SEMINAIRE MERCREDI 11 FEVRIER 2004 14 heures Salle Séminaire 5 Centre de Physique Théorique Marseille-LuminyGroupe de travail des CPT-LATP: (GOMS)
Guides d'Ondes, Milieux Stratifiés et Diffusion par des Surfaces
Thomas G. Pedersen Institute of Physics and Nanotechnology Aalborg University Denmark Titre: Quantum theory and properties of one-dimensional semiconductors Abstract: Conjugated polymers, inorganic quantum wires, porous silicon and certain carbon nanotubes are all quasi-one-dimensional semiconductors. The electronic and optical properties of these materials are distinctly different from those of ordinary semiconductors for a number of reasons. First, the materials are highly anisotropic. Secondly, singularities in the density-of-states lead to unusual features. Finally, the strong confinement may enhance the Coulomb interaction between electrons and holes by several orders of magnitude compared to three-dimensional semiconductors. In this talk, effective mass, empirical tight-binding and ab initio tight-binding models of one-dimensional materials will be discussed. Results for (i) optical spectra of materials, (ii) one-dimensional systems in strong electric fields (Franz-Keldysh effect) and (iii) Coulomb effects in various one-dimensional materials will be presented. 15h: Pause café 15h15: Discussions