Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 95: Micro- and Nanopatterning (DS jointly with O)
O 95.5: Vortrag
Freitag, 4. April 2014, 10:30–10:45, CHE 89
Nanoscale low energy electron induced graphitization in tetrahedral amorphous carbon thin films — •Frederik Klein and Thomas Mühl — Leibniz Institute for Solid State and Materials Research Dresden, PF 270116, D-01171 Dresden, Germany
Under ambient or vacuum conditions diamond and related materials like tetrahedral amorphous carbon (ta-C) are in a metastable state. By application of energy the material is able to undergo a phase change to a graphitic or sp2-hybridised state. We induce local phase changes in ta-C thin films by eV and low keV electron beams in ultrahigh vacuum provided by a scanning tunneling microscope (STM) and a scanning electron microscope (SEM), respectively. These are accompanied by huge changes in many physical properties such as electrical conductivity.
The graphitization is analyzed by STM-based current-distance spectroscopy and conductive atomic force microscopy (c-AFM). The total tip-sample circuit contains the tunneling gap resistance in series with the resistance of the carbon thin film Rcarbon. An analysis of the STM spectra provides the tunneling barrier height Φ and Rcarbon.
We observe a decrease of Rcarbon as well as an increase of Φ in the graphitized areas. However, an expected surface elevation due to a reduction of the material’s mass density cannot be seen.