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Showing 1 to 20 of 153 for “"Quantum wells."”.
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Sun polarised dynamics in quantum wells
… a photoexcited carrier population in a quantum well by optical pumping methods has enabled us to study the fine structure and some of the parameters governing the spin relaxation dynamics of excitons, heavy-holes and electrons in a number of type I GaAs/AlxGa1-xAs and type I …
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Carrier relaxation in doped quantum wells
The relaxation time of an electron in a quantum well is derived within the random-phase approximation including full multi-subband and frequency dependent screening. The resulting expression encompasses both electron-electron and electron-phonon scattering taking into account the mutual …
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MULTICOLOR INFRARED DETECTION USING STEP QUANTUM WELLS
Quantum well infrared photodetectors (QWIPs) based on intersubband transitions are widely investigated in recent years. Due to the mature III-V material and processing technology, great progress has been made successfully for the fabrication of large scale quantum well infrared focal plane arrays …
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Magneto - optical studies of quantum wells and superlattices
Contains fulltext : mmubn000001_028979664.pdf (Publisher’s version ) (Open Access)
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Electronic and optical properties of semiconductor quantum wells
… optical properties of GaAs-AlGaAs semiconductors quantum wells. The light and heavy hole subbands are strongly hybridized and this subband mixing has important effects on electronic and optical properties. A systematic study of the mixing effects on valence subband structure, exciton binding …
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Exciton transport and thermodynamics in gallium arsenide quantum wells
… transport and energy relaxation of excitons in quantum well systems. I discuss the mechanism of carrier-induced changes in the absorption spectrum of a 210A GaAs multiple quantum well, and show that at moderate densities, the enhanced transmission at the heavy-hole exciton energy is due to …
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Carrier excitations and nonlinear optical effects in semiconductor quantum wells
… nonlinear optical properties of semiconductor quantum-well devices. The generation of terahertz electromagnetic pulses from ultrafast optical pulse excitations of semiconductor heterostructures is studied in the time domain with a three-level model. Coupled optical Bloch equations are derived …
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Theoretical studies of the optoelectronic properties of semiconductor quantum wells
The valence-band structure of a semiconductor quantum 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 …
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Modeling of electroluminescence in InSb quantum wells and inversion asymmetric effects
… mechanisms underpinning electroluminescence from quantum wells. The dissertation contains original contribution of methodological and phenomenological character. We have described in detail the eight band model within the envelope function approximation(EFA) using the Löwd in perturbation method …
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Theory of the optical properties of III-V semiconductor quantum wells
… and optical properties of III-V semiconductor quantum wells, specifically those based on the GaAs-AlGaAs system. Both the linear and non-linear optical properties of these systems are considered. A theoretical model for the refractive index in GaAs-AlGaAs quantum well structures for optical …
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Optical control of polariton condensation and dipolaritons in coupled quantum wells
… strongly couple to indirect excitons in coupled quantum wells. In this system quantum tunnelling of electrons can be controlled with bias voltage. This allows tuning the dipolariton properties optically and electrically, with exciting prospects for future experiments. A conclusion and outlook …
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Effects of asymmetry on electron spin dynamics in gallium arsenide quantum wells
… spin dynamics in gallium arsenide (GaAs) quantum wells, focusing on the effect of inversion asymmetric confinement potentials on spin lifetimes in quantum wells grown on (110)-oriented substrates. Inversion asymmetry in the presence of the spin orbit interaction offers the possibility of …
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Slow Light Based on Quantum Effects in Quantum Wells and Quantum Dots
This is a detailed study of slow light based on quantum effects in semiconductor nanostructures. We propose to implement an optical buffer using semiconductor quantum dots and quantum wells based on coherent population oscillation and spin related electromagnetically induced transparency. We …
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Increasing the Critical Thickness of InGaAs Quantum Wells Using Strain-Relief Technologies
… to fabricate long-wavelength (1.35 mum) InGaAs quantum wells on a GaAs substrate.
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Many-body effects in metals, modulation doped quantum wells and doped semiconductors
… hole, which is realized in modulation doped quantum wells or wires. In this case we approximately diagonalize the Hamiltonian by treating exactly the most important terms leading to nonperturbative behavior. The terms neglected are identified and can be treated in perturbation theory. Our …
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Experimental Realisation of Energy Harvesters built from Quantum Dots and Quantum Wells
… harvester built from two resonant-tunnelling quantum dots. A device, proposed by Jordan et al. [1], harvests energy from an area of 90 μ m2 of a two-dimensional electron gas (2DEG), using the energy-selective transport of electrons through a pair of quantum dots. It has proven to be an …
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Long wavelength infrared detectors utilizing multiple quantum wells in III-V compound semiconductors
… infrared detectors based on multiple GaAs/AlGaAs quantum wells. Due to the great flexibility in the growth, dimensions, and composition of these structures, the electrical and optical characteristics of the photodetector may be significantly altered. This investigation explores both theoretically …
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The growth and microstructural characterization of ZnSe/GaAs quantum wells and double heterostructures
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
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