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 128 for “"effective mass"”.
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Hole mobility and effective mass in SiGe heterostructure-based PMOS devices
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
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Calculation of the optical conductivity for the Anderson impurity model using the slave boson technique
… level . This method has been used to find the effective mass of the conduction electrons for temperatures above and below the Kondo tempera ture. For low temperatures, the mass enhancement is f ound to be large while a t high t emperatures, the mass enhancement is sma ll. The conductivity i s f …
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Quantum capacitance in scaled down III-V FETs
… a very promising technology. In particular, low-effective mass materials with high electron velocities, such as InGaAs and InAs are of great interest. A concern with this approach is the relatively small inversion-layer capacitance that is associated with a low-effective mass channel and the …
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Interdimensional effects in systems of fermions
… propagation properties through a change in effective mass, and two-dimensional quantum well, analytic models allow for the calculation of the density of states inside the low-dimensional substructure. The density of states describes the availability of charge carriers in a given material, …
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Accurate Treatments of Electronic Correlation: Phase Transitions in an Idealized One-Dimensional Ferroelectric and Modelling Experimental Quantum Dots
… on realistically modelled quantum dots in the effective mass approximation. The potentials of these dots are determined using the FEM method to solve Poisson's equation and the effective mass is allowed to spatially vary in our QMC simulations. We find that in arrays of QD's, LSDA may be …
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Photon-induced tunneling in graphene-boron nitride-graphene heterostructures
… (holes) with an intrinsic barrier height and effective mass of 1.33eV and 1.1 9me, respectively. These numbers agree well with theoretical calculations of the offset between the top of the valence band in boron nitride and the charge neutrality point in graphene, and the effective mass of …
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The anisotropy of the upper critical field of chevrel phase compounds
… in the (001) plane. The data were fit to the effective mass model with uniaxial symmetry. A two-fold symmetry was observed in the Cu1.sMo6S8 in the (2TO) plane. Oscillations with three-fold symmetry have been observed for the first time in the (001) plane. The effective mass model was unable …
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Effects of Bottom Chord Extensions on the Static and Dynamic Performance of Steel Joist Supported Floors
… natural frequency, damping, mode shape and effective mass, extensive analytical and experimental studies were conducted on single span and three span joist supported laboratory footbridges with different bottom chord extension configurations. Finite element computer models were created to …
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Impurities in a Bose-Einstein condensate using quantum Monte-Carlo methods: ground-state properties.
… well depth. We calculate the binding energy, the effective mass and the pair correlation functions of a impurity along the attractive and the repulsive polaron branch. In particular, at the unitary limit of the impurity-bosons interaction, we find that the binding energy is much larger than the …
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Feasibility study of air catcher for natural ventilation application
… removing stale air. Natural ventilation is an effective method to save energy required to condition building and to improve indoor air quality. It is widely recognized as contributing in low energy building design. In present work, five types of low Reynolds number airfoils were used to design …
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Electroabsorption effects near the direct and indirect edges of germanium
… gap agrees with the theory derived from an effective mass approximation. Analysis of the data below the gap resulted in an effective mass of 0.022 m at room temperature and 0.024 m at the lower temperatures. The amplitude of 6a is very sensitive to the temperature, while the shape of the …
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Effect of temperature on tunneling and quantum efficiency in cigs solar cells
… by including the temperature-dependent effective masses and nonparabolicity effects, an investigation of the temperature dependent band-to-band tunneling process is discussed. In comparison with the parabolic approximation and non- parabolic approximation, the tunneling probability is …
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Interplay between chemical bonding, band structure and charge transport in thermoelectric chalcogenides
… GexSn1-xTe alloys. The strong anisotropy of the effective mass tensor of the relevant charge carriers is found to be the underlying mechanism. Other aspects of charge transport are also studied. Afterwards, a tight-binding model is defined for the band structure of crystalline group IV …
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Head Acceleration Measurements in Helmet-Helmet Impacts and the Youth Population
… on helmet-helmet impacts, and the difference in effective mass and head acceleration measurements between the striking player and the struck player. The study involved working with football players outfitted with a sensor integrated into their helmets containing a 6 accelerometer array, capable …
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Theoretical studies of the optoelectronic properties of semiconductor quantum wells
… well is calculated based on the multiband effective-mass theory. A unitary transformation is found to diagonalize the six-by-six Luttinger-Kohn Hamiltonian into two three-by-three blocks, making the computation more efficient. With this new formulation, the effect of strain on the band …
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Exploring Matter-wave Dynamics with a Bose-Einstein Condensate
… potential is in fact characterized by the bare mass, and only over timescales long compared to that of interband dynamics is the usual effective mass an appropriate description. This breakdown of the effective mass description on fast timescales is difficult to observe in traditional solid state …
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Determination of the complex mass density of air contained in a rigid porous solid by an acoustic method
… for determining the frequency dependent complex effective mass density p(eff) of air contained in a rigid porous solid is investigated. An apparatus was designed and built which holds an air-filled porous solid sample within a cylindrical tube capped on each end by identical moving-coil …
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Thermal Conductivity of Tl(2)Ba(2)CuO(6+delta) and Fluctuation Diamagnetism of YBa(2)Cu(3)O(6+x)
… more anisotropic samples. Within the anisotropic-effective-mass 3D-XY model, the change in anisotropy with reduced transition temperature is directly related to the magnitude of the fluctuation signal at T$\sb{\rm c}.$ It is found that both the ratio $\gamma$ = (m$\sb{\rm c}$/m$\sb{\rm …
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High-Pressure Studies of Some Heavy Fermion Materials
… hosting a heavy fermion state with a large effective mass and antiferromagnetic order. Antiferromagnetism can be suppressed to a quantum critical point around 30 kbar, where there exists a dome of superconductivity with Tc ≈ 0.2 K. Chapter 3 focuses on this superconducting phase, which has a …
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