₂), a substance that exhibits a phase transition from the insulating state to the metallic state at approximately 68 °C, shows significant changes in its electrical conductivity and optical properties. To get pure VO2 thin films, and get optimum parameters for deposition, several parameters were varied during the manufacturing process,including temperature, oxygen-argon ratio, and coating time. Then, electrical characterization of the produced films was performed. Examining the temperature dependence of the resistance of thin films has been a critical aspect of electrical measurements to determine the MIT transition. With the help of the probe station, it was determined that the MIT transition occurred at approximately 68 °C. The results obtained using structural characterization techniques revealed that characteristic vibration modes were observed in the analyses performed with Raman spectroscopy, while XRD analyses revealed that the crystal structure was preserved. Additionally, XPS analyses did not detect any surface contamination other than carbon. SEM and EDX analyses evaluated the surface morphology and elemental stoichiometry and showed that the internal structure of the films was intact. These results support the usability of VO₂ thin films in advanced electronic and optical applications and contribute to the determination of optimum production parameters. This thesis demonstrates the potential of VO₂ in various technological applications by efficiently utilizing MIT properties.Master Thesis The Growth of Vanadium Dioxide Thin Films by Magnetron Sputtering Technique and Terahertz Wave Modulation Characteristics(01. Izmir Institute of Technology, 2020) Özyüzer, Lütfi; Ata, Bengü; Özyüzer, Lütfi; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of ScienceVanadium dioxide (VO2) is a fascinating material thanks to its unique insulator-metal transition (IMT) at 68 °C which is very close to the room temperature. This reversible change in electrical resistivity is around several orders of magnitude and the electrical change accompanied by optical and structural change as well. Thanks to these unique properties vanadium dioxide material has been studied intensively past decades. This phase transition allows us to apply the transition properties widen application such as field effect transistor (FET), uncooled bolometers, tunable metamaterial filters, high data rate wireless communication etc. Especially for terahertz region which is the most unexplored region of the electromagnetic spectrum, vanadium dioxide is a promising material having ability to modulate terahertz waves by IMT phenomena. In this work, vanadium dioxide (VO2) thin films fabricated by reactive DC magnetron sputtering method and its properties optimized to minimize the amounts of secondary phases by optimizing the oxygen concentration, sputtering power and deposition time. Samples which show the maximum resistivity change during the transition have been used for the terahertz modulation experiments. It has been observed that when the VO2 samples triggered by continuous wave (CW) laser, VO2 transforms to the metallic phase, behave as an opaque material to the terahertz wave. At room temperature, in insulating phase it is partially transparent to terahertz radiation. This results indicate that VO2 thin films can be a good candidate for THz wave modulators.