Synthesis and characterization of zinc oxide nanowires, and their use in spintronic and photovoltaic applications

Semiconducting nanowires are a unique class of nanoscale materials that are receiving much research interest both for their novel fundamental physical properties but also for their potential applications into a variety of technologies and devices. In particular, zinc oxide (ZnO) nanowires are among the most versatile and useful nanomaterials currently in existence, and have been envisioned to be potentially useful in many different types of new nanoscale devices. In this dissertation, I will present the solution-phase synthesis and characterization of pure and doped ZnO nanowires for a variety of different applications, including spintronics and photovoltaics.;Spintronics, or spin-based electronics, seeks to utilize both the charge and spin degrees of freedom of carriers in electronic devices. One class of materials that has been proposed for this purpose is known as dilute magnetic semiconductors (DMS), which are typically III-V or II-VI semiconductors that have been doped with magnetically active cations, such as transition metals. Although DMS materials have been extensively studied in bulk and thin film systems, there are comparatively few existing studies on nanowires. In addition, there is tremendous controversy in the experimental DMS literature regarding the origins of the observed magnetic behavior. Here, I will present detailed structural and spectroscopic characterization of a series of transition metal-doped ZnO nanowires, along with correlations to the nanowire magnetic properties in the context of DMS theory.;Additionally, ZnO nanowires can be quite useful in photovoltaic devices. Prior work has seen ZnO nanowire arrays used in dye-sensitized solar cells, as well as polymer-inorganic hybrid cells. Here, I will present an all-inorganic solar cell with oxide materials, zinc oxide nanowires and cuprous oxide nanoparticles, as both photovoltaic components. In many ways, the combination of using nanowire arrays along with environmentally benign and stable oxide materials represents the ideal design of a solar cell.