2 resultados para Elemental semiconductors

em Brock University, Canada


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This thesis uses a multifaceted process to engage with the topic of food sovereignty in California. It employs diverse methods, including critical and creative prose, photography, autoethnographic mixed media, storytelling and poetry. I am particularly concerned with the " " challenges of approaching food sovereignty, a radical praxis that combines subsistence practices with anti-capitalist resistance, while in my own "skin," which is thoroughly embedded in white, urban, middle classed culture and in corltextualizing ecological relationshipslkinships via cultural, historical and economic trajectories. The project utilizes a processual methodlology drawing substantially from the work of Brian Massumi to explore these issues through four creative narrative pieces which coalesce around the elemental metaphors of air, fire, water and earth. Following Deleuze and Guatarri's concept ofrhizomatic plateaus, the thesis narratives are comprised of many non-hierarchical layers and can be read from many angles. Each is offered "in process" rather than as a finished piece, thus practically validating the concept of the ongoing work of research and suggesting the equally omnipresent possibility of change and mutation in the formation relationally based knowledges. Cultivating ecological ethic and healing on multisensory levels, as well as commitment to emergent and re-productivist worldviews are goals of this project's research.

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This thesis reports on the optical properties of the dilute magnetic semiconductors, Sb1.97 V 0.03 Te3 and Sb1.94Cr0.06Te3, along with the parent compound Sb2Te3' These materials develop a ferromagnetic state at low temperature with Curie temperatures of 22 K and 16 K respectively. All three samples were oriented such that the electric field vector of the light was perpendicular to the c-axis. The reflectance profile of these samples in the mid-infrared (500 to 3000 cm-1) shows a pronounced plasma edge which retracts with decreasing temperature. The far-infrared region of these samples exhibits a phonon at ~ 60 cm-1 which softens as temperature decreases. Kramers-Kronig analysis and a Drude-Lorentz model were employed to determine the optical constants of the bulk samples. The real part of the optical conductivity is shown to consist of intraband contributions at frequencies below the energy gap (~0.26 eV) and interband contributions at frequencies above the energy gap. The temperature dependence of the scattering rate show that a mix of phonon and impurity scattering are present, while the signature of traditional spin disorder (magnetic) scattering was difficult to confirm.