TitleInvestigation of solution-based processes for functional metal oxides : printing, nanostructures, and applications
Publication TypeThesis
Year of Publication2011
AuthorsHan, S-Y
UniversityOregon State University
CityCorvallis, Or.
Thesis TypeDissertation

The various solution-based processes, spin coating, inkjet printing, microreactor assisted nanoparticle deposition (MANDTM) and spin-successive ionic layer absorption and reaction (Spin-SILAR) were used to demonstrate thin film electronics and anti-reflective coatings. Several aspects of thin film transistors (TFTs) were tested including a range of temperatures, annealing atmosphere, and deposition methods. At high processing temperature, TFTs with spin coated-InO, -IWO, -IZO and -IGO achieved high mobilites of 55.26, 37.86, 6.06 and 5.50 cm2/V·s, some of the highest reported mobilities for the spin coating process. Inkjet printed-ZTO, -IGZO and -IGTO from metal halide chemistry were fabricated and achieved mobilities of 3.09, 25.62 and 14.96 cm2/V·s, the highest reported values in inkjet printed TFTs. At low processing temperature, an ozone annealing process was adopted. TFTs with spin coated InO, IWO and IZO were processed with ozone. High mobilities of 0.85 {\textasciitilde} 16.76 cm2/V·s and I[subscript on/off] of 105 {\textasciitilde} 106 were achieved with the ozone annealing process at temperatures as low as 200 °C. A newly developed MANDTM system was used to fabricate ZnO TFTs which were shown to have strong potential for high performance devices made with low processing temperature. In addition, solution processing was used to produce anti-reflective coating of biomimic moth-eye structure on polished aluminum substrates, a textured silicon surface, glass slides and eyeglass lenses. Two films materials were explored - ZnO nanostructures, by MANDTM, and silica nanoparticles, by batch process - in which experimental conditions were tested and characterized. On aluminum two ZnO nanostructures were created by controlling temperature, flower-like shapes which dramatically reduced reflectance from {\textasciitilde}65% to {\textasciitilde}4% and chrysanthemum shapes which reduced reflectance down to {\textasciitilde}0.7%. On silicon, pyramid shaped texture reduced reflectance and was used with and without a Ag nanoparticle seed layer as a substrate for ZnO nanostructures; the presence of a seed layer initiated a unique orzo nanostructured shape, which minimized anti-reflectance for silicon from 30.8% of polished silicon, 10.6% of textured silicon to 3.4% with the orzo structure. SiO2 nanoparticles were deposited on glass and CR-39 substrates with and without hardcoat material and it was found that the smallest produced SiO2 nanoparticles gave the highest performance and that a very dilute layer of hard coat material followed by nanoparticle deposition, and again followed by a very dilute layer of hard coat material was successful in preserving the biomimic nanostructure of the film and producing a minimized reflectance of as low as 1%, while maintaining a higher durability than commercially available products. Overall, these films achieved a minimization in reflectance and high durability.