Papers by Keyword: Scanning Tunneling Spectroscopy

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Authors: M. D'Angelo, H. Enriquez, M. Silly, V. Derycke, V.Yu. Aristov, P. Soukiassian, C. Ottaviani, M. Pedio, P. Perfetti
Authors: P. Soukiassian, M. Silly, C. Radtke, H. Enriquez, M. D'Angelo, V. Derycke, V.Yu. Aristov, F. Amy, Y.J. Chabal, P. Moras, M. Pedio, S. Gardonio, C. Ottaviani, P. Perfetti
Authors: E. Maccallini, G. Kalantzopoulos, T. Tsoufis, R.G. Agostino, G. Chiarello, V. Formoso, T. Caruso, A. Policicchio, D. Gournis, E. Colavita
Abstract: The identification of features in the Local Density of States (LDOS) of carbon nanotubes (CNTs) obtained by Scanning Tunneling Spectroscopy (STS) is of great importance in order to understand their properties. In this work, Single- and Multi-Wall Carbon Nanotubes are compared with Multi-Wall CNTs filled with tin nanowires (Sn@CNTs) in order to investigate the effect on morphological and electronic properties of the CNTs metallic filling. The LDOS of CNTs, together with topology changes, is investigated by using spatially resolved STM/STS at room temperature and in air and compared to the LDOS of highly oriented pyrolitic graphite (HOPG). The LDOS of CNTs is dominated from different electronic states filling the C 2pσ-2pσ* band gap. The appearance of those states is linked to the diameter and the defects of the CNTs. In fact, Snnanowires encapsulation induces changes in the structure of the CNTs and the appearance of electronic states in the LDOS inside the band gap. A more extensive description of the samples is obtained depicting the morphological features and the vibrational structure on wider areas using Scanning Electron Microscopy (SEM) and Raman spectroscopy, respectively.
Authors: S. Nie, R.M. Feenstra
Abstract: Scanning tunneling microscopy and spectroscopy have been used to study the electronic states of oxidized 6H-SiC interfaces. The SiC surfaces were oxidized by annealing in an ultra-high vacuum chamber at 600−800°C under 1×10-7 Torr pressure of molecular oxygen. Tunneling spectra revealed two dominant states at –1.8 and 1.5 eV relative to the Fermi level, which lie outside the band gap region but are inhomogeneously broadened such that they extend into the gap, together with additional features within the band gap.
Authors: Arramel, Tsuyoshi Hasegawa, Tohru Tsuruoka, Masakazu Aono
Abstract: We present the surface characterization and the local electronic properties of archetypical p-type perylene-based semiconductor organic molecule of Perylene Tetra Carboxylic Dianhydride (PTCDA) thermally evaporated on a transparent conducting metal oxide surface. A modified indium tin oxide (ITO) surface was successfully obtained by employing a subsequent chemical and physical treatment. Physisorbed PTCDA molecules exhibited a stacked-grain structure covering completely ITO surface. Scanning tunneling spectroscopy (STS) spectra of physisorbed PTCDA molecules were performed. In contrast to the previous studies of the homolog n-type perylene derivative thin films, here we successfully extracted both of the outmost frontier energy levels by measuring the current-voltage characteristics of PTCDA molecules in an estimated tunneling resistance from 4.17 to 100 GΩ at room temperature. Using numerical derivative of the I-V spectra, we extracted the series of transport gap of PTCDA molecule are lies in the region of 4.70-4.87 eV.
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