Synthesisation and characterisation of zinc oxide nanowires via microwave-assisted ultrasonic technique / Nurul Zulaikha Mohammad Zamri

Nanometer sized particles (1-100 nm) are of considerable interest for a wide variety of applications, ranging from electronics via ceramics to catalysts, due to their unique or improved properties that are primarily determined by size, composition, and structure. Several processes have been developed to synthesise and characterise high-quality ZnO nanowires. Besides that, nanostructured materials commonly used would be zinc oxide (ZnO) which had been studied for decades due to its unique properties which boost excellent performances when applied to electrical devices. Additionally, the uses of pure ZnO has a number of limitations such as high resistivity and low carrier concentrations, which restrict their potential applications. ZnO NWs also are highly sensitive to the surrounding environment. Changes in temperature, humidity, or exposure to gases can influence the electrical and optical properties of ZnO NWs, making them less reliable for certain applications where stability is crucial. Other than that, ZnO NWs often exhibit a high density of structural defects, such as dislocations, stacking faults, and grain boundaries. These defects can affect the electrical and optical properties of the NWs, leading to reduced device performance and reliability. This thesis focuses on the synthesis and characterization of ZnO nanowires (NWs) using a microwave-assisted ultrasonic technique. It includes the deposition of a seed layer consisting of ZnO nanoparticles (NPs) through ultrasonic-assisted sol-gel spin-coating. The main objectives are to successfully grow ZnO NWs and comprehensively analyze their structural, optical, and electrical properties using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible-infrared spectrophotometry (UV-Vis). The optimization of critical processing parameters, such as growth time, deposition power, and precursor concentrations, is a key aspect of this research. The outcomes will serve as a foundation for future studies and provide guidance for further advancements in this area of research. In summary, the analysis of ZnO nanowires revealed that increasing the growth duration did not affect the diameter of the nanowires. The highest transmittance was observed in the sample grown for 15 minutes in the visible region.