Graduation date: 2007The focus of this study is to develop a general and low-cost solution-based process to fabricate micro- and nano-structured semiconductors that are suitable for electronics. This process uses simple metal halide precursors dissolved in a solvent (organic or aqueous) and is capable of forming uniform and continuous thin films via digital fabrication (e.g. inkjet printing) and blanket coating (e.g. spin coating and chemical bath deposition). It has been demonstrated for the deposition of a variety of semiconducting metal oxides including binary oxides (ZnO, In2O3, SnO2), ternary oxides (Zinc-Indium-Oxide (ZIO), Indium-Tin-Oxide (ITO), Zinc- Tin-Oxide (ZTO)) and quaternary oxides, Indium-Zinc-Tin-Oxide (IZTO). Functional thin film transistors with high field-effect mobility were successfully fabricated using channel layers deposited from this process (μFE ≅ 30 cm2/V-sec from inkjet printed IZTO channel layers). This rather simple solution-based deposition process was used to fabricate 3-D nano-structured silicate-based luminescent materials from diatom frustules. A diatom is a single-celled microalgae that possesses cell walls composed of amorphous silica (SiO2) with nano- and microstructures. Nanocrystalline Zn2SiO4 thin films with Mn dopants on the frustules isolated from the cultured marine diatoms Pinnularia sp. by a combination of chemical solution deposition of ZnO thin film and solid-solid reaction between ZnO and SiO2(diatom) by thermal annealing processes. This material exhibited bright green photoluminescence. Two types of nanostructures could be generated depending upon the level of the initial chemical deposition coverage. This process is capable of preserving the threedimensional shape of the diatom frustules at the nanometer scale. Using this process and the direct writing capability of the inkjet printing process, patterned Zn2SiO4:Mn2+ green phosphors and Yi2SiO5:Eu3+ were fabricated. At first, a layer of diatom frustules was spun-coated onto a silicon substrate and followed by the inkjet printing of aqueous metal halide solutions with desired patterns. The metal silicate phosphors were generated after a thermal annealing process. SEM analysis verified that the nano- and microstructures of the diatom frustules were preserved after the process. The patterned phosphors exhibited highly bright green (Mn2+ dopant) and orange (Eu3+ dopant) photoluminescence under 254nm UV excitation.