Sökning: "quantum wells"
Visar resultat 1 - 5 av 68 avhandlingar innehållade orden quantum wells.
Sammanfattning : In this thesis, spectroscopic studies of quantum wells (QWs), quantum wires (QWRs) and quantum dots (QDs) in III-V semiconductors are presented. The electronic structure of these low-dimensional structures have been studied by absorption, photocurrent, electroreflectance, photoluminescence (PL), and photoluminescence excitation (PLE) spectroscopy. LÄS MER
Sammanfattning : This dissertation deals with the optical properties of Quantum Cascade Lasers (QCLs). Studies are performed using transport calculations employing the theory of Non-Equilibrium Green's Functions, and screening is studied within the Random Phase Approximation. Focus is put on the temperature dependent effects in THz QCLs. LÄS MER
3. Surface-normal multiple quantum well electroabsorption modulators : for optical signal processing and asymmetric free-space communication
Sammanfattning : Electroabsorption is the physical phenomenon by which the absorption of light in a medium can be controlled by applying an electric field. The Quantum–Confined Stark Effect, which makes the absorption band–edge in quantum wells very field–dependent, together with the strong absorption peak provided by excitons, are the physical foundations for the success of electroabsorption modulators based on quantum well structures in telecommunication networks. LÄS MER
Sammanfattning : Metalorganic vapour phase epitaxy is used for growth of low-dimensional III-V semiconductor structures. The roughness of heterointerfaces in GaAs/GaInP quantum well structures is studied by photoluminescence emission from extremely narrow quantum wells. LÄS MER
Sammanfattning : Today, semi-conductor nanowires can be grown with very high precision, using epitaxy. This allows for studies of new nanowire-based quantum devices, likely to be part of novel quantum technologies in the future. This thesis concerns nanostructures based on InAs nanowires. LÄS MER