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

Thesis (M.S.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M. S.)--Florida State University, 2005. / Advisor: Dr. Mark H. Weatherspoon, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Sept. 19, 2005). Document formatted into pages; contains viii, 70 pages. Includes bibliographical references.

Thesis (M.S.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 191-206).

Au cours des dernières années le silicium est apparu comme un matériau hôte prometteur pour les qubits de spin. Grâce à la microélectronique moderne, la technologie du silicium a connu un formidable développement. Réaliser des qubits utilisant la technologie bien établie de fabrication CMOS de semi-conducteurs favoriserait clairement leur intégration à grande échelle.Dans cette thèse nous présentons les travaux effectués dans une perspective des qubits CMOS. En particulier, nous avons abordé les problèmes de confinement des charges et des spins dans les boîtes quantiques, la manipulation des spins et la lecture des charges et des spins.Nous avons exploré les différentes propriétés de confinement de charge et de spin dans des échantillons de tailles et de géométries différentes. Les MOSFETs de taille extrêmement réduites montrent du blocage de Coulomb jusqu'à température ambiante, avec des énergies de charges jusqu'à 200meV. Les dispositifs multi-grilles avec des dimensions géométriques plus grandes ont été utilisés pour confiner les spins et lire leur état par blocage de spin, en réalisant ainsi une conversion spin / charge.La manipulation des spins est réalisée au moyen d'un dipôle électronique induisant la résonance de spin (EDSR). Les deux plus basses vallées de la bande de conduction du silicium sont visibles sous forme de transitions de spin intra et inter-vallées. Nous observons une levée de dégénérescence de vallée d'amplitude 36μeV. La résonance de spin que l'on observe résulte de la géométrie spécifique de l'échantillon, de la physique des vallées et de l'interaction spin-orbite de type Rashba. Des signatures de manipulation cohérente, sous forme d'oscillations de Rabi, ont été mesurées, avec une fréquence de Rabi de 6MHz. Nous discutons également de la lecture rapide des charges et des spins effectuée par réflectométrie dispersive couplée à la grille. Nous montrons comment l'utiliser pour reconstruire le diagramme de stabilité de charge du dispositif et le signal attendu pour un système à double boîte isolé. La tension de polarisation finie modifie la réponse du système et nous l'avons utilisée pour sonder les états excités et leur dynamique. / In the recent years, silicon has emerged as a promising host material for spin qubits. Thanks to its widespread use in modern microelectronics, silicon technology has seen a tremendous development. Realizing qubit devices using well-established complementary metal-oxide-semiconductor (CMOS) fabrication technology would clearly favor their large scale integration.In this thesis we present a detailed study on CMOS devices in a perspective of qubit operability.In particular we tackled the problems of charge and spin confinement in quantum dots, spin manipulation and charge and spin readout.We explored the different charge and spin confinement capabilities of samples with different sizes and geometries. Ultrascaled MOSFETs show Coulomb blockade up to room temperature with charging energies up to 200meV. Multigate devices with larger geometrical dimensions have been used to confine spins and read their states through spin-blockade as a way to perform spin to charge conversion.Spin manipulation is achieved by means of Electron Dipole induced Spin Resonance (EDSR). The two lowest valleys of silicon's conduction band originate as intra and inter-valley spin transitions; we probe a valley splitting of 36μeV. The origin of this spin resonance is explained as an effect of the specific geometry of the sample combined with valley physics and Rashba spin-orbit interaction. Signatures of coherent Rabi oscillations have been measured, with a Rabi frequency of 6MHz. We also discuss fast charge and spin readout performed by dispersive gate-coupled reflectometry. We show how to use it to recover the complete charge stability diagram of the device and the expected signal for an isolated double dot system. Finite bias changes the response of the system and we used it to probe excited states and their dynamics.

Investigations performed in order to understand the electronic and optoelectronic properties of field effect transistors based on few layers of 2D Copper Indium Selenide (CuIn7Se11) are reported. In general, field effect transistors (FETs), electric double layer field effect transistors (EDL-FETs), and photodetectors are crucial part of several electronics based applications such as tele-communication, bio-sensing, and opto-electronic industry. After the discovery of graphene, several 2D semiconductor materials like TMDs (MoS2, WS2, and MoSe2 etc.), group III-VI materials (InSe, GaSe, and SnS2 etc.) are being studied rigorously in order to develop them as components in next generation FETs. Traditionally, thin films of ternary system of Copper Indium Selenide have been extensively studied and used in optoelectronics industry as photoactive component in solar cells. Thus, it is expected that atomically thin 2D layered structure of Copper Indium Selenide can have optical properties that could potentially be more advantageous than its thin film counterpart and could find use for developing next generation nano devices with utility in opto/nano electronics. Field effect transistors were fabricated using few-layers of CuIn7Se11 flakes, which were mechanically exfoliated from bulk crystals grown using chemical vapor transport technique. Our FET transport characterization measurements indicate n-type behavior with electron field effect mobility µFE ≈ 36 cm^2 V^-1 s^-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. We found that in such back gated field effect transistor an on/off ratio of ~ 10^4 and a subthreshold swing ≈ 1 V/dec can be obtained. Our investigations further indicate that Electronic performance of these materials can be increased significantly when gated from top using an ionic liquid electrolyte [1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)]. We found that electron field effect mobility µFE can be increased from ~ 3 cm^2 V^-1 s^-1 in SiO2 back gated device to ~ 18 cm^2 V^-1 s^-1 in top gated electrolyte devices. Similarly, subthreshold swing can be improved from ~ 30 V/dec to 0.2 V/dec and on/off ratio can be increased from 10^2 to 10^3 by using an electrolyte as a top gate. These FETs were also tested as phototransistors. Our photo-response characterization indicate photo-responsivity ~ 32 A/W with external quantum efficiency exceeding 10^3 % when excited with a 658 nm wavelength laser at room temperature. Our phototransistor also exhibit response times ~ tens of µs with specific detectivity (D*) values reaching ~ 10^12 Jones. The CuIn7Se11 phototransistor properties can be further tuned & enhanced by applying a back gate voltage along with increased source drain bias. For example, photo-responsivity can gain substantial improvement up to ~ 320 A/W upon application of a gate voltage (Vg = 30 V) and/or increased source-drain bias. The photo-responsivity exhibited by these photo detectors are at least an order of magnitude better than commercially available conventional Si based photo detectors coupled with response times that are orders of magnitude better than several other family of layered materials investigated so far. Further photocurrent generation mechanisms, effect of traps is discussed in detail.

Les transistors organiques attirent actuellement beaucoup d'attention en raison des avantages uniques par rapport à leur homologue inorganique. En revanche, la compréhension physique du fonctionnement et du transport des porteurs de charge est très limitée. L'objectif de cette thèse est de contribuer à apporter une meilleure compréhension des transistors organiques. Le Chapitre 1 présente les semi-conducteurs organiques : le mécanisme de conduction, les paramètres essentiels, les matériaux typiques etc. Le Chapitre 2 discute des transistors organi-ques en termes de structures, de mécanismes de fonctionnement, de paramètres principaux et des procédés de fabrication. Le Chapitre 3 étudie la caractérisation statique. Après les méthodes classiques, la méthode de la fonc-tion Y est introduite. Subséquemment, des techniques pour extraire les paramètres principaux sont présentées sé-parément. Enfin, les résultats expérimentaux sur nos échantillons sont exposés. Sur la base des données mesurées, les travaux de modélisation sont présentés dans le chapitre 4. Premièrement, une solution de l'équation Poisson est introduite qui donne la distribution de potentiel et donc la distribution de porteurs dans le film organique. Avec la prise en compte des pièges, les résultats obtenus par simulation sont en bon accord avec les données expérimen-tales. A partir de mesures des caractéristiques de courant –tension effectuées à basse température, on propose une procédure d'analyse de la mobilité en utilisant l'intégrale de Kubo-Greenwood. Ensuite, prenant en compte la dis-tribution de porteurs dans le film organique, une solution de l'équation de Poisson est donnée et la mobilité effec-tive est calculée en fonction de la tension de grille et de la température. Le Chapitre 5 est consacré à l'analyse du bruit à basse fréquence. On étudie d'abord le bruit du canal où une domination du bruit provenant des contacts est observée. En conséquence, une méthode TLM pour l'extraction du bruit des contacts est présentée. Ensuite, un procédure d'analyse des sources de bruit dû au contact est aussi proposée. Les résultats de bruit obtenus sur des transistors organiques de différentes origines sont également discutés à la fin. / Organic transistors recently attract much attention because of their unique advantages over the conventional inorganic counterparts. However, the understanding of their operating mechanism and the carrier transport process are still very limited, this thesis is devoted to such a subject. Chapter 1 presents the organic semiconductors regarding carrier transport, parameters, typically applied materials. Chapter 2 describes the issues related to organic transistors: structure, operating mechanism, principal parameters and fabrication technologies. Chapter 3 deals with the static properties characterization. The commonly used methods are firstly presented and then the Y function method is introduced. Afterwards, the characterization methods for principles parameters are separately discussed. The experimental results on our organic transistors are finally described. Chapter 4 focuses on the mod-eling on the basis of the experimental data, regarding DC characteristics modeling with a solution for Poisson's equation, carrier mobility modeling with using Kubo-Greenwood integral as well as a theoretical analysis of OFETs' carrier mobility involving a solution of Poisson's equation. Chapter 5 analyzes the low-frequency noise in organic transistors. One firstly addresses the channel noise sources and then concentrates on the contact noise extraction and contact noise sources diagnosis. The noise measurements on other samples are also presented.

O transistor de efeito de campo de porta estendida e separada (SEGFET) é um dispositivo alternativo ao tradicional transistor de efeito de campo seletivo a íons (ISFET). A grande vantagem desse dispositivo se refere ao seu fácil processamento, ou seja, se restringe somente a manipulação do eletrodo de porta, evitando processos convencionais de microeletrônica. Neste sentido, sensores iônicos e biossensores podem ser facilmente implementados combinando materiais de reconhecimento químico e/ou biológico. Por sua vez, a técnica de fabricação de filmes finos camada por camada (layer-by-layer, LbL) se mostra versátil para manipulação de diversos tipos de materiais em nível molecular. Materiais orgânicos e inorgânicos podem ser automontados em substratos sólidos por meio da simples adsorção eletrostática formando compósitos com propriedades únicas com o objetivo de serem aplicados em sensores ou biossensores. Neste trabalho, o conceito de dispositivo SEGFET foi combinado com a técnica LbL por meio da manipulação de materiais orgânicos (polieletrólitos, dendrímeros e polianilina) e inorgânicos (TiO2 e V2O5) nanoparticulados a fim de se obter novos sensores de pH e biossensores para a detecção de glicose e uréia, dois importantes analitos de interesse clínico. Numa primeira etapa, diferentes filmes LbL foram produzidos, caracterizados e testados como camada sensível (porta estendida) em dispositivos SEGFETs. Todos os sistemas estudados se mostraram promissores como sensores de pH, ou seja, com uma sensibilidade próxima do valor teórico sugerido pela equação de Nernst (59,15 mV.pH-1). Esses resultados podem ser atribuídos à natureza anfotérica do material da última camada no filme LbL. Numa segunda etapa, as enzima glicose oxidase (GOx) e urease foram convenientemente imobilizadas nos filmes LbL. Pelo fato dessas enzimas gerarem ou consumirem prótons durante a catálise da reação, os filmes LbL modificados enzimaticamente foram utilizados em biossensores de glicose e uréia, apresentando eficiente detecção. Assim, a união de dispositivos SEGFET com a técnica de automontagem se mostrou promissora para construção de sensores e biossensores eficientes e de baixo custo. / Separative extended gate field-effect transistor (SEGFET) device is an alternative to the conventional ion-sensitive field-effect transistor (ISFET). The great advantage of SEGFET refers to its easy processing, i.e., it is limited under only manipulation of the gate electrode, avoiding the conventional microelectronic processes. In this way, ion sensors and biosensors can be easily implemented combining chemical and/or biological recognition materials. In turn, the layer-by-layer (LbL) technique shows be versatile for handling various types of materials at molecular level. In this thesis, the concept of SEGFET device was combined with the LbL technique through the manipulation of organic (polyelectrolytes, dendrimers and poly (aniline)) and inorganic materials (TiO2 and V2O5 nanoparticles) in order to get new pH sensors and biosensors for the detection of glucose and urea, two important analytes of clinical interest. In a first step, different LbL films were produced, characterized and tested as the sensitive layer (extended gate) in SEGFETs devices. All studied systems were promissing as pH sensors, i.e., with a sensitivity close to the theoretical value suggested by Nernst equation (59.15 mV.pH-1). These results can be attributed to the amphoteric nature of the material in the last layer of the LbL films. In a second step, glucose oxidase (GOx) and urease enzymes were conveniently immobilized onto LbL films. Because these enzymes generate or consume protons during catalysis of the reaction, the enzymatically modified LbL films were used in biosensors for glucose and urea, with efficient detection. Thus, the union of SEGFET devices with the LbL technique is promising to building up efficient and low-cost sensors and biosensors.

Orientadores: Peter Jurgen Tatsch, Jose Alexandre Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-13T19:29:46Z (GMT). No. of bitstreams: 1 Souza_JairFernandesde_M.pdf: 4396662 bytes, checksum: cf77f050e25403e0bd758bdb52214aa2 (MD5) Previous issue date: 2009 / Resumo: Esta dissertação consiste de duas etapas. Inicialmente são estudados filmes de nitreto de silício depositados por LPCVD, Low Pressure Chemical Vapor Deposition, utilizando-se diferentes relações de concentração de gases reagentes, [SiH2Cl2]/[NH3], e utilizando-se como substrato lâminas de silício tipo p, com e sem camada almofada de oxinitreto de silício; estruturas SiNx/Si e SiNx/SiOxNy/Si, respectivamente. Os filmes foram caracterizados física e eletricamente, bem como do ponto de vista da capacidade de adsorção de monocamadas biologicamente ativas. As características dos filmes foram comparadas, buscando-se identificar um filme cujas propriedades fossem adequadas para utilização como material dielétrico a ser empregado na porta de Transistores de Efeito de Campo química e bioquimicamente sensíveis. Os resultados da elipsometria realizada apontaram filmes com índices de refração variando de 1,875 a 1,990, indicando filmes ricos em nitrogênio, e com espessura diretamente proporcional à relação de concentração dos gases reagentes, ou seja, o aumento na relação de concentração de gases produz aumento na taxa de deposição dos filmes. A espectroscopia de absorção de infra-vermelho permitiu analisar as ligações químicas presentes nos filmes e nas monocamadas automontadas formadas pela imobilização de biomoléculas. Os espectros dos filmes apresentam picos de absorção em 827/837 cm-1 e 451/484 cm-1 que correspondem a ligações Si-N, confirmando a indicação da elipsometria referente à presença de nitrogênio. Após a formação das camadas automontadas, compostas de proteínas do tipo Imunoglobulina, IgG 2,5 e 5%, os espectros mostraram bandas de absorção de IR em torno de 3300 cm-1 e nas faixas de 1700 a 1600 cm-1 e 1600 a 1500 cm-1. Este espectro caracteriza a formação de grupos amida A, I e II, respectivamente, ou seja, a formação das monocamadas biologicamente ativas. Através de espectroscopia micro-Raman foram detectados deslocamentos nos picos principais do substrato de silício. Tais deslocamentos foram relacionados com o stress provocado pelos filmes depositados. Foram fabricados capacitores Metal/Isolante/Semicondutor, MIS, utilizando-se as estruturas dielétrico/semicondutor obtidas. Os capacitores possibilitaram realizar a caracterização elétrica dos filmes através de medidas C-V, capacitância-voltagem, de alta frequência de 1MHz, obtendo-se a densidade de cargas existente na interface dielétrico/semicondutor, em torno de 1011cm-2, e permitiram observar o comportamento da interface com a realização de etapas térmicas e a degradação em suas propriedades de recombinação. Após a fabricação e a caracterização das camadas dielétricas, foi iniciada a segunda etapa do trabalho com a fabricação de matrizes de Transistores de Efeito de Campo, FETs. Foi usado como dielétrico de porta os filmes da etapa anterior que apresentaram melhor desempenho do ponto de vista físico, elétrico, químico e biológico. A caracterização elétrica dos FETs foi realizada utilizando-se dispositivos de controle dispostos isoladamente nas pastilhas. Foram obtidas as características elétricas dos dispositivos e observado seu comportamento nas etapas térmicas. A sensibilidade química foi verificada aplicando-se analitos com diferentes concentrações de íons H+ , correspondente a diferentes valores de pH, na região de porta dos FETs. Foi demonstrada a viabilidade da utilização dos FETs fabricados na detecção química/bioquímica, com possibilidade de emprego em atividades de diagnóstico médico, controle ambiental, controle da produção de fármacos e cosméticos, e aplicações agropecuárias / Abstract: This dissertation consists of two stages. Initially are studied Silicon Nitride films deposited by LPCVD (Low Pressure Chemical Vapor Deposition) using different relationship of reagent gases concentration ([SiH2Cl2] / [NH3]) and using as substratum Silicon wafers p-type with and without pad layer of Silicon Oxinitride - SiNx/Si and SiNx/SiOxNy /Si structures. The films were characterized physically and electrically as well as the point of view of adsorption capacity of biologically active monolayer. The films characteristics were compared, seeking to identify a film whose characteristics are adequate to be used as dielectric material applied at the project and fabrication of chemically and biochemically sensitive Field Effect Transistors - FETs. Ellipsometry results pointed films with refraction indexes ranging from 1,875 to 1,990, it indicating films rich in Nitrogen, and with thickness directly proportional to the relationship of reagent gases concentration. In the other words, the increase of the relationship of gases concentration produces an increase of the films deposition rates. The infra-red absorption spectroscopy allowed us to analyze the chemical bonds present in the dielectric films and in the self assembled monolayers formed by the immobilization of biological molecules. The films spectrum have absorption spike in 827/837 cm-I and 451/484 cm-I that correspond to Si-N bonds, confirming the indication of the ellipsometry regarding as nitrogen presence. After self assembled monolayers formation composed by proteins of the type Immunoglobulin - IgG 2.5 and 5%, the spectra showed absorption bands of IR, around 3300 cm-1 and in the ranges of 1700 to 1600 cm-1 and 1600 to 1500 cm-1, spectrum that characterizes the formation of amida groups A, I and II, respectively, in other words, the formation of biologically active monolayers. Through micro-Raman spectrometry were detected displacements in the main spikes of the Silicon substratum. This displacement has been related with the stress induced by the deposited films. It was manufactured Metal Insulating Semiconductor (MIS) capacitors, using the structures dielectric/semiconductor obtained. The capacitors made possible to accomplish the electric characterization of the films through high frequency (1 MHz) capacitance-voltage (C-V) measurements, obtained the density of charges existent on the interface dielectric/semiconductor - around 1011 cm-2; and to observe the behavior of the interface with the accomplishment of thermal stages and the degradation in its recombination properties. After production and characterization of the dielectric layers, has been accomplished the second stage of the work with the production of FETs, being used as dielectric gate the films that presented better performance of the point of view physical, electric, chemical and biological. The electric characterization of the FETs that compose the arrays, has been accomplished being used the control devices disposed separately in the dies allowing to raise the characteristics of the devices construction, as well as, the behavior of the same ones when submitted to thermal stages. The chemical sensibility was verified being applied analytes with different H+ ions concentrations - different pH values - in the gate area of the FETs that compose the arrays. The viability of use of the modified FETs for chemistry/biochemistry detection was demonstrated, with employment possibility in activities of medical diagnosis, environmental control, control of the production of drugs and cosmetics and agricultural applications. / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica