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 22 for “"multiple quantum wells"”.
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Long wavelength infrared detectors utilizing multiple quantum wells in III-V compound semiconductors
… presented on various 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 …
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Design and application of a soft X-ray detector using GaAs multiple quantum wells
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
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Growth and Behaviors of InN/GaN Multiple Quantum Wells by Plasma-Assisted Molecular Beam Epitaxy
… and many detrimental alloying problems. InN/GaN multiple quantum wells (MQWs) and super lattices (SLs) are expected to be promising alternatives to random InGaN alloys since in principle they can achieve the equivalent band gap of InGaN random alloys with arbitrarily high In-content and at the …
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Quasi-two-dimensional phenomena at AlGaAs-GaAs heterointerfaces, multiple quantum wells and modulation-doped structures
… at AIGaAs-GaAs heterointerfaces related to multiple quantum wells and modulation-doped structures. In the first section. two important results concerning multiple quantum well systems are described: optical absorption coefficients and exciton oscillator strengths in AIGaAs-GaAs multiple …
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Quasi-Two-Dimensional Phenomena at Aluminum-Gallium - Arsenide - Gallium-Arsenide Heterointerfaces: Multiple Quantum Wells and Modulation-Doped Structures (Superlattice, Modfet, Semiconductors)
… at AlGaAs-GaAs heterointerfaces related to multiple quantum wells and modulation-doped structures. In the first section, two important results concerning multiple quantum well systems are described: optical absorption coefficients and exciton oscillator strengths in AlGaAs-GaAs multiple …
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I. Excitonic phase diagram in Si: evidence for two condensed phases ; II. Motion of photoexcited carriers in GaAs/Alx̳Ga1̳-̳x̳As multiple quantum wells : anomalous confinement at high densities
… of Photoexcited Carriers in GaAs/AlxGal-xAs Multiple Quantum Wells-Anomalous Confinement at High Densities We have measured the in-plane motion of photoexcited carriers in semiconductor quantum wells with 5 {lm spatial and 10 ps temporal resolution and have discovered several surprising …
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I. Excitonic Phase Diagram in Silicon: Evidence for Two Condensed Phases. II. Motion of Photoexcited Carriers in Gallium-Arsenide/aluminum(x)gallium(1-X)arsenide Multiple Quantum Wells--Anomalous Confinement at High Densities
This thesis describes work on the thermodynamics and transport properties of photoexcited carriers in bulk and two-dimensional semiconductors. Two major topics are addressed.
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Growth and characterization of mid-infrared phosphide-based semiconductor diode lasers
… Ino.85 Gao.15As/Alo.1Ino.4 8Gao.42As strained multiple quantum wells structures have being built on InP substrates. Structural, optical, and electrical properties of the material have being tested and summarized.
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Nanostructures for Coherent Light Sources and Photodetectors
… including single semiconductor epilayers, multiple quantum wells, and graphene-semiconductor heterostructures to develop coherent light sources and photodetectors in silicon. To develop coherent light sources, we reported the demonstration of room-temperature lasing at the technologically …
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Investigation of carrier dynamics in InN, InGaN, and GaAsBi by optical pump-probe techniques /
… photo-excitation levels in MOCVD-grown InGaN multiple quantum wells. Transient grating measurements in MBE-grown GaAsBi layers with different Bi content revealed that Bi induced potential fluctuations determine the tenfold decrease in nonequilibrium hole mobility, if compare to GaAs.
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Theoretical investigation of metal-cavity nanolasers and nanoLEDs and comparison with experiments
… from calculating its gain profile of coupled multiple quantum wells (MQWs) and fit the experimental light output power versus the current (L-I) curve using the rigorous rate equations with temperature dependence. Our study shows that the nonradiative recombinations, including the surface …
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Theory of terahertz intervalence band polaritons and antipolaritons.
… This model is applied to GaAs/Al[0.3]Ga[0.7]As multiple quantum wells embedded in a microcavity. The energy dispersion relations leading to THz polaritons and antipolaritons are obtained and investigated for different carrier densities and cavity configurations. Recently, intersubband based THz …
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Expanding ultrafast photoacoustics for investigation of mechanical properties and thermal transport
… film, and strained piezoelectric InGaN/GaN multiple quantum wells were used as transducers. Acoustic wave detection methods included monitoring of optical transmittance/ reflectance, polarization, and diffraction over time. A magnetostrictive material galfenol (Fe₁₋[subscript x] Ga[subscript …
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Comparative study of dilute nitride and bismide sub-junctions for tandem solar cells
… designs which include p-i-n bulk and p-i-n multiple quantum wells (MQWs), and n-i-p-i structures are studied comparatively. Performance in this context refers to: the magnitude and quality of the dark current generated by the devices, the spectral response of the solar cells especially in …
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Integrated Inp Photonic Switches
… optical beam steering device based on InGaAsP multiple quantum wells is also demonstrated. The degree of lateral current spreading is easily regulated by controlling the zinc depth, allowing optimization of the injected currents. Beam steering over a 21 microns lateral distance with electrical …
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Excitonic optical nonlinearities in semiconductors and semiconductor microstructures.
… optical nonlinearities as one goes from bulk to quantum-confined structures. Included are experimental studies of molecular-beam-epitaxially-grown bulk GaAs and ZnSe, GaAs/AlGaAs multiple-Quantum-Wells (MQW's), and finally, quantum-confined CdSe-doped glasses. The microscopic origins and …
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Microscopy of porous nitride materials for long wavelength light emitting diodes
… a pseudo-substrate for the overgrowth of InGaN multiple quantum wells (MQWs). Partial strain relaxation with respect to the GaN buffer layer has been achieved in the InGaN SL template via porosification, and this strain relaxation also results in relaxation of the overgrown InGaN MQWs. The …
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The transistor-injected quantum cascade laser
Since its invention in 1994 the quantum cascade laser has become the most important coherent emission source for mid-infrared and terahertz ranges. The quantum cascade laser is a unipolar semiconductor laser that utilizes electron transitions between quantized states in the conduction band for …
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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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Investigation of intracavity phase interferometry applied to nano-metrology
… first one is a Nd:YVO4 laser, mode-locked by a multiple quantum wells (MQW) saturable absorber. The presence of a solid state saturable absorber introduced a dead band in the beat note response of the system. A new coupling between group and phase velocity was discovered experimentally, and …
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