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Sergueev, Nikolai. "Electron-phonon interactions in molecular electronic devices." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102171.
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Over the past several decades, semiconductor electronic devices have been miniaturized following the remarkable "Moores law". If this trend is to continue, devices will reach physical size limit in the not too distance future. There is therefore an urgent need to understand the physics of electronic devices at nano-meter scale, and to predict how such nanoelectronics will work. In nanoelectronics theory, one of the most important and difficult problems concerns electron-phonon interactions under nonequilibrium transport conditions. Calculating phonon spectrum, electron-phonon interaction, and their effects to charge transport for nanoelectronic devices including all atomic microscopic details, is a very difficult and unsolved problem. It is the purpose of this thesis to develop a theoretical formalism and associated numerical tools for solving this problem.<br>In our formalism, we calculate electronic Hamiltonian via density functional theory (DFT) within the nonequilibrium Green's functions (NEGF) which takes care of nonequilibrium transport conditions and open device boundaries for the devices. From the total energy of the device scattering region, we derive the dynamic matrix in analytical form within DFT-NEGF and it gives the vibrational spectrum of the relevant atoms. The vibrational spectrum together with the vibrational eigenvector gives the electron-phonon coupling strength at nonequilibrium for various scattering states. A self-consistent Born approximation (SCBA) allows one to determine the phonon self-energy, the electron Green's function, the electronic density matrix and the electronic Hamiltonian, all self-consistently within equal footing. The main technical development of this work is the DFT-NEGF-SCBA formalism and its associated codes.<br>A number of important physics issues are studied in this work. We start with a detailed analysis of transport properties of C60 molecular tunnel junction. We find that charge transport is mediated by resonances due to an alignment of the Fermi level of the electrodes and the lowest unoccupied C60 molecular orbital. We then make a first step toward the problem of analyzing phonon modes of the C60 by examining the rotational and the center-of-mass motions by calculating the total energy. We obtain the characteristic frequencies of the libration and the center-of-mass modes, the latter is quantitatively consistent with recent experimental measurements. Next, we developed a DFT-NEGF theory for the general purpose of calculating any vibrational modes in molecular tunnel junctions. We derive an analytical expression for dynamic matrix within the framework of DFT-NEGF. Diagonalizing the dynamic matrix we obtain the vibrational (phonon) spectrum of the device. Using this technique we calculate the vibrational spectrum of benzenedithiolate molecule in a tunnel junction and we investigate electron-phonon coupling under an applied bias voltage during current flow. We find that the electron-phonon coupling strength for this molecular device changes drastically as the bias voltage increases, due to dominant contributions from the center-of-mass vibrational modes of the molecule. Finally, we have investigated the reverse problem, namely the effect of molecular vibrations on the tunneling current. For this purpose we developed the DFT-NEGF-SCBA formalism, and an example is given illustrating the power of this formalism.
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Kula, Mathias. "Understanding Electron Transport Properties of Molecular Electronic Devices." Doctoral thesis, KTH, Teoretisk kemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4500.
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his thesis has been devoted to the study of underlying mechanisms for electron transport in molecular electronic devices. Not only has focus been on describing the elastic and inelastic electron transport processes with a Green's function based scattering theory approach, but also on how to construct computational models that are relevant to experimental systems. The thesis is essentially divided into two parts. While the rst part covers basic assumptions and the elastic transport properties, the second part covers the inelastic transport properties and its applications. It is discussed how di erent experimental approaches may give rise to di erent junction widths and thereby di erences in coupling strength between the bridging molecules and the contacts. This di erence in coupling strength is then directly related to the magnitude of the current that passes through the molecule and may thus explain observed di erences between di erent experiments. Another focus is the role of intermolecular interactions on the current-voltage (I-V) characteristics, where water molecules interacting with functional groups in a set of conjugated molecules are considered. This is interesting from several aspects; many experiments are performed under ambient conditions, which means that water molecules will be present and may interfere with the experiment. Another point is that many measurement are done on self-assembled monolayers, which raises the question of how such a measurement relates to that of a single molecule. By looking at the perturbations caused by the water molecules, one may get an understanding of what impact a neighboring molecule may have. The theoretical predictions show that intermolecular e ects may play a crucial role and is related to the functional groups, which has to be taken into consideration when looking at experimental data. In the second part, the inelastic contribution to the total current is shown to be quite small and its real importance lies in probing the device geometry. Several molecules are studied for which experimental data is available for comparison. It is demonstrated that the IETS is very sensitive to the molecular conformation, contact geometry and junction width. It is also found that some of the spectral features that appear in experiment cannot be attributed to the molecular device, but to the background contributions, which shows how theory may be used to complement experiment. This part concludes with a study of the temperature dependence of the inelastic transport. This is very important not only from a theoretical point of view, but also for the experiments since it gives experimentalists a sense of which temperature ranges they can operate for measuring IETS.<br>QC 20100804. Ändrat titeln från: "Understanding Electron Transport Properties in Molecular Devices" 20100804.
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Kula, Mathias. "Understanding electron transport properties in molecular electronic devices /." Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4500.
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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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Barlow, Iain J. "Nanostructured Molecular Electronic Devices." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486548.
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Candidate organic semiconductor materials based on a,ro-dihexylquaterthiophene (dH4T) and a,ro-dihexylbis(phenylene)bithiophene (dHPTTP) core systems were synthesised. The tenninal positions of the alkyl substituents were substituted with, thioacetate, phosphonic acid, glycolic ester and allyl ether groups to enable the fonnation of self-assembled monolayers (SAMs) of the adsorbates onto Au, Ah03 and H-Si surfaces. These were then probed with x-ray photoelectron spectroscopy (XPS) and friction force microscopy (FFM). Analysis of the XPS spectra confirmed that the oligomers fonned monolayer films onto the respective substrates although the allyl-terminated oligomers were subject to oxidation when attached onto H-Si by thermally-initiated radical attachment. Comparison of this method with photochemical initiation highlighted a potentially competing photolysis reaction. FFM showed that the frictional properties of both the thiolate and phosphonic acid SAMs on Au and Ah03 for the oligomers depended on both the tail group polarity and the density of packing for the adsorbates, whilst the allyl-capped materials formed disordered monolayers on H-Si. Chemical patterns of the thioacetate and phosphonic acid-terminated oligomers were produced by the irradiation of methyl-tenninated alkanethiols and alkylphosphonic acids with 244 nm UV light. The irradiation and subsequent displacement of the exposed adsorbates with the dH4T and dHPTTP-based thioactetates and phosphonic acids resulted in areas of relatively high and low friction, which was imaged by FFM. The SAM photomodification process on Ah03 was monitored by XPS, and suggested C-P bond photolysis as a potential mechanism. Scanning near-field photolithography (SNP) was then used to generate dH4T and dHPTTP features into alkanethiol and phosphonate SAMs. The smallest features, of 40 nm fwhm demonstrate that SNP is a viable method for the preparation of organic semiconductors with nanometre resolution, with potential application in the production of self-assembled monolayer field-effect transistors (SAMFETs).
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Driskill-Smith, Alexander Adrian Girling. "Nanoscale vacuum electronic devices." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621660.
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Malti, Abdellah. "Upscaling Organic Electronic Devices." Doctoral thesis, Linköpings universitet, Fysik och elektroteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122022.
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Conventional electronics based on silicon, germanium, or compounds of gallium require prohibitively expensive investments. A state-of-the-art microprocessor fabrication facility can cost up to $15 billion while using environmentally hazardous processes. In that context, the discovery of solution-processable conducting (and semiconducting) polymers stirred up expectations of ubiquitous electronics because it enables the mass-production of devices using well established high-volume printing techniques. In essence, this thesis attempts to study the characteristics and applications of thin conducting polymer films (<200 nm), and scale them up to thick-films (>100 μm). First, thin-films of organic materials were combined with an electric double layer capacitor to decrease the operating voltage of organic field effect transistors. In addition, ionic current-rectifying diodes membranes were integrated inside electrochromic displays to increase the device’s bistability and obviate the need for an expensive addressing backplane. This work also shows that it is possible to forgo the substrate and produce a self-standing electrochromic device by compositing the same water-processable material with nanofibrillated cellulose (plus a whitening pigment and high-boiling point solvents). In addition, we investigated the viability of these (semi)conducting polymer nanopaper composites in a variety of applications. This material exhibited an excellent combined electronic-ionic conductivity. Moreover, the conductivities in this easy-to-process composite remained constant within a wide range of thicknesses. Initially, this (semi)conducting nanopaper composite was used to produce electrochemical transistors with a giant transconductance (>1 S). Subsequently, it was used as electrodes to construct a supercapacitorwhose capacitance exceeds 1 F.
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Cao, Hui. "Dynamic Effects on Electron Transport in Molecular Electronic Devices." Doctoral thesis, KTH, Teoretisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12676.
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HTML clipboardIn this thesis, dynamic effects on electron transport in molecular electronic devices are presented. Special attention is paid to the dynamics of atomic motions of bridged molecules, thermal motions of surrounding solvents, and many-body electron correlations in molecular junctions. In the framework of single-body Green’s function, the effect of nuclear motions on electron transport in molecular junctions is introduced on the basis of Born-Oppenheimer approximation. Contributions to electron transport from electron-vibration coupling are investigated from the second derivative of current-voltage characteristics, in which each peak is corresponding to a normal mode of the vibration. The inelastic-tunneling spectrum is thus a useful tool in probing the molecular conformations in molecular junctions. By taking account of the many-body interaction between electrons in the scattering region, both time-independent and time-dependent many-body Green’s function formula based on timedependent density functional theory have been developed, in which the concept of state of the system is used to provide insight into the correlation effect on electron transport in molecular devices. An effective approach that combines molecular dynamics simulations and first principles calculations has also been developed to study the statistical behavior of electron transport in electro-chemically gated molecular junctions. The effect of thermal motions of polar water molecules on electron transport at different temperatures has been found to be closely related to the temperature-dependent dynamical hydrogen bond network.<br>QC20100630
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Taher, Elmasly Saadeldin Elamin. "Electronic evaluation of organic semiconductors towards electronic devices." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22541.
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Organic p-conjugated macromolecules, (polymers and oligomers) are an important class of semiconductor which are used in applications such as: field effect transistors, photovoltaics, organic light emitting diodes and electrochromic devices. The p-conjugated systems have tuneable band gaps (Eg) and redox properties, whilst offering the potential for flexibility and low cost. In this thesis, the macromolecular compounds and their low molecular weight precursors were characterised by determining their electrochemical and optical properties which were measured using a series of techniques such as: cyclic voltammetry; UV/vis spectroscopy; emission spectroscopy; spectroelectrochemistry; Raman spectroscopy and thermal analyses. Chapter 2 Presents thiophene copolymers with electroactive nitrogen heterocycles. In section 1, a series of monomers containing heteropentalene mesomeric betaine derivatives were characterized. In particular the 3,4-ethylenedioxythiophene (EDOT) derivative (9) was successfully electropolymerised, yielding a polymer with small optical and electrochemical Eg. In Section 2 the characterisation of EDTT, 3-hexylthiophene and EDOT units (17, 18 and 19 respectively) along with their benzothiadiazole (BT) copolymers are shown. Interesting changes in planarity were observed between the PEDOT and PEDTT compounds. Section 3 and 4 produced many EDOT/thiophene derivatives from phenanthroline and [Ru(bpy)2]) as the core unit. (20-26) All polymers exhibited lower electrochemical Eg when compared to their monomers. Compound 26 was polymerised with high oxidative stability to anodic conditions, however, monomer 25 did not polymerise, due to the domination of the strong RuII/RuIII oxidation process. Section 5 shows bis-EDOT pyridine based monomers (27 and 28). Monomer 28 displayed significant effect of the intramolecular charge transfer (ICT) process and lower electrochemical Eg. Three are new compounds 29, 30 and 31 in the section 6, BODIPY cores with two EDOT, thiophene and EDTT units respectively. When all were compared, Compound 29 showed red shift in the absorption spectra, due to stronger electron donating effect of EDOT. Chapter 3: In section 1 the optical and electrochemical properties of three oligofluorene substituted DPP macromolecules (32, 33, 34) and the core precursors (35, 36, 37 and 38) were investigated. The absorption spectra of all compounds in CH2Cl2 revealed two peaks attributed to p-p* transition of quaterfluorene arms and the absorption of DPP core. Compound 33 exhibited a higher LUMO level compared to the other compounds, which was attributed to the effects of the hexyldecyl and phenyl groups. Section 2 describes six new C3-symmetric compounds containing BT units and truxene core (41-46). The UV-absorption spectra of compounds 41-45, reveal an ICT band which is hypsochromically shifted in the case of compound 41 and is not resolved for compound 46. Compounds 41-44 exhibited a good agreement between electrochemical and optical Eg, while a significant difference between those of compound 46 indicates the poor HOMO-LUMO overlap. Chapter 4 A novel processing methodology was used to fabricate multi-layer organic electronic devices by employing electropolymerisation to form a PEDOT/PEDTT bi-layer. The fabricated device did not exhibit any distinctive photo-response when it was assessed in a diode configuration. This was due to inefficient charge separation at the donor- acceptor interface.
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Forsberg, Erik. "Electronic and Photonic Quantum Devices." Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3476.
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<p>In this thesis various subjects at the crossroads of quantummechanics and device physics are treated, spanning from afundamental study on quantum measurements to fabricationtechniques of controlling gates for nanoelectroniccomponents.</p><p>Electron waveguide components, i.e. electronic componentswith a size such that the wave nature of the electron dominatesthe device characteristics, are treated both experimentally andtheoretically. On the experimental side, evidence of partialballistic transport at room-temperature has been found anddevices controlled by in-plane Pt/GaAs gates have beenfabricated exhibiting an order of magnitude improvedgate-efficiency as compared to an earlier gate-technology. Onthe theoretical side, a novel numerical method forself-consistent simulations of electron waveguide devices hasbeen developed. The method is unique as it incorporates anenergy resolved charge density calculation allowing for e.g.calculations of electron waveguide devices to which a finitebias is applied. The method has then been used in discussionson the influence of space-charge on gate-control of electronwaveguide Y-branch switches.</p><p>Electron waveguides were also used in a proposal for a novelscheme of carrierinjection in low-dimensional semiconductorlasers, a scheme which altogether by- passes the problem ofslow carrier relaxation in suchstructures. By studying aquantum mechanical two-level system serving as a model forelectroabsorption modulators, the ultimate limits of possiblemodulation rates of such modulators have been assessed andfound to largely be determined by the adiabatic response of thesystem. The possibility of using a microwave field to controlRabi oscillations in two-level systems such that a large numberof states can be engineered has also been explored.</p><p>A more fundamental study on quantum mechanical measurementshas been done, in which the transition from a classical to aquantum "interaction free" measurement was studied, making aconnection with quantum non-demolition measurements.</p>
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Said, Elias. "Electrolyte-Based Organic Electronic Devices." Licentiate thesis, Linköping : Department of Science and Technology, Linköping University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9955.
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Yun, Youngjun. "Pentacene based organic electronic devices." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/532/.
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This thesis describes a study of pentacene-based organic electronic devices with poly(methyl methacrylate) (PMMA) and cross-linked PMMA (cPMMA) gate dielectrics. The electrical characteristics of pentacene-based organic thin-film transistors (OTFTs) using PMMA as the gate dielectric are reported. Uniform pinhole-free and crack-free films of PMMA could be obtained by spin-coating, with a lower limit to the thickness of about 150 nm. The effects of the insulator thickness and channel dimensions on the performance of the devices has been investigated. Leakage currents, which are present in many devices using polymeric gate dielectrics, were reduced by patterning the pentacene active layer. The resulting transistors exhibited minimal hysteresis in their output and transfer characteristics with an acceptable performance (a field-effect mobility of 0.33 cm2 V−1 s−1, a threshold voltage of -11 V, an on/off current ratio of 1.2X106 and a subthreshold slope of 1.5 V per decade). A bootstrapped inverter incorporating optimised pentacene OTFT structures, with PMMA as the gate dielectric, has been designed, fabricated and tested. The inverter uses capacitive coupling and bootstrapping effects, and exhibits superior performance to the normal diode-connected load inverter. The circuit has a 30 us rise time and 450 us fall time, at an operating frequency of 1 kHz and 30 V drive voltage. Pentacene-based OTFTs incorporating a PMMA gate insulator usually possess a large operating voltage, related to the thickness of the PMMA layer. A physical method, in particular ion-beam irradiation, to produce ultra-thin cross-linked layers of PMMA (33 nm) is introduced. It is demonstrated that physical cross-linking of the PMMA gate dielectric can be used to produce OTFTs with improved performance (a field-effect mobility of 1.1 cm2 V−1 s−1, a threshold voltage of -1 V, an on/off current ratio of 1.0X106 and a subthreshold slope of 220 mV per decade) and operating at low voltages, < 10 V. Low voltage memory transistors based on various charge storage elements (gold nanoparticles, ultra-thin aluminium and silver films) with cPMMA as the gate dielectric, have been investigated. Solution-processed OTFTs based on 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene with PMMA and cPMMA as the gate dielectric were also studied.
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Wu, Yudong. "Simulation of graphene electronic devices." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1554/.
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Since the publication of research in the mid-1980s describing the formation of freeform graphene there has been an enormous growth in interest in the material. Graphene is of interest to the semiconductor industry because of the high electron mobility exhibited by the material and, as it is planar, it is compatible with silicon technology. When patterned into nanoribbons graphene can be made into regions that are semiconducting or conducting and even into entire circuits. Graphene nanoribbons can also be used to form the channel of a MOSFET. This thesis describes numerical simulations undertaken on devices formed from graphene. The energy band structure of graphene and graphene nanoribbons is obtained using nearest-neighbour and third nearest-neighbour interactions within a tight binding model. A comparison of the current-voltage characteristics of MOS structures formed on graphene nanoribbons and carbon nanotubes suggests that the nanoribbon devices may be better for switching applications. Conductivities of graphene nanoribbons and junctions formed from them were obtained using a nonequilibrium Green’s function formulation. The effects of defects and strain on these systems were also studied using this technique. Advancements were made when the self-energies used within the nonequilibrium Green’s function were obtained from an iterative scheme including third nearestneighbour interactions. An important result of this work is that accurate simulations of graphene based devices should include third nearest-neighbour interactions within the tight binding model of the energy band structure.
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Jin, Jidong. "Metal-oxide-based electronic devices." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/metaloxidebased-electronic-devices(2ccabdd1-398b-4787-9455-e034f9001867).html.
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Metal oxides exhibit a wide range of chemical and electronic properties, making them an extremely interesting subject for numerous applications in modern electronics. The primary goal of this research is to develop metal-oxide-based electronic devices, including thin-film transistors (TFTs), resistance random-access memory (RRAM) and planar nano-devices. This research requires different processing techniques, novel device design concepts and optimisation of materials and devices. The first experiments were carried out to optimise the properties of zinc oxide (ZnO) semiconductors, in particular the carrier concentration, which determines the threshold voltage of the TFTs. Thermal annealing is one common method to affect carrier concentration and most work in the literature reports performing this process in a single-gas environment. In this work, however, annealing was carried out in a combination of air and nitrogen, and it was found that the threshold voltage could be tuned over a wide range of pre-determined values.Further experiments were undertaken to enhance the carrier mobility of ZnO TFTs, which is the most important material quality parameter. By optimising deposition conditions and incorporating a high-k gate dielectric layer, the devices showed saturation mobility values over 50 cm2/Vs at a low operating voltage of 4 V. This is, to our knowledge, one of the highest field-effect mobility values achieved in ZnO-based TFTs by room temperature sputtering. As an important type of metal-oxide-based novel memory devices, which have been studied intensively in the last few years, RRAM devices were also explored. New materials, such as tin oxide (SnOx), were tested, exhibiting bipolar-switching operations and a relatively large resistance ratio. As a novel process variation, anodisation was performed, which yielded less impressive results than SnOx, but with a potential for ultra-low-cost manufacturing. Finally, novel planar nano-devices were explored, which have much simpler structures than conventional multi-layered transistors and diodes. Three types of ZnO-based nano-devices (a side-gated transistor, a self-switching diode and a planar inverter) were fabricated using both e-beam lithography and chemical wet etching. After optimisation of the challenging wet etching procedure at nanometre scale, ZnO nano-devices with good reproducibility and reliability have been demonstrated.
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Zhang, Anping. "Gallium nitride-based electronic devices." [Gainesville, Fla.] : University of Florida, 2001. http://etd.fcla.edu/etd/uf/2001/anp1299/Title.PDF.
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Thesis (Ph. D.)--University of Florida, 2001.<br>Title from first page of PDF file. Document formatted into pages; contains vii, 145 p.; also contains graphics. Vita. Includes bibliographical references (p. 137-144).
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Bonifas, Andrew Paul. "Spectroscopy, Fabrication, and Electronic Characterization of Molecular Electronic Devices." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1305653420.
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Richards, David Robert. "The electronic structure and optical properties of GaAs two-dimensional electron systems." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359697.
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Brada, Matej. "Graphene electronic devices in magnetic field." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21800.
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This thesis discusses the two dimensional allotrope of carbon known as graphene in presence of magnetic field, with special focus on edge states. The structure of graphene is described in detail and from the structure, two models are formed. The Dirac equation is a good description of graphene for large samples, far away from edges, where the boundaries can be ignored. However, it causes problems with most types of edge and hard wall approximation has to be implemented. The Dirac equation is described in detail and used to obtain an energy spectrum, wavefunction and density of states for graphene edge in a strong magnetic field. For comparison, a Bohr-Sommerfield approximation was used to find the dispersion relation and compare it to the results obtained numerically from the Dirac equation. The second model, better fitting for nano-scale systems, is the tight binding model. This model was utilized to find Energy spectrum for graphene flakes in magnetic field, which resembles Hofstadter's butterfly spectrum. The spectrum was analyzed and periodic oscillations of magnetisation dependent on magnetic field (known as the de Haas-van Alphen effect) were described. The oscillation of magnetisation depends on the shape of the dot, even though the main properties remain the same: at low magnetic field, periodic oscillations due to Aharonov-Bohm effect, turning into more chaotic oscillations depending on the boundary conditions of the given quantum dot.
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Shafqat, Adnan. "Mobile Usability of Intelligent Electronic Devices." Thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-10526.
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Context: The Human Machine Interface (HMI) for Intelligent Electronic Devices (IEDs) is limited in its capability and is often the most common cause of failure when interacting with devices. A new approach to interact with these devices is needed with focus on improving interaction and effective visualization of information. Objectives: In this thesis, we investigate and propose a solution to visualize data of existing IED in interactive way. A mobile based prototype is proposed to list alarms, events and disturbances. Further single line diagram shown with capability to switch controls. Objective of proposed solution is to investigate specific use of mobile device from the perspective of usability and compare the new prototype with existing use of IED monochrome screen interface. Methods: Mixed approach based on qualitative and quantitative methods is conducted for analysis of the problem, method and approach to solve the problems in the domain of Substation automation. Analysis of the problem was carried out with the literature review of the technical documentation of IEDs. Experiments are performed in real environment to test and verify the usability of prototype. Results: Experiments results of proposed solution indicate that new approach is acceptable. The interfaces developed in mobile provide better results than traditional interfaces of IED. The difference between them is significant. Conclusions: We conclude that mobile usability gives better interaction, freedom, visualization of information and enhance the users’ experience by providing context specific information as compared to the existing Local Human Machine Interface of Intelligent Electronic Devices. The study provides strong results that recent developments of mobile technologies have revolutionized users’ possibilities to access information in an easy and better way.
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Lo, Jinqin. "Information Management of Intelligent Electronic Devices." Thesis, University of Canterbury. Engineering Management, 2013. http://hdl.handle.net/10092/7455.
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The advent of cheaper, more powerful substation relays, now commonly known as Intelligent Electronic Devices (IEDs), will have a substantial impact on Powerco information systems. Their impact is two-fold; the sheer volume of information associated with modern relays will require a more capable relay management system than the one currently being used. The second effect is the amount of data that can be gathered and used for network improvement. Improper management of both types of information will lead to worse outcomes for Powerco reliability performance, and ultimately its financial performance.
This report details two projects concerned with the management of IED information.The first project is concerned with a proposed upgrade of the Powerco relay management system. This involved requirements engineering, investigation of database systems and a commercial tendering process. It was found that the data schema had a large effect on efficiency and efficacy of relay management systems. The optimal solution would be to procure a proven relay management system from an established vendor, given resource constraints and proven-for-purpose data schema.
The second project is focused on the deployment of automated event report collection software. The impetus of this project was the inefficiencies that arise from manual collection and processing of network event data from substation relays. These hamper the network improvement process, negatively affecting Powerco network reliability. A Cost-Benefit Analysis was performed to determine if such functionality was worth deploying across the network. It was found that automated event report collection produced operational savings from reduced technician dispatch frequency. Other benefits include greater data captured, faster fault response time, and a transformation of the existing reactive network improvement engineering process to one that is proactive. This will require additional engineering resources to be dedicated to event analysis. A deployment schedule was formulated based on historical reliability and agreed service levels.
The larger implications of this report are that additional resourcing, and careful consideration of the information management processes are required to take advantage of the greater volume of data generated by IEDs.
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Russell, Ben. "Modelling of novel opto-electronic devices." Thesis, University of York, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444759.
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Celebi, Kemal. "Optical modeling of organic electronic devices." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45431.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.<br>Includes bibliographical references (p. 51-53).<br>Organic materials, with their superior photoluminescence and absorbance properties have revolutionized the technologies for displays and solar energy conversion. Due to the large transition dipoles, the localization of excited states or excitons in organic materials necessitates optical models that extend beyond classical far field methods. In this thesis we propose an extended near field calculation method using dyadic Green's functions and demonstrate the applications of both our extended model and traditional far field models for different types of devices such as surface plasmon detectors, cavity organic light emitting devices and organic photovoltaics with external antennas.<br>by Kemal Celebi.<br>S.M.
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Parker, William P. (William Peter). "Output devices for dynamic electronic holography." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/12714.
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McNeil, Robert Peter Gordon. "Surface acoustic wave quantum electronic devices." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610718.
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Xu, Zheng. "Organic electronic devices and their interfaces." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1722412901&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Doublet, Thomas. "Neuroscience applications of organic electronic devices." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5076.
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Les enregistrements életrophysiologiques ont apporté des informations considérables sur le fonctionnement et le dysfonctionnement du cerveau. Améliorer les dispositifs d'enregistrement permettrait d'approfondir les connaissances au niveau de la science fondamentale et serait bénéfique pour les patients. Les principales limitations des électrodes en contact direct avec le cerveau comprennent leur invasivité, leur biocompatibilité et leur SNR. Il serait aussi souhaitable de mesurer simultanément les signaux électriques et moléculaires. Le couplage entre l'activité électrique et métabolic est encore mal comprise. Le but de ce travail était de fournir des solutions technologiques à ces défis dans le contexte de l’épilepsie.Nous avons développé des grilles flexibles de 4 µm d’épaisseur résolvant les problèmes d’invasivité, de rigidité et de biocompatibilité. Afin d’améliorer le SNR, des sites d'enregistrement en polymère hautement conducteur PEDOT: PSS ont été faits. La qualité des signaux enregistrés in vivo était meilleure que celui obtenu avec de l’or. Puis nous avons validé des sites d'enregistrement en transistors électrochimiques organiques, permettant l'amplification locale des signaux. Les grilles ont été testées in vivo et le SNR a été multiplié par 10. Enfin, nous avons fonctionnalisé les sites avec une enzyme pour mesurer le glucose. Par rapport aux dispositifs classiques, le capteur de glucose a montré une stabilité et une sensibilité inégalée in vitro.En conclusion, l'électronique organique semble être une solution technologique prometteuse pour les limitations des systèmes actuels visant à enregistrer l'activité électrique et moléculaire du cerveau<br>Electrophysiological recordings brought considerable information about brain function and dysfunction. Improving recording devices would further our understanding at the basic science level and would be beneficial to patients. Major limitations of current electrodes that are in direct contact with brain tissue include their invasiveness, their poor biocompatibility, their rigidity and a suboptimal signal-to-noise ratio. In addition, it would be desirable to measure simultaneously molecular signals. The coupling between the electrical activity of neurons and metabolism is still poorly understood in vivo. The goal of this work was to provide technological solutions to such challenges in the context of epilepsy. We generate 4 µm thick, totally flexible but resilient grids, thus solving the challenge of invasiveness, rigidity and biocompatibility. In order to improve the signal-to-noise ratio, recording sites were made of the highly conductive polymer PEDOT:PSS. The quality of the in vivo signals recorded was better than that obtained with conventional gold contacts. Going a step further, we made the recording site as an organic electrochemical transistor, which enables local amplification of signals. The grid was tested in vivo and the SNR was increased by a factor of 10. Finally, we functionalized PEDOT:PSS sites with glucose oxidase to measure glucose. Compared to conventional devices, the glucose sensor showed unsurpassed stability and sensitivity in vitro. In conclusion, organic electronics appears to be a promising technological solution to the limitations of current systems designed to record the electrical and molecular activity of the brain
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Ji, Tao. "Inelastic electron tunneling spectroscopy in molecular electronic devices from first-principles." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96883.
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In this thesis, we present the first-principle calculations of inelastic electron tunneling spectroscopy(IETS) in single molecular break junctions. In a two-probe electrode-molecule-electrode setup, density functional theory(DFT) is used for the construction of the Hamiltonian and the Keldysh non-equilibrium Green's function(NEGF) technique will be employed for determining the electron density in non-equilibrium system conditions. Total energy functional, atomic forces and Hessian matrix can be obtained in the DFT-NEGF formalism and self-consistent Born approximation(SCBA) is used to integrate the molecular vibrations (phonons) into the framework once the phonon spectra and eigenvectors are calculated from the dynamic matrix. Geometry optimization schemes will also be discussed as an indispensable part of the formalism as the equilibrium condition is crucial to correctly calculate the phonon properties of the system.To overcome the numerical difficulties, especially the large computational time demand of the electron-phonon coupling problem, we develop a numerical approximation for the electron self-energy due to phonons and the error is controlled within numerical precision. Besides, a direct IETS second order I-V derivative expression is derived to reduce the error of numerical differentiation under reasonable assumptions. These two approximations greatly reduce the computation requirement and make the calculation feasible within current numerical capability.As the application of the DFT-NEGF-SCBA formalism, we calculate the IETS of the gold-octanedithiol(ODT) molecular junction. The I-V curve, conductance and IETS from ab-inito calculations are compared directly to experiments. A microscopic understanding of the electron-phonon coupling mechanism in the molecular tunneling junctions is explained in this example. In addition, comparisons of the hydrogen-dissociative and hydrogen-non-dissociative ODT junctions as well as the different charge transfer behaviors are presented to show the effects of thiol formation in the ODT molecular junction.<br>Dans cette thèse, nous présentons des calculs ab initio de la spectroscopie à effet tunnel par électron inélastique (IETS)appliqués à des jonctions moléculaires. Dans le cadre d'une configuration électrode-molécule-électrode,la théorie de la fonctionnelle de la densité (DFT) est utilisée pour construire l'hamiltonien et les fonctions de Green hors-équilibres(NEGF) sont employées pour déterminer la densité électroniquedans des conditions hors-équilibre. Le cadrede la DFT-NEGF nous permet de calculer des quantités telles que la fonctionnelle d'énergie totale,les forces atomiques ainsi que la matrice de Hessian. L'approximationauto-consistante de Born (SCBA) est employée afin d'intégrer les vibrations moléculaires (phonons) dans le formalisme DFT-NEGF,une fois que le spectre des phonons et les vecteurs propres ont été calculés à partir de la matrice dynamique. Des méthodes d'optimisations géométriques sont aussi discutées en tant que part indispensable du formalisme,étant donné que la condition d'équilibre mécanique est essentielle afin de calculer correctement les propriétés des phonons du système.Afin de surmonter les difficultés numériques, particulièrement concernant la grande demandecomputationnelle requise pour le calcul du couplage électron-phonon, nous développons une approximation numérique pour la self-énergie associée aux phonons. De plus, en employant quelques hypothèses raisonables, nous dérivons une expression pour l'IETS calculée à partir de laseconde dérivée de la courbe I-V dans le butde réduire l'erreur associée à la différentiation numérique. L'utilisation de ces deux approximations diminuent grandement les exigences computationnelles et rendent les calculs possibles avec les capacités numériques actuelles.Comme application du formalisme DFT-NEGF-SCBA, nous calculons l'IETS de la jonction moléculaire or-octanedithiol(ODT)-or. La courbe I-V, la conductance et l'IETS obtenues par calculs ab initio sontdirectement comparées aux données expérimentales. Une compréhension microscopique du couplage électron-phonon pour une jonction moléculaire à effet tunnel est élaborée dans cet exemple. De plus, des comparaisons entre les jonctions ODT à hydrogène dissociatif et à hydrogène non-dissociatif ainsi queles différents comportements de transfert de charges sont présentés afin de montrer les effets de la formation du thiol dans la jonction moléculaire ODT.
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Clare, Jonathan Charles. "Computer aided design of power electronic systems." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315209.
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Kocybik, Peter Franz. "Electronic control of torque ripple in brushless motors." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/2643.
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Brushless motors are increasingly popular because of their high power density, torque to inertia ratio and high efficiency. However an operational characteristic is the occurrence of torque ripple at low speeds. For demanding direct drive applications like machine tools, robot arms or aerospace applications it is necessary to reduce the level of torque ripple. This thesis presents an in depth investigation into the production and nature of torque ripple in brushless machines. Different torque ripple reduction strategies are evaluated and one reduction strategy using Park's transform as a tool is identified as the promising strategy. The unified machine theory is checked to clarify the theory behind Park's transform; in particular assumptions made and general validity of the theory. This torque ripple reduction strategy based on Park's transform is extended to include the effect of armature reaction. A novel adaptive torque ripple reduction algorithm is designed. The ineffectiveness of the conventional approach is demonstrated. Further a novel torque ripple reduction strategy using direct measurements of the torque ripple is suggested, reducing implementation time and allowing higher accuracies for torque ripple reduction. Extensive measurements from the experimental system show the validity of the novel torque ripple reduction strategies. The experimental results allow derivation of a formula for all load 111 situations. This formula makes it possible to further increase the reduction accuracy and enables improved real time implementation of the torque ripple reduction algorithm. The work presented here makes a substantial contribution towards understanding the nature of torque ripple in brushless motors and solving the associated problems. The novel reduction strategies form the basis for the development of intelligent dynamometers for motor test beds. Further the torque ripple reduction method presented here can be used to overcome manufacturing imperfections in brushless machines thus removing the cost for precise manufacturing tools. Future designs of controllers can "build" their own correction formula during set-up runs, providing a motor specific torque ripple correction. IV
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Holcroft, B. "Novel electronic devices incorporating Langmuir-Blodgett films." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235171.
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Su, Wenyong. "First Principles Study of Molecular Electronic Devices." Licentiate thesis, Stockholm : Bioteknologi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3882.
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Rajagopalan, Dharmashankar. "Opto-Electronic Processes in SrS:Cu ACTFEL Devices." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_theses/273.
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The a. c. thin film electroluminescent (ACTFEL) devices are of scientific interest due to their applications in large area, flat panel displays. Of particular interest to the research community is the mechanism of electron transport and luminance in these devices. Toward this end, a physical model and a mathematical model for SrS:Cu ACTFEL Devices were developed and published earlier by our group. The purpose of this thesis is to obtain a qualitative and quantitative match between experiment and theory. A brief summary of the model can be found here [1]. Effects of variation in drive parameters in experimental steady state measurements, and analysis of VIL (Voltage-Current-Luminance) plots for different simulated device and drive parameters are performed. The effects of voltage amplitude, activator concentration, interface energy levels, and critical field for dipole collapse were studied. The plots matched qualitatively in that all major experimental features were produced in the simulated waveforms. The measured and the simulated peak currents are 72.5 mA/cm2 and 66.42 mA/cm2 for VA = 123 V. Experimental and theoretical charge transferred per pulse were 2.75 C/cm2 and 2.26 C/cm2. Peak experimental and simulated luminance values for VA = 123 V were 531 cd/m2 and 49150 cd/m2. Total experimental and simulated luminance values for VA = 123 V case were 6.2 cd/m2 and 561.2 cd/m2 respectively. The large difference is attributed to the loss factors such as optical losses (due to total internal reflection), scattering of electrons by impurities in the bulk phosphor layer, and concentration quenching; these have not been incorporated in the model yet.
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Shepherd, Justin Thomas. "Characterisation of molecular materials for electronic devices." Thesis, University of Abertay Dundee, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242116.
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Bagwell, Philip F. (Philip Frederick). "Quantum mechanical transport in submicron electronic devices." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/44264.
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Said, Elias. "Electrolyte : Semiconductor Combinations for Organic Electronic Devices." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15775.
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The discovery of semi-conducting organic materials has opened new possibilities for electronic devices and systems because of their solution processibility, lightweight and flexibility compared to inorganic semiconductors. The combination of semiconductors with electrolytes, and more especially organic semiconductors and solid electrolytes has attracted the attention of researchers because of the multiple phenomena originating from the simultaneous motion of electrons and ions. This thesis deals with organic-based devices whose working mechanism involves electrolytes. By measuring electrochromism induced by the field in isolated segments of conjugated polymer films, which is in contact with an electrolyte, the direction and the magnitude of the electric field along an electrolyte is quantified (paper I). In addition, using a polyanionic proton conductor in organic field-effect transistor (OFET) as gate dielectric results in low operation voltage and fast response thanks to the high capacitance of the electric double layer (EDLC) that is formed at organic semiconductor/ polyelectrolyte interface (paper III). Because an electrolyte is used as a gate insulator, the effect of the ionic currents on the performance of an EDLC-OFET has been investigated by varying the relative humidity of the device ambience (paper IV). Since the EDLC-OFET and the electrochromic display cell both are operated at low voltages, the transistor has been monolithically integrated with an electrochromic pixel, i.e. combining a solid state device and an electrochemical device (paper V). Further, a theoretical study of the electrostatic potential within a so called pen-heterojunction made up of two semi-infinite, doped semiconductor media separated by an electrolyte region is reported (paper II).
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Mannl, U., B. Magunje, and C. van den Berg. "Electronic Devices Based on Printed Silicon Nanoparticles." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34778.
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We have demonstrated that our high quality silicon
nanoparticles can be used for various application in
printed electronics. The use of silicon nanoparticles as the active layer in electronic materials, which can be
printed using simple techniques on low-temperature
substrates, such as paper, brings a great advantage for
producing flexible electronics. Moreover we showed that the resistances of customised inks, produced in our laboratories are comparable with those of commercial available inks.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34778
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Alzaid, Meshal Mufleh. "Flexible Nanocomposite Thin Films for Electronic Devices." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29393.
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Electronic technology is moving towards flexible, durable, and smaller devices with multifunctional capability. To accelerate this movement, creating materials with outstanding properties is critical. Nanocomposites based on single wall carbon nanotubes (SWCNTs) have received considerable attention because of their unique mechanical and electrical properties. When SWCNTs are formed as a sheet, they provide large contact area and ease of control, especially when incorporated into a flexible format. However, when SWCNT films are adhered to an elastic substrate, there are challenges with their use in flexible electronics, such as a reduction Young?s modulus under deformation. SWCNT films can undergo plastic behavior at even a small strain because individual SWCNTs slide past each other in response to deformation. To address these challenges, a strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) method was used to query SWCNT film mechanics. The buckling wavelength and the film thickness are two main factors that influence the mechanics of nanocomposite thin films adhered to elastomeric substrates. SWCNT films coated with a second nanomaterial, such as a polymer thin film or nanocrystals (NCs), have shown a significant enhancement in elasticity. The studies described in this dissertation demonstrate that polymer thin film can reduce the strain softening of SWCNT films, where both yield strain and Young?s modulus increase with the introduction of SWCNT-polymer layers. Specifically, the films started to exhibit a strong synergy between SWCNT and polymer at a film thickness of around 20 nm, which is attributed to the thickness approaching the characteristic interfacial width between the two materials. Both a ?passive? polymer thin film (for example, polystyrene-PS) and an ?active? polymer thin film, the conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS), were investigated, spanning a bilayer to the bulk limit of SWCNT-polymer multilayers. In addition, ultrathin SWCNT films coated with colloidal NCs have also been investigated. We have utilized two approaches to coat SWCNT films with NCs: Langmuir-Blodgett (LB) and spray coating. Both Si and CdSe nanocrystals showed a roughly two-fold enhancement in film elasticity, which was attributed to an excluded volume effect that prevents the SWCNT rearrangement under an applied strain.
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Allen, Monica Theresa. "Quantum Electronic Transport in Mesoscopic Graphene Devices." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493258.
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Graphene provides a rich platform for the study of interaction-induced broken symmetry states due to the presence of spin and sublattice symmetries that can be controllably broken with external electric and magnetic fields. At high magnetic fields and low temperatures, where quantum effects dominate, we map out the phase diagram of broken symmetry quantum Hall states in suspended bilayer graphene. Application of a perpendicular electric field breaks the sublattice (or layer) symmetry, allowing identification of distinct layer-polarized and canted antiferromagnetic v=0 states. At low fields, a new spontaneous broken-symmetry state emerges, which we explore using transport measurements.
The large energy gaps associated with the v=0 state and electric field induced insulating states in bilayer graphene offer an opportunity for tunable bandgap engineering. We use local electrostatic gating to create quantum confined devices in graphene, including quantum point contacts and gate-defined quantum dots.
The final part of this thesis focuses on proximity induced superconductivity in graphene Josephson junctions. We directly visualize current flow in a graphene Josephson junction using superconducting interferometry. The key to our approach involves reconstruction of the real-space current density from magnetic interference using Fourier methods. We observe that current is confined to the crystal boundaries near the Dirac point and that edge and bulk currents coexist at higher Fermi energies. These results are consistent with the existence of "fiber-optic" edge modes at the Dirac point, which we model theoretically. Our techniques also open the door to fast spatial imaging of current distributions along more complicated networks of domains in larger crystals.<br>Physics
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Longa, Chevarría Bryan Henry. "Rest Api for management of electronic devices." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/624358.
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cosas. La cual propone permitirnos un cuasi completo control de nuestro entorno el cual nos brinda una gama de aplicaciones muy amplia, entre estas la domótica, seguridad del hogar y empresa, automatización de tareas y control de dispositivos en general.
La necesidad de conexión entre un cliente universal y estos dispositivos de la IoT es lo que da inicio a Rapimed. Este proyecto tiene como principal propósito la creación de una interfaz universal que proporcione la capacidad a un desarrollador de controlar dispositivos electrónicos desde cualquier lenguaje de programación que sea capaz de comunicarse con servicios en la nube.
Los retos que presenta el proyecto caben en diferentes aristas. En primer lugar, el componente de control de los dispositivos electrónicos con capacidad de comunicación con el servidor. En segundo lugar, la conexión entre este dispositivo controlador electrónico de bajo nivel y el cliente. Este componente es el que se encarga de la comunicación especializada y brinda una Interfaz de programación (API) a través de servicios RESTful. Por último, cómo el usuario final va a controlar o se va a comunicar con estos dispositivos.
En síntesis, siguiendo la megatendencia del Internet of Things y la mayor necesidad de comunicación entre dispositivos electrónicos y clientes multiplataforma se crea el proyecto RAPIMED el cual apunta a crear una interfaz de programación a través de servicios RESTful que pueda ser consumida desde cualquier lenguaje de programación.<br>One of the current megatrends of technology is the development of the IoT or the Internet of things. This allows a quasi complete control of our environment which gives us a wide range of applications, including home automation, home and business security, automation of tasks and control of devices in general.
The need for connection between a universal client and these devices of the IoT is what starts Rapimed. The main purpose of this project is the creation of a universal interface that provides a developer with the ability to control electronic devices from any programming language that is capable of communicating with cloud services.
The challenges presented by the project fit in different edges. First the control component of electronic devices with communication capability with the server Secondly the connection between this low-level electronic driver device and the client. This component is responsible for specialized communication and provides a programming interface (API) through RESTful services. Finally, how the end user will control or communicate with these devices.
In short, following the megatrend of the Internet of Things and the greater need for communication between electronic devices and multiplatform clients, the RAPIMED project is created, which aims to create a programming interface through RESTful services that can be consumed from any programming language.<br>Tesis
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Zhang, Jiawei. "Oxide-semiconductor-based thin-film electronic devices." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/oxidesemiconductorbased-thinfilm-electronic-devices(c8cde776-b68b-47b5-ab63-382a86dbb94b).html.
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Oxide semiconductors have been envisaged to find applications in ubiquitous flexible electronics in daily life such as wearable electronic gadgets to offer novel user experiences. However, one of the bottlenecks to realise these applications is a lack of oxide-semiconductor components capable of wireless communications. As Bluetooth and Wi-Fi are the two dominant communication interfaces, fast enough front-end rectifiers must be developed to operate at their gigahertz (GHz) transmission frequencies. Furthermore, despite of significant developments of n-type oxide semiconductors in the last decade, widespread flexible electronics also requires high-performance p-type oxide semiconductors for use in complementary logic circuits. The objectives of this dissertation are to develop high quality Schottky barriers, achieve GHz speed Schottky diodes on rigid and flexible substrates, evaluate the noise properties of the Schottky diodes, develop p-type oxide semiconductor using sputtering technology, elucidate the hole transport mechanism in p type transistors, and demonstrate their potential applications such as radio receivers, complementary inverters and ring oscillators. First, indium gallium zinc oxide (IGZO) Schottky diodes were fabricated by using radio frequency magnetron sputtering. The oxygen content at the metal-IGZO interface was found to have a profound effect on the electrical performance. By introducing 3% O2 during the deposition of Pt or IGZO, the diodes exhibited excellent electrical properties without requiring any annealing treatment, thus allowing for the realisation of flexible IGZO Schottky diodes. The high-frequency properties of Pt-IGZO Schottky diodes on glass substrates were optimised by testing a range of IGZO thicknesses and diode active areas. The achieved highest cut-off frequency was beyond 20 GHz, which is to the best of our knowledge the fastest oxide-semiconductor device to date. On flexible substrates, the diodes also showed cut-off frequencies up to 6.3 GHz, well beyond the critical benchmark speed of 2.45 GHz for typical wireless communications. In order to assess the feasibility of using IGZO Schottky diodes in practical applications, measurements were taken to discern their low-frequency noise properties. In the as-deposited diodes, logarithmic dependence of the noise spectral density on the applied bias was observed, revealing that the dominant noise was generated in the space-charge region at low biases and in the series-resistance region at high biases, respectively. After annealing the diodes, very different noise mechanism was observed and the interface-trap-induced noise dominated the noise spectra. As one of the most promising p-type oxide semiconductors, SnO was also studied at low temperatures in this thesis. The experiment revealed that hole-transport mechanism was governed by either band conduction or variable range hopping in different temperature ranges. Finally, the potential for fully oxide-based electronics was demonstrated by an amplitude-modulation radio receiver comprising of an IGZO Schottky diode as the demodulator and a complementary ring oscillator based on IGZO and SnO transistors. In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the University of Manchester's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.
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Eminente, Simone <1978>. "Modelling and characterization of decananometric electronic devices." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/463/1/Tesi_PhD_Eminente.pdf.
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Eminente, Simone <1978>. "Modelling and characterization of decananometric electronic devices." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/463/.
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Yang, Liu. "Quantum chemistry studies of molecular electronic devices from electronic structure to current flow /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 156 p, 2010. http://proquest.umi.com/pqdweb?did=1997524081&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ali, Nazar Thamer. "Opto-electronic characterization of multi-terminal polysilicon switching devices." Thesis, University of Bradford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304120.
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Ullah, Saif. "Electronic properties of ladder-structured oligomers and the fabrication of electronic devices." Thesis, Kingston University, 2008. http://eprints.kingston.ac.uk/20430/.
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Dihydroquinoxalino [2,3b]phenazine or dihydrotetraazapentacene (L5H[sub]2) has a similar structure to the pentacene molecule, which has recently caused a great deal of interest in a number of research corporations, as well as in academia for potential applications in molecular electronics. This project is mainly concerned with a comparative study of electrical and electronic properties of vacuum evaporated undoped and doped thin films of L5H[sub]2 and pentacene. The vacuum-evaporated thin films of both L5H[sub]2 and pentacene give high-quality amorphous thin films on conductive (ITO) glass, highly doped silicon (n-Si) and silicon dioxide (SiO[sub]2) substrates. The conduction processes in both L5H[sub]2 and pentacene thin films, occurs via positive charge carriers and the layers exhibit p-type semiconducting properties. The electrical conductivities and charge carrier mobilities for these vacuum evaporated thin films were found to be low, indicatives of charge carrier transport in a narrow polaron band with thermally assisted intermolecular hopping or tunnelling. Schottky diode devices based on L5H[sub]2 and pentacene thin films have been successfully fabricated using a range of metal contacts (Al, Au, Cu, Pb, Sn). The electronic device characteristics were mathematically modelled to determine the Schottky barrier heights at the various metal-semiconductor interfaces. The measurement of Schottky barrier heights were carried out using conventional Current-Voltage (I-V) and Capacitance-Voltage (C-Y) techniques. The measured Schottky barrier heights for both L5H[sub]2 and pentacene thin films, are largely independent of metal workfunction, which suggests that the Fermi level in these devices are pinned at mid gap by a high density of states at the interfaces. Results are also presented for organic field effect transistors (OFETs) based on thin films of L5H[sub]2 and pentacene. For the first time operational OFET devices based on L5H[sub]2 thin films have been reported. The device characteristics for these OFETs based on L5H[sub]2 are compared to device characteristic for similarly fabricated device structures based on pentacene thin films. The OFET characteristics were investigated to determine the field effect charge carrier mobilities, on/off ratios and threshold voltages for both L5H[sub]2 and pentacene devices. The effects of thin film morphology, channel length and dielectric thickness on OFET device characteristics have also been considered. The research work presented here clearly shows that OFETs based on L5H[sub]2 thin film are possible and their operational device characteristic could be improved immensely by better molecular 'organisation in the thin film layers, which would result in higher charge carriers mobilities, and better charge injection at the source/drain metal contacts.
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Toffanin, Stefano. "Multifunctional organic semiconductors as active materials for electronic and opto-electronic devices." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3426094.
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Since the first discovery of the photoelectric effect in anthracene, organic compounds have been studied as multi-functional materials because of their capability of showing a variety of properties such as charge transport, light absorption/emission, photoconductivity, electroluminescence and superconductivity.
The work presented in this Ph.D. thesis aims at studying different classes of ?-conjugated organic materials that present functional properties suitable for the realization of opto-electronic devices. In particular we focus our attention on the two specific properties that are deeply correlated to the molecular arrangement in the realization of nano-scale multifunctional devices: charge transport and light emission.
In the technologically appealing thin-films, the molecular arrangement is extremely sensitive to the deposition procedures and to the nature of the substrate. Thus, of great interest is the understanding at the micro- and nano-scale of the molecular architecture and morphological features which favour charge transport and/or energy transfer, in order to enhance performances of opto-electronic devices based on thin films. We show that in general linear ?-oligothiophenes can organize advantageously in thin-films in so as to guarantee the proper overlap between molecular orbitals which enables efficient field-effect charge transport. Introducing a new class of branched oligothiophenes (namely spider-like oligothiophenes) we aim at studying how complex 3D molecular architecture can affect optical emission, supermolecular organization and charge transport properties.
Investigation on the enhancement of light emission efficiency of organic molecular systems is then carried out presenting a new host-guest lasing system obtained by co-evaporation of an oligo(9,9-diarylfluorene) derivative (T3, donor) with a well-known red-emitter dye (DCM, acceptor). In this binary blend, an efficient Förster energy transfer takes place from the T3 matrix to the dye molecules when the dye concentration is properly optimized. Moreover the mirrorless lasing measurements reveal that amplified spontaneous emission threshold of the 2% DCM:T3 sample is almost an order of magnitude lower than the 2% DCM:Alq3 model system measured in the same experimental conditions.
The possibility of combining different functionalities in a single device is of great relevance for the further development of organic electronics in integrated components and circuitry. Organic light-emitting transistors (OLETs) have been demonstrated to be able to combine in a single device the electrical switching functionality of a field-effect transistor and the capability of light generation. When organic materials are implemented as active layers in device realization, interfaces formed by different materials are intrinsically important. The comprehension of the physics behind each interface is a crucial point to design new materials for device applications or to improve the performances of the existing ones
Here we present a new approach for realizing ambipolar light-emitting transistor. In the heterostructure we propose the first layer and third layers are optimized for field-effect charge (electrons and holes) transport. The second layer is formed by a host-guest matrix with high optical performance and showing amplified spontaneous emission under optical pumping.
The specificity of the presented tri-layer based OLET is the intrinsic separation of the charge transport region from the exciton formation region thus preventing completely the exciton-carrier quenching.
The optimization of the charge transport and light emission properties allows the realization of a tri-layer heterojunction presenting balanced electron and hole mobility (~10-1-10-2 cm2/Vs), high charge carrier density in correspondence of the maximum electroluminescence emission (~ 1 KA/cm2) and intense light generation.<br>Fin dalla scoperta dell’effetto fotoelettrico nell’antracene, i composti organici sono stati studiati come materiali multifunzionali data la loro capacità di mostrare una varietà di proprietà differenti, come il trasporto di carica, emissione/assorbimento di luce, fotoconduttività, elettroluminescenza e superconduttività.
Il lavoro presentato in questa tesi di dottorato si prefigge lo scopo di studiare differenti classi di materiali organici ? coniugati che presentino le proprietà funzionali adatte per la realizzazione di dispositivi optoelettronici.
In particolare viene prestata particolare attenzione allo studio di due specifiche proprietà che sono profondamente connesse con l’organizzazione molecolare nei dispositivi multifunzionali con dimensioni nanometriche: il trasporto di carica e l’emissione di luce.
Nei film sottili, univocamente considerati interessanti dal punto di vista tecnologico, l’organizzazione molecolare è fortemente dipendente dai processi di deposizione e dalla natura del substrato. Per aumentare le prestazioni dei dispositivi basati sui film sottili risulta fondamentale comprendere le strutture supermolecolari e le caratteristiche morfologiche su scala micro- e nanometrica che possono favorire il trasporto di carica e/o i processi di trasferimento di energia.
Si dimostra che in generale gli oligotiofeni lineari depositati in film sottile possano organizzarsi vantaggiosamente in modo da garantire l’opportuna sovrapposizione tra gli orbitali molecolari che permette un efficiente trasporto di carica.
Introducendo una nuova classe di oligotiofeni ramificati, denominati spider-like, ci proponiamo di studiare come una complessa architettura 3D possa modificare le proprietà di emissione, di organizzazione supermolecolare e di trasporto.
Si procede quindi ad indagare la possibilità di aumentare l’efficienza di emissione di luce di sistemi organici molecolari mediante l’introduzione di un nuovo sistema host-guest con proprietà di lasing ottenuto sublimando un derivato diarilfluorenico (T3, donore) con una noto colorante emettitore nel rosso (DCM, accettare).
In questa soluzione solida binaria, si verifica un efficiente trasferimento di energia alla Förster tra la matrice di T3 e le molecole di colorante quando la concentrazione di colorante viene opportunamente ottimizzata. Inoltre, la soglia di emissione spontanea amplificata del campione avente le molecole di DCM disperse al 2% in peso nel T3 risulta quasi un ordine di grandezza più bassa rispetto a quella del campione modello misurato nelle stesse condizioni sperimentali avente la stessa concentrazione in peso si molecole di DCM disperse in una matrice di Alq3.
La possibilità di combinare diverse proprietà funzionali in un unico dispositivo risulta di notevole interesse per un ulteriore sviluppo dell’elettronica organica nei componenti integrati e nei circuiti. Si è dimostrato che i transistor organici ad emissione di luce sono capaci di combinare in un singolo dispositivo le proprietà di switch dei transistor ad effetto di campo con la capacità di generare luce.
Quando i materiali organici vengono utilizzati come strati attivi nei dispositivi, le interfacce formate dai diversi materiali assumono un ruolo di primaria importanza. La comprensione dei processi fisici che avvengono ad ogni interfaccia è cruciale per disegnare nuovi materiali per dispositivi o per aumentare le prestazioni quelli già esistenti.
In questo lavoro di tesi viene presentato un nuovo approccio per realizzare transistor ambipolari ad emissione di luce. Nell’eterogiunzione che viene proposta il primo e il terzo strato sono dedicati al trasporto di portatori di carica (elettroni e lacune) per effetto di campo mentre il secondo strato è formato da una soluzione solida host-guest che mostra efficiente emissione di luce ed emissione spontanea di luce se pompata otticamente.
La specificità dell’approccio che presentiamo è che le regioni di trasporto di carica sono fisicamente separate da quella in cui avviene la formazione dell’eccitone. In questo modo viene ridotta completamente l’interazione tra l’eccitone e il portatore di carica.
Dopo aver ottimizzato il trasporto di carica e le proprietà di emissione di luce, si è potuto realizzare un dispositivo basato sull’eterogiunzione a tre strati che presenta valori di mobilità per gli elettroni e le lacune bilanciati (~10-1-10-2 cm2/Vs), alta densità di portatori di carica in corrispondenza del massimo di elettroluminescenza (~ 1 KA/cm2) e intensa emissione di luce.
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Al-Amin, Chowdhury G. "Advanced Graphene Microelectronic Devices." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2512.
Full textAbstract:
The outstanding electrical and material properties of Graphene have made it a promising material for several fields of analog applications, though its zero bandgap precludes its application in digital and logic devices. With its remarkably high electron mobility at room temperature, Graphene also has strong potential for terahertz (THz) plasmonic devices. However there still are challenges to be solved to realize Graphene’s full potential for practical applications.
In this dissertation, we investigate solutions for some of these challenges. First, to reduce the access resistances which significantly reduces the radio frequency (RF) performance of Graphene field effect transistors (GFETs), a novel device structure consisting of two additional contacts at the access region has been successfully modeled, designed, microfabicated/integrated, and characterized. The additional contacts of the proposed device are capacitively coupled to the device channel and independently biased, that induce more carriers and effectively reduce access resistance.
In addition to that, in this dissertation, bandgap has been experimentally introduced to semi-metallic Graphene, by decorating with randomly distributed gold nano-particles and zinc oxide (ZnO) nano-seeds, where their interaction breaks its sublattice symmetry and opens up bandgap. The engineered bandgap was extracted from its temperature dependent conductivity characteristics and compared with reported theoretical estimation. The proposed method of device engineering combined with material bandgap engineering, on a single device, introduces a gateway towards high speed Graphene logic devices.
Finally, THz plasmon generation and propagation in Graphene grating gate field effect transistors and Graphene plasmonic ring resonators have been investigated analytically and numerically to explore their potential use for compact, solid state tunable THz detectors.
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Gagliardi, Alessio. "Theoretical modeling and simulation of electron-phonon scattering processes in molecular electronic devices." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=98556282X.
Full text
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Zhang, Zhigang. "Modeling, analysis and control of quantum electronic devices." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1811.
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Texidó, Bartes Robert. "Novel electronic stretchable materials for future medical devices." Doctoral thesis, Universitat Ramon Llull, 2017. http://hdl.handle.net/10803/402945.
Full textAbstract:
L’electrònica convencional basada en el silici te grans dificultats a l’hora de ser implementada en dispositius electrònics que estiguin en contacte amb les corbes i las plasticitat dels teixits del cos humà. Futures aplicacions mèdiques como la pell electrònica, sistemes de alliberació de fàrmac transdèrmic o nous bio-sensors requereixen de sistemes electrònics capaços de ser doblegats, retorçats o enrotllats en superfícies corbes. Tot i els prometedors resultats mostrats por la investigació en electrònica flexible, no hi ha aplicacions comercials directes dins de l’àrea mèdica. La dependència de components només presents en l’electrònica convencional limita el complet desenvolupament d’aquests dispositius posant de manifest la necessitat de trobar nous materials en aquest camp.
Amb l’objectiu de potenciar nous sistemes electrònics flexibles, en aquest treball es proposen noves estratègies per proveir de flexibilitat als materials utilitzats en electrònica sense perdre de vista la directa aplicabilitat. Primerament, s’ha estudiat l’aplicació de polímers conductors mitjançant impressió inkjet. Aquesta tecnologia permet l’obtenció de films polimèrics molt fins sobre sistemes flexibles més complexos. Anant un pas més enllà, s’han desenvolupat noves metodologies per poder depositar polímers conductors sobre substrats elastomèrics mantenint el bon rendiment elèctric. Aquesta part culmina amb l’estudi d’un nou polielectròlit per la síntesis del polipirrol basat en l’àcid hialurònic modificat amb grups dopamina. Aquest polielectròlit aporta noves propietats que milloren l’adaptabilitat del polipirrol obtenint nanosuspensions estables que poden ser depositades directament sobre substrats elastomèrics.
Centrant-nos en los materials metàl·lics de la electrònica, s’ha desenvolupat un mètode per la deposició selectiva de plata conductora sobre substrats elastomèrics. Les pistes fabricades amb aquest procediment han demostrat un comportament de galga extensomètrica sota deformació mecànica.
Finalment la aplicabilitat de las estratègies desenvolupades ha estat avaluada per veure como es poden aplicar en dispositius mèdics actuals y futurs tals como sensors fisiològics, galgas extensomètriques portables para seguiment o nous stents de tràquea electrònics.<br>La implementación de la electrónica convencional basada en el silicio en dispositivos electrónicos que entren en contacto con la plasticidad y las curvas de los tejidos del cuerpo humano presenta serias dificultades. Futuras aplicaciones médicas como la piel electrónica, sistemas de liberación de fármaco transdérmico o nuevos bio-sensores requieren sistemas electrónicos capaces de ser doblados, retorcidos o enrollados en superficies curvas. A pesar de los prometedores resultados mostrados por la investigación en electrónica flexible, muy pocas tecnologías se han visto adaptadas en una aplicación comercial dentro del área médica. Problemas como la dependencia de componentes solo presentes en la electrónica convencional limita el completo desarrollo de estos dispositivos poniendo de manifiesto la necesidad de encontrar nuevos materiales en este campo.
Con el objetivo de potenciar nuevos sistemas electrónicos flexibles, este trabajo propone nuevas estrategias para aportar flexibilidad a los materiales empleado para la electrónica sin perder de vista su aplicabilidad. Primeramente, se ha estudiado la aplicación de polímeros conductores usando impresión inkjet. Esta tecnología permite la obtención de films poliméricos muy delgados sobre sistemas flexibles más complejos. Dando un paso más allá, se han desarrollado nuevas metodologías para poder depositar polímeros conductores sobre substratos elastómericos manteniendo un buen rendimiento eléctrico. Esta parte culmina con el estudio de un nuevo polielectrolito para la síntesis del polipirrol basado en el ácido hyaluronico modificado con dopamina. Este polielectrolito aporta nuevas propiedades que mejoran la adaptabilidad del polipirrol obteniendo nanosuspensiones estables que pueden ser depositadas directamente sobre substratos elastómeros.
Estudiando también los materiales metálicos en la electrónica, se ha desarrollado un método para la deposición selectiva de plata conductora sobre substratos elastómeros. Las pistas fabricadas con este procedimiento han mostrado un interesante comportamiento de galga extensométrica cuando son sometidas a una deformación.
Finalmente, la aplicabilidad de las estrategias desarrolladas ha sido evaluada para ver cómo se puede aplicar en dispositivos médicos actuales y futuros tales como sensores fisiológicos, galgas extenso métricas portables para seguimiento o nuevos stents traqueales electrónicos.<br>Conventional electronics based in rigid and planar silicon wafers presents several difficulties to be implemented in systems where a direct contact with the soft and curved geometries of the tissues of the human body is required. The future medical devices such as electronic skin, transdermal drug delivery systems or novel wearable biosensors requires electronic materials with the ability to be twisted, folded and conformably wrapped onto arbitrarily curved surfaces. Despite the promising results on stretchable electronic research, the applications have not yet been translated into commercial medical devices. The dependence of components still only present in conventional silicon electronics limits the full development of the stretchable strategies, revealing the need for new materials in this field.
Aiming to potentiate new electronic stretchable systems, this works proposes novel strategies to provide stretchability to electronic materials always having in mind the final application. Firstly, the study of conducting polymers to be deposited using ink jet printing have been performed. This kind of implementation allows the formation of conductive thin films on more complex flexible systems. Going further, it has been developed novel methodologies using plasma treatments to fabricate conducting polymeric coating on stretchable substrate with good electrical performance. The culmination of this part consisted in the synthesis of polypyrrole with a novel polyelectrolyte based on a hyaluronic acid modified with dopamine groups that allows stable nanosuspension able to directly form a film onto stretchable substrates.
Focusing on metallic materials, conductive silver deposition on selective stretchable substrate have been developed. The electrical performance under mechanical deformation revealed strange gauge sensor behaviour of the silver paths with promising applicability in the medical device.
Finally, the applicability of the approaches developed in this work have been studied to evaluate its suitability on actual and future applications in the field of medical devices such as physiological sensors, wearable strain gauge sensors or tracheal stent able to monitor deformations.