Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 87-94). Also available in electronic format on the Internet.

Orientador: Carlos Alberto dos Reis Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-05T12:05:57Z (GMT). No. of bitstreams: 1 Cajueiro_JoaoPauloCerquinho_D.pdf: 1564955 bytes, checksum: 6ff645ea51f6ee2dcb9e7ab8db6363aa (MD5) Previous issue date: 2005 / Resumo: Uma nova técnica de compensação de temperatura para implementar tensões de referência em circuitos CMOS é descrita, desde o seu fundamento teórico até a comprovação experimental feita com amostras de circuitos integrados protótipos que a implementam. A ténica proposta se baseia no fato de que a tensão entre gate1, e fonte, VGS, de um transistor MOS pode tanto aumentar como diminuir com o aumento da temperatura, dependendo da corrente com que opera. Com base nisto, é possível empilhar n transistores, que estejam polarizados com uma corrente adequada de tal maneira que a queda de tensão sobre esta pilha de transistores, que tem amplitude nVGS, tenha, ao mesmo tempo, a mesma taxa de variação térmica que a tensão VGS produzida por um único transistor. Em tais condições, a diferença entre estas duas tensões é constante, tornando-se uma referencia de tensão. Uma implementação alternativa à pilha de transistores para produzir a tensão nVGS consiste num único transistor de gate ?utuante no qual a tensão VGS equivalente tem amplitude ajustável em campo. Diversos circuitos que se baseiam nesta técnica foram projetados e alguns deles fabricados em tecnologia CMOS 0,35 µm.O desempenho do melhor circuito fabricado atingiu coe?ciente térmico de 100 ppm/°C na faixa térmica de -40 a 120 °C. Outras configurações foram simuladas mostrando que é possível atingir coeficientes térmicos menores que 10 ppm/°C. O estado da arte é representado por referências de tensão que têm coeficientes térmicos de 1 ppm/°C na mesma faixa térmica em que se caracterizam os circuitos desenvolvidos. Tais referências de tensão se baseiam principalmente nos circuitos chamados de bandgap. Há também, um produto recente da empresa Intersil que utiliza um transistor que opera como memória análoga fornecendo uma tensão referência memorizada com altíssima estabilidade térmica. O princípio em que este produto se baseia, entretanto, é diferente do que está sendo proposto neste trabalho apesar do uso comum de um transistor de gate ?utuante. A contribuição deste trabalho não está no desempenho que as fontes de referência que se baseiam no princípio atingiram. Sua contribuição reside na forma como pode ser implementada, utilizando somente transistores MOS e no fato de que tem amplitude ajustável em campo. 1A palavra gate está sendo usada em toda extensão do texto, em lugar da palavra ¿porta¿, para identi?car o terminal de alta resistência de um transistor MOS / Abstract: A new technique of temperature compensation to implement a voltage reference in CMOS circuits is described, from theoretical basis to experimental evidence made with samples of integrated circuits prototypes that implement it. The proposed technique is based on the fact that the voltage between gate and source, VGS, of a MOS transistor can either increase as diminish with the increase of temperature, depending on the current with that it operates. Based in this, it is possible to pile up n transistors, that are polarized with an adequate current in such way that the voltage on this stack of transistors, that has amplitude nVGS, has, at the same time, the same thermal variation than the VGS voltage produced in only one transistor. In such conditions, the difference between these two voltages is constant, becoming a voltage reference. An alternative implementation to the stack of transistors to produce the nVGS volage consists of a ?oating gate transistor in which equivalent VGS has adjustable amplitude in ?eld. Diverse circuits that are based on this technique had been projected and some of them manufactured in technology CMOS 0,35 µm. The performance of the best manufactured circuit reached 100 ppm/°C of thermal coefficient in the thermal band of -40 to 120 °C. Other con?gurations had been simulated showing that it is possible to reach thermal coe?cients lesser that 10 ppm/°C. The state of the art is represented by voltage references that have thermal coefficients of 1 ppm/°C in the same thermal band where the developed circuits had been characterized. Such voltage references are mainly based on the circuits called bandgap. There is, also, a recent product of the Intersil company who uses a transistor that operates as analogical memory supplying a voltage reference memorized with highest thermal stability. The base principle of this product is, however, different of that being considered in this work despite the use of a ?oating gate transistor. The contribution of this work is not in the performance that the reference sources that are based on the principle had reached. Its contribution inhabits in the form as it can be implemented, only using MOS transistors and in the fact that it has adjustable amplitude in ?eld / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Orientadores: Peter Jurgen Tatsch, Stanislav A. Moshkalev / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T09:15:24Z (GMT). No. of bitstreams: 1 Nunes_AlcineiMoura_D.pdf: 5060090 bytes, checksum: 2e93ff0bc8213b48460167d7e4cbbcc3 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho foram desenvolvidas cinco aplicações de processos de corrosão por plasmas frios (temperatura ambiente), utilizando reatores dos tipos RIE (Corrosão por Íon Reativo) e ICP (Plasma Acoplado Indutivamente): Afinamento de porta de transistor CMOS - métodos convencionais como fotogravação, com resolução maior que 2 ?m, e corrosão por plasma em um reator RIE com as misturas gasosas SF6/CF4/CHF3 e SF6/CF4/N2, foram utilizados na obtenção de estruturas submicrométricas. A pressão foi variada de 50 mTorr a 150 mTorr e a potência de 30 W a 85 W. Corrosão de estruturas GaAs e AlGaAs para aplicação em transistores HEMT - as corrosões foram realizadas em um reator RIE com misturas de gás contendo SiCl4/Ar para a corrosão e O2/SF6/Ar para processo de limpeza da câmara; Corrosão de corpo para fabricação de sensores de pressão - foi utilizado um reator ICP e plasma de mistura gasosa SF6/Ar; Corrosão profunda para separação de patilhas utilizando métodos convencionais - foi utilizado um reator ICP para corrosão profunda dos canais. As misturas gasosas foram SF6/Ar, com polarização do eletrodo inferior para corrosão de Si (silício), e O2/Ar para remoção de fotorresiste; Teste de resistência de máscaras de Ni-P, Ni-B e SiO2 em processos de corrosão profunda e do tipo Bosch - as máscaras foram testadas em um reator ICP com plasma de misturas gasosas SF6/Ar e C4/F8. Em cada uma das aplicações foi feito um estudo sobre seus principais requerimentos, a fim de se obter o melhor compromisso entre os parâmetros do processo de corrosão / Abstract: This thesis is based on etching processes applications in cold plasmas (room temperature) using RIE (Reactive Ion Etching) and ICP (Inductively Coupled Plasma), as reactors, applied to specific areas of microelectronics and MEMS devices in semiconductors industries and laboratories. Five applications are presented: Thinning gate CMOS Transistor - conventional methods such as photolithography with resolution greater than 2 ?m and RIE reactor with gaseous mixtures: SF6/CF4/CHF3 and SF6/CF4/N2 were used to obtain structures below 1 ?m; GaAs and AlGaAs structures etching for HEMT transistors application - RIE reactor and mixtures containing SiCl4/Ar for etching and O2/SF6/Ar for cleaning were used; Bulk etching for pressure sensors - ICP reactor and gas mixture SF6/Ar were used; Deep Si etching for die separating - ICP reactor and gas mixtures SF6/Ar with bias for channel etching and O2/Ar for photoresist removal were used; Ni-P, Ni-B and SiO2 masks testing in deep etching processes - ICP reactor and gas mixtures as SF6/Ar and C4/F8 were used. In each applications a study of its main requirements was made, to achieve a better commitment between the parameters of the etching process / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

Metal Oxide (MO)semiconductors are one of the most widely used materials in commercial gas sensor devices. The basic principle of chemoresistive gas sensor operation stems on the high sensitivity of electrical resistance to ambient gaseous conditions. Depending on whether the oxide is "p type" or "n type", the resistance increases (or decrease), when placed in atmosphere containing reducing (or oxidizing) gases. The study of conductometric metal oxide semiconductor gas sensors has dual importance in view of their technological device applications and understanding fundamental MO-gas interactions. Metal oxides based sensors offer high thermal, mechanical and chemical stability. A large number of MOs show good sensitivities to various gases like CO, NOX, SOX, NH3, alcohols and other Volatile Organic Compounds (VOCs). VOCs are very common hazardous pollutants in the environment. Gas sensors are in great demand for their various applications such as food quality control, fermentation industries, road safety, defence, environmental monitoring and other chemical industries. The aim of the study is to explore the possibility of advancements in semiconducting MO based gas sensor devices through tuning microstructural parameters along with chemical dopants or additives. And further to investigate the underlying mechanism of conductometric MO gas sensors. The novel synthesis method employed is based on the solution combustion method coupled with ultrasonically nebulized spray pyrolysis technique. The well studied SnO2 and relatively unexplored Cr2O3 oxide systems are selected for the study. The non-equilibrium processing conditions result in unique microstructure and defect chemistry. In addition, using this technique MO - Reduced Graphene Oxide (RGO) nanocomposite films has also been fabricated and its application to room temperature gas sensor devices is demonstrated. The thesis comprises of seven chapters. the following section describe the summery of individual chapters. The Chapter 1 describes the introduction and background literature of this technology. A brief review of developments in gas sensor technology so far has been enlisted. This chapter also gives a glimpse of applications of MO semiconductors based sensors. The underlying mechanism involved in the sensing reaction and the primary factors influencing the response of a gas sensor device are enlisted. Further in the later part of the chapter focused the material selection criteria, effect of additives/dopants and future prospects of the technology. The end of this chapter highlights the objective and scope of the work in this dissertation. In the Chapter 2 the the materials selection, characterization techniques and particularly the experimental setups used are elaborated. This includes the deposition method used, which is developed in our group and the the in house built gas sensing system including its working principles and various issues have been addressed. The Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) is a novel deposition method devised, which is a combination of conventional spray pyrolysis and solution combustion technique. Spray pyrolysis is versatile, economic and simple technique, which can be used for large area deposition of porous films. The intention is to exploit the exothermicity of combustion reaction in order to have high crystallinity, smaller crystallite size with high surface area, which are extremely important in gas sensor design and its efficiency. Further the gas sensing system and its operation are discussed in detail including the advantages of vertical sensing chamber geometry, wider analyte concentration range (ppm to percentage) obtained through vapor pressure data and simultaneous multi sensor characterization allowing better comparison. Here in this work, Chromium oxide (Cr2O3) and Tin oxide (SnO2) are selected as gas sensing materials for this work as a p-type and n-type metal oxide semiconductors respectively. Nevertheless Cr2O3 is a less explored gas sensing material as compared to SnO2, which is also being used in many commercially available gas sensor devices. Thus, studying and comparing gas sensing properties of a relatively novel and a well established material would justify the potential of the novel deposition technique developed. In Chapter 3, the effect of exothermic reaction between oxidizer and fuel, on the morphology, surface stoichiometry and observed gas sensing properties of Cr2O3 thin films deposited by UNSPACM, is studied. An elaborative study on the structural, morphological and surface stoichiometry of chromium oxide films is undertaken. Various deposition parameters have been optimized. An extensive and systematic gas sensing study is carried out on Cr2O3 films deposited, to achieve unique microstructure. The crystallinity and microstructure are investigated by varying the deposition conditions. Further, the effect of annealing in oxygen gas atmospheres on the films was also investigated. The gas sensing properties are studied for various VOCs, in temperature range 200 - 375 oC. The possible sensing mechanism and surface chemical processes involved in ethanol sensing, based on empirical results, are discussed. In chapter 4, the effect of 1% Pt doping on gas sensing properties of Cr2O3 thin films prepared by UNSPACM, is investigated. The chemical analysis is done using x-ray photoelectron spectroscopy to find the chemical state of Pt and quantification is done. The gas sensing is done towards gases like NO2, Methane and Ethanol. The enhancement in sensitivity and remarkable reduction in response as well as recovery times have been modeled with kinetic response analysis to study the variation with temperature as well as concentration. Further the analysis of observations and model fittings is discussed. The Chapter 5 deals with the defects induced ferromagnetism and gas sensing studies SnO2 nanoparticles prepared by solution combustion method. The structural, chemical analysis of as-synthesized and annealed SnO2 nanoparticles reveal gradual reduction in defect concentration of as-prepared SnO2. The findings of various characterization techniques along with optical absorption and magnetic studies to investigate the defect structure of the material are presented. As defects play crucial role in gas sensing properties of the metal oxide material, the defect induced room temperature ferromagnetism in undoped SnO2 has been used as a potential tool to probe the evidence of the defects. Finally a correlation is established between observed room temperature ferromagnetism and gas sensing studies and primary role of defects in gas sensing mechanism over microstructure is realized . The Chapter 6 presents the deposition of SnO2 thin films by UNSPACM method on glass substrates for gas sensing application. The readiness of UNSPACM in making sensor materials with unform dopant distribution is demonstrated in order to improve the sensor performance in terms of response and selectivity. The chemical composition, film morphology and gas sensing studies are reported. The SnO2 is doped with Cr and Pt to enhance the sensing properties of the material. The doped Oxide films are found to show enhancement in sensitivity and improve the selectivity of the films towards specific gases like NO2 and CO. Further in Chapter 7 an effort has been made to overcome the problem of high operating temperature of metal oxide gas sensors through use of Reduced Graphene Oxide (RGO) and metal oxide nanocomposite films. Although RGO shows room temperature response towards many toxic and hazardous gases but it exhibits poor sensor signal recovery. This has been successfully solved by making nanohybrids of RGO and SnO2. It not only improves the sensor signal kinetics but it enhances the sensitivity also. Thus this chapter endeavors towards low power consumption gas sensing devices. The key findings and future aspects are summarized in the Chapter 8.

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη, το σχεδιασμό, την πρσοομοίωση και την κατασκευή κυκλώματος για την οδήγηση και τον έλεγχο στροφών κινητήρα τύπου DC Brushless.Η εργασία αυτή εκπονήθηκε στο εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Ηλεκτρονικών Υπολογιστών. Σκοπός της παρούσας εργασίας είναι η μελέτη και η κατασκευή κυκλώματος τριφασικού αντιστροφέα ισχύος για να επιτύχουμε οδήγηση και έλεγχο κινητήρα τύπου DC Brushless. Ο κινητήρας αυτού του τύπου είναι Σύγχρονος κινητήρας Μόνιμου Μαγνήτη. Για το λόγο αυτό το πρώτο πράγμα που μελετήθηκε στην παρούσα εργασία είναι κάποιες θεμελιώδεις ιδιότητες του μαγνητικού πεδίου, καθώς και τα χαρακτηριστικά των μαγνητικών υλικών που χρησιμοποιούνται σε τέτοιους τύπους κινητήρων. Στην συνέχεια αναλύονται οι κινητήρων Brushless DC ως προς την κατασκευή τους καθώς και τη λειτουργία τους. Παρατίθενται οι εξισώσεις που περιγράφουν τη λειτουργία τους και οι χαρακτηριστικές ροπής-ταχύτητας και επιπλέον γίνεται σύγκριση αυτών με κινητήρες άλλων τύπων. Ακολουθεί η περιγραφή της προσομοίωσης του συστήματος η οποία πραγματοποιήθηκε στο πρόγραμμα προσομοίωσης ηλεκτρικών κυκλωμάτων Simulink του Matlab. Αναλύεται η λογική στην οποία βασιστήκαμε για την προσομοίωση και παρατίθενται οι κυματομορφές της τάσης και του ρεύματος σε διάφορα σημεία του κυκλώματος. Έπειτα γίνεται μια θεωρητική ανάλυση του κυκλώματος του αντιστροφέα που κατασκευάστηκε καθώς και όλων των άλλων κυκλωμάτων και στοιχείων που απαιτήθηκαν για τη λειτουργία της διάταξης. Επιπλέον περιγράφεται η μέθοδος παλμοδότησης που χρησιμοποιήθηκε για την έναυση/σβέση των διακοπτικών στοιχείων ισχύος. Τέλος γίνεται αναλυτική παράθεση του τελικού κυκλώματος που κατασκευάστηκε. Προχωράμε με την περιγραφή των ιδιοτήτων και δυνατοτήτων του μικροελεγκτή που χρησιμοποιήθηκε στην πλακέτα μας, καθώς επίσης και με τη λογική που ακολουθήθηκε κατά τον προγραμματισμό του. Τέλος παραθέτονται τα αποτελέσματα των πειραμάτων και τα παλμογραφήματα που ελήφθησαν κατά τη διεξαγωγή τους. Γίνεται σχολιασμός των αποτελεσμάτων αυτών και αξιολόγηση της κατασκευής. / This thesis is focused in the study and development of a Drive System for a DC Brushless motor. This work was conducted in the Laboratory of Electromechanical Energy Conversion, at the department of Electrical and Computer Engineering, in the University of Patras, Greece. DC Brushless motors, have been used in the last years they are used in a number of applications. They combine all the benefits of a DC motor, such as their operation simplicity and their linear characteristics, avoiding the brushes and the necessary excitation of DC motors, making them a suitable choice for low and medium power applications. The main purpose of this project is the Study and Construction of a Three-Phase Voltage Source Inverter for the control of the performance of a DC Brushless Motor by the implementation of a Scalar control. This thesis began with the simulation of the motor, since it is necessary for the understanding of its dynamic behavior. Then an analysis on the design and construction of the required circuit boards is done. Finally the used microcontroller (dsPIC family) was studied thoroughly, before writing the necessary code(C & assembly) for open and closed loop control. Finally, measurements were taken for the open loop control system. Conclusions were made as far as the behavior of the motor and ways to optimize the control were discussed.

Algumas técnicas foram criadas com o objetivo de reduzir o consumo de potência, dentre elas o uso de Mútiplas Tensões de Alimentação ajustadas de Forma Dinâmica(Multiple Dynamic Supply Voltage - MDSV). Essa técnica visa reduzir o consumo dinâmico utilizando pelo menos três tensões de alimentação diferentes dentro do chip. Para isso, é necessário que circuitos especiais de proteção sejam adicionados ao chip. Os conversores de tensão tem como objetivo aumentar ou diminuir o nível de tensão do sinal de entrada. O custo de introduzir os conversores de tensão, em circuitos que utilizam a técnica MDSV, é alto. Uma vez que isso causa aumento da área total e altera a temporização do chip. Com base nisso, esse trabalho propõem adicionar um caminho alternativo para a corrente, desviando e desligando os conversores de tensão enquanto eles não são necessários. Cabe salientar que alguns conversores de tensão ficam sem utilidade por causa da característica dinâmica dos circuitos contruídos usando MDSV. Com isso, neste trabalho é proposta uma nova construção para os conversores de tensão utilizados em conjunto com o MDSV. Nas simulações elétricas, os circuitos contendo essa nova construção apresentaram redução no tempo de propagação de até 13%, em comparação aos circuitos tradicionalmente utilizados para conversão de tensão. Além da redução no tempo de atraso, foram alcançadas reduções no consumo de potência na ordem de 14%. / Some techniques have been created with the purpose of reducing power consumption, among them the Multiple Dynamic Supply Voltage (MDSV). This technique aims to reduce the dynamic consumption using at least three different supply voltages inside the chip. Therefore, it is necessary that special protection circuits to be added to the chip. Level shifter aims to increase or decrease the voltage level of the input signal. The cost of introducing the voltage converters in circuits using the MDSV technique is high. As this causes increased total area and changes the timing of the chip. Based on this, this paper proposes to add an alternate path for current, deflecting off and the voltage converters as they are not required. It should be noted that some voltage converters are useless because of the dynamic characteristic of contruidos circuits using MDSV. Thus, this work proposes a new construction for the voltage converters used in conjunction with MDSV. In electric simulations, the circuit containing this new construction decreased to 13% in the propagation time in comparison to the circuits traditionally used for voltage conversion. In addition to reducing the delay time, reductions were achieved in the power consumption on the order of 14%.

Two-dimensional numerical simulation was used to study the scaling properties of SOI p-MOSFETs. Based on the design criteria for the threshold voltage and DIBL, a set of design curves for different designs was developed. Data for subthreshold slope, SCE and threshold voltage sensitivity to silicon film thickness are also given. Results show that short-channel effects can be controlled by increasing the doping level or by thinning the silicon film thickness. The first approach is more effective for p+ gate design with high body doping, while the second approach is much more effective for n+ gate design with low body doping. Then+ gate design is more suited for the design of fully depleted (FD) devices since we need to keep the doping low to minimize the threshold adjustment implant dose and to use thin silicon films to control the SCE. The design of both p-MOSFET and Si 1-xGex p-MOSFET requires the implantation for the threshold voltage adjustment. The p+ gate design is more suited for the partially depleted (PD) or near-fully depleted device design since we need to use high doping for the threshold voltage adjustment and this results in large threshold voltage sensitivity to silicon film thickness for FD devices. The design of Si SOI p-MOSFET is done by properly adjusting the body doping. For the Si1-xGex SOI p-MOSFET large reduction in VTH requires large body doping. This increases the parasitic capacitances and slows down the device.

With increasing demand for complex and faster circuits, CMOS technologies are progressing towards the deep-submicron level. Process complexity increases dramatically, and costly techniques are to be developed to create dense field isolation and shallow junctions. Silicon-On-Insulator (SOI) may solve some of these problems. On the other hand, strained Si 1_xGex layers have been successfully grown on Si substrates and demonstrated much higher hole mobility than bulk Si. This can be used to build high-mobility p-MOSFET with a buried Si 1_xGex channel. A high mobility p-MOSFET would improve both the circuit speed and the level of integration. The purpose of the present study was to model and simulate the effective mobility (μeff) of SOI Si 1-xGex p-MOSFET, and to investigate the suitability of local mobility models provided by simulator MEDICI for studying SOI Si 1_xGex p-MOSFET. The simulation is performed by using the two-dimensional device simulation program (MEDICI). The design parameters, such as Si-cap thickness, Ge profile and back-gate bias, were also investigated. A long channel (6μ) and a short channel (0.25μ) SOI and bulk Si 1_xGex p MOSFET were used for the study. Simulation reveals good effective mobility μeff match with experimental results if Si Ge channel of p-MOSFET can simply be treated like a bulk silicon with mobility 250cm2 /Vs. Mobility models provided by MEDICI are two types: a) mobility model (SRFMOB2) that is dependent on transverse electric field only at Si/ Si02 interface, which means that the effective mobility is a function of grid spacing at Si/ Si02 interface, and b) mobility models (PRPMOB, LSMMOB and HPMOB) that are dependent on transverse electric field anywhere in the device. PRPMOB and LSMMOB produce very good μef f and are insensitive to the grid spacing. HP MOB gives slight over estimation of effective mobility μef f. Silicon cap thickness can significantly influence the effective mobility μef f. In general, the thin silicon cap have better effective mobility μef f, but it is limited by manufacturing process. Graded Si 1_:z:Ge:z: channel presents nearly 100% improvement of effective mobility μeff for p-MOSFET over its bulk counterpart. This improvement is sustained up to gate voltage of 2.5 V. Simulation also indicates that large improvement of effective mobility μef f requires higher Ge concentration at the top of SiGe channel with steep grading. The influence of back-gate bias on μeff is small, hence, SOI SiGe MOSFET is well suited to building CMOS circuits.

A measurement system is to be presented, which is used to obtain the I-V characteristics of a solar cell and to track its temperature during irra-diation before mounting it into a complete array/module. This project presents both the design and implementation of an Electronic load for testing the solar cell under field conditions of 10000 W/m^2, which is able to provide current versus voltage and power versus voltage charac-teristics of a solar cell using a software based model developed in Lab-VIEW. An efficient water cooling method which includes a heat pipe array system is also suggested. This thesis presents the maximum power tracking of a solar cell and the corresponding voltage and current values. In addition, the design of the clamp system provides an easy means of replacing the solar cell during testing.Keywords: Solar cell, Metal Oxide Semiconductor Field Effect Transistor (MOSFET), I-V characteristics, cooling system, solar cell clamp system, LabVIEW, Graphical User Interface (GUI).

<p>Traditional dosimetric devices are inherently point dose dosimeters (PDDs) and can only measure the magnitude of the radiation exposure; hence, they are one-dimensional (1D). To measure the magnitude and spatial location of dose within a volume either several PDDs must be used at one time, or one PDD must be translated from point-to-point. Using PDDs for spatially distributed, two-dimensional (2D), dosimetry is laborious, time consuming, limited in spatial resolution, susceptible to positioning errors, and the currently accepted approach to measuring dose distribution in 2D. This work seeks to expand the current limits of indirectly ionizing radiation dosimetry by using radiochromic film (RCF) for a high-resolution, accurate dosimetry system. Using RCF will extend the current field of radiation dosimetry to spatially quantitative 2D and three-dimensional (3D) measurements. </p> <p>This work was generalized into two aims. The first aim was the development of the RCF dosimetry system; it was accomplished by characterizing the film and the readout devices and developing a method to calibrate film response for absolute dose measurements. The second aim was to apply the RCF dosimetry system to three areas of dosimetry that were inherently volumetric and could benefit from multiple dimensional (2D or 3D) dose analysis. These areas were representative of a broad range of radiation energy levels and were: low-mammography, intermediate-computed tomography (CT), and high-radiobiologcal small animal irradiation and cancer patient treatment verification. The application of a single dosimeter over a broad range of energy levels is currently unavailable for most traditional dosimeters, and thus, was used to demonstrate the robustness and flexibility of the RCF dosimetry system.</p> <p>Two types of RCF were characterized for this work: EBT and XRQA film. Both films were investigated for: radiation interaction with film structure; light interaction with film structure for optimal film readout (densitometry) sensitivity; range of absorbed dose measurements; dependence of film dose measurement response as a function of changing radiation energy; fractionation and dose rate effects on film measurement response; film response sensitivity to ambient factors; and stability of measured film response with time. EBT film was shown to have the following properties: near water equivalent atomic weight (Z_eff); dynamic dose range of (10<super>-1</super>-10<super>2</super>) Gy; 3% change in optical density (OD) response for a single exposure level when exposed to radiation energies from (75-18,000) kV; and best digitized using transmission densitometry. XRQA film was shown to have: a Zeff of ~25; a 12 fold increase in sensitivity at lower photon energies for a dynamic dose range of 10-3-100 Gy, a difference of 25% in OD response when comparing 120 kV to 320 kV, and best digitized using reflective densitometry. Both XRQA and EBT films were shown to have: a temporal stability (&#916;OD) of ~1% for t > 24 hr post film exposure for up to ~20 days; a change in dose response of ~0.03 mGy hr-1 when exposed to fluorescent room lighting at standard room temperature and humidity levels; a negligible dose rate and fractionation effect when operated within the optimal dose ranges; and a light wavelength dependence with dose for film readout.</p> <p>The flat bed scanner was chosen as the primary film digitizer due to its availability, cost, OD range, functionality (transmission and reflection scanning), and digitization speed. As a cost verses functionality comparison, the intrinsic and operational limitations were determined for two flat bed scanners. The EPSON V700 and 10000XL exhibited equal spatial and OD accuracy. The combined precision of both the scanner light sources and CCD sensors measured < 2% and < 7% deviation in pixel light intensities for 50 consecutive scans, respectively. Both scanner light sources were shown to be uniform in transmission and reflection scan modes along the center axis of light source translation. Additionally, RCFs demonstrated a larger dynamic range in pixel light intensities, and to be less sensitive to off axis light inhomogeneity, when scanned in landscape mode (long axis of film parallel with axis of light source translation). The EPSON 10000XL demonstrated slightly better light source/CCD temporal stability and provided a capacity to scan larger film formats at the center of the scanner in landscape mode. However, the EPSON V700 only measured an overall difference in accuracy and precision by 2%, and though smaller in size, at the time of this work, was one sixth the cost of the 10000XL. A scan protocol was developed to maximize RCF digitization accuracy and precision, and a calibration fitting function was developed for RCF absolute dosimetry. The fitting function demonstrated a superior goodness of fit for both RCF types over a large range of absorbed dose levels as compared to the currently accepted function found in literature.</p> <p>The RCF dosimetry system was applied to three novel areas from which a benefit could be derived for 2D or 3D dosimetric information. The first area was for a 3D dosimetry of a pendant breast in 3D-CT mammography. The novel method of developing a volumetric image of the breast from a CT acquisition technique was empirically measured for its dosimetry and compared to standard dual field digital mammography. The second area was dose reduction in CT for pediatric and adult scan protocols. In this application, novel methodologies were developed to measure 3D organ dosimetry and characterize a dose reduction scan protocol for pediatric and adult body habitus. The third area was in the field of small animal irradiation for radiobiology purposes and cancer patient treatment verification. Two methods for small animal irradiation were analyzed for their dosimetry. The first technique was within a gamma irradiator environment using a <super>137</super>Cs source (663 keV), and the second, a novel approach to mouse irradiation, was developed for fast neutron (10 MeV) irradiated by a Tandem Van de Graff accelerator in a <super>2</super>H(d,n)<super>3</super>He reaction. For the patient cancer treatment, RCF was used to verify a 3D radiochromic plastic, PRESAGETM, using multi-leaf collimation (MLC) on a medical linear accelerator (LINAC) with 6 MV x-rays. The RCF and PRESAGE<super>TM</super> dosimeters were employed to verify a simple respiratory-gated lung treatment for a small nodule; the film was considered the gold standard. In every case, the RCF dosimetry system was verified for accuracy using a traditional PDD as the golden standard. When considering all areas of radiation energy applications, the RCF dosimetry system agreed to better than 7% of the golden standard, and in some cases within better than 1%. In many instances, this work provided vital dosimetric information that otherwise was not captured using the PDD in similar geometry. This work demonstrates the need for RCF to more accurately measure volumetric dose.</p> / Dissertation