Zinc oxide (ZnO) has higher exiton binding energy (60 meV) and high band gap (~3.4 eV) that can provide efficient ultraviolet (UV) light at room temperature (RT). The easily etched in acids and alkalis that provides the fabrication of small-size ZnO-based devices. Electrodeposition is the growth method that can deposit high quality film and modify the characterizations of film by changing its deposition electrolyte concentration, temperature, and current density. Firstly, the ZnO is deposited on n-type Si substrate by electrodeposition by different deposited temperature, electrolyte concentration, and current density. The deposited films contain zinc nitrate, metal Zn, and ZnO while electrodeposited at various deposition parameters. For the deposited film contains only ZnO, no UV light is found measured by macroscopic photoluminescent analysis even annealed at different ambient and temperature. According to previous papers, an ideal UV light intensity can be obtained by thermal treated metal Zn or Zn ion implantation into oxide materials after annealing. Annealing the Zn-ZnO structure formed in 30oC by electrodeposition can observe intense UV light. This method improves the disadvantages of insufficient light intensity and no UV light observation from conventionally electrodeposited ZnO. The variation of UV light wavelength of ZnO oxidized from metal Zn is associated with the quantum-confinement effect that was discussed by previous papers. It is found that the size of ZnO is not small enough to realize the quantum-confinement effect, herein, we suggest that the variation of UV light wavelength is affected by the metal Zn resides in ZnO. Otherwise, the electrodeposition of ZnO is not easily performed on p-type substrate, an aluminum film on the back side of p-type Si can deposit ZnO by smaller potential, and different ZnO nanostructures are obtained by modifying the current density. Recently, different characteristics were found in nano-size noble metal crystals. In this thesis, the porous structure of Au-ZnO and Pt-ZnO were co-deposited by electrodeposition to enhance the photocatalytic activity. Si is the dominant material in semiconductor technology, but its indirect band gap property makes it not allowed in optoelectronics application. However, since 1990, the visible light is observed from porous Si fabricated by electrochemically etching of Si; though the light mechanism of porous Si is not clear, it can be divided into two parts, the quantum-confinement effect of Si nanocrystals and surface states on porous Si. Porous Si emits efficient visible light, but its light wavelength is readily influence by environment. We developed three methods, electrochemically etching the pre-treated Si substrate, adding chemical solution into electrolyte during etching process, and post-treatment of Si substrate after etching to prevent the emission of porous Si from being affected by environment.

Nanostructured ZnO films were obtained via thermal oxidation of thin films formed with metallic Zn-nanoparticle dispersions. Commercial zinc nanoparticles used for this work were characterized by microscopic and thermal analysis methods to analyze the Zn-ZnO core shell structure, surface morphology and oxidation characteristics. These dispersions were spin-coated on SiO₂/Si substrates and then annealed in air between 100 and 600 °C. Significant nanostructural changes were observed for the resulting films, particularly those from larger Zn nanoparticles. These nanostructures, including nanoneedles and nanorods, were likely formed due to fracturing of ZnO outer shell due to differential thermal expansion between the Zn core and the ZnO shell. At temperatures above 227 °C, the metallic Zn has a high vapor pressure leading to high mass transport through these defects. Ultimately the Zn vapor rapidly oxidizes in air to form the ZnO nanostructures. We have found that the resulting films annealed above 400 °C had high electrical resistivity. The zinc nanoparticles were incorporated into zinc indium oxide solution and spin-coated to form thin film transistor (TFT) test structures to evaluate the potential of forming nanostructured field effect sensors using simple solution processing. The functionalization of zinc tin oxide (ZTO) films with self-assembled monolayers (SAMs) of n-hexylphosphonic acid (n-HPA) was investigated. The n-HPA modified ZTO surfaces were characterized using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and electrical measurements. High contact angles were obtained suggesting high surface coverage of n-HPA on the ZTO films, which was also confirmed using XPS. The impact of n-HPA functionalization on the stability of ZTO TFTs was investigated. The n-HPA functionalized ZTO TFTs were either measured directly after drying or after post-annealing at 140 °C for 48 hours in flowing nitrogen. Their electrical characteristics were compared with that of non-functionalized ZTO reference TFTs fabricated using identical conditions. We found that the non-functionalized devices had a significant turn-on voltage (V[subscript ON]) shift of ~0.9 V and ~1.5 V for the non-annealed and the post-annealed conditions under positive gate bias stress for 10,000 seconds. The n-HPA modified devices showed very minimal shift in V[subscript ON] (0.1 V), regardless of post-thermal treatment. The VON instabilities were attributed to the interaction of species from the ambient atmosphere with the exposed ZTO back channel during gate voltage stress. These species can either accept or donate electrons resulting in changes in the channel conductance with respect to the applied stress. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Jan. 6, 2012 - Jan. 6, 2013