Dissertations / Theses on the topic 'Single electron devices'
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1
Scholze, Andreas. "Simulation of single-electron devices /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13526.
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Wasshuber, Christoph. "About single-electron devices and circuits /." Wien : Österr. Kunst- und Kulturverl, 1998. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=008183172&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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He, J. "Few-electron transfer devices for single-electron logic applications." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603913.
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Silicon-compatible single-electron circuit architectures may provide a promising solution for the development of very large-scale integrated circuits using nanoscale devices. In these circuits, single-electron charging effects may be used to control the transport of electrons with single-electron precision. Single-electron devices are also inherently small and have low power dissipation. This raises the possibility of very large-scale integrated circuits that combine large integration and low power dissipation. In this work, few-electron transfer devices, for use as the basic element for logic applications, are implemented using nanowire single-electron transistors, in silicon-on-insulator material. A two-way few-electron switch, based on the operation of two bi-directional electron pumps, was fabricated and characterised electrically at 4.2 K. The switch was implemented using three SETs and the circuit was driven by a sine-wave r.f. signal. It was possible to switch few-electron packets ~ 600 electrons in size, using an input gate voltage, from one entry branch into one of two exit branches. Another few-electron transfer device, the ‘universal electron switch’, similar in the general design to the two-way switch, was also fabricated and characterised at 4.2 K. This switch can switch electron packets ~ 10 electrons in size, from any one of three branches to any other branch. These switches may be used for the precise transfer and steering of few-electron packets and as the basic element in few-electron logic applications, such as binary decision diagram logic applications. A radio-frequency single-electron transistor was also developed in silicon-on-insulator material. This device incorporates an SET with an LC resonant circuit and forms a highly-sensitive fast-response electrometer. This device was characterised using 813 MHz microwave at 4.2 K, in order to investigate the high frequency response of an SOI single-electron transistor.
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Pooley, David Martin. "Vertical silicon single-electron devices with silicon nitride tunnel barriers." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621302.
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Alkhalil, Feras. "Development of novel fabrication technology for SOI single electron transfer devices." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/360500/.
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This report presents the design, simulation and fabrication of a spin qubit platform on ultrathin SOI (Silicon-on-Insulator) using A1 FinSET (Single electron transistor) gates and Si side gates. A new design layout is proposed for the double spin qubits co-integrated with a single electron electrometer, a waveguide and a nanomagnet. This platform aims to demonstrate the full operation of double spin qubits by integrating the following three key techniques in one compact footprint: a precisely controlled single electron transfer technology, a high speed charge detection technique and a single spin detection technology based on spin to charge conversion. A single electron transfer device (SETD) integrated with an electrometer is introduced here as the main building block of the spin qubit platform. The single electron transfer device consists of three nanowire (MOSETs) connected in series, and is capacitively coupled to an SET electrometer. A unique layout design for the SETD and a novel single electron transfer voltage pulse sequence are introduced. Simulation and dynamic analysis of this device operation are preformed using a finite element capacitance based simulation method and a Monte Carlo based single electron circuit simulation. The simulations demonstrated the ability of this platform to transfer single electrons and these characteristics are analyzed to optimize the layout. A novel fabrication process to realize high density silicon quantum dots (QDs) with A1 FinSET gates and close proximity Si gates on ultrathin SOI, for single electron transfer and detection, is successfully established with a number of different device layouts realized. In these devices, A1 FinSET gates surround an SOI nanowire channel forming electrically tunable potential barriers and defining QDs among them; Si plunger side gates are included to enable precise control of the QDs potential. Five SETD and electrometer device generations have been realized, tested and analyzed to improve the device yield; this extensive process development work is concluded with a novel fabrication approach to demonstrate successful FinSET A1 gae technology for SOI nanowires. This QDs platform is fabricated using a multi-layer electron beam lithography process that is fully compatible with metal oxide semiconductor technology. The fabrication process is fully developed with a yield of 92% and a great flexibility to enable the realization of more complex structures and even for devices beyond the scope of this project as shown in the appendices of this report.
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Carroll, Natalie R. Sohlberg Karl William Dr. "Theoretical descriptions of electron transport through single molecules: developing design tools for molecular electronic devices /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/330.
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Chu, Rongming. "AlGaN-GaN single- and double-channel high electron mobility transistors /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20CHU.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 74-82). Also available in electronic version. Access restricted to campus users.
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Rajagopal, Senthil Arun. "SINGLE MOLECULE ELECTRONICS AND NANOFABRICATION OF MOLECULAR ELECTRONIC DEVICES." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1155330219.
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Nicol, Robert Leiper. "Fabrication and characterization of ultra-small tunnel junctions for single electron devices." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/5365/.
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Work on the fabrication processes has shown that traditional tunnel junction formation techniques result in structure sizes which are too large to provide the high temperature effects required. Where lithographic techniques alone are used to shrink pattern dimensions, the processes become unreliable. In the case of the suspended mask shadow evaporation process used here, a limiting reliable overlap width of 40nm is expected and experienced. Attempts to fabricate structures below this size resulted in unreliable tunnel junction formation. The second technique investigated, the crossed track technique, suffered from serious problems arising from the angled evaporation process and from step coverage difficulties. The third fabrication technique attempts to control the placement of grains within the aluminium film. This technique has the advantages of simplicity and ability to form the smallest tunnel junctions with the material system used here. This system was chosen as the main fabrication process for investigation of high temperature single electron devices in this work. Measurements of resistivity and resistivity temperature dependence of the aluminium films were used to characterize the film types. The temperature dependence and magnitude of the resistivity have shown the films to be very conductive, or metallic. By virtue of this high conductivity, the structure behaviour should be dominated by the device, or tunnel junction, properties. The results obtained from the devices at 4.2K do not show the presence of single electron effects. However, the fabricated structures did demonstrate tunnelling behaviour. The absence of single electron effects has been attributed to the structure sizes. Despite being among the smallest possible in aluminium metallizations, these granular structures are apparently too large. The explanation for this is derived from the presence of stray capacitances between the grains forming the tunnel junctions. This raises the junction capacitance and therefore reduces the charging energy of the junction and the temperature of operation.
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Kleinschmidt, Peter. "Applications of single-electron devices in electrical metrology and far-Infrared detection." Thesis, Royal Holloway, University of London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444545.
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Robinson, Andrew Malcolm. "Dynamics and noise in surface-acoustic-wave-based single-electron- transport devices." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620234.
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Romero, Javier. "Electronic transport and correlations in single magnetic molecule devices." Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6348.
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In this dissertation, we study the most important microscopic aspects that grant molecules such as Single Molecule Magnets (SMMs) their preferential spin direction. We do so by proposing and solving a model that includes correlations between electrons occupying atomic orbitals. In addition, we study the relation between the non-equilibrium electronic transport signatures in a SMM model weakly coupled to a three-terminal single electron transistor device, and the interference features of the SMM model in the presence of a magnetic field. Finally, we investigate the equilibrium transport features in a giant-spin model of a SMM in the Kondo regime. We study how the magnetic field modulation of the energy in a highly anisotropic molecule can affect the conductance of the molecule in the Kondo regime.Ph.D.
Doctorate
Physics
Sciences
Physics
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Kim, Jong Un. "Error rate and power dissipation in nano-logic devices." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2224.
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Current-controlled logic and single electron logic processors have been investigated with respect to thermal-induced bit error. A maximal error rate for both logic processors is regarded as one bit-error/year/chip. A maximal clock frequency and an information channel capacity at a given operation current are derived when a current-controlled logic processor works without error. An available operation range in a current-controlled processor with 100 million elements is discussed. The dependence of an error-free condition on temperature in single electron logic processors is derived. The size of the quantum dot of single electron transistor is predicted when a single electron logic processor with the a billion single electron transistors works without error at room temperature.
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Herrmann, Oliver [Verfasser], Laurens W. [Gutachter] Molenkamp, and Matthias [Gutachter] Bode. "Graphene-based single-electron and hybrid devices, their lithography, and their transport properties / Oliver Herrmann ; Gutachter: Laurens W. Molenkamp, Matthias Bode." Würzburg : Universität Würzburg, 2017. http://d-nb.info/1130587924/34.
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Dittmann, Niklas [Verfasser], Nicole Akademischer Betreuer] Helbig, Janine [Akademischer Betreuer] Splettstößer, and Volker [Akademischer Betreuer] [Meden. "Dynamics and fluctuations in single-electron tunneling devices : analytical and numerical methods for time-dependent quantum transport in interacting nanosystems / Niklas Dittmann ; Nicole Helbig, Janine Splettstößer, Volker Meden." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1189672197/34.
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Alecce, Antonio. "Selected problems in quantum mechanics: towards topological quantum devices and heat engine." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3421931.
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The work presented in this thesis meanly addresses two topics in theoretical physics which are quantum thermodynamics and topological order. In the first case, physicists are trying to build up a theory able to describe quite in general phenomena involving heat and energy exchanges in quantum systems. The second topic, instead, is related to exotic phenomena and states of matter like the quantum Hall effect (QHE) or topological insulators and topological superconductors.
In the first part od the thesis we define the quantum dynamics for closed and open systems. This is a key ingredient to address the field of quantum thermodynamics. Then, after an introductory part about the quantum thermodynamic transformations, we move toward the field of nonequilibrium fluctuation relations. We address the problem of irreversibility in classical as well as quantum mechanics. Here we present one of our main result. We characterize the "thermodynamic" irreversible adiabatic evolution of a quantum system starting such branch in a thermal equilibrium state at inverse temperature ßi. We give the amount of thermodynamic entropy growth for the process. As direct application of the preceding result we then address a quantum Otto cycle (QOC) working at finite power. We saw that the increasing of irreversible character of the evolution affects the main figures of merit of the cycle.
The second part of the thesis addresses the field of topological order. At first we introduce the concept of topological orders, classes and invariants. Then we introduce the well known Kitaev model for 1 D superconductors. This model predicts Majorana zero mode at the ends of the wire (the 1 D system). MZM are topological states showing great resistance against disorder, local perturbations and any dissipative element. Then we consider a generalized Kitaev model where long range interactions are accounted. We get rich topological phase diagrams showing the presence of several MZM per edge. We study the appearing/disappearing dynamics of the modes according to the time reversal symmetry, that is fundamental in the study of topological phase. The phase diagrams we obtained also show the presence of massive edge modes. In this last case the topological invariants do not well describe any transition. At last we focused on a very limit cases where MZM are obtained at finite length of the wire. Such cases are really interesting since the great advance we can get from the finiteness of the wire in an experimental setup.
The last part is about single electron tunneling devices. Here we got a different ability to work as "heat-to-current harvester" for a device using quantum dots respect to an analogue one using metallic dots.
These different arguments find their unity by considering recent scientific works in which heat transport is addressed in single electron transistor devices where some element of the circuit shows a topological behaviour. This is a perfect system from hich we can get new transport phenomena.Il lavoro presentato in questa tesi tratta principalmente due argomenti quali le termodinamica quantistica e l'ordine topologico. Nel primo caso fisici stanno provando a costruire una teoria capace to descrivere abbastanza in generale gli scambi di calore ed energia in sistemi quantistici. Il secondo argomento, invece, si relaziona a fenomini e stati della meteria esotici come l'effetto "fractional quantum hall" o gli isolanti e superconduttori topologici. Nella prima parte della tesi definiamo la dinamica quantistica per un sistema chiuso ed aperto. Questo é fondamentale per trattare il campo della termodinamica quantistica. Poi, dopo una parte introduttiva sulle trasformazioni termodinamiche quantistiche, ci si sposta verso il campo delle relazioni di fluttuazione non all'equilibrio. Viene trattato il problema dell'irreversibilità tanto nella meccanica classica quanto in quella quantistica. Qui presentiamo uno dei nostri maggiori risultati. Caratterizziamo un'evoluzione adiabatica "termodinamica" irreversibile di un sistema quantistico il cui stato iniziale é uno di equilibrio alla temperatura inversa iniziale ßi. Viene ricavato l'incremento di entropia termodinamica del processo. Come applicazione diretta del risultato precedente si é considerato un ciclo Otto quantistico (QOC). Abbiamo notato che l'aumentare del carattere irreversibile dell'evoluzione inficia le principali figure di merito del ciclo. La seconda parte della tisi, invece, guarda al campo dell'ordine topologico. All'inizio introduciamo i concetti di ordine, classi ed invarianti topologici. Poi introduciamo il ben noto modello di Kitaev per superconduttori 1 D. Questo modello prevede "Majorana zero mode" (MZM) ai capi del filo (il sistema 1 D). I Majorana zero modes sono stati topologici che mostrano una grande resistenza contro il disordine, perurbazioni locali e ogni genere di elemento dissipativo. In viene considerata una generalizzazione del modello di Kitaev con interazioni a molti vicini. Vengono ricavati diagrammi di fase topologica molto "ricchi" che mostrano la presenza di molti MZM per lato. Inoltre si studia l'apparire e scomparire di tali modi a seconda della simmetria di inversione temporale, che é fondamentale per lo studio della fase topologica. I diagrammi di fase mostrano anche la presenza di massive edge modes. In questo ultimo caso gli invarianti topologici non descrivono bene tutte le transizioni. In fine ci siamo focalizzati sul caso limite dove gli MZM sono ottenuti quando il sistema ha una lunghezza finita. Tali casi sono molto interressanti visto il grande vantaggio che possiamo ricavarne in un setup sperimentale dato che il sistema può grandezza ridotta. L'ultima parte é sui dispositivi single electron tunneling. Qui abbiamo descritto la differente capacità a lavorare come "heat-to-current harvester" per un dispositivo che usa quantum dots rispetto ad uno analogo che usa metallic dots. Questi argomenti differenti trovano un punto di unione considerando lavori scientifici recenti in cui si considera trasporto di calore su dispositivi "single electron tuunneling" in cui alcune delle componenti circuitali dei dispositivi mostrano una natura topologica. Sono sistemi perfetti dai quali possiamo ottenere nuovi fenomeni di trasporto.
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Ruess, Frank Joachim Physics Faculty of Science UNSW. "Atomically controlled device fabrication using STM." Awarded by:University of New South Wales. Physics, 2006. http://handle.unsw.edu.au/1959.4/24855.
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We present the development of a novel, UHV-compatible device fabrication strategy for the realisation of nano- and atomic-scale devices in silicon by harnessing the atomic-resolution capability of a scanning tunnelling microscope (STM). We develop etched registration markers in the silicon substrate in combination with a custom-designed STM/ molecular beam epitaxy system (MBE) to solve one of the key problems in STM device fabrication ??? connecting devices, fabricated in UHV, to the outside world. Using hydrogen-based STM lithography in combination with phosphine, as a dopant source, and silicon MBE, we then go on to fabricate several planar Si:P devices on one chip, including control devices that demonstrate the efficiency of each stage of the fabrication process. We demonstrate that we can perform four terminal magnetoconductance measurements at cryogenic temperatures after ex-situ alignment of metal contacts to the buried device. Using this process, we demonstrate the lateral confinement of P dopants in a delta-doped plane to a line of width 90nm; and observe the cross-over from 2D to 1D magnetotransport. These measurements enable us to extract the wire width which is in excellent agreement with STM images of the patterned wire. We then create STM-patterned Si:P wires with widths from 90nm to 8nm that show ohmic conduction and low resistivities of 1 to 20 micro Ohm-cm respectively ??? some of the highest conductivity wires reported in silicon. We study the dominant scattering mechanisms in the wires and find that temperature-dependent magnetoconductance can be described by a combination of both 1D weak localisation and 1D electron-electron interaction theories with a potential crossover to strong localisation at lower temperatures. We present results from STM-patterned tunnel junctions with gap sizes of 50nm and 17nm exhibiting clean, non-linear characteristics. We also present preliminary conductance results from a 70nm long and 90nm wide dot between source-drain leads which show evidence of Coulomb blockade behaviour. The thesis demonstrates the viability of using STM lithography to make devices in silicon down to atomic-scale dimensions. In particular, we show the enormous potential of this technology to directly correlate images of the doped regions with ex-situ electrical device characteristics.
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Esmail, Adam Ashiq. "Charge dynamics in superconducting double dots." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270018.
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The work presented in this thesis investigates transitions between quantum states in superconducting double dots (SDDs), a nanoscale device consisting of two aluminium superconducting islands coupled together by a Josephson junction, with each dot connected to a normal state lead. The energy landscape consists of a two level manifold of even charge parity Cooper pair states, and continuous bands corresponding to charge states with single quasiparticles in one or both islands. These devices are fabricated using shadow mask evaporation, and are measured at sub Kelvin temperatures using a dilution refrigerator. We use radio frequency reflectometry to measure quantum capacitance, which is dependent on the quantum state of the device. We measure the quantum capacitance as a function of gate voltage, and observe capacitance maxima corresponding to the Josephson coupling between even parity states. We also perform charge sensing and detect odd parity states. These measurements support the theoretical model of the energy landscape of the SDD. By measuring the quantum capacitance in the time domain, we observe random switching of capacitance between two levels. We determine this to be the stochastic breaking and recombination of single Cooper pairs. By carrying out spectroscopy of the bath responsible for the pair breaking we attribute it to black-body radiation in the cryogenic environment. We also drive the breaking process with a continuous microwave signal, and find that the rate is linearly proportional to incident power. This suggests that a single photon process is responsible, and demonstrates the potential of the SDD as a single photon microwave detector. We investigate this mechanism further, and design an experiment in which the breaking rate is enhanced when the SDD is in the antisymmetric state rather than the symmetric state. We also measure the quantum capacitance of a charge isolated double dot. We observe 2e periodicity, indicating the tunnelling of Cooper pairs and the lack of occupation of quasiparticle states. This work is relevant to the range of experiments investigating the effect of non-equilibrium quasiparticles on the operation of superconducting qubits and other superconducting devices.
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Zhang, Yong. "A single-pulse cycloconverter induction motor drive." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260012.
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Gao, Yuanfang. "Microfabricated devices for single cell analysis." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4429.
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Thesis (Ph.D.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 1, 2009) Vita. Includes bibliographical references.
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Yang, Yang. "Electronic devices based on individual single wall carbon nanotubes." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708116.
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Hopfensperger, Bernhard. "Field oriented control of single and cascaded doubly-fed induction machines." Thesis, University of Newcastle Upon Tyne, 1998. http://hdl.handle.net/10443/514.
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A single doubly-fed induction machine (SDFM) is a wound rotor induction machine with the stator connected to a supply network and the rotor fed by a bi-directional converter. A cascaded doubly-fed induction machine (CDFM) is a. connection of two wound rotor induction machines with the rotors connected electrically and mechanically thus avoiding brushes. One stator is connected to the supply network and the other is fed by a bidirectional converter. Both schemes, the SDFM and the CDFM, have in common that the VA-rating of the power converter is reduced compared to a singly-fed system. This thesis presents investigations of the field oriented control for the SDFM and the CDFM. - After reviewing and categorising doubly-fed machines a thorough steady state analysis and stator flux oriented control treatment of the SDFM is presented. Although the steady state analysis and the field oriented control of a SDFM is well established it is necessary that this is included as foundation for the CDFM control behaviour and for the sensorless control investigations. Steady state analysis of the CDFM highlights similarities to the SDFM. Two different field oriented control schemes are applied to the CDFM. A previously developed combined flux oriented scheme is modified to be applicable to a CDFM consisting of any machine combination. Furthermore, the scheme is simplified by removing a mathematical control extension in the q-axis, which has a stabilising effect on the control performance. Justified by steady state analysis the stator flux oriented control structure initially developed for the SDFM is applied to the CDFM. Two variations of a position sensorless scheme taking advantage of the proportionalitics between stator and rotor quantities are applied to the SDFM. Differentiating the estimated position angle allows the schemes to be extended for speed control purposes. The performance of the scnsorless field oriented control methods are also investigated on the CDFM. Harmonic analysis of the SDFM / CDFM systeme stablishes harmonic sources and harmonic current propagation through the system. A theoretical harmonic current prediction process incorporating simulation and steady state modeling delivers good results. All theoretical investigations are confirmed by experimental results. The experimental realtime controlled drive system consists of two 2.25 kW wound rotor induction machines, a bidirectional IGBT converter and the control hardware comprises two 8OC167 microcontrollers.
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Hu, Gongfan. "Computer aided analysis and design of a single phase induction actuator." Thesis, University of Dundee, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334764.
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FERRARIO, ALBERTO. "Atmospheric neutron induced soft errors on electronic devices." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28334.
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Soft errors at sea level, originating from scattered particles in the atmosphere or alpha-emitting contaminants in chip materials, are a known source of disturbances in SRAM's and, to a lesser extent, in DRAM's. Relatively less is known about the sensitivity of Floating Gate memories, one of the most pervasive type of memory. An extensive literature covers the effects of heavy ions on floating gate cells, but little data obtained with particles matching the terrestrial neutron environment are available.
The purpose of this thesis is to investigate atmospheric neutron effects on floating gate cells in NAND Flash memories. Experimental data were obtained with neutron irradiation on commercial devices from different vendors. Irradiation was performed at the line of the ISIS facility at the Rutherford Appleton Laboratory, in Didcot, UK, using a wide-energy neutron beam. The VESUVIO neutron spectrum reasonably reproduces the terrestrial environment, with several orders of magnitude of acceleration.
A Geant4-based code has been developed to simulate the irradiation of three technological floating gate cells. With Matlab data post processing, simulations have provided physical informations about the interactions between incident neutrons and chip materials.
Finally, a relation between experimental data and simulations has been studied. The thesis is organized as follows:
Chapter 1 gives an overview of radiations effects. Different sources of neutrons,
like space environments, terrestrial environments, but also man-made radiation facilities are introduced. The second part of Chapter 1 is focused on
radiation effects on CMOS technology, with attention on single event effects.
Chapter 2 is a brief survey of Flash technology. The Chapter explains the basic
principles and operation of non-volatile memories, with attention on the cell array architecture. The multi level cell memories are also introduced. Then, the reliability problems of industry-standard Flash Cell and scaling issues of the latest Flash structures are presented.
Chapter 3 contains the experimental work of this thesis. In the first part, general
published data of ionizing radiation on
floating gate cell are given. Hence,
experimental data of neutron radiation on commercial Flash memories at the
Isis facility are presented, focusing on the Cross Section and the Threshold
Voltage shift.
Chapter 4 presents the simulation work. After an introduction of the general
concepts of the Geant4 toolkit, the chapter explains the developed simulation tool in terms of 3D Geometry, Materials, Sensitive Detector and
the simulated Particles Spectrum. Data obtained from simulations and
analysed, in all their components, are exposed, suggesting a relation with
the experimental data.
Appendices gives the reader details of the Geant4 source code implemented for
this work. In particular, the descriptions of the Sensitive Detector and the
Physic List are reported.
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Wu, Yimin A. "Towards large area single crystalline two dimensional atomic crystals for nanotechnology applications." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:bdb827e5-f3fd-4806-8085-0206e67c7144.
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Nanomaterials have attracted great interest due to the unique physical properties and great potential in the applications of nanoscale devices. Two dimensional atomic crystals, which are atomic thickness, especially graphene, have triggered the gold rush recently due to the fascinating high mobility at room temperature for future electronics. The crystal structure of nanomaterials will have great influence on their physical properties. Thus, this thesis is focused on developing the methods to control the crystal structure of nanomaterials, namely quantum dots as semiconductor, boron nitride (BN) as insulator, graphene as semimetal, with low cost for their applications in photonics, structural support and electronics. In this thesis, firstly, Mn doped ZnSe quantum dots have been synthesized using colloidal synthesis. The shape control of Mn doped ZnSe quantum dots has been achieved from branched to spherical by switching the injection temperature from kinetics to thermodynamics region. Injection rates have been found to have effect on controlling the crystal phase from zinc blende to wurtzite. The structural-property relationship has been investigated. It is found that the spherical wurtzite Mn doped ZnSe quantum dots have the highest quantum yield comparing with other shape or crystal phase of the dots. Then, the Mn doped ZnSe quantum dots were deposited onto the BN sheets, which were micron-sized and fabricated by chemical exfoliation, for high resolution imaging. It is the first demonstration of utilizing ultrathin carbon free 2D atomic crystal as support for high resolution imaging. Phase contrast images reveal moiré interference patterns between nanocrystals and BN substrate that are used to determine the relative orientation of the nanocrystals with respect to the BN sheets and interference lattice planes using a newly developed equation method. Double diffraction is observed and has been analyzed using a vector method. As only a few microns sized 2D atomic crystal, like BN, can be fabricated by the chemical exfoliation. Chemical vapour deposition (CVD) is as used as an alternative to fabricate large area graphene. The mechanism and growth dynamics of graphene domains have been investigated using Cu catalyzed atmospheric pressure CVD. Rectangular few layer graphene domains were synthesized for the first time. It only grows on the Cu grains with (111) orientation due to the interplay between atomic structure of Cu lattice and graphene domains. Hexagonal graphene domains can form on nearly all non-(111) Cu surfaces. The few layer hexagonal single crystal graphene domains were aligned in their crystallographic orientation over millimetre scale. In order to improve the alignment and reduce the layer of graphene domains, a novel method is invented to perform the CVD reaction above the melting point of copper (1090 ºC) and using molybdenum or tungsten to prevent the balling of the copper from dewetting. By controlling the amount of hydrogen during the growth, individual single crystal domains of monolayer over 200 µm are produced determined by electron diffraction mapping. Raman mapping shows the monolayer nature of graphene grown by this method. This graphene exhibits a linear dispersion relationship and no sign of doping. The large scale alignment of monolayer hexagonal graphene domains with epitaxial relationship on Cu is the key to get wafer-sized single crystal monolayer graphene films. This paves the way for industry scale production of 2D single crystal graphene.
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Brown, Daniel F. Jr. "Single crystal piezoelectric pumping using displacement amplification." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19124.
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Teh, Aun Shih. "In-situ synthesis of single wall carbon nanotubes for electronic devices." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612322.
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Johnson, Nigel Christopher. "All-optical regenerative memory using a single device." Thesis, Aston University, 2009. http://publications.aston.ac.uk/15331/.
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In recent years the optical domain has been traditionally reserved for node-to-node transmission with the processing and switching achieved entirely in the electrical domain. However, with the constantly increasing demand for bandwidth and the resultant increase in transmission speeds, there is a very real fear that current electronic technology as used for processing will not be able to cope with future demands. Fuelled by this requirement for faster processing speeds, considerable research is currently being carried out into the potential of All-optical processing. One of the fundamental obstacles in realising All-optical processing is the requirement for All-optical buffering. Without all-optical buffers it is extremely difficult to resolve situations such as contention and congestion. Many devices have been proposed to solve this problem however none of them provide the perfect solution. The subject of this research is to experimentally demonstrate a novel all-optical memory device. Unlike many previously demonstrated optical storage devices the device under consideration utilises only a single loop mirror and a single SOA as its switch, whilst providing full regenerative capabilities required for long-term storage. I will explain some of the principles and characteristics of the device, which will then be experimentally demonstrated. The device configuration will then be studied and investigated as to its suitability for Hybrid Integrated Technology.
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Schulze, Gunnar [Verfasser]. "Elementary processes in single molecule devices : electronic transport and molecular isomerization / Gunnar Schulze." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/102433547X/34.
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Badada, Bekele H. "Probing Electronic Band Structure and Quantum Confined States in Single Semiconductor Nanowire Devices." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470043382.
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Kim, Sung Soo. "Single-walled carbon nanotube electrodes for all-plastic, electronic device applications." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6453.
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In this thesis, new mechanically robust, high performance transparent conducting films of commercially sourced arc-made Single-Walled Carbon Nanotubes (SWCNTs) on both glass and flexible substrates were produced using spin-coating or spray deposition, interlayer or stencil patterning methods and used for fabricating efficient, flexible polymer-fullerene bulk hetero-junction solar cells. After carefully optimizing the dispersion process of SWCNTs with H2O:SDS (up to 0.03 wt.%) and developing and efficient surfactant removal/p-doping procedure with nitric acid, highly conductive and smooth SWCNT thin films (ca. 30 nm) were obtained with more than 6,500 Scm-1 at > 69 % transmittance and 7 nm (r.m.s.) roughness. In particular, SWCNT films spray coated from H2O:SDS exhibited electrical conductivities of up to 7694 ± 800 Scm-1. To our knowledge, these values are the highest so far reported for SWCNT electrodes. Peak values for the ratio of the dc conductivity to the optical conductivity (σdc/σop) were obtained as up to 24, which is quite similar to state of the art SWCNT films so far reported. In addition, two patterning methods were developed to define electrode patterns of SWCNT thin films for electronic device applications. Interlayer lithography provided a fast and high resolution patterning procedure for SWCNT thin films at micron and sub-micron length scales, which is important for the fabrication of high-speed transistors requiring short channel lengths, and offers an attractive route to fabricating high-density integrated circuits. In addition, stencil patterning provides a simple and fast method, which is well suited for low resolution electronic device applications such as organic solar cells. The patterned highly conductive SWCNT electrodes were incorporated into P3HT:PCBM bulk heterojunction solar cell applications, obtaining the best device performance of 3.6 %, which is the best result so far reported in the literature. Finally, to break through the limited performance (σdc/σop < 25) of SWCNT thin films, layered hybrid thin films of SWCNTs on reduced Graphene-Oxide were fabricated by a simple spray coating method and the optimised hybrid films were incorporated into relatively efficient organic solar cells (2 % efficiency).
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Al-Khaykanee, Mohsin. "Quantum theory of electronic and thermal transport through nano-scale and single-molecule devices." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/90161/.
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This thesis presents a series of studies into the electronic, thermal and thermoelectric properties of molecular junctions containing single organic molecules. The exploration and understanding the electronic and phononic characteristics of molecules connected to metallic leads is a vital part of nanoscience if molecular electronics is to have a future. This thesis documents a study for various families of organic and organometallic molecules, studied using a combination of density functional theory (DFT), which is implemented in the SIESTA code, and the Green’s function formalism of transport theory. The main results of this thesis are as follows: To elucidate the nature of the high and low conductance groups observed in break-junction measurements of single 4,4-bipyridine molecules, I present a combined experimental and theoretical study of the electrical conductance of a family of 4,4-bipyridine molecules, with a series of sterically-induced twist angles α between the two pyridyl rings. I show that their conductances are proportional to cos2(α), confirming that pi-pi overlap between adjacent rings plays a dominant role. Since both peaks exhibit a cos2 (α) dependence of conductance on torsion angle, this is evidence that the high and low conductances correspond to molecular orientations within the junctions, in which the electrical current passes through the C-C bond linking the pi systems of the two rings. Furthermore, this result demonstrates that the Fermi energy is located within the HOMO-LUMO gap and not close to a transmission resonance. A theoretical investigation into the Seebeck coefficient in pi-stacked molecular junctions is performed using a first principles quantum transport method. Using oligo (phenyleneethynylene) (OPE)-type molecules as a model system, I show that quantum interference produces anti-resonances in the gap between the HOMO and LUMO resonances and the stacking geometry can control the position of this quantum interference feature. The shifting of this resonance enhances the thermopower S is expected when the junction is tuned through a node in the transmission function. We found supramolecular π-π interactions between two molecules changed the sign of thermopower. I have investigated a family molecules with various side branched atoms to study the electron and phonon transport through nanoscale molecular junctions, with a view to understanding the performance thermoelectric materials. My calculations focus on the effect of heteroatoms formed from C, Si, Ge, and Sn on the thermal phonon conductance, electrical conductance, and Seebeck Coefficient. I also examine how the thermoelectric figure of merit is affected by side branched atoms, as the bond length and mass play an important role in determining the thermal phonon conductance of molecular wires. Due to the rigid nature of C-side branching, the thermal phonon conductance decreases monotonically with the bond length and mass, whereas thermal phonon conductance with Si-side branches increases with the length of the bond and mass. The low thermal conductance kel with S-bridging, combined with their higher thermopower and higher electrical conductance leads to a maximum thermoelectric figure of merit of ZT = 1.76, which is several orders of magnitude higher than that of bridges.
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Neri, Lorenzo. "Time Resolved Single Photon Imaging Device with Single Photon Avalanche Diode." Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/183.
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We have studied a new optical sensor characterized by performances that will extend the capabilities of several new physical investigation techniques. Our imaging device is based on a two-dimensional array of Single Photon Avalanche Diode (SPAD), sensitive to the single photon with a subnanosecond timing precision. It is able to perform a continuous photon acquisition without the necessity to break to perform the readout process. Moreover it is not damageable by intense light sources. The proposed solution constitutes a step forward for all Time Correlated Single Photon Counting analysis, as Fluorescence Lifetime Imaging Microscopy, Dynamic Light Scattering, 3D Camera, Particle Imaging Velocimetry and Adaptive Optics. An electric characterization of the single SPAD has been carried out to perform multiple readout strategies, and an electric model has been used to perform the simulation of different two-dimensional electric array configurations. We have also deeply studied the source of the counting distortion of the single passive quenched SPAD and have been able to extend the dynamic range of four order of magnitude and to use the dead time saturation as a compression feature for data produced by our imaging sensor. The dead time compensation laws established in Literature have been extended over the steady state analysis to include the time dependent source and any type of dead time. The acquisition electronics, the sensor calibration and the imaging reconstruction algorithm have been performed on a working prototype. The device has been tested with many experimental setups, developed to evaluate the features and the limits of our technological solutions.Abbiamo studiato un nuovo sensore ottico caratterizzato da prestazioni che estenderanno le funzionalita' di molte nuove tecniche di indagine fisica. Il nostro dispositivo si basa su una matrice bidimensionale di Single Photon Avalanche Diode (SPAD), in grado di fornire il tempo di arrivo di ogni singolo fotone con una precisione del decimo di nanosecondo. Il nostro apparato e' in grado di acquisire là ¢ arrivo dei fotoni con continuita', senza interruzioni dovute al processo di lettura, ed e' inoltre resistente a fonti di luce eccessiva che costituiscono una limitazione per i normali dispositivi a singolo fotone. La soluzione proposta costituisce un passo in avanti per tutte le analisi basate sulla correlazione temporale a singolo fotone, come la Fluorescence Lifetime Imaging Microscopy, Dynamic Light Scattering, 3D Camera, Particle Imaging Velocimetry e Adaptive Optics. Grazie allo studio delle caratteristiche elettriche del singolo SPAD e' stato possibile individuare varie strategie di lettura. Il modello elettrico sviluppato e' stato inoltre utilizzato per simulare diverse configurazioni elettriche della matrici bidimensionali di sensori. Abbiamo studiato le caratteristiche funzionali del singolo SPAD ponendo l'attenzione sui fenomeni che alterano la linearita' di ri-sposta, siamo stati cosi' in grado di estendere di quattro ordini di grandezza il suo intervallo di utilizzo, e di utilizzare la saturazione come una funzione di compressione dei dati prodotti dal sensore. Le equazioni presentate estendono la correzione degli effetti del tempo morto, gia' presenti in letteratura, dallà ¢ analisi del caso stazionario a quello delle sorgenti variabili nel tempo, e sono inoltre estendibili a qualunque configurazione di tempo morto. La produzione di un prototipo funzionante ha compreso inoltre la realizzazione dell'elettronica di acquisizione, dell'algoritmo di calibrazione del sensore e di ricostruzione delle immagini. Il dispositivo e' stato testato realizzando diversi esperimenti, che hanno permesso di valutare le caratteristiche e i limiti delle soluzioni tecnologiche adottate.
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Sutanto, Bintoro Jemmy. "An Electromagnetic Actuated Microvalve Fabricated on a Single Wafer." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4891.
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Microvalves are essential components of the miniaturization of the fluidic systems to control of fluid flow in a variety of applications as diverse as chemical analysis systems, micro-fuel cells, and integrated fluidic channel arrangements for electronic cooling. Using microvalves, these systems offer important advantages: they can operate using small sample volumes and provide rapid response time.
This PhD dissertation presents the world first electromagnetically actuated microvalve fabricated on a single wafer with CMOS compatibility. In this dissertation, the design, fabrication, and testing results of two different types of electromagnetic microvalves are presented: the on/off microvalve and the bistable microvalve with latching mechanism. The microvalves operate with power consumption of less than 1.5 W and can control the volume flow rate of DI water, or a 50% diluted methanol solution in the range 1 - 50 µL in. The leaking rate of the on/off microvalve is the order of 30 nL/min. The microvalve demonstrated a response time for latching of 10 ms in water and 0.2 ms in air. This work has resulted in a US patent, application no. 10/699,210.Other inventions that have been developed as a result of this research are bidirectional, and bistable-bidirectional microactuators with latching mechanism, that can be utilized for optical switch, RF relay, micro mirror, nano indenter, or nano printings.
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Gabrysch, Markus. "Charge Transport in Single-crystalline CVD Diamond." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122794.
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Diamond is a semiconductor with many superior material properties such as high breakdown field, high saturation velocity, high carrier mobilities and the highest thermal conductivity of all materials. These extreme properties, as compared to other (wide bandgap) semiconductors, make it desirable to develop single-crystalline epitaxial diamond films for electronic device and detector applications. Future diamond devices, such as power diodes, photoconductive switches and high-frequency field effect transistors, could in principle deliver outstanding performance due to diamond's excellent intrinsic properties. However, such electronic applications put severe demands on the crystalline quality of the material. Many fundamental electronic properties of diamond are still poorly understood, which severely holds back diamond-based electronic device and detector development. This problem is largely due to incomplete knowledge of the defects in the material and due to a lack of understanding of how these defects influence transport properties. Since diamond lacks a shallow dopant that is fully thermally activated at room temperature, the conventional silicon semiconductor technology cannot be transferred to diamond devices; instead, new concepts have to be developed. Some of the more promising device concepts contain thin delta-doped layers with a very high dopant concentration, which are fully activated in conjunction with undoped (intrinsic) layers where charges are transported. Thus, it is crucial to better understand transport in high-quality undoped layers with high carrier mobilities. The focus of this doctoral thesis is therefore the study of charge transport and related electronic properties of single-crystalline plasma-deposited (SC-CVD) diamond samples, in order to improve knowledge on charge creation and transport mechanisms. Fundamental characteristics such as drift mobilities, compensation ratios and average pair-creation energy were measured. Comparing them with theoretical predictions from simulations allows for verification of these models and improvement of the diamond deposition process.
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Alberts, Stefan Francois. "Real-time Software Hand Pose Recognition using Single View Depth Images." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86442.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The fairly recent introduction of low-cost depth sensors such as Microsoft’s Xbox Kinect has encouraged a large amount of research on the use of depth sensors for many common Computer Vision problems. Depth images are advantageous over normal colour images because of how easily objects in a scene can be segregated in real-time. Microsoft used the depth images from the Kinect to successfully separate multiple users and track various larger body joints, but has difficulty tracking smaller joints such as those of the fingers. This is a result of the low resolution and noisy nature of the depth images produced by the Kinect. The objective of this project is to use the depth images produced by the Kinect to remotely track the user’s hands and to recognise the static hand poses in real-time. Such a system would make it possible to control an electronic device from a distance without the use of a remote control. It can be used to control computer systems during computer aided presentations, translate sign language and to provide more hygienic control devices in clean rooms such as operating theatres and electronic laboratories. The proposed system uses the open-source OpenNI framework to retrieve the depth images from the Kinect and to track the user’s hands. Random Decision Forests are trained using computer generated depth images of various hand poses and used to classify the hand regions from a depth image. The region images are processed using a Mean-Shift based joint estimator to find the 3D joint coordinates. These coordinates are finally used to classify the static hand pose using a Support Vector Machine trained using the libSVM library. The system achieves a final accuracy of 95.61% when tested against synthetic data and 81.35% when tested against real world data.
AFRIKAANSE OPSOMMING: Die onlangse bekendstelling van lae-koste diepte sensors soos Microsoft se Xbox Kinect het groot belangstelling opgewek in navorsing oor die gebruik van die diepte sensors vir algemene Rekenaarvisie probleme. Diepte beelde maak dit baie eenvoudig om intyds verskillende voorwerpe in ’n toneel van mekaar te skei. Microsoft het diepte beelde van die Kinect gebruik om verskeie persone en hul ledemate suksesvol te volg. Dit kan egter nie kleiner ledemate soos die vingers volg nie as gevolg van die lae resolusie en voorkoms van geraas in die beelde. Die doel van hierdie projek is om die diepte beelde (verkry vanaf die Kinect) te gebruik om intyds ’n gebruiker se hande te volg oor ’n afstand en die statiese handgebare te herken. So ’n stelsel sal dit moontlik maak om elektroniese toestelle oor ’n afstand te kan beheer sonder die gebruik van ’n afstandsbeheerder. Dit kan gebruik word om rekenaarstelsels te beheer gedurende rekenaargesteunde aanbiedings, vir die vertaling van vingertaal en kan ook gebruik word as higiëniese, tasvrye beheer toestelle in skoonkamers soos operasieteaters en elektroniese laboratoriums. Die voorgestelde stelsel maak gebruik van die oopbron OpenNI raamwerk om die diepte beelde vanaf die Kinect te lees en die gebruiker se hande te volg. Lukrake Besluitnemingswoude ("Random Decision Forests") is opgelei met behulp van rekenaar gegenereerde diepte beelde van verskeie handgebare en word gebruik om die verskeie handdele vanaf ’n diepte beeld te klassifiseer. Die 3D koördinate van die hand ledemate word dan verkry deur gebruik te maak van ’n Gemiddelde-Afset gebaseerde ledemaat herkenner. Hierdie koördinate word dan gebruik om die statiese handgebaar te klassifiseer met behulp van ’n Steun-Vektor Masjien ("Support Vector Machine"), opgelei met behulp van die libSVM biblioteek. Die stelsel behaal ’n finale akkuraatheid van 95.61% wanneer dit getoets word teen sintetiese data en 81.35% wanneer getoets word teen werklike data.
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Llobet, Sixto Jordi. "Focused ion beam implantation as a tool for the fabrication of nano electromechanical devices." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/384934.
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La tesi doctoral titulada “Focused ion beam implantation as a tool for the fabrication of nano electromechanical devices” aborda el repte de la fabricació de ressonadors nano-mètrics des d’una nova òptica basada en la implantació iònica mitjançant un feix de ions focalitzat (FIB). Aquest nou mètode permet fabricar nano-dispositius suspesos funcionals, des del punt de vista elèctric i mecànic, sense necessitat d’utilitzar resina d’una forma i) ràpida i simple, només son necessàries tres etapes de fabricació; ii) flexible, permet definir dispositius amb gran llibertat geomètrica; iii) alta resolució, es demostra la fabricació de dispositius suspesos de 4 μm de longitud per 10 nm de diàmetre; iv) reproduïble i v) compatible amb la tecnologia CMOS.
Partint d’un xip de silici o SOI (silici - diòxid de silici - silici), el mètode de fabricació comença amb un procés d’implantació FIB on es defineixen les estructures i les connexions elèctriques del dispositiu. El segon pas consisteix en el gravat humit del silici, on s’ataca el silici que no està protegit per la implantació FIB, permetent la suspensió o alliberació dels dispositius. En aquest estadi, on les estructures ja estan definides, el silici és amorf, conté gal·li i no és elèctricament funcional (ρ ~1 Ω·m). El darrer pas consisteix en un tractament tèrmic a alta temperatura fins a 1000ºC, en ambient de nitrogen i amb un precursor sòlid de bor on es propicia la recristal·lització del silici formant nano-cristalls, dopar el silici amb bor (tipus p) i eliminar el gal·li. Aquest tractament a alta temperatura, on les estructures no son oxidades, permet obtenir dispositius elèctricament funcionals (ρ ~10-4 Ω·m).
Els principals resultats obtinguts es poden classificar en tres àmbits:
Investigació de l’efecte de la implantació amb ions gal·li en el silici, pel que fa tant a aspectes de processament com de propietats nanoelectromecàniques del material.
En aquest treball hem caracteritzat l’estructura del material en les diferents etapes de fabricació i hem caracteritzat elèctrica i electromecànicament els dispositius finals obtinguts pel mètode descrit.
Desenvolupament i optimització del procés de fabricació, especialment pel que respecte al control de dimensions i a la combinació amb altres processos
Es mostra el treball realitzat en la optimització dels diferents paràmetres de fabricació, des de la posta a punt de la dosi d’ions fins a la selectivitat del gravat. A través del disseny de les estructures es pot establir estratègies per controlar i minimitzar els efectes d’”under-etching” en el silici, a través de la definició d’estructures de compensació, i també evitar el col·lapse de les estructures més llargues, degut a les tensions superficials que es produeixen durant els processos de gravat humit, fabricant pilars per sostenir les estructures.
Aquest mètode de fabricació permet obtenir dispositius a mida convertint-lo en una eina versàtil de prototipatge i de fabricació petites quantitats, que permet aconseguir dispositius de dimensions nano-mètriques per a l’experimentació acadèmica i científica.
Investigació de les propietats electròniques, mecàniques i electromecàniques dels dispositius, i concretament en el cas de nanofils de silici suspesos que es poden aplicar com a ressonadors mecànics d’altra freqüència o transistors d’un sol forat.
Hem pogut fabricar ressonadors de diferents geometries que ens ha permès estudiar i demostrar la relació que existeix entre la simetria/asimetria dels dispositius i el senyal piezoresistiu mesurat durant la transducció electromecànica. Hem investigat i fabricat transistors d’efecte camp ultra-fins (10 ~ 15 nm) i transistors suspesos on les característiques elèctriques a baixa temperatura mostren efectes de “Coulomb blockade” gracies als nano-cristalls que es formen, dins dels nano-fils de silici suspesos, durant l’etapa de tractament tèrmic.The thesis entitled “Focused ion beam implantation as a tool for the fabrication of nano electromechanical devices” aboard the challenge of the fabrication of nanometric resonators from a new approach based on ion implantation by a focused ion beam (FIB) . This new method allows the fabrication of functional suspended nanodevices, from the electrical and mechanical point of view, without using any resist. This method is i) fast and simple, where only three steps are needed; ii) flexible, it is feasible the definition of structures of different shape; iii) high resolution, it is demonstrated the fabrication of 4 μm length and 10 nm diameter suspended devices; iv) reproducible and v) CMOS compatible. The starting point is a silicon or SOI (silicon – silicon dioxide – silicon) chip. The fabrication approach starts with a FIB implantation process where the structures and the electrical connections of the device are defined. The second step consists on silicon wet etching, where silicon that is not protected by the FIB implantation is etched, allowing the release of the devices. The defined structures are made of amorphous silicon, they contains gallium and they are not functional electrically (ρ ~1 Ω·m). The last step consists on diffusive boron doping at high temperature (up to 1000ºC) in a boron environment, where it is promoted the recrystallization of silicon forming nanocrystals, the boron doping (p type) of silicon and the removal of gallium. In this last step at high temperature the structures are not oxidized obtaining electrically functional devices (ρ ~10-4 Ω·m). The principal results can be classified in three areas: Investigation of the effect of gallium ion implantation onto silicon from the process and nanoelectromechanical material properties point of view. In this work the material structure in the different fabrication steps has been characterized, as well as the electrical and electromechanical properties of the final devices obtained by the described method. Development and optimization of the fabrication process, especially controlling the dimensions and the combination with other fabrication processes. The work done in the optimization of the different fabrication parameters are shown, from the tuning of the ion dosage to the etching selectivity. It is possible to stablish design strategies to control and minimize the under-etching effects onto silicon, as well as to avoid the collapse of long structures, that are the result of the superficial sticking produced during the wet etching processes, by the fabrication of sustaining posts. That method permits to obtain customized devices. It is a versatile prototyping method that allows the fabrication of small batches of devices of nanometric dimensions that can be employed for the scientific and academic experimentation. Investigation of the electronical, mechanical and electromechanical properties of the devices, specifically suspended silicon nanowires that can be employed as high frequency mechanical resonators or single hole transistors. We fabricated resonators of different geometries for the study and demonstration of the relation between the geometrical symmetry/asymmetry of the devices and the piezoresistive signal measured during the electromechanical transduction. We investigated and fabricated ultra-thin field effect transistors (10 ~ 15 nm) and suspended transistors that exhibits Coulomb blockade electrical characteristics at low temperature thanks to the nanocrystals that are grown during the high temperature fabrication step.
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Hillig, Mark Alexander. "Automated Channel Assessment for Single Chip MedRadio Transceivers." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1005.
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Modern implantable and body worn medical devices leverage wireless telemetry to improve patient experience and expand therapeutic options. Wireless medical devices are subject to a unique set of regulations in which monitoring of the available frequency spectrum is a requirement. To this end, implants use software protocols to assess the in-band activity to determine which channel should be used. These software protocols take valuable processing time and possibly degrade the operational lifetime of the battery. Implantable medical devices often take advantage of a single chip transceiver as the physical layer for wireless communications. Embedding the channel assessment task in the transceiver hardware would free the limited resources of the microprocessor. This thesis proposes hardware modifications to existing transceiver architectures which would provide an automated channel assessment means for implantable medical devices. The results are applicable beyond medical device applications and could be employed to benefit any low-power, wireless, battery-operated equipment.
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Shah, Pratikkumar. "Development of a Lab-on-a-Chip Device for Rapid Nanotoxicity Assessment In Vitro." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1834.
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Increasing useof nanomaterials in consumer products and biomedical applications creates the possibilities of intentional/unintentional exposure to humans and the environment. Beyond the physiological limit, the nanomaterialexposure to humans can induce toxicity. It is difficult to define toxicity of nanoparticles on humans as it varies by nanomaterialcomposition, size, surface properties and the target organ/cell line. Traditional tests for nanomaterialtoxicity assessment are mostly based on bulk-colorimetric assays. In many studies, nanomaterials have found to interfere with assay-dye to produce false results and usually require several hours or days to collect results. Therefore, there is a clear need for alternative tools that can provide accurate, rapid, and sensitive measure of initial nanomaterialscreening. Recent advancement in single cell studies has suggested discovering cell properties not found earlier in traditional bulk assays. A complex phenomenon, like nanotoxicity, may become clearer when studied at the single cell level, including with small colonies of cells. Advances in lab-on-a-chip techniques have played a significant role in drug discoveries and biosensor applications, however, rarely explored for nanomaterialtoxicity assessment. We presented such cell-integrated chip-based approach that provided quantitative and rapid response of cellhealth, through electrochemical measurements. Moreover, the novel design of the device presented in this study was capable of capturing and analyzing the cells at a single cell and small cell-population level. We examined the change in exocytosis (i.e. neurotransmitterrelease) properties of a single PC12 cell, when exposed to CuOand TiO2 nanoparticles. We found both nanomaterials to interfere with the cell exocytosis function. We also studied the whole-cell response of a single-cell and a small cell-population simultaneously in real-time for the first time. The presented study can be a reference to the future research in the direction of nanotoxicity assessment to develop miniature, simple, and cost-effective tool for fast, quantitative measurements at high throughput level. The designed lab-on-a-chip device and measurement techniques utilized in the present work can be applied for the assessment of othernanoparticles' toxicity, as well.
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Jouvet, Nicolas. "Intégration hybride de transistors à un électron sur un noeud technologique CMOS." Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00863770.
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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.
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Vladimirova, Kremena. "Nouveaux concepts pour l'intégration 3D et le refroidissement des semi-conducteurs de puissance à structure verticale." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00738000.
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L'électronique de puissance est en pleine mutation matérielle, technologique et conceptuelle. Cette évolution bouscule l'approche traditionnelle de la conception et de la fabrication des convertisseurs statiques avec pour objectif de proposer des solutions plus performantes, plus fiables et plus compactes et tout cela dans un contexte technico économique de plus en plus exigeant. Cette thèse analyse et expérimente un concept innovant de terminaisons en tension verticales ouvrant la voie vers l'intégration en 3D des composants de puissance mais également l'intégration, au sein même de la zone active d'un échangeur thermique. En s'appuyant sur la technique de réalisation des tranchées profondes issue de la micro électronique, ce document présente une approche permettant la co-intégration de plusieurs composants de puissance indépendants partageant la même électrode et le même substrat en face arrière. L'autre volet de ce travail de thèse est focalisé sur le concept DRIM Cooler (Drift Region Integrated Microchannel Cooler), un réseau de microcanaux perpendiculaires au plan de jonction du composant de puissance permettant son refroidissement direct. Les analyses numériques sont complétées par de nombreuses réalisations, caractérisations et mises en œuvre des approches précitées.
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Widmer, Johannes. "Charge transport and energy levels in organic semiconductors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-154918.
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Organic semiconductors are a new key technology for large-area and flexible thin-film electronics. They are deposited as thin films (sub-nanometer to micrometer) on large-area substrates. The technologically most advanced applications are organic light emitting diodes (OLEDs) and organic photovoltaics (OPV). For the improvement of performance and efficiency, correct modeling of the electronic processes in the devices is essential. Reliable characterization and validation of the electronic properties of the materials is simultaneously required for the successful optimization of devices. Furthermore, understanding the relations between material structures and their key characteristics opens the path for innovative material and device design. In this thesis, two material characterization methods are developed, respectively refined and applied: a novel technique for measuring the charge carrier mobility μ and a way to determine the ionization energy IE or the electron affinity EA of an organic semiconductor. For the mobility measurements, a new evaluation approach for space-charge limited current (SCLC) measurements in single carrier devices is developed. It is based on a layer thickness variation of the material under investigation. In the \"potential mapping\" (POEM) approach, the voltage as a function of the device thickness V(d) at a given current density is shown to coincide with the spatial distribution of the electric potential V(x) in the thickest device. On this basis, the mobility is directly obtained as function of the electric field F and the charge carrier density n. The evaluation is model-free, i.e. a model for μ(F, n) to fit the measurement data is not required, and the measurement is independent of a possible injection barrier or potential drop at non-optimal contacts. The obtained μ(F, n) function describes the effective average mobility of free and trapped charge carriers. This approach realistically describes charge transport in energetically disordered materials, where a clear differentiation between trapped and free charges is impossible or arbitrary. The measurement of IE and EA is performed by characterizing solar cells at varying temperature T. In suitably designed devices based on a bulk heterojunction (BHJ), the open-circuit voltage Voc is a linear function of T with negative slope in the whole measured range down to 180K. The extrapolation to temperature zero V0 = Voc(T → 0K) is confirmed to equal the effective gap Egeff, i.e. the difference between the EA of the acceptor and the IE of the donor. The successive variation of different components of the devices and testing their influence on V0 verifies the relation V0 = Egeff. On this basis, the IE or EA of a material can be determined in a BHJ with a material where the complementary value is known. The measurement is applied to a number of material combinations, confirming, refining, and complementing previously reported values from ultraviolet photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES). These measurements are applied to small molecule organic semiconductors, including mixed layers. In blends of zinc-phthalocyanine (ZnPc) and C60, the hole mobility is found to be thermally and field activated, as well as increasing with charge density. Varying the mixing ratio, the hole mobility is found to increase with increasing ZnPc content, while the effective gap stays unchanged. A number of further materials and material blends are characterized with respect to hole and electron mobility and the effective gap, including highly diluted donor blends, which have been little investigated before. In all materials, a pronounced field activation of the mobility is observed. The results enable an improved detailed description of the working principle of organic solar cells and support the future design of highly efficient and optimized devicesOrganische Halbleiter sind eine neue Schlüsseltechnologie für großflächige und flexible Dünnschichtelektronik. Sie werden als dünne Materialschichten (Sub-Nanometer bis Mikrometer) auf großflächige Substrate aufgebracht. Die technologisch am weitesten fortgeschrittenen Anwendungen sind organische Leuchtdioden (OLEDs) und organische Photovoltaik (OPV). Zur weiteren Steigerung von Leistungsfähigkeit und Effizienz ist die genaue Modellierung elektronischer Prozesse in den Bauteilen von grundlegender Bedeutung. Für die erfolgreiche Optimierung von Bauteilen ist eine zuverlässige Charakterisierung und Validierung der elektronischen Materialeigenschaften gleichermaßen erforderlich. Außerdem eröffnet das Verständnis der Zusammenhänge zwischen Materialstruktur und -eigenschaften einen Weg für innovative Material- und Bauteilentwicklung. Im Rahmen dieser Dissertation werden zwei Methoden für die Materialcharakterisierung entwickelt, verfeinert und angewandt: eine neuartige Methode zur Messung der Ladungsträgerbeweglichkeit μ und eine Möglichkeit zur Bestimmung der Ionisierungsenergie IE oder der Elektronenaffinität EA eines organischen Halbleiters. Für die Beweglichkeitsmessungen wird eine neue Auswertungsmethode für raumladungsbegrenzte Ströme (SCLC) in unipolaren Bauteilen entwickelt. Sie basiert auf einer Schichtdickenvariation des zu charakterisierenden Materials. In einem Ansatz zur räumlichen Abbildung des elektrischen Potentials (\"potential mapping\", POEM) wird gezeigt, dass das elektrische Potential als Funktion der Schichtdicke V(d) bei einer gegebenen Stromdichte dem räumlichen Verlauf des elektrischen Potentials V(x) im dicksten Bauteil entspricht. Daraus kann die Beweglichkeit als Funktion des elektrischen Felds F und der Ladungsträgerdichte n berechnet werden. Die Auswertung ist modellfrei, d.h. ein Modell zum Angleichen der Messdaten ist für die Berechnung von μ(F, n) nicht erforderlich. Die Messung ist außerdem unabhängig von einer möglichen Injektionsbarriere oder einer Potentialstufe an nicht-idealen Kontakten. Die gemessene Funktion μ(F, n) beschreibt die effektive durchschnittliche Beweglichkeit aller freien und in Fallenzuständen gefangenen Ladungsträger. Dieser Zugang beschreibt den Ladungstransport in energetisch ungeordneten Materialien realistisch, wo eine klare Unterscheidung zwischen freien und Fallenzuständen nicht möglich oder willkürlich ist. Die Messung von IE und EA wird mithilfe temperaturabhängiger Messungen an Solarzellen durchgeführt. In geeigneten Bauteilen mit einem Mischschicht-Heteroübergang (\"bulk heterojunction\" BHJ) ist die Leerlaufspannung Voc im gesamten Messbereich oberhalb 180K eine linear fallende Funktion der Temperatur T. Es kann bestätigt werden, dass die Extrapolation zum Temperaturnullpunkt V0 = Voc(T → 0K) mit der effektiven Energielücke Egeff , d.h. der Differenz zwischen EA des Akzeptor-Materials und IE des Donator-Materials, übereinstimmt. Die systematische schrittweise Variation einzelner Bestandteile der Solarzellen und die Überprüfung des Einflusses auf V0 bestätigen die Beziehung V0 = Egeff. Damit kann die IE oder EA eines Materials bestimmt werden, indem man es in einem BHJ mit einem Material kombiniert, dessen komplementärer Wert bekannt ist. Messungen per Ultraviolett-Photoelektronenspektroskopie (UPS) und inverser Photoelektronenspektroskopie (IPES) werden damit bestätigt, präzisiert und ergänzt. Die beiden entwickelten Messmethoden werden auf organische Halbleiter aus kleinen Molekülen einschließlich Mischschichten angewandt. In Mischschichten aus Zink-Phthalocyanin (ZnPc) und C60 wird eine Löcherbeweglichkeit gemessen, die sowohl thermisch als auch feld- und ladungsträgerdichteaktiviert ist. Wenn das Mischverhältnis variiert wird, steigt die Löcherbeweglichkeit mit zunehmendem ZnPc-Anteil, während die effektive Energielücke unverändert bleibt. Verschiedene weitere Materialien und Materialmischungen werden hinsichtlich Löcher- und Elektronenbeweglichkeit sowie ihrer Energielücke charakterisiert, einschließlich bisher wenig untersuchter hochverdünnter Donator-Systeme. In allen Materialien wird eine deutliche Feldaktivierung der Beweglichkeit beobachtet. Die Ergebnisse ermöglichen eine verbesserte Beschreibung der detaillierten Funktionsweise organischer Solarzellen und unterstützen die künftige Entwicklung hocheffizienter und optimierter Bauteile
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Zare, Firuz. "Multilevel converter structure and control." Thesis, Queensland University of Technology, 2001. https://eprints.qut.edu.au/36142/7/36142_Digitsed%20Thesis.pdf.
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In recent years, multilevel converters are becoming more popular and attractive than traditional converters in high voltage and high power applications. Multilevel converters are particularly suitable for harmonic reduction in high power applications where semiconductor devices are not able to operate at high switching frequencies or in high voltage applications where multilevel converters reduce the need to connect devices in series to achieve high switch voltage ratings. This thesis investigated two aspects of multilevel converters: structure and control.
The first part of this thesis focuses on inductance between a DC supply and inverter components in order to minimise loop inductance, which causes overvoltages and stored energy losses during switching. Three dimensional finite element simulations and experimental tests have been carried out for all sections to verify theoretical developments. The major contributions of this section of the thesis are as follows:
The use of a large area thin conductor sheet with a rectangular cross section separated by dielectric sheets (planar busbar) instead of circular cross section wires, contributes to a reduction of the stray inductance. A number of approximate equations exist for calculating the inductance of a rectangular conductor but an assumption was made that the current density was uniform throughout the conductors. This assumption is not valid for an inverter with a point injection of current. A mathematical analysis of a planar bus bar has been performed at low and high frequencies and the inductance and the resistance values between the two points of the planar busbar have been determined.
A new physical structure for a voltage source inverter with symmetrical planar bus bar structure called Reduced Layer Planar Bus bar, is proposed in this thesis based on the current point injection theory. This new type of planar busbar minimises the variation in stray inductance for different switching states. The reduced layer planar busbar is a new innovation in planar busbars for high power inverters with minimum separation between busbars, optimum stray inductance and improved thermal performances. This type of the planar busbar is suitable for high power inverters, where the voltage source is supported by several capacitors in parallel in order to provide a low ripple DC voltage during operation.
A two layer planar busbar with different materials has been analysed theoretically in order to determine the resistance of bus bars during switching. Increasing the resistance of the planar busbar can gain a damping ratio between stray inductance and capacitance and affects the performance of current loop during switching. The aim of this section is to increase the resistance of the planar bus bar at high frequencies (during switching) and without significantly increasing the planar busbar resistance at low frequency (50 Hz) using the skin effect. This contribution shows a novel structure of busbar suitable for high power applications where high resistance is required at switching times.
In multilevel converters there are different loop inductances between busbars and power switches associated with different switching states. The aim of this research is to consider all combinations of the switching states for each multilevel converter topology and identify the loop inductance for each switching state. Results show that the physical layout of the busbars is very important for minimisation of the loop inductance at each switch state. Novel symmetrical busbar structures are proposed for multilevel converters with diode-clamp and flying-capacitor topologies which minimise the worst case in stray inductance for different switching states. Overshoot voltages and thermal problems are considered for each topology to optimise the planar busbar structure.
In the second part of the thesis, closed loop current techniques have been investigated for single and three phase multilevel converters. The aims of this section are to investigate and propose suitable current controllers such as hysteresis and predictive techniques for multilevel converters with low harmonic distortion and switching losses. This section of the thesis can be classified into three parts as follows:
An optimum space vector modulation technique for a three-phase voltage source inverter based on a minimum-loss strategy is proposed. One of the degrees of freedom for optimisation of the space vector modulation is the selection of the zero vectors in the switching sequence. This new method improves switching transitions per cycle for a given level of distortion as the zero vector does not alternate between each sector. The harmonic spectrum and weighted total harmonic distortion for these strategies are compared and results show up to 7% weighted total harmonic distortion improvement over the previous minimum-loss strategy. The concept of SVM technique is a very convenient representation of a set of three-phase voltages or currents used for current control techniques.
A new hysteresis current control technique for a single-phase multilevel converter with flying-capacitor topology is developed. This technique is based on magnitude and time errors to optimise the level change of converter output voltage. This method also considers how to improve unbalanced voltages of capacitors using voltage vectors in order to minimise switching losses. Logic controls require handling a large number of switches and a Programmable Logic Device (PLD) is a natural implementation for state transition description. The simulation and experimental results describe and verify the current control technique for the converter.
A novel predictive current control technique is proposed for a three-phase multilevel converter, which controls the capacitors' voltage and load current with minimum current ripple and switching losses. The advantage of this contribution is that the technique can be applied to more voltage levels without significantly changing the control circuit. The three-phase five-level inverter with a pure inductive load has been implemented to track three-phase reference currents using analogue circuits and a programmable logic device.
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Pu, Long. "Nanostructured Materials for Pseudocapacitors and Single-Electron Devices." Thesis, 2014. http://hdl.handle.net/10012/8464.
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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.
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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.
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Luo, Xiangning. "Resistive CrO[subscript x] thin film for single-electron devices." 2005. http://etd.nd.edu/ETD-db/theses/available/etd-04132005-125629/.
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Thesis (Ph. D.)--University of Notre Dame, 2005.Thesis directed by Gregory L. Snider and Alexei O. Orlov for the Department of Electrical Engineering. "April 2005." Includes bibliographical references (leaves 138-141).
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Huang, Zih-Hsuan, and 黃子萱. "Characterization of high-frequency filtering techniques for single electron devices." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/69088868605101813427.
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碩士國立交通大學
電子物理系所
103
We investigate the influence of electromagnetic noise on the measurement of mesoscopic samples. Using a Nickel film, we show that the electron temperature of the sample can remain above that of the cryostat. This may be due to high frequency noise reaching the sample. We demonstrate the influence of this noise on the properties of a superconducting SET, and use different filters to improve the measurement. We find that metal film resistors give good filtering, allowing us to characterize the SET device. We find that our SET device is suitable for sensitive charge detection experiments.
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Ray, Vishva. "Room-temperature single-electron devices based on CMOS fabrication technology." 2008. http://hdl.handle.net/10106/1886.
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Dan, Surya Shankar. "Impact Of Energy Quantization On Single Electron Transistor Devices And Circuits." Thesis, 2009. http://hdl.handle.net/2005/666.
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Although scalingof CMOS technology has been predicted to continue for another decade, novel technological solutions are required to overcome the fundamental limitations of the decananometer MOS transistors. Single Electron Transistor (SET) has attracted attention mainly because of its unique Coulomb blockade oscillations characteristics, ultra low power dissipation and nanoscale feature size. Despite the high potential, due to some intrinsic limitations (e.g., very low current drive) it will be very difficult for SET to compete head-to-head with CMOS’s large-scale infrastructure, proven design methodologies, and economic predictability. Nevertheless, the characteristics of SET and MOS transistors are quite complementary. SET advocates low-power consumption and new functionality (related to the Coulomb blockade oscillations), while CMOS has advantages like high-speed driving and voltage gain that can compensate the intrinsic drawbacks of SET. Therefore, although a complete replacement of CMOS by single-electronics is unlikely in the near future, it is also true that combining SET and CMOS one can bring out new functionalities, which are unmirrored in pure CMOS technology. As the hybridization of CMOSand SET is gaining popularity, silicon SETs are appearing to be more promising than metallic SETs for their possible integration with CMOS. SETs are normally studied on the basis of the classical Orthodox Theory, where quantization of energy states in the island is completely ignored. Though this assumption greatly simplifies the physics involved, it is valid only when the SET is made of metallic island. As one cannot neglect the quantization of energy states in a semi conductive island, it is extremely important to study the effects of energy quantization on hybrid CMOSSET integrated circuits. The main objectives of this thesis are: (1) understand energy quantization effects on SET by numerical simulations; (2) develop simple analytical models that can capture the energy quantization effects; (3)analyze the effects of energy quantization on SET logic inverter, and finally; (4)developa CAD framework for CMOS-SETco-simulation and to study the effects of energy quantization on hybrid circuits using that framework.
In this work the widely accepted SIMON Monte Carlo (MC) simulator for single electron devices and circuits is used to study the effects of energy quantization. So far SIMON has been used to study SETs having metallic island. In this work, for the first time, we have shown how one can use SIMON to analyze SET island properties having discrete energy states.It is shown that energy quantization mainly changes the Coulomb Blockade region and drain current of SET devices and thus affects the noise margin, power dissipation, and the propagation delay of SET logic inverter. Anew model for the noise margin of SET inverter is proposed, which includes the energy quantization term. Using the noise margin as a metric, the robustness of SET inverter is studied against the effects of energy quantization. An analytical expression is developed, which explicitly defines the maximum energy quantization (termedas “Quantization Threshold”)that an SET inverter logic circuit can withstand before its noise margin upper bound crosses the acceptable tolerance limit. It is found that SET inverter designed with CT : CG =0.366 (where CT and CG are tunnel junction and gate capacitances respectively) offers maximum robustness against energy quantization. Then the effects of energy quantization are studied for Current biased SET (CBS), which is an integral part of almost all hybrid CMOS-SET circuits. It is demonstrated that energy quantization has no impact on the gain of the CBS characteristics though it changes the output voltage levels and oscillation periodicity. The effects of energy quantization are further studied for two circuits: Negative Differential Resistance (NDR) and Neurone Cell, which use CBS. A new model for the conductance of NDR characteristics is also formulated that includes the energy quantization term. A novel CAD framework is then developed for CMOS-SET co-simulation, whichuses MCsimulator for SET devices alongwithconventional SPICE. Using this framework, the effects of energy quantization are studied for some hybrid circuits, namely, SETMOS, multiband voltage filter, and multiple valued logic circuits. It is found that energy quantization degrades the performance of hybrid circuit, which could be compensated by properly tuning the bias current of SET devices. Though this study is primarily done by exhaustive MC simulation, effort has also been put to develop first order compact model for SET that includes energy quantization effects. Finally it has been demonstrated that the SET behavior under energy quantization can be predicted byslightlymodifyingthe existing SETcompact models that are valid for metallic devices having continuous energy states.
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Lin, Shang-Wei, and 林上偉. "Study of Forming Si/Ge Quantum dots for Single-Electron Devices." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/17073552506973351786.
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碩士國立中央大學
電機工程研究所
92
In this thesis, the technique of forming Si & Ge quantum dots for Single-electron devices will be proposed. The advantages of the technique are well controllable, reproducible and compatible with traditional CMOS process.
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Chou, Chuan-Sheng, and 周詮勝. "Characterization of electron trap energy spectrum in single-ended non-overlapped implantation devices." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/ne6tp4.
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碩士中原大學
電子工程研究所
102
In the semiconductor industry, non-volatile memory (NVM) applications are extensive, and the relative markets have been well developed. For developing semiconductor NVM devices, the effect and improvement of reliability characteristics play important roles. This work is aimed at investigating the surface states and energy profile of single-side non-overlapped implantation (SNOI) MOSFETs which use the drain-side spacer region to store charges by hot carrier injection. To extract the interface state of energy distribution and trap density, we used the two-level charge pumping method and three-level charge pumping methods for investigating SNOI devices. Based on the charge pumping measurement results, the interface trap and trap energy can be found. Finally, by using the charge pumping method, the energy distribution will shift about 60meV to the shallow site, and the interface trap density will increase to about 2.5x1010 (cm-2eV-1) after the program process.