Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Development of Conductive Oxide Based Thin Film Modified Electrodes and Biosensors Applications(Izmir Institute of Technology, 2021) Özyüzer, Lütfi; Yurttaş, Betül; Özyüzer, Lütfi; Erdem Gürsan, Kadriye Arzum; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of ScienceFrom the first biosensor produced in 1956 to the present day, biosensors have been highly developed and diversified. In biosensor manufacturing, thin films have become a rapidly emerging field. Depending on the thin film material used, thin films have many advantageous properties for biosensors, such as high surface-to-volume ratio, conductivity, stability, specificity, biocompatibility, and good electrocatalytic activity. Dopamine is a neurotransmitter that has a significant impact on the emergence and treatment of certain diseases such as Alzheimer's and Parkinson's diseases. Dopamine monitoring is important for the prevention of these diseases, and it is a favorable option to use biosensors, which are useful and practical tools, instead of time-consuming and expensive conventional methods. For this purpose, in this thesis, a non-enzymatic electrochemical biosensor based on thin film electrodes was developed for monitoring dopamine levels. The electrodes were developed by deposition of Zn2SnO4 (ZTO) thin film on ITO thin film substrate by DC magnetron sputtering technique. The properties of the electrodes were determined by thickness, optical transmittance, XRD and SEM analysis. Electrochemical analysis, namely CV, EIS and DPV measurements, were performed before and after the electrodes were sonicated and modified with APTES before their application to the voltammetric detection of dopamine. In addition, electrochemical measurements were performed before/after sonication, APTES modification. Dopamine was detected by a voltammetric method using DPV technique. Furthermore, experiments in the presence of interferents such as ascorbic acid (AA), uric acid (UA) etc. showed that the thin film electrodes can be successfully applied for voltammetric determination of dopamine. As a result, the biosensor technology developed in this study has the potential to be wearable in the future, enabling non-invasive monitoring of dopamine levels in body fluids such as saliva, tears and sweat.Master Thesis Flexible Transparent Conducting Electrodes Based on Silver Nanowire, Graphene, and Two-Dimensional Transition Metal Dichalgogenide(01. Izmir Institute of Technology, 2020) Balcı, Sinan; Balcı, Sinan; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn recent years, transparent conductive electrodes have attracted great interests owing to their critical applications in various optoelectronic devices, such as light emitting diodes, solar cells, liquid crystal displays, optical modulators, and touch screens. In this thesis, graphene-silver nanowires-transition metal dichalcogenide based hybrid transparent and conductive electrodes have been fabricated. In order to reach this goal; (1) single layer graphene on copper foil has been synthesized in large area in a CVD furnace, (2) ultrathin and very long silver nanowires have been synthesized by using wet chemistry methods, (3) MoS2 and WS2 single layer flakes and multilayer thin films have been synthesized in a CVD furnace, (4) electrodes of graphene, silver nanowires, and transition metal dichalcogenides have been fabricated on rigid and flexible substrates.Master Thesis Developing Epitaxial Graphene Electrodes for Silicon Carbide Based Optoelectronic Devices(Izmir Institute of Technology, 2015) Kuşdemir, Erdi; Çelebi, Cem; Sevinçli, Haldun; Çelebi, Cem; Sevinçli, Haldun; 04.05. Department of Pyhsics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this thesis work, I studied the fabrication and characterization of graphene-semiconductor-graphene ultraviolet photodetector based on the rectifying character of Schottky junction at the interface between epitaxial graphene and silicon carbide semiconductor. As-grown single layer epitaxial graphene is interdigitated as transparent conductive electrode to probe photo-generated charge carriers in a semi-insulating 4H-silicon carbide substrate. The fabricated device exhibits the typical current-voltage characteristics of a conventional metal-semiconductor-metal type photodetector with low leakage current. Time-resolved photocurrent measurements suggest an excellent photocurrent reversibility and high response speed of the device. The measurements performed for different illumination wavelengths showed that the sample reveals higher responsivity values when it is exposed to the light with 254 nm wavelength. The obtained results imply that epitaxial graphene can be used readily as transparent conductive electrode for SiC based optoelectronic device applications. Finally, in the last chapter, I discuss how the photoresponsivity of the graphene-semiconductor-graphene photodetector can be enhanced by CdTe/CdS quantum dots. The drop casted CdTe/CdS quantum dots have been shown to increase the photoconductivity of the device. The thickness of the quantum dots is found to effect the enhancement factor of the photoresponsivity of the device.