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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Self-Assembled In0.5Ga0.5As Quantum Dots On Gap, Yuncheng Song, Paul J. Simmonds, Minjoo Larry Lee
Self-Assembled In0.5Ga0.5As Quantum Dots On Gap, Yuncheng Song, Paul J. Simmonds, Minjoo Larry Lee
Paul J. Simmonds
We demonstrate the growth and luminescence of coherently strained In0.5Ga0.5As self-assembled quantum dots on GaP. Cross-sectional and planar-view transmission electron microscopy confirmed the dislocation-free nature of the In0.5Ga0.5As quantum dots and GaP cap layers. Intense photoluminescence from the quantum dots was measured at 80 K and was visible to the unaided eye in ambient lighting. The photoluminescence results show that emission energy can be controlled by varying the In0.5Ga0.5As deposition thickness. In combination with recent advances in the growth of GaP on Si, the In0.5Ga0.5 …
Induced Absorption Dynamics In Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Induced Absorption Dynamics In Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
Two-color pump-probe measurements are used to study the carrier dynamics of InAs/GaAs quantum dots in a waveguide structure under reverse bias conditions. For the case of initially populating the ground state (GS), we find relaxation dynamics that include both absorptive and bleaching components in the excited state (ES) wavelength range. We reproduce the main features of this induced absorption dynamics using a simple model with an additional term for induced absorption at the ES due to carriers injected at the GS. The induced absorption dynamics includes multiple recovery timescales which can be attributed to phonon-assisted processes of GS/ES interaction.
Charge And Energy Transport In Single Quantum Dot/Organic Hybrid Nanostructures, Kevin Thomas Early
Charge And Energy Transport In Single Quantum Dot/Organic Hybrid Nanostructures, Kevin Thomas Early
Open Access Dissertations
Hybrid quantum dot /organic semiconductor systems are of great interest in optoelectronic and photovoltaic applications, because they combine the robust and tunable optical properties of inorganic semiconductors with the processability of organic thin films. In particular, cadmium selenide (CdSe) quantum dots coordinated with oligo-(phenylene vinylene) ligands have displayed a number of hybrid optical properties that make them particularly well-suited to these applications. When probed on an individual particle level, these so-called CdSe-OPV nanostructures display a number of surprising photophysical characteristics, including strong quenching of fluorescence from coordinating ligands, enhanced emission from the CdSe quantum dot core, suppression of fluorescence intermittency, …
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The refractive index dynamics of InAs/GaAs quantum dot based waveguide absorbers is studied using heterodyne pump-probe measurements. Absorption reduction due to the pump can be accompanied by either positive or negative refractive index changes depending on the wavelength used. This change in sign of the phase amplitude coupling can be understood by considering the atomlike nature of the quantum dot transitions involved.
Tensile Strained Iii-V Self-Assembled Nanostructures On A (110) Surface, Minjoo L. Lee, Paul J. Simmonds
Tensile Strained Iii-V Self-Assembled Nanostructures On A (110) Surface, Minjoo L. Lee, Paul J. Simmonds
Paul J. Simmonds
The vast majority of research on epitaxial quantum dots use compressive strain as the driving force for self-assembly on the (001) surface, with InAs/GaAs(001) and Ge/Si(001) being the best-known examples. In this talk, I will discuss our work on determining the feasibility of growing coherent, tensile-strained III-V nanostructures on a (110) surface. GaP on GaAs(110) was chosen as an initial test system. It is hoped that our efforts on self-assembled, tensile-strained dots on a (110) surface will lead the way to new devices exploiting the fundamental differences between the (110) and (001) surfaces. Furthermore it is anticipated that this work …
Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel
Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel
Electronic Theses and Dissertations
The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of …
New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir
New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir
Electronic Theses and Dissertations
The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold …
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur
Electronic Theses and Dissertations
In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits …
Quantum Dot Quantum Computation In Iii-V Type Semiconductor, Sanjay K. Prabhakar
Quantum Dot Quantum Computation In Iii-V Type Semiconductor, Sanjay K. Prabhakar
Legacy Theses & Dissertations (2009 - 2024)
Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and spin of the electron can be manipulated through the application of gate potentials. In the thesis, there are two major contributions of the manipulation of electron spin. In regard to the first contribution, we present numerical simulations of such a spin in single electron devices for realistic asymmetric potentials in electrostatically confined quantum dot. Using analytical and numerical techniques we show that breaking in-plane rotational symmetry of the confining potential by applied gate voltage leads to a significant effect on the tuning …