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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nanostructured Materials for Pseudocapacitors and Single-Electron Devices

Pu, Long January 2014 (has links)
As a result of increasing demand of power in the modern society, energy storage/consumption is playing a more important role on future economics. Therefore energy storage systems which are more environmentally friendly, low-cost and high-performance have attracted much attention. Among electrochemical systems, supercapacitors are considered as a prominent candidate for the modern energy storage systems due to the high power density, high charge/discharge rate, and long lifetimes. Nevertheless, the performance of supercapacitors is limited by the significant disadvantage of low energy density. Metal oxides with high pseudocapacitance such as MnO2 are used as the electrode materials for supercapacitors to resolve the lack of energy density in supercapacitors. The specific capacitance is notably enhanced by the metal oxides because of the reversible redox reactions. Previous studies confirmed that only a thin layer of MnO2 is involved in the redox process and is electrochemically active, which makes surface area a critical factor of energy storage. To increase surface area of MnO2, ZnO nanostructure is introduced in the electrode material as a template for electrodeposition of MnO2. In the first part of the research, we synthesize a nanomaterial which combines 0-1-2 dimensional properties of different nanostructures and significantly increases the energy capacity of MnO2. iv In the second part of the research, we demonstrate an in situ synthesis of a hybrid device that combines two materials to investigate the individual characteristic of two nanomaterials. In this study, a ZnO nanorod interface on Au nanoparticle arrays is fabricated, and results in the photo-modulation of the array characteristics. We find the use of nanoparticle arrays as electrochemical systems by electrodepositing ZnO on Au nanoparticle arrays. The method expands their potential use in sensors, multifunctional materials, single electron transistors and nanoscale energy systems. Characteristic behavior of Au nanoparticle arrays including Coulomb blockade at room temperature, single electron charging effects and a power law dependence in current-voltage were observed, and Schottky behavior and photocurrent generation due to the ZnO nanorods were also proved. From the modulation of the threshold voltage of the Au array due to the electron-hole pairs generated by photo excitation in the ZnO rods, it can be seen that the system also has coupling between the Au nanoparticles and ZnO rods other than the individual characteristics. Au nanoparticles can be used as electrochemical systems with both structural and spatial confinement of the synthesized material. The possibility of using Au nanoparticle chains as electroactive sites significantly expands their potential use in sensors, multifunctional materials, single electron transistors and nanoscale energy systems.
2

Intégration hybride de transistors à un électron sur un noeud technologique CMOS / Hybrid integration of single electron transistor on a CMOS technology node

Jouvet, Nicolas 21 November 2012 (has links)
Cette étude porte sur l’intégration hybride de transistors à un électron (single-electron transistor, SET) dans un noeud technologique CMOS. Les SETs présentent de forts potentiels, en particulier en termes d’économies d’énergies, mais ne peuvent complètement remplacer le CMOS dans les circuits électriques. Cependant, la combinaison des composants SETs et MOS permet de pallier à ce problème, ouvrant la voie à des circuits à très faible puissance dissipée, et à haute densité d’intégration. Cette thèse se propose d’employer pour la réalisation de SETs dans le back-end-of-line (BEOL), c'est-à-dire dans l’oxyde encapsulant les CMOS, le procédé de fabrication nanodamascène, mis au point par C. Dubuc. / This study deals with the hybrid integration of Single Electron Transistors (SET) on a CMOS technology node. SET devices present high potentiels, particularly in terms of energy efficiency, but can't completely replace CMOS in electrical circuits. However, SETs and CMOS devices combination can solve this issue, opening the way toward very low operating power circuits, and high integration density. This thesis proposes itself to use for Back-End-Of-Line (BEOL) SETs realization, meaning in the oxide encapsulating CMOS, the nanodamascene fabrication process devised by C. Dubuc.

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