Elastic Stability and Piezoelectric Power Generation Using ZnO Nanostructures

Abstract: Nanotechnology combines the effort between science and engineering using the approaches of either top-to-bottom or bottom-to-top techniques. A hybrid approach of the above techniques is also used for the fabrication of nanodevices. In nanotechnology one and zero dimensional structures are considered as the basic building blocks for multidimensional systems. One dimensional nanostructure such as nanorods, nanowires and nanotubes has become the research core of science and engineering, because of their unique and interesting properties for device applications.In this thesis a mechanical property i.e. elastic stability, the behavior of piezoelectric power nanogenerator and the effects of ions irradiations were investigated for ZnO nanostructures.Buckling phenomena was employed for the elastic stability investigation using Hysitron nanoindentor. ZnO nanostructures were loaded axially to a prescribed controlled load and then unloaded in the same fashion by the tip of a nanoindentor to investigate the first critical load and other unstable configurations. The present buckling study concluded that the elastic stability of ZnO nanostructures were mainly dependent on the slenderness ratio and the verticality of the structures to the substrates.Piezoelectric power nanogenerators were investigated using ZnO nanowires. The performance of different piezoelectric power nanogenerators were observed on the bases of the aspect ratio, density of state, spatial density and the growth methods. A higher and stable voltage signal was generated by the vapor-liquid-solid (VLS) grown samples compared to the aqueous chemical growth (ACG) grown samples. The finite element (FE) method was also used to calculate the expected output voltage signal from ZnO nanogenerator with different aspect ratio. From the FE results we found that the output voltage of the nanogenerator was decreased above an aspect ratio of 80 for ZnO nanowires.Ions irradiation effects were investigated using ZnO nanowires grown by the ACG method on Si substrate. Iodine and argon ions of energy 40 MeV and 30 keV were used using fluencies of 3 ×1016 ions/cm2, and 1.3 ×1013 ions/cm2, respectively. The results show that heavy and high energy irradiation modifies the morphology, crystalline structure and optical properties of ZnO nanowires.