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1	Spatial Dynamics of Wave Packets in Semiconductor Heterostructures / Räumliche Wellenpaketdynamik in Halbleiterheterostrukturen Meinhold, Dirk 11 June 2005 (has links) (PDF) This thesis presents the first study of the damping of a Bloch oscillating wave packet by Zener tunneling to above-barrier states [1]. We investigate the time evolution of an below-barrier subband Wannier-Stark wave packet in a strongly coupled GaAs/AlGaAs superlattice (SL) with shallow quantum well barriers by optical interband spectroscopy. We use a sub-100 fs homodyne pump-probe technique which is sensitive to the intraband polarization. The presented experimental data unambiguously show an electric field-dependent continuous decrease of the intraband coherence time. Besides the continuous field-induced damping of the intraband polarization, we observe the signature of resonant Zener tunneling of a Bloch oscillating wave packet between discrete states belonging to below and above-barrier bands. This coupling manifests itself as a revival of the intraband polarization [2]. The experiment is modelled in two aspects. First, in a 1D single-particle calculation the wave functions the BO wave packet is composed of are derived. Here, the inter-subband dynamics are found to be given by the energetic splitting between nearly-degenerate below and above-barrier states. The wave packet tunnels from the below-barrier band to the above-barrier band while remaining coherently oscillating. At this time, it is spatially spread over more than 100 nm... Bloch Oszillationen Feldinduzierte Delokalisierung Pump-Probe Spektroskopie Resonanter Zener-Durchbruch Wellenfunktionstomographie Wellenpaketdynamik Zener-Durchbruch Übergitter Bloch oscillation Pump probe spectroscopy Zener breakdown field-induced delocalisation field-induced delocalization graded superlattice resonant Zener breakdown superlattice wave function tomography wave packet dynamics ddc:530 rvk:UF 5000 Delokalisierung Dynamik Optische Spektroskopie Schwingung Tomographie Wellenfunktion Wellenpaket Zener-Effekt Übergitter
2	Spatial Dynamics of Wave Packets in Semiconductor Heterostructures Meinhold, Dirk 13 May 2005 (has links) This thesis presents the first study of the damping of a Bloch oscillating wave packet by Zener tunneling to above-barrier states [1]. We investigate the time evolution of an below-barrier subband Wannier-Stark wave packet in a strongly coupled GaAs/AlGaAs superlattice (SL) with shallow quantum well barriers by optical interband spectroscopy. We use a sub-100 fs homodyne pump-probe technique which is sensitive to the intraband polarization. The presented experimental data unambiguously show an electric field-dependent continuous decrease of the intraband coherence time. Besides the continuous field-induced damping of the intraband polarization, we observe the signature of resonant Zener tunneling of a Bloch oscillating wave packet between discrete states belonging to below and above-barrier bands. This coupling manifests itself as a revival of the intraband polarization [2]. The experiment is modelled in two aspects. First, in a 1D single-particle calculation the wave functions the BO wave packet is composed of are derived. Here, the inter-subband dynamics are found to be given by the energetic splitting between nearly-degenerate below and above-barrier states. The wave packet tunnels from the below-barrier band to the above-barrier band while remaining coherently oscillating. At this time, it is spatially spread over more than 100 nm... info:eu-repo/classification/ddc/530 ddc:530

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Spatial Dynamics of Wave Packets in Semiconductor Heterostructures / Räumliche Wellenpaketdynamik in Halbleiterheterostrukturen

Spatial Dynamics of Wave Packets in Semiconductor Heterostructures