Carbon based semiconductors such as conjugated polymer or single walled carbon nanotubes (SWNT) are promising materials for use next generation printable and wearable electronics. Thin film transistors (TFTs) are often viewed as a building block for more complex electronic device, however, lack of proper characterization of these devices using these novel carbon-based materials is preventing their large-scale adoption. This thesis has two sections; in the first section I explored and improved a novel electrical model originally developed for organic or polymer-based TFTs called the organic virtual source emission diffusion model (OVSED). I improved this model by adding a variable contact resistance parameter and effective gate voltages. I then found better agreement between model and experimental data using this improved OVSED model against the conventional MOSFET based models: the SH and Y-function models, for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)) based OTFTs. The new model proved to be an efficient tool for benchmarking polymer based TFTs and provided an efficient way to characterize and reduce contact resistance in the devices. In the second section, I explore the effect of light on a series of conjugated polymer wrapped SWNT TFTs. A structure property relationship was established between the wrapping polymer structure and the exposure wavelength intensity. We demonstrated that SWNT TFTs can act as photodetectors after an initial light soak. Finally, we further characterized the SWNT TFTs using our OVSED model validating the observed structure property relationship. Overall this thesis demonstrates steps towards proper characterization of emerging carbon based semiconductors used in TFTs. -- Les semi-conducteurs à base de carbone, tels que les polymères conjugués ou les nanotubes de carbone à paroi simple (SWNT), sont des matériaux prometteurs pour la prochaine génération d'appareils électroniques imprimables et portables. Les transistors à couche mince (TFT) sont souvent considérés comme un élément de base pour des dispositifs électroniques plus complexes, mais la caractérisation incorrecte de ces dispositifs utilisant ces nouveaux matériaux à base de carbone empêche leur adoption à grande échelle. Cette thèse comporte deux sections ; dans la première, j'ai exploré et amélioré un nouveau modèle électrique développé à l'origine pour les TFT organiques ou à base de polymères, appelé le modèle de diffusion d'émission de source virtuelle organique (OVSED). J'ai amélioré ce modèle en ajoutant un paramètre de résistance de contact variable et des tensions de grille effectives. J'ai ensuite constaté une meilleure concordance entre le modèle et les données expérimentales en utilisant ce modèle OVSED amélioré par rapport aux modèles conventionnels basés sur les MOSFET : les modèles à fonction SH et Y, pour les OTFT à base de poly{[N,N'-bis(2-octyldodecyl)-naphtalène-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophène)} (P(NDI2OD-T2)). Le nouveau modèle s'est avéré être un outil efficace pour comparer les TFT à base de polymères et a fourni un moyen efficace de caractériser et de réduire la résistance de contact dans les dispositifs. Dans la deuxième partie, j'explore l'effet de la lumière sur une série de TFT à base de SWNT enveloppés de polymères conjugués. Une relation structure-propriété a été établie entre la structure du polymère enveloppant et l'intensité de la longueur d'onde d'exposition. Nous avons démontré que les SWNT TFT peuvent agir comme des photodétecteurs après une imprégnation initiale de lumière. Enfin, nous avons caractérisé les SWNT TFT à l'aide de notre modèle OVSED en validant la relation structure-propriété observée. Dans l'ensemble, cette thèse démontre les étapes vers une caractérisation appropriée des semi-conducteurs émergents à base de carbone utilisés dans les TFT.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23723号 / 理博第4813号 / 新制||理||1689(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Since conformation changes of proteins and biomolecular interactions (including protein-DNA, or protein-protein interactions) are essential processes for biological functions, detections of these processes are important in chemistry and biochemistry to understand the reactions. For the detection of these processes, a variety of techniques have been developed. UV/vis absorption spectroscopy or emission spectroscopy are very powerful to trace the time development of reactions. However, these techniques have a limitation to detect the conformation changes of proteins and biomolecular interactions. Recently, our group discovered that the translational diffusion coefficient can be a useful and sensitive probe to detect the conformation change as well as the intermolecular interaction changes. Although many techniques, e.g., dynamic light scattering, Taylor dispersion, capillary method, NMR spectroscopy, have been developed to monitor molecular diffusion, molecular diffusion has never been considered as a time dependent property during reactions. We have been developing a method based on the pulsed-laser induced transient grating (TG) technique to detect the time-dependent diffusion. Here, we repot the time-resolved detection of protein conformation changes of a blue light sensor protein of phototropin by using the diffusion coefficient.

La problématique scientifique de cette thèse est centrée sur le développement decommunications par lumière visible (Visible Light Communications - VLC) dans lesapplications automobiles. En permettant la communication sans fil entre les véhicules, ou entreles véhicules et l’infrastructure routière, la sécurité et l'efficacité du transport peuvent êtreconsidérablement améliorées. Compte tenu des nombreux avantages de la technologie VLC,cette solution se présente comme une excellente alternative ou un complément pour lescommunications actuelles plutôt basées sur les technologies radio-fréquences traditionnelles.Pour réaliser ces travaux de recherche, un système VLC à faible coût pour applicationautomobile a été développé. Le système proposé vise à assurer une communication très robusteentre un émetteur VLC à base de LED et un récepteur VLC monté sur un véhicule. Pour l'étudedes communications véhicule à véhicule (V2V), l'émetteur a été développé sur la base d’un pharearrière rouge de voiture, tandis que pour l'étude des communications de l'infrastructure auvéhicule (I2V), l'émetteur a été développé sur la base d'un feu de circulation. Considérant lerécepteur VLC, le problème principal réside autour d’un capteur approprié, en mesured'améliorer le conditionnement du signal et de limiter les perturbations dues des conditionsenvironnementales. Ces différents points sont abordés dans la thèse, d’un point de vue simulationmais également réalisation du prototype.La validation expérimentale du système VLC a été réalisée dans différentes conditions etscénarii. Les résultats démontrent que la VLC peut être une technologie viable pour lesapplications envisagées. / The scientific problematic of this PhD is centered on the usage of Visible LightCommunications (VLC) in automotive applications. By enabling wireless communication amongvehicles and also with the traffic infrastructure, the safety and efficiency of the transportation canbe substantially increased. Considering the numerous advantages of the VLC technologyencouraged the study of its appropriateness for the envisioned automotive applications, as analternative and/or a complement for the traditional radio frequency based communications.In order to conduct this research, a low-cost VLC system for automotive application wasdeveloped. The proposed system aims to ensure a highly robust communication between a LEDbasedVLC emitter and an on-vehicle VLC receiver. For the study of vehicle to vehicle (V2V)communication, the emitter was developed based on a vehicle backlight whereas for the study ofinfrastructure to vehicle (I2V) communication, the emitter was developed based on a traffic light.Considering the VLC receiver, a central problem in this area is the design of a suitable sensorable to enhance the conditioning of the signal and to avoid disturbances due to the environmentalconditions, issues that are addressed in the thesis. The performances of a cooperative drivingsystem integrating the two components were evaluated as well.The experimental validation of the VLC system was performed in various conditions andscenarios. The results confirmed the performances of the proposed system and demonstrated thatVLC can be a viable technology for the considered applications. Furthermore, the results areencouraging towards the continuations of the work in this domain.

Single-photon avalanche diodes’ (SPADs) capabilities of detecting even a single photon with excellent timing resolution and compatibility with strong magnetic fields make them the most promising sensor for positron emission tomography imaging systems. With the advancements of silicon fabrication techniques, SPADs designed in standard planar complementary metal-oxide-semiconductor (CMOS) processes show competitive performance and a lower manufacturing cost. Additionally, CMOS SPADs have the potential for monolithic integration with other CMOS signal conditioning and processing circuits to achieve simple, low-cost, and high-performance imaging solutions. This work targets the design and optimization of SPAD sensors to improve their performance using low-cost standard CMOS technologies. Firstly, a detailed review on the SPADs in recent literature is presented. Then, the random telegraph signal (RTS) noise is investigated based on n+/p-well SPADs fabricated in a standard 130 nm CMOS process. Through the measurements and analysis, the RTS noise of a SPAD is found to correlate with its dark count rate and afterpulsing. Next, we design n+/p-well SPADs with field poly gates to improve the noise performance. Furthermore, a SPAD pixel, consisting of a p+/n-well SPAD and a compact and high-speed active quench and reset circuit is designed and fabricated in a standard TSMC 65 nm CMOS process. The post-layout simulations show that this pixel achieves a short 0.1 ns quenching time and a 3.35 ns minimum dead time. The measurement results show that the SPAD pixel has a dark count rate of 21 kHz, a peak photon detection probability of 23.8% at a 420 nm wavelength and a timing jitter of 139 ps using a 405 nm pulsed laser when the excess voltage is set to 0.5 V. Due to the short quenching time, almost no afterpulsing is observed even at a low operating temperature of -35 °C. Finally, a new differential quench and reset (QR) circuit consisting of two QR circuits on both the cathode and anode to quench and reset the SPAD through both terminals is proposed to reduce the reset time, to increase the count rate, to reduce the afterpulsing and to reject the common-mode noise. / Thesis / Doctor of Philosophy (PhD) / Positron emission tomography (PET) imaging is a powerful tool for diagnosis and assessment of cancers and tumors in the clinical field. Due to their capabilities of detecting even a single photon, excellent timing resolution, and their compatibility with magnetic fields to build PET/MRI (magnetic resonance imaging) multimodal imaging systems; single-photon avalanche diodes (SPADs) become the most promising sensor technology for PET imaging applications. SPADs fabricated in standard complementary metal-oxide-semiconductor (CMOS) technologies allow for a lower manufacturing cost and present the potential to integrate with other CMOS circuits to form a complete imaging system. In this thesis, random telegraph signal noise in SPADs is investigated first. Then, the poly gate is used in the design of an n+/p-well SPAD to improve the noise performance. In addition, a compact and high-speed SPAD pixel is designed and fabricated using an advanced standard CMOS process. Thanks to the fast quench and reset circuit, the SPAD pixel achieves a very short quenching time and a high-count rate. Finally, a differential quench and reset (QR) circuit consisting of two QR circuits on both the cathode and anode to quench and reset the SPAD through both terminals is proposed and studied.