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HL: Fachverband Halbleiterphysik

HL 15: C/diamond I

HL 15.11: Vortrag

Dienstag, 24. März 2009, 12:15–12:30, POT 51

Ab initio calculations of the phonon spectra of graphene nanoribbons — •Roland Gillen, Marcel Mohr, Janina Maultzsch, and Christian Thomsen — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin

During the past decades, graphite-related materials of nanoscale, such as nanotubes, have been subject to scientific research. Their remarkable optical and electronical properties make them promising for use in future nanotechnology. Recently, another type of nanoscale materials, narrow strips of graphene (single layer graphite), have been fabricated and investigated regarding their electronical and transport properties. Those graphene nanoribbons correspond to "unrolled" carbon nanotubes, i.e. the model system used in zone-folding calculations of carbon nanotube properties. We use DFT calculations to obtain the bandstructures and phonon dispersions of nanoribbons of various shapes and widths. Group theory was applied to classify the resulting phonon modes. We show that most of the phonon modes can be interpreted as "overtones" of a few "fundamental modes" and that these overtones can be understood from zone folding the phonon dispersions of graphene. Shape and size dependences are found. Similarities between nanoribbons and carbon nanotubes will be discussed.