Thesis (M.S.)--Oregon State University, 2004. / Typescript (photocopy). Includes bibliographical references (leaves 73-77). Also available on the World Wide Web.

No description available.

A transparent conductive electrode (TCE) is an important component in many of our modern optoelectronic devices like photovoltaics, light emitting diodes and touch screens. These devices require good current injection and spreading as well as a high transparency. In this thesis we explore the use of graphene as an alternative to the current widely used indium tin oxide (ITO) as TCE in gallium nitride (GaN) based light emitting diodes (LEDs). Monolayer crystalline graphene can be produced on copper foils using chemical vapor deposition (CVD), where metals (especially copper) has a catalysing effect on the formation of graphene. However, transfer of graphene from copper foils is not suitable for an industrial scale and it results in a poor contact with the target substrate. We investigate the possibility of directly integrating graphene on GaN-based LEDs by using plasma-enhanced chemical vapor deposition (PECVD). We try to obtain the optimal conditions under these catalyst-free circumstances and propose a recipe adapted for the setup that we used. We will also study ideas of using a metal (we tried copper and nickel) to assist the direct growth that could help to increase the fraction of sp2 carbon bonds and reduce the sheet resistance. The metals are evaporated onto our samples either before or after we grow a carbon film to either assist the growth or rearrange the carbon respectively. The focus was not on trying to optimize the conditions for one metal treatment but rather to briefly explore multiple methods to find a suitable path for further studies. The direct grown pristine carbon films shows indications from Raman measurements of being nanocrystalline graphene with a sheet resistance ranging from about 20-50 kΩ/sq having a transmittance of approximately 96 % at 550 nm. A transmittance at this level is closely related to the value of an ideal monolayer graphene, which indicates that our carbon films could be close to one atom in thickness while being visually homogeneous and complete in coverage. Due to the use of a temperature close to the melting point of copper we struggled to keep the assisting copper from evaporating too fast or staying homogeneous after the treatment. Nickel has a higher melting temperature, but it appears as if this metal might be diffusing into the GaN substrate which changes the properties of both the GaN and carbon film. Even though the metal treatments that we tested did not provide any noticeable improvements, there is need for further investigations to obtain suitable treatment conditions. We suggest that the treatments involving copper are a more promising path to pursue as nickel seem to cause unavoidable intermixing problems.

Methods and ideas for the creation of ‘transparent’ music in the classroom The aims of this port-folio are as follows;  To provide a coherent sequence of pieces and methods which can be used to create music in an educational context and also encourage students and teachers to develop their own creativity.  To provide pieces which develop student’s confidence in their own ability to create music in a variety of ways including composition, improvisation and creative leadership.  To provide exercises and pieces which help to develop the listening and appreciation skills essential for ensemble musicmaking.  To provide methods that enable the creation of ‘transparent music’. This is music in which the some, or all, of the decision making involved in the creation of a piece is accessible and apparent to an audience during its performance. This submission consists of a teaching book containing thirteen pieces/exercises, instructions giving guidance on their possible use in a teaching context and recorded examples. Also included are separate instructions where appropriate for the use of pieces in a concert or other non-educational setting and two essays giving context and background information on the ideas behind the pieces.

Silver nanowire transparent electrodes have recently received much attention as a replacement for indium tin oxide (ITO) for use in various electronic devices such as touch panels, organic solar cells, and displays. The fabrication of silver nanowire electrodes on glass substrates with a sheet resistance as low as 9 Ω/□ and 90% optical transparency at 550 nm is demonstrated. These resistance and transparency values match that of commercially available indium tin oxide and are superior to other alternatives such as carbon nanotube electrodes. The nanowire electrodes are low cost and easy to fabricate. Moreover, by depositing nanowire films on plastic substrates, mechanically flexible electrodes are obtained. The silver nanowire electrodes are integrated into several electronic devices: transparent heaters, organic solar cells, and switchable privacy glass. The concerns about the suitability of silver nanowire electrodes for use in commercial electronic devices are discussed. High surface roughness, one of the major concerns, is addressed by introducing a new method of embedding silver nanowires in a soft polymer. The instability of silver nanowire electrodes under current flow is also demonstrated for the first time. It is shown that silver nanowire electrodes fail under current flow after ass little as 2 days. This failure is caused by Joule heating which causes the nanowires to break up and thus create an electrical discontinuity in the nanowire film. Suggestions for improving the longevity of the electrodes are given.

In this thesis, it mainly studies the performance characteristics of the bending losses in semiconductor waveguides and the quantum dots semiconductor optical amplifier. We used InP-subtract and InGaAlAs /InAlAs multiple quantum wells epitaxial wafer grown by MBE as our material(£fg=1.41£gm). We had successfully fabricated a series of bending strip-loaded waveguides. On the quantum dots semiconductor optical amplifier, symmetric InGaAlAs/GaAs quantum well structure is used to fabricate the optical waveguide. We have established an automatic optical measurement system to measure the device characteristics more accurately. Design respect of bending waveguide, we design a series of radius, is 60£gm, 80£gm, 110£gm, 170£gm,and 260£gm respectively, and utilize Fabry-Perot resonant, measurement and estimate the loss of bending waveguide in quantity. We find the bending waveguide loss as radius for 260£gm and contain deeply etching process was quite equal to straight waveguide loss. On the quantum dots semiconductor optical amplifier, we design a single mode waveguide and a broad area waveguide to compare the difference of their electron-hole combination situation. A single mode waveguide with longer cavity length had better combination situation than shorter (C311 of cavity length 4000£gm ,0.00066£gW *A/cm2). And the broad area waveguide had more better combination situation to single mode waveguide (C311 of cavity width 150£gm, length 4000£gm , 0.0966£gW *A/cm2). For the gain to the pump signal, C311 singe mode waveguide (emission peak:1211nm,pump signal:1260nm) could get a gain about 3.56dB¡Fand C374 singe mode waveguide (emission peak:1255nm,pump signal:1260nm) could get a gain about 6.1dB.

Geogrids have been used for decades as reinforcement for mechanically stabilized earth retaining walls and base layers of pavements. However, literature on these applications is contradictory regarding the displacement and strain levels at which the bearing mechanism of interaction between soil and geogrid is developed along the transverse ribs of geogrids. No data are available on the deflections and displacement profiles of transverse ribs during loading of geogrids. Field and laboratory data on strain distributions along geogrids are limited. Accordingly, the objective of this study is to better understand the mechanisms of soil-geogrid interaction that develop at different stages of pullout tests, especially at small displacements and strains. Moreover, the behavior of transverse ribs throughout pullout testing is evaluated. Pullout loads were obtained from a load cell synchronized with two 5 MP cameras. Images of the geogrid were analyzed using the Particle Image Velocimetry (PIV) technique to obtain displacement profiles along the entire geogrid specimen throughout the duration of the test. Five transparent pullout tests were conducted using a confining pressure of 35 kPa (5 psi) on polypropylene geogrids with different configurations. Displacements along the polypropylene geogrid used in this study are well represented by an exponential equation. The bearing mechanism along transverse ribs was observed to develop at small viii displacements. The contribution of the bearing mechanism was first observed at 25 % of the maximum pullout force. Interference between transverse ribs was first observed at approximately 60 % of the maximum pullout force. High interference between transverse ribs was observed when the ratio of spacing between transverse ribs (S) over the thickness of the transverse ribs (B) was equal to 24. Negligible interference was observed when S/B was equal to 57. Displacements of soil particles were observed when the ratio distance from the soil-geogrid interface (d) over the D₅₀ of the soil was equal to 3, but they were orders of magnitude smaller than the displacements of the geogrid specimens. The observed boundary of the zone of influence of geogrids was for values of 3 < d/D₅₀ < 7 for the transparent soil used in this study. / text

Transparent conducting oxides (TCOs) usually have high conductivity and transparency in the visible range and have been widely used in daily life. Recently, TCOs have attracted great interest due to their potential applications in various new optical and electrical devices (flat-panel displays, energy efficient windows, etc.). Nanostructured TCOs can induce new size related properties, for example, when sizes of TCOs are controlled at the nanometer scale, various defects can introduce different defect-related optical emissions. These new nanostructured TCOs combining traditional and new size dependent properties may be used for construction of next generation optical devices. To investigate the optical properties of TCOs at nanoscale, in this thesis, several new kinds of colloidal nanocrystals (NCs) of TCOs have been synthesized and their optical emission and transparency have been explored. The first part of my work focuses on ITO (indium tin oxide) NCs demonstrates phase and size dependence of surface plasmon absorption in the near infrared region. The second part of the thesis describes colloidal synthesis of γ-Ga2O3 with size tunable photoluminescence, further study reveals that the photoluminescence is defect related and can be tuned by changing the defect concentration. In the last part of my study, I develop a methodology for lanthanide doped γ-phase Ga2O3 NCs and reveal tunable chromaticity of the lanthanide doped NCs.

Transparent conducting oxides (TCOs) usually have high conductivity and transparency in the visible range and have been widely used in daily life. Recently, TCOs have attracted great interest due to their potential applications in various new optical and electrical devices (flat-panel displays, energy efficient windows, etc.). Nanostructured TCOs can induce new size related properties, for example, when sizes of TCOs are controlled at the nanometer scale, various defects can introduce different defect-related optical emissions. These new nanostructured TCOs combining traditional and new size dependent properties may be used for construction of next generation optical devices. To investigate the optical properties of TCOs at nanoscale, in this thesis, several new kinds of colloidal nanocrystals (NCs) of TCOs have been synthesized and their optical emission and transparency have been explored. The first part of my work focuses on ITO (indium tin oxide) NCs demonstrates phase and size dependence of surface plasmon absorption in the near infrared region. The second part of the thesis describes colloidal synthesis of γ-Ga2O3 with size tunable photoluminescence, further study reveals that the photoluminescence is defect related and can be tuned by changing the defect concentration. In the last part of my study, I develop a methodology for lanthanide doped γ-phase Ga2O3 NCs and reveal tunable chromaticity of the lanthanide doped NCs.

Silver nanowire transparent electrodes have recently received much attention as a replacement for indium tin oxide (ITO) for use in various electronic devices such as touch panels, organic solar cells, and displays. The fabrication of silver nanowire electrodes on glass substrates with a sheet resistance as low as 9 Ω/□ and 90% optical transparency at 550 nm is demonstrated. These resistance and transparency values match that of commercially available indium tin oxide and are superior to other alternatives such as carbon nanotube electrodes. The nanowire electrodes are low cost and easy to fabricate. Moreover, by depositing nanowire films on plastic substrates, mechanically flexible electrodes are obtained. The silver nanowire electrodes are integrated into several electronic devices: transparent heaters, organic solar cells, and switchable privacy glass. The concerns about the suitability of silver nanowire electrodes for use in commercial electronic devices are discussed. High surface roughness, one of the major concerns, is addressed by introducing a new method of embedding silver nanowires in a soft polymer. The instability of silver nanowire electrodes under current flow is also demonstrated for the first time. It is shown that silver nanowire electrodes fail under current flow after ass little as 2 days. This failure is caused by Joule heating which causes the nanowires to break up and thus create an electrical discontinuity in the nanowire film. Suggestions for improving the longevity of the electrodes are given.