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This thesis is concerned with the development of MOS charge-coupled device (CCD) technology for future applications in X-ray astronomy. Of particular interest is increased detection efficiency of high energy X-ray photons and increased pixel readout speed for large area sensors. Chapter 2 reviews the generation of X-rays, methods for extra-terrestrial X-ray observations, detectors and provides an overview of X-ray astronomy missions. Chapter 3 discusses the CCD and introduces some of the recent technological developments that improve their overall performance for optical and X-ray photon detection. Chapter 4 presents the basic laboratory equipment and methods used to carry out the experimental work of this thesis. Chapter 5 presents the characterisation of new high resistivity devices that were manufactured by e2v technologies during the work of this thesis. Chapter 6 describes a method for estimating the depletion depth of a CCD by analysing the X-ray event patterns that are generated in CCD image data. Chapter 7 presents the equipment developed and experimental measurements taken to evaluate the high energy X-ray quantum efficiency of a high resistivity CCD. Finally, Chapter 8 describes the ongoing development and characterisation of low noise ASICs that are intended for use in future X-ray astronomy missions.

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Orientador: Tomaz Manabu Hashimoto / Banca: Marcelo dos Santos Pereira / Banca: Antonio Jorge Abdalla / Resumo: O ataque químico seletivo para alteração da composição superficial de ligas de ouro, é um processo que permite retirar os elementos de liga, de uma camada superficial de uma peça confeccionada com liga de ouro, produzindo assim uma camada formada por uma liga mais resistente aos ataques químicos e de cor diferente da liga original. Reagentes e procedimentos para aplicação do processo, apresentando baixa toxidez e fácil aquisição, foram aplicados em corpos de prova confeccionados com a liga de ouro ternária 75 Au, 12,5 Cu, 12,5 Ag, obtendo-se camadas com composição alterada com espessuras de até 50 æm. Reagentes diferentes produziram camadas de composições diferentes. O reagente contendo Na Cl, K NO3 e Fe2 SO4, mostrou maior eficiência na remoção do cobre, não interferindo significativamente no porcentual de prata, produzindo uma camada com porcentual de cobre praticamente igual a zero e o porcentual de prata em torno dos valores originais da liga. O reagente contendo Na Cl, K NO3 e KAl (SO4)2, apresentou remoção total da prata e do cobre, produzindo uma camada com 50 æm de espessura, composta praticamente de 100% de ouro. / Abstract: The selective chemical attack for alteration of the superficial layer of gold alloys is a process that allows the removal of base metals and silver from the surface layer, of one part made with gold alloy, thus producing a layer composed of a more resistant alloy to the chemical attacks and with different color from the original alloy. Reagents and procedures, composed of low toxicity and easy acquisition substances, had been applied in test specimens prepared with ternary gold alloy 75 Au, 12,5 Cu and 12,5 Ag, getting layers with composition modified with thicknesses up to 50 æm. Different reagents had produced layers of different compositions. The reagent contend Na Cl, K NO3 and Fe2 SO4 showed great efficiency removing copper and not intervening significantly with the silver percentage, producing a layer with practically no copper and the silver amount around the original values. The reagent contained, Na Cl, K NO3 and KAl (SO4)2 showed total removals of the silver and copper, producing a layer 50 æm thick, composed basically of gold. / Mestre

Abstract This thesis examines global warming and the possible contribution that ozone depletion provides to this warming. An examination is performed to determine the extent of any warming/cooling events within the Earth-atmosphere system. The change in energy corresponding to this warning of the Earth- atmosphere system is estimated as being equivilent to an increase of mean solar input of 0.22W/m2. This is compared to the predicted changes of solar input for the two most common global warming scenarios: greenhouse gases and solar irradiance variance; and for a less well explored scenario, snow-ice albedo change. Examination of ozone depletion data shows that an absence of ozone in the stratosphere produces an increase in UV-B radiation at the surface of the Earth. This increase in UV-B light has not previously been thourougly examined in any of the global warming scenarios. This is presented as a fourth scenario for global warming. An analytical three layer model of the Earth-atmosphere, based on an earlier two layer model, is developed. Using this model it is determined that greenhouse gases, solar irradiance, snow-ice albedo feedback and ozone depletion can cause warming of the Earth's atmosphere. After comparison with other models, a snow-ice albedo mechanism is incorporated into the three layer model. This produces an amplification effect of any warming that occurs. Compared to the observed increase of surface temperature between 1975-2000 of 0.55 K, the model using a snow-ice albedo feedback, produced an increase of temperature of 1.4 K for greenhouse gases, 0.294 K for a solar irradiance increase and 0.119 K caused by a decrease in the ozone layer. Of the greenhouse gas, solar irradiance and ozone depletion scenarios, ozone depletion demonstrates the most realistic relative changes with a cooling of the stratosphere and a warming of the troposphere and Earth's surface as has been observed. It is concluded that ozone depletion is likely for a reasonable part of observed global warming.

In deep submicron region, scaling the sizes of devices and chips down is indispensable. The silicide at ultra-shallow extension area is used in order to keep low sheet resistance while junction depth is scaled. To introduce the implant between source and channel keeps high saturation current. Furthermore, we put two blocks of oxide between source and channel to suppress the short channel effect, which are able to resist depletions. We also demonstrate the capacitor-less memory cell. We use the variation of the charge and bias replacing the real capacitor. The device is promising candidate for reduced chip size. According to the simulation results of ISE TCAD, the device with silicide at ultra-shallow extension area and the implantation between source and channel provide higher saturation current. The MOS with block oxide has high Ion/Ioff and low DIBL. We simulate different materials, different high and width of the block oxide, and discuss the effects of those device¡¦ characteristics. We show two methods of the implantation which can improve the charge density of pseudo neutral region. Those three structures provide an solution to make device and chip be scaled down easily.