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 12 of 12 for “"quantum confined Stark effect"”.
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Theoretical investigation of the quantum-confined Stark effect
… treatment of electronic excitation in large quantum dots and nanoparticles is challenging because of the large number of electrons in the system. The quasiparticle representation provides an alternative representation that can partially alleviate the computational bottleneck associated with …
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Ultrafast carrier dynamics and enhanced electroabsorption in (gallium,indium)arsenide/(aluminum,indium)arsenide asymmetric double quantum well structures
… in (Ga,In)As/Al,In)As asymmetric double quantum wells (ADQWs) is presented. A single time constant is observed at low carrier densities indicating the holes tunnel from the narrow well (NW) to the wide well (WW) at least as fast as electrons. At high carrier densities a two component …
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Optical properties of GaAs coupled quantum wells and superlattices: electric and magnetic field effects
In this thesis the effects of electric and magnetic fields on the optical transmission and reflection spectra of GaAs/ AlGaAs coupled quantum wells and superlattices are investigated and their potential application in optical modulation demonstrated. Quenching and enhancement of excitonic …
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On-chip single photon sources based on quantum dots in photonic crystal structures
… the enormous potential of schemes in optical quantum information processing, readily scalable photonic circuits will be required. A major obstacle for this scalability is the monolithic integration of quantum light sources with the photonic circuit on a single chip. This dissertation presents …
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Optical Characterization of Electrochemically Self-Assembled Compound Semiconductor Nanowires
… peak, which is red shifted, possibly due to quantum confined Stark effect associated with built in charges in the alumina. This feature can be exploited to produce light emitting devices whose frequency can be modulated with an external electric field. Such devices could be novel ultra-violet …
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Growth, processing and chracterization of gallium nitride based coaxial LEDs grown by MOVPE
… m-plane GaN sidewalls, which helps eliminate the quantum confined Stark effect (QCSE) and improve the radiative recombination efficiency of LEDs. The recent evolution of a catalyst free, scalable, repeatable and industrially viable device quality GaN nanowire and nanowall metal organic vapor phase …
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Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes
… and tunable emission colors make colloidal quantum-dot light-emitting diodes (QD-LEDs) interesting for the next generation of display and lighting technologies. However, there still remain various hurdles to the commercialization of QD-LEDs, including their relatively low external quantum …
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Enhancing quantum-dot luminescence in visible and infrared light emitting devices
We investigate how the external quantum efficiency (EQE) of colloidal quantum-dot light emitting devices (QD-LEDs) can be enhanced by addressing in situ QD photoluminescence (PL) quenching mechanisms occurring with and without applied bias. QD-LEDs promise efficient, high colour-quality solid-state …
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Entwicklung von optisch pumpbaren UVC-Lasern auf AlGaN-Basis
… Emissionswellenlänge in den Quantenfilmen (Quantum Wells, QWs) ergibt. Außerdem können die Stufen in den Lasern als Streuzentren wirken und die optischen Verluste erhöhen. Andererseits führen sie aber auch zum Abknicken von Versetzungen und damit zu einer insgesamt reduzierten …
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Growth and optimization of quantum dots-in-a-well infrared photodetectors
Quantum dot infrared photodetectors (QDIPs) have been shown to be a key technology in mid and long wavelength (3-14 μm) infrared detection due to their potential for normal incidence operation and low dark current. In our research group, we have been investigating infrared detectors based on …
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Polarization multiplexed photonic integrated circuits for 100 Gbit/s and beyond
… DP modulation. The EAMs make use of multi-quantum well (MQW) layers, thin sheets of semiconductor that break the symmetry of the InP crystal. The electronic and optoelectronic effects in MQW-based EAMs are studied to verify that the proposed DP EAM can indeed be demonstrated with good …
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Theory and simulation of quantum nanostructures for integrated photonics
Quantum nanostructures such as quantum wells (QWs) and quantum dots (QDs) are employed in a variety of integrated photonic devices, including lasers, electro-absorption modulators (EAMs), single-photon sources, and photodetectors. Theoretical analysis of these devices is required to enable …