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Visar resultat 1 - 5 av 19 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. The density-matrix formalism for description of step-wise laser-excitations of atoms and molecules in high-collisional media

    Författare :Peter Ljungberg; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; density-matrix; pulsed lasers; anomalous saturation curved; laser spectroscopy; stark split; degenerate states; rate-equations;

    Sammanfattning : .... LÄS MER

  3. 2. Spatiotemporal carrier dynamics in graphene

    Författare :Roland Jago; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; spatiotemporal dynamics; density matrix formalism; graphene; relaxation dynamics; carrier multiplication; Bloch equations; photoconduction effect; bolometric effect;

    Sammanfattning : Graphene as an atomically thin material exhibits remarkable optical and electronic properties that suggest its technological application in novel optoelectronic devices, such as graphene-based photodetectors and lasers. To understand the properties of such devices on a microscopic level, we study the interplay of optical excitation, carrier-carrier, carrier-phonon, and carrierphoton scattering as well as diffusion processes. LÄS MER

  4. 3. Electron dynamics in graphene in the presence of an electrical field

    Författare :Roland Jago; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bloch equations; density matrix formalism; graphene; relaxation dynamics; photoconduction effect; carrier multiplication;

    Sammanfattning : Graphene as atomically thin two-dimensional material exhibits remarkableoptical and electronic properties that suggest its technological applicationin novel optoelectronic devices, such as graphene-based lasers and photodetectors.The linear electronic bandstructure and the vanishing band gap atthe Dirac point open up new relaxation channels, such as Auger scattering. LÄS MER

  5. 4. Microscopic Theory of Exciton Dynamics in Two-Dimensional Materials

    Författare :Samuel Brem; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; exciton-phonon interaction; van der Waals materials; relaxation dynamics; excitons; 2D materials; density matrix formalism;

    Sammanfattning : Transition Metal Dichalcogenides (TMDs) present a giant leap forward towards the realization of nanometer-sized quantum devices. As a direct consequence of their truly two-dimensional character, TMDs exhibit a strong Coulomb-interaction, leading to the formation of stable electron-hole pairs, so-called excitons. LÄS MER

  7. 5. Microscopic Mechanisms of the Formation, Relaxation and Recombination of Excitons in Two-Dimensional Semiconductors

    Författare :Samuel Brem; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; relaxation dynamics; 2D materials; density matrix formalism; excitons; exciton-phonon interaction; Bloch equations;

    Sammanfattning : Monolayers of Transition Metal Dichalcogenides (TMDs) present a giant leap forward towards the realization of semiconductor devices with atomic scale thickness. As a natural consequence of their two-dimensional character TMDs exhibit a reduced dielectric screening, leading to the formation of unusually stable excitons, i.e. LÄS MER