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Amorphous oxide semiconductors are of potential interest in the display industry due to their high carrier mobility, transparency at visible wavelengths and excellent operational stability. In this dissertation, n-channel zinc-tin oxide thin-film transistors are fabricated based on a solution-based deposition approach, which allows low fabrication cost and high throughput. The effects of device configuration and process conditions on transistor performance are investigated, and circuit applications including inverters, amplifiers, and ring oscillators are demonstrated. Charge transport in the zinc-tin oxide field-effect transistors is also investigated. A transition from thermally-activated to band-like transport is observed with increasing carrier concentration in high mobility samples, which agrees well with the key predictions of the multiple trap and release model and also Mott’s mobility edge model. In addition, velocity distribution of charge carriers is studied with a time-resolved technique. This provides a more detailed picture of charge transport in field-effect transistors. P-channel organic semiconductor field-effect transistors are also investigated with a view to combine them with n-channel amorphous oxide transistors to create a hybrid organic-inorganic complementary technology. / text

Amorphous Oxide semiconductors have gained large interest in the display industry owing to their high carrier mobilities and low fabrication costs. In this thesis, n-channel solution based zinc-tin oxide (ZTO) thin-film transistors (TFTs) are studied from a circuit design perspective. The study includes an iterative process of circuit design, layout and test procedure of the fabricated devices in the lab. The device models used in circuit simulations are refined following the data fed back from each of these iterations which has enabled more accurate design of complex circuits using ZTO devices. The requirement and development of a physical compact model for performing accurate and predictive circuit simulations has been presented. The use of ZTO devices in low cost, transparent and flexible electronic applications has been investigated through the study of basic circuit blocks such as amplifiers, ring oscillators, inverters and a four stage Operational Amplifier. / text

Amorphous Oxide Semiconductors (AOS) are widely being explored in the field of flexible and transparent electronics. In this thesis, solution processed zinc-tin oxide (ZTO) n-channel TFT based circuits are studied. Inverters, single stage amplifiers and ring oscillators are designed, fabricated and tested. 7-stage ring oscillators with output frequencies up to 106kHz and 5-stage ring oscillators with frequencies up to 75kHz are reported. A stable three stage op-amp with a buffered output is designed for a gain of 39.9dB with a unity gain frequency of 27.7kHz. A 7-stage ring oscillator with output frequency close to 1MHz is simulated and designed. The op-amp and the ring oscillator are ready to be fabricated and tested. An RPI model for a-Si, adapted to fit the ZTO device characteristics, is used for simulation. Development of a new model based on the physics behind charge transport in ZTO devices is explored. An expression for gate bias dependent mobility in ZTO devices is derived. / text

This dissertation presents the design of organic/inorganic hybrid 2D and 3D nanostructured arrays via controlled assembly of nanoscale building blocks. Two representative nanoscale building blocks such as carbon nanotubes (one-dimension) and metal nanoparticles (zero-dimension) are the core materials for the study of solution-based assembly of nanostructured arrays. The electrical, mechanical, and optical properties of the assembled nanostructure arrays have been investigated for future device applications. We successfully demonstrated the prospective use of assembled nanostructure arrays for electronic and sensing applications by designing flexible carbon nanotube nanomembranes as mechanical sensors, highly-oriented carbon nanotubes arrays for thin-film transistors, and gold nanoparticle arrays for SERS chemical sensors. In first section, we fabricated highly ordered carbon nanotube (CNT) arrays by tilted drop-casting or dip-coating of CNT solution on silicon substrates functionalized with micropatterned self-assembled monolayers. We further exploited the electronic performance of thin-film transistors based on highly-oriented, densely packed CNT micropatterns and showed that the carrier mobility is largely improved compared to randomly oriented CNTs. The prospective use of Raman-active CNTs for potential mechanical sensors has been investigated by studying the mechano-optical properties of flexible carbon nanotube nanomembranes, which contain freely-suspended carbon nanotube array encapsulated into ultrathin (<50 nm) layer-by-layer (LbL) polymer multilayers. In second section, we fabricated 3D nano-canal arrays of porous alumina membranes decorated with gold nanoparticles for prospective SERS sensors. We showed extraordinary SERS enhancement and suggested that the high performance is associated with the combined effects of Raman-active hot spots of nanoparticle aggregates and the optical waveguide properties of nano-canals. We demonstrated the ability of this SERS substrate for trace level sensing of nitroaromatic explosives by detecting down to 100 zeptogram (~330 molecules) of DNT.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 75-79). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 145-153). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 78-82). Also available on the World Wide Web.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2006. / Bibliography: leaves 83-91. Also available online.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 165-173). Also available on the World Wide Web.