Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

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 R_carbon. An analysis of the STM spectra provides the tunneling barrier height Φ and R_carbon.

We observe a decrease of R_carbon 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.