Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 174 for “"charge carriers"”.
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Nanocarbons as charge carriers in organic solar cells
… to the enhancement of OPV performance, such as charge carrier mobility, thermal conductivity, mechanical strength, increased optical absorption and solubility in organic solvents. Nanocarbons also can improve the morphology of the active layer, which is critical to the optimization of OPV …
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Polaronic charge carriers and their optical excitations in insulating La₂CuO₄ây̳
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1993.
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Discovery of a Pseudogap Attributed to Charge Density Wave Order at the β-β′ Phase Transition in As2Te3 and the Influence of Cu and Ge Doping on its Properties
… β-As2Te3 to β'-As2Te3 phase transition is due to charge density wave order. This charge density wave transition is observed to be tunable with both Ge and Cu doping, with evidence indicating that the increase in the number of charge carriers due to doping drives the transition temperature lower …
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VISIBLE-LIGHT-ACTIVE SEMICONDUCTOR HETEROJUNCTIONS FOR ENHANCED PHOTOCATALYTIC ACTIVITY
… band gap (h Eg). The resulting photo-excited charge carriers can either recombine with no activity or migrate to the surface of the semiconductor without recombination, where they can be involved in redox processes. The photocatalytic efficiency depends on the number of charge carriers taking …
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Charge Storage Mechanism of Redox Polymers for Energy Storage
… of this dissertation is to investigate the charge storage mechanism of three n-type polymers by electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D). The solvation structures of charge carriers and swelling behaviors of polymers were investigated, and their …
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Analysis of Energy-Transport Models for semiconductors
… we study the energy transport models of the charge carriers in the semiconductors, in the unipolar and one-dimensional case. These are macroscopic models, that are useful to describe the thermal eff ects in the semiconductor devices. Usually the set of equations are given by the balance …
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Designing a Simulator for an Electrically-Pumped Organic Laser Diode
… for optical gain. The challenge occurs when charge carriers appear in the organic material. The charge carriers must reach a concentration such that population inversion occurs producing optical gain. However, between the overlapping emission and absorption spectra of the organic material and …
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Thermoelectric Properties and Transport of Semicrystalline Conjugated Polymer and Single-Wall Carbon Nanotube Composites
… and to achieve a good understanding of their charge transport mechanisms. Through investigating the s-SWCNT:PBTTT model system, some general design guidelines for optimising the power factor and figure of merit of CNT:polymer based composites are established. Charge accumulation spectroscopy …
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Critical behavior and transport properties of lanthanum manganite
… thermally activated hopping of polarons. The charge carriers appear to consist of two different types which add according to the Nordheim-Gorter rule. The mixing fraction of the two populations around the transition temperature can be extracted with an effective medium approach. Magnetization …
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Quantum transport in graphene heterostructures
The two dimensional charge carriers in mono- and bilayer graphene are described by massless and massive chiral Dirac Hamiltonians, respectively. This thesis describes low temperature transport experiments designed to probe the consequences of this basic fact. The first part concerns the effect of …
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Field effect investigations of charge carrier transport in organic semiconductors
… conventional technologies. The understanding of charge transport in these materials and minimizing electrical losses in organic devices is essential to improve device output. In this thesis the transport properties of charge carriers in solution processed organic semiconductors were investigated …
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Magneto-thermal Transport and Machine Learning-assisted Investigation of Magnetic Materials
… quasiparticles in crystals, including phonons, charge carriers, and magnetic excitations. In most materials, thermal transport can be understood as the flow of phonons and charge carriers; magnetic heat flow is less well-studied and less well understood. Recently, the concept of the flat band, …
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Growth and electronic properties of gallium arsenide and germanium metal insulator semiconductor structures
… does not stand out in its ability to pass charge carriers with the highest speed. Significant improvements in the performance of many areas of electronics would result if another, high mobility semiconductor could be implemented into a high quality MIS structure.
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Charged ferroelectric domain walls: the next generation in 2D functional materials
… present my investigations into the properties of charge carriers in conducting ferroelectric domain walls in single crystals of YbMnO3, ErMnO3 and lithium niobate. <br/><br/>Through the use of atomic force microscopy (AFM), electron microscopy and electrical measurements I measured Hall mobility …
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Design of Multilayer Optical Media: Organic Photovoltaics and Optical Data Storage
… is converted to electric current by generating charge carriers in semiconductors. These charge carriers are then moved to opposing electrodes generating an electric current. These components: semiconductor, electrodes, and a supporting substrate form a layered optical system that can be …
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CHARGE TRANSPORT IN ORGANIC AND HYBRID PEROVSKITE FIELD EFFECT TRANSISTORS
… layers generates trapping states and localize charge carriers, leading to a surprising universal scaling between the activation energy of the devices and the interfacial thermal expansion mismatch coefficient.
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Anomalous Hall effect and persistent valley currents in graphene p-n junctions/
… a detailed picture of this unusual effect for charge carriers in graphene nanostructures. The Hall effect is nonzero in each valley but is of opposite signs in different valleys, giving rise to charge-neutral valley currents. Our analysis reveals that p-n junctions in graphene support …
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An Investigation of Contact Electrification and Triboelectric Charging in Insulating Materials
… materials by definition do not have free charge carriers and it is not obvious how charge can be transferred. Due to the often deleterious effects of triboelectricity, establishing a fundamental understanding is desired. In this research, we investigated two aspects of triboelectric …
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Investigations of the electronic, vibrational and structural properties of single and few-layer graphene
… by 30-femtosecond laser pulses, we find that the charge carriers in graphene cool by the emission of strongly coupled optical phonons in a few 10's of femtoseconds and thermalize among themselves even more rapidly. The charge carriers and the strongly coupled optical phonons are thus essentially …
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