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 57 for “"2DEG"”.
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Ultra-high Mobility 2DEG Heterostructure Fabricate by Oxide Molecular Beam Epitaxy for Device Application
… with two-dimensional electron gas (2DEG) interface have been reported with remarkable electron transport properties, which is the demand for application of wide bandgap semiconductor devices in modern power electronics industries. Both LaAlO3 and SrTiO3 are stable insulators with …
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The effect of a top gate voltage on the Quantum Hall measurement of a 2DEG InGaAs/InAlAs hetero-structure
The main purpose of this thesis is to investigate the quantization of the Hall resistance "Rxy " as well as the Shubnikov De Haas oscillations of the longitudinal "Rxx " resistance in a two dimensional electron system at different gate voltages. The sample measured utilised the InGaAs/InAlAs …
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Nonlinear transport in two-dimensional electron gas at large filling factors.
… transport in high-mobility 2D electron gas (2DEG) forming in modulation-doped GaAs/AlGaAs quantum wells. Transport nonlinearities induced by a pure dc electric field as well as by coexisting dc and microwave fields were studied at very high Landau level filling factors. It was observed that a …
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Investigations of the quantum Hall effect in graphene
… Hall effect in the two-dimensional electron gas (2DEG); we review and discuss the Hartree-Fock method which has been successfully used to investigate various aspects of the quantum Hall effect in the 2DEG. We then utilize the Hartree-Fock method to investigate the quantum Hall effect in graphene …
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Electrostatic simulations of interactions between a scanning probe and quantum Hall liquid
… group [1]. The main interest was to explore the 2DEG charge densities for a different system geometries, magnetic field applied, and tip voltages. We modelled quantum bubble formation under the metal probe, incompressible strip formation beneath the edge of the metal gate, and 2DEG density …
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AlGaN/GaN heterostructures for enhancement mode transistors
… cui si forma un gas bidimensionale di elettroni (2DEG). Basandosi sulla presenza del 2DEG, le eterostrutture AlGaN/GaN sono particolarmente interessanti per la realizzazione di transistori ad elevata mobilità di elettroni (HEMT). Inoltre, dispositivi AlGaN/GaN HEMT che lavorino in modalità di …
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Competing polar and nonpolar distortions and phase transitions in low-dimensional materials
… the formation of a two-dimensional electron gas (2DEG) which screens the polar discontinuity there. In spite of the interest, tunability, and very special properties of the 2DEG, important uncertainties remain about the character of the metal--insulator transition induced by film thickness and/or …
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Theoretical study of polar complex oxide heterostructures
… conductivity is quasi-two-dimensional (a 2DEG) and under certain conditions magnetic and/or superconducting, however its origin is still debated. This thesis aims to provide helpful guidelines, using basic theoretical principles, towards understanding the possible origins of the 2DEG in …
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Cooling an electron gas using quantum dot based electronic refrigeration
Studies of two-dimensional electron gases (2DEGs) in semiconductors form an active and productive field of condensed matter physics research. As well as having interesting inherent properties, they are used as the foundation for constructing various nano-scale electronic devices, such as quantum …
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AlGaN/GaN HFET with composite 'slow/fast' gate
… high-density two dimensional electron gas (2DEG) channel, high breakdown fields, temperature stability and chemical robustness. Radio Frequency (RF) switches based on such HFETs demonstrate very low insertion loss, high power handling capability and broad range of operating temperatures. …
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Quantum Monte Carlo: Applications of the Twist -Averaged Boundary Conditions and the Calculation of Forces
… gas (3DEG), the two dimensional electron gas (2DEG), the liquid 3He and the electronic surface. We studied the spin polarization transition of 3DEG with optimized wavefunctions including backflow and three-body correlations. We found electrons spontaneously polarize at low densities. The …
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Electron transport in confined structures in very high mobility GaAs in perpendicular magnetic fields
… GaAs/AlGaAs two-dimensional electron gas (2DEG). In the first set of experiments, we study the suppression of the spin splitting of the Landau levels in QPCs compared to the bulk 2DEG. By using QPCs with different lithographic widths and varying the voltage applied on the gates, we can …
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Quantum Monte Carlo: Applications of the Twist-averaged Boundary Conditions and the Calculation of Forces
… gas(3DEG), the two dimensional electron gas(2DEG), the liquid 3He and the electronic surface. We studied the spin polarization transition of 3DEG with optimized wavefunctions including backfiow and three-body correlations. We found electrons spontaneously polarize at low densities. The …
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Growth-induced non-stoichiometry in complex oxide systems
… presence of a 2-dimensional electron gas (2DEG). Our results indicate that the presence of cation defects in the LaAlO3 has a profound impact on the electronic properties of the 2DEG interface. Finally, we have similarly shown that cation non-stoichiometry can cause the …
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Terahertz waveguide spectroscopy of two-dimensional plasmons in GaAs
… of high-mobility, two-dimensional electron gas (2DEG) systems, such as GaAs quantum wells, have been well-studied at low frequencies and in extreme conditions of high magnetic fields and ultralow temperatures. While high-frequency excitations of 2DEGs have been examined to some extent from …
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Structure-Property Relationships in Nitride Electronic Devices
… having similar two-dimensional electron gas (2DEG) sheet carrier density but different AlxGa1-xN barrier layers are compared using the two developed techniques. The thicker AlxGa1-xN barrier layer with a lower Al content leads to a more homogeneous Vth distribution. The cross-section of a …
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Time-domain terahertz magneto-spectroscopy of semiconductors
… a high-mobility two-dimensional electron gas (2DEG) in a GaAs quantum well and lightly-doped InSb. In the 2DEG, I have observed very long-lived (up to ∼ 50 ps) coherent THz oscillations, which correspond to a time-domain observation of cyclotron resonance. From the data both the real and …
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First Principles Studies of Magnetic Oxides, Spin-Driven Ferroelectricity, and the Effect of Polarization in the Chemistry of Functional Heterointerfaces
… the emergence of two-dimensional electron gas (2DEG) at the interface, is investigated to explain the experimental observation of a surface chemically switchable luminescence process after water treatment. We determine that water dissociates at the surface of LaAlO$_{3}$/SrTiO$_{3}$, which leads …
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Determining Energy Relaxation Length Scales in Two-Dimensional Electron Gases
… systems such as two-dimensional electron gases (2DEGs). This is problematic because the electron temperature, Te, is often of far greater importance than TL in such systems. Recent efforts have been made to develop thermometry techniques that are directly sensitive to Te. These techniques include …
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Investigation of lateral gated quantum devices in Si/SiGe heterostructures
… may be more favorable to supply electrons in the 2DEG through capactive gating, instead of a delta doping layer. We therefore discuss efforts to fabricate Si/SiGe quantum dots from undoped heterostructures and the difficulties encountered. A new method for fabricating ohmics in undoped …
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