Fabrication, characterization and investigation of application areas of silver and nickel doped zinc oxide (ZnO) nanorods

In general, gas sensors are a system based on detecting the change in the physical properties of the sensitive material in the gas environment. In this sense, sensor materials have been created in nanostructures in order to produce lower cost, high efficiency products. Nanorods are one of these structures. Some of the most commonly used semiconductor metal oxide materials in the production of nanorods are zinc oxide (ZnO), tungsten oxide (WO3), manganese oxide (MnO), titanium dioxide (TiO2), tin dioxide (SnO2) ect. The change in the properties such as electrical, optical and sensing due to the effect of the material doped to ZnO is an important factor in the intensive work in this field. Doping processes can be carried out by many different methods such as hydrothermal method, electrochemical method, chemical vapor deposition and sol-gel method. Within the scope of this thesis, undoped, silver (Ag) and nickel (Ni) doped ZnO nanorod structures were synthesized by the hydrothermal method. Structural, electrical, optical and gas sensing properties of the fabricated nanostructures were investigated. Sol gel method was used for seed layer synthesis during the production phase. X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were performed during the characterization processes such as crystal structure and surface morphology of the produced doped and undoped ZnO nanorods. X-ray diffraction analysis showed that pure and doped ZnO nanorods crystallized in hexagonal wurtzite structure. While the diameters of undoped ZnO nanorods were approximately 50nm, as a result of Ni doping, the diameters of the nanorods increased and nanorods with a diameter of approximately 180nm were obtained. In our studies for Ag doping, Ag particles were formed on the ZnO nanorods. The pure ZnO nanorods produced on quartz crystal microbalance (QCM) were tested for relative humidity measurements in the range of 5% to 94%. As a result of the test, it was observed that the sensor was stable. The current-voltage (I-V) measurements of the pure and Ni-doped nanorods and the current change depending on the temperature were investigated. The responses of the Ni and Ag-doped ZnO nanorods produced on different substrates to various gases were evaluated. It was observed that the pure ZnO nanorods were sensitive to humidity.