ABSTRACT In this study, the rf magnetron sputtering was used to deposit (Ba0.8Sr0.2)(Ti0.9Zr0.1)O3 (BSTZ) ferroelectric thin films on SiO2/Si substrates, and MFIS structure was also fabricated. The effects of various sputtering parameters effects on the characteristics of BSTZ thin films, such as the oxygen concentrations, deposition temperature, rf power, chamber pressure and deposition time were be discussed. As deposited on Pt/Ti/SiO2/Si substrate, the electrical and physical properties of BSTZ thin films after RTA and CTA thermal treatment were be also discussed. In XRD and SEM analysis, the crystal structure and grain size of as-deposited BSTZ thin film could be observed. From the C-V and J-E curves obtained, the memory window and leakage current density of MFIS structure were about 9.5V and 2.76¡Ñ 10-9 A/cm2, respectively. After RTA and CTA post-treatment, the capacitances of MFM structure were about 2.06nF and 1.93nF. We found that dielectric constant of as-deposited BSTZ thin film increased to 183 and 194, respectively. In addition, the leakage current density of RTA and CTA treated BSTZ films were about 3.82¡Ñ 10-6 A/cm2 and 1.16¡Ñ 10-6 A/cm2. Finally, the one-transistor-capacitor (1TC) structure of ferroelectric random access memory (FeRAM) with the gate oxide of BSTZ thin films on the polysilicon TFT structure have been fabricated and investigated.From the experimental results, the on/off drain current ratio is two orders, and its value is much smaller than those of the most reported bottom-gated TFTs devices by using different ferroelectric materials as gate oxide. From these results in this study, the BSTZ thin films for top-gate polysilicon thin-film transistor will be an excellent candidate to fabricate higher storage capacitance ferroelectric random access memory (FeRAM) devices for system on panel (SOP) applications.

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Semiconductor technology has already got into nanometer scale. As the dimension keeping scaling down, we can get more transistor in the same area, and furthermore the frequency and performance are also enhanced. But nowadays the development of the lithography technology has come to the neck; we must find another way to improve the performance of transistor. In this study, we fully discuss the electrical characteristics and the low temperature effect as the channel of the N-MOSFET being strained. In order to strain the channel, silicon substrate is bent by applying external mechanical stress, the lattice of channel will be strained after applying uni-axial tensile stress. Therefore, we had improved successfully drain current and carrier mobility of NMOS, and the increasing rates are 9% and 12% respectively. In addition, we can understand the influence of low temperature effect on strain silicon by bending silicon substrate with external mechanical stress. It is great that there is no general normal single crystalline silicon to come instead in the change to temperature of Mobility and operate-current. This is this experiment was worth probing into.

Thesis (Ph. D.)--University of Chicago, Dept. of Anthropology, August 2003. / Includes bibliographical references. Also available on the Internet.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

No description available.

Neste trabalho é apresentado um estudo comparativo da resposta de diodos de Si para dosimetria de radiação gama. Os diodos investigados, crescidos pelas técnicas de fusão zonal (Fz) e Czchocralski magnético (MCz), foram processados no Instituto de Física da Universidade de Helsinki no âmbito das pesquisas e desenvolvimento de dispositivos de Si resistentes a danos de radiação segundo a colaboração RD50 do CERN (European Organization for Nuclear Research). Para estudar a resposta dosimétrica dos diodos, eles foram acoplados diretamente no modo fotovoltaico na entrada de um eletrômetro digital para medir o sinal de fotocorrente devido a incidência de raios gama provenientes de uma fonte de 60Co (Gammacell 220). O parâmetro dosimétrico usado para estudar a resposta destes dispositivos foi a carga, obtida pela integração do sinal de corrente pelo tempo de exposição, em função da dose absorvida. Estudos da influência dos procedimentos de pré-irradiação na sensibilidade e estabilidade destes diodos mostraram que a sensibilidade decresce com a dose total absorvida mas depois de uma pré-irradiação de cerca de 873 kGy, eles se tornaram mais estáveis. Efeitos dos danos de radiação eventualmente produzidos nos diodos foram monitorados mediante medidas dinâmicas de corrente e de capacitância depois de cada etapa de irradiação. Ambas as amostras exibiram boa reprodutibilidade de resposta, 2,21% (Fz) e 2,94% (MCz), obtida com 13 medidas consecutivas de 15 kGy comparadas com a equivalente dose de 195 kGy absorvida em uma única etapa de irradiação. É importante notar que estes resultados são melhores do que aqueles obtidos com dosímetros de rotina de polimetilmetacrilato (PMMA) usados em processamento por radiação. / In this work it is presented the comparative study of Si diodes response for gamma radiation dosimetry. The diodes investigated, grown by float zone (Fz) and magnetic Czchcralski (MCz) techniques, were processed at the Physics Institute of Helsinki University in the framework of the research and development of rad-hard silicon devices. To study the dosimetric response of these diodes they were connected in the photovoltaic mode to the input of a digital electrometer to measure the photocurrent signal due to the incidence of gamma-rays from a 60Co source (Gammacell 220). The dosimetric parameter utilized to study the response of these devices was the charge, obtained trough the integration of the current signals, as a function of the absorbed dose. Studies of the influence of the pre-irradiation procedures on both sensivity and stability of these diodes showed that the sensitivity decreased with the total absorbed dose but after a preirradiation of about 873 kGy they became more stable. Radiation damage effects eventually produced in the devices were monitored trough dynamic current and capacitance measurements after each irradiation step. Both samples also exhibited good response reproducibility, 2,21% (Fz) and 2,94% (MCz), obtained with 13 consecutive measurements of 15 kGy compared with the equivalent 195 kGy absorbed dose in one step of irradiation. It is important to note that these results are better than those obtained with routine polimetylmetacrilate (PMMA) dosimeters used in radiation processing dosimetry .

Notre travail de recherche a consisté à examiner « comment et de quelle manière le SI contribue-t-il à la performance organisationnelle » et à vérifier si cette contribution diffère selon l’orientation stratégique de l’entreprise. Nous nous positionnons dans le courant de recherche de l’évaluation en nous basant sur la théorie de ressources, l’approche processuelle et le modèle ISSM. Les responsables de 102 entreprises industrielles tunisiennes ont évalué les actifs de leur SI ainsi que leurs contributions aux processus et à la performance individuelle et organisationnelle. Des outils de mesure ont été élaborés et validés : qualité du SI, valeur d’usage du SI. Notre approche processuelle en quatre étapes assure une bonne explication de nos construits latents : qualité du SI, valeur d’usage du SI, contribution du SI à la performance individuelle et organisationnelle, performance concurrentielle et taux de croissance moyen du chiffre d’affaires. Notre modèle structurel explique 12 % du taux de croissance du chiffre d’affaires avec un GoF de 54 %. Les relations entre l’orientation stratégique, le SI et la performance, soulèvent plusieurs dilemmes auxquels des recherches futures devraient pouvoir répondre. / Our research consists in examining "how IS contributes to organizational performance" and whether this contribution differs depending on the strategic orientation of the firm.We position ourselves in the field of research assessment based on the theory of resources, process-based approach and the ISSM model. Officials of 102 industrial firms Tunisian have valued the assets IS and their contributions to the process and the individual and organizational performance.Measurement tools have been developed and validated: IS quality, use value of SI. Our four-step process approach provides a good explanation of our latent constructs: quality of IS , use value of IS , IS contribution to individual and organizational performance, competitive performance and average growth rate of sales. Our structural model explains 12% of the growth rate of sales with GoF 54%. The relationships between strategic orientation, IS and performance, raise several dilemmas for which future research should be able to respond.

Neste trabalho é apresentado um estudo comparativo da resposta de diodos de Si para dosimetria de radiação gama. Os diodos investigados, crescidos pelas técnicas de fusão zonal (Fz) e Czchocralski magnético (MCz), foram processados no Instituto de Física da Universidade de Helsinki no âmbito das pesquisas e desenvolvimento de dispositivos de Si resistentes a danos de radiação segundo a colaboração RD50 do CERN (European Organization for Nuclear Research). Para estudar a resposta dosimétrica dos diodos, eles foram acoplados diretamente no modo fotovoltaico na entrada de um eletrômetro digital para medir o sinal de fotocorrente devido a incidência de raios gama provenientes de uma fonte de 60Co (Gammacell 220). O parâmetro dosimétrico usado para estudar a resposta destes dispositivos foi a carga, obtida pela integração do sinal de corrente pelo tempo de exposição, em função da dose absorvida. Estudos da influência dos procedimentos de pré-irradiação na sensibilidade e estabilidade destes diodos mostraram que a sensibilidade decresce com a dose total absorvida mas depois de uma pré-irradiação de cerca de 873 kGy, eles se tornaram mais estáveis. Efeitos dos danos de radiação eventualmente produzidos nos diodos foram monitorados mediante medidas dinâmicas de corrente e de capacitância depois de cada etapa de irradiação. Ambas as amostras exibiram boa reprodutibilidade de resposta, 2,21% (Fz) e 2,94% (MCz), obtida com 13 medidas consecutivas de 15 kGy comparadas com a equivalente dose de 195 kGy absorvida em uma única etapa de irradiação. É importante notar que estes resultados são melhores do que aqueles obtidos com dosímetros de rotina de polimetilmetacrilato (PMMA) usados em processamento por radiação. / In this work it is presented the comparative study of Si diodes response for gamma radiation dosimetry. The diodes investigated, grown by float zone (Fz) and magnetic Czchcralski (MCz) techniques, were processed at the Physics Institute of Helsinki University in the framework of the research and development of rad-hard silicon devices. To study the dosimetric response of these diodes they were connected in the photovoltaic mode to the input of a digital electrometer to measure the photocurrent signal due to the incidence of gamma-rays from a 60Co source (Gammacell 220). The dosimetric parameter utilized to study the response of these devices was the charge, obtained trough the integration of the current signals, as a function of the absorbed dose. Studies of the influence of the pre-irradiation procedures on both sensivity and stability of these diodes showed that the sensitivity decreased with the total absorbed dose but after a preirradiation of about 873 kGy they became more stable. Radiation damage effects eventually produced in the devices were monitored trough dynamic current and capacitance measurements after each irradiation step. Both samples also exhibited good response reproducibility, 2,21% (Fz) and 2,94% (MCz), obtained with 13 consecutive measurements of 15 kGy compared with the equivalent 195 kGy absorbed dose in one step of irradiation. It is important to note that these results are better than those obtained with routine polimetylmetacrilate (PMMA) dosimeters used in radiation processing dosimetry .

En este trabajo se ha estudiado el crecimiento epitaxial de capas de silicio sobre substrato de Si (001) y capas pseudomórficas de Si1-yCy utilizando silano y tetrametilsilano como gases precursores en el crecimiento vía Deposición Química en Fase Vapor. La temperatura mínima de epitaxia de las capas de Si ha sido del orden de 600°C. Dependiendo de los flujos y la temperatura se ha observado la formación de micromaclas a lo largo de la dirección {111}. También se ha efectuado el crecimiento de las aleaciones mediante Epitaxia en Fase Sólida utilizando una dosis de implantación de carbono elevada . La implantación iónica de Si en substrato de Si (180 keV, 5x1015 ion/cm2) ha resultado en la formación de una capa enterrada de silicio amorfo. Las muestras recocidas a temperaturas de 650°C, han crecido pseudomorficamente, con la presencia de máximos de interferencia en la zona de bajos ángulos con respecto al pico del substrato. Estos máximos son consecuencia de las zonas con esfuerzos de compresión y de fenómenos de interferencia entre las distintas zonas. La implantación de C se ha efectuado a 40 keV y 9x1015 ion /cm2; bajo estas condiciones se ha conseguido el crecimiento epitaxial en fase sólida de aleaciones de Si1-yCy a temperaturas bajas de 450°C. A pesar de la elevada cantidad de carbono introducido, los resultados obtenidos muestran incorporaciones substitucionales del orden de 0.3-0.4 %. La baja incorporación de carbono esta relacionada con la presencia de intersticiales de Si en exceso. Los intersticiales generados actúan como trampas para los átomos de carbono formando complejos Si-C. La formación de estos complejos reduce el estrés asociado y limita la cantidad de C substitucional en el sistema. Un estudio detallado a través del ajuste de las curvas rocking mediante teoría dinámica de rayos X, ha permitido una estimación de los espesores de las capas, la composición y otros parámetros estructurales de los perfiles de difracción. / Strained layer heterostructures based on group IV elements are of current interest because of the potential applications to build devices with improved carrier mobilities and suitable properties. In this work we investigated the strain and damage produced on Si substrates by high -dose ion implantation of Si and C after thermal treatment by double and triple crystal X-ray diffraction, high resolution transmission electron microscopy (HRTEM) and Secondary Ion Mass Spectroscopy (SIMS). Si implantation (180 keV, 5x1015 Si at/cm2) al liquid nitrogen temperature forms a buried amorphous layer. Annealing at temperatures close to 650°C results in epitaxial films with significant defects recovery. X-ray rocking curves show the existence of interference fringes on the left hand side of (004) Si peak indicating the presence of tensile strained Si layers due to the generation of Si interstitials during the implantation process. C implantation, at 60 keV, 7x1015 ion/cm2 and 450°C, in the preamorphized Si wafers results in the growth of Si1-yCy epitaxial films with a low amount of substitutional carbon (y =0.2%). Rapid annealing at 750°C results in highly defective films with a maximum carbon content close to 0.4%. the high density defects is responsible for the partial strain relaxation observed in those layers. The amount of substitutional Si also decreases drastically with increasing temperature. Profile fitting of rocking curves using dynamical X-ray theory is used to estimate the carbon concentration and the strain and disorder profiles of the heterostructures.