Thesis (M. Sc.)--Carleton University, 2001. / Includes bibliographical references (p. 79-84). Also available in electronic format on the Internet.

Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2006. / Embargoed. Vita. Bibliography: 99-115.

Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-17Bitstream added on 2014-06-13T18:50:42Z : No. of bitstreams: 1 bataginneto_a_me_bauru.pdf: 728792 bytes, checksum: 1630464fa8b5bc3088ecee698a2e6b9e (MD5) / Os polímeros orgânicos conjugados têm sido amplamente utilizados em diversos campos tecnológicos devido às suas características semicondutoras e ópticas. Recentemente foi relatada a possibilidade de sua utilização na área de dosimetria. O polímero MEH-PPV, quando diluído em solventes que contenham halogênios, tem apresentado características bastante promissoras nesta área, contudo não há ainda uma completa compreensão dos mecanismos envolvidos. No presente trabalho realizou-se o estudo conformacional e da estrutura eletrônica do polímero MEH-PPV em clorofórmio e as possíveis alterações provenientes da irradiação desta solução com radiações ionizantes. Métodos de modelagem de materiais foram utilizados a fim de simular o sistema. Resultados experimentais sugerem que os efeitos observados são oriundos da interação do solvente com a cadeia polimérica. A fim de investigar tal possibilidade, uma análise dos prováveis sítios de maior reatividade sobre o polímero foi realizada, apontando um mecanismo de incorporação de radicais sobre a cadeia principal. / Organic conducting polymers have been employed in several technological fields due to its semiconducting and optical properties. Recently, several reports points to applications in radiation dosimetry. When diluted in halogen-containing solvents, the polymer MEH-PPV shows interesting properties after gamma irradiation. Despite the promising application, still is lacking a complete understanding of the underlying phenomena. In the present work, we studied the geometry conformation and electronic structure of MEH-PPV in the presence of chloroform employing molecular modeling techniques to simulate the system. Several possibilities for polymer modification under gamma radiation were investigated, following suggestion from experimental results. Finally, a model for the color modifications of the solution is present.

No description available.

Este trabalho apresenta um estudo sobre a degradação de parâmetros elétricos de transistores CMOS tecnologia 0,35 μm, fabricados com o processo AMS C35B4, devido aos efeitos de dose total ionizante. Os efeitos de dose total são resultado do acúmulo de cargas em estruturas dielétricas de dispositivos semicondutores; em transistores MOS, este acúmulo de carga afeta parâmetros elétricos como a tensão de limiar, subthreshold swing, ruído 1/f, corrente de fuga e mobilidade efetiva dos portadores de carga. Com o objetivo de mensurar o impacto dos efeitos de dose total em transistores CMOS 0,35 μm, foi realizado um ensaio de irradiação, submetendo-se transistores de uma tecnologia comercial à radiação ionizante e realizando a caracterização destes dispositivos para diferentes doses totais acumuladas. Os resultados obtidos indicam a degradação dos transistores devido aos efeitos de dose total, bem como apontam a influência da polarização dos dispositivos durante o ensaio de irradiação nesta degradação. Estes resultados podem ser utilizados para, através de simulação elétrica de circuitos, estimar a tolerância à dose total de uma determinada topologia de circuito ou sistema. / This work presents a study on the degradation of electrical parameters of 0,35 μm CMOS transistors, fabricated with an AMS C35B4 process, due to total ionizing dose (TID) effects. The TID effects are the result of the trapping of charges in dielectric structures of semiconductor devices; in MOS transistors, this charge trapping affects electrical parameters such as threshold voltage, subthreshold swing, 1/f noise, leakage current and carrier effective mobility. In order to measure the impact of TID effects on electrical parameters of 0,35μm CMOS transistors, an irradiation test was performed, exposing transistors from a commercial technology to ionizing radiation and characterizing these devices under different total doses. The results obtained in this work indicate transistor degradation due to TID effects, as well as the impact of device polarization during the irradiation test on transistor degradation. These results may be used, through electrical simulation of circuits, to estimate the impact of TID effects on the operation of a circuit or system.

abstract: Total dose sensing systems (or radiation detection systems) have many applications, ranging from survey monitors used to supervise the generated radioactive waste at nuclear power plants to personal dosimeters which measure the radiation dose accumulated in individuals. This dissertation work will present two different types of novel devices developed at Arizona State University for total dose sensing applications. The first detector technology is a mechanically flexible metal-chalcogenide glass (ChG) based system which is fabricated on low cost substrates and are intended as disposable total dose sensors. Compared to existing commercial technologies, these thin film radiation sensors are simpler in form and function, and cheaper to produce and operate. The sensors measure dose through resistance change and are suitable for applications such as reactor dosimetry, radiation chemistry, and clinical dosimetry. They are ideal for wearable devices due to the lightweight construction, inherent robustness to resist breaking when mechanically stressed, and ability to attach to non-flat objects. Moreover, their performance can be easily controlled by tuning design variables and changing incorporated materials. The second detector technology is a wireless dosimeter intended for remote total dose sensing. They are based on a capacitively loaded folded patch antenna resonating in the range of 3 GHz to 8 GHz for which the load capacitance varies as a function of total dose. The dosimeter does not need power to operate thus enabling its use and implementation in the field without requiring a battery for its read-out. As a result, the dosimeter is suitable for applications such as unattended detection systems destined for covert monitoring of merchandise crossing borders, where nuclear material tracking is a concern. The sensitive element can be any device exhibiting a known variation of capacitance with total ionizing dose. The sensitivity of the dosimeter is related to the capacitance variation of the radiation sensitive device as well as the high frequency system used for reading. Both technologies come with the advantage that they are easy to manufacture with reasonably low cost and sensing can be readily read-out. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017

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