Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 9: Hard Coatings II

DS 9.5: Talk

Monday, March 26, 2007, 16:15–16:30, H34

Electronic properties of graphite-like ion tracks in insulating tetrahedral amorphous carbon — Anne-Katrin Nix¹, Daniel Schwen¹, Carsten Ronning¹, Johann Krauser², Christina Trautmann³, and •Hans Hofsäss¹ — ¹II. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Hochschule Harz, Friedrichstrasse 57-59, 38855 Wernigerode, Germany — ³Gesellschaft für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt, Germany

We investigated the formation of quasi one-dimensional conducting filaments in diamond like carbon (DLC) films created by swift heavy ion irradiation. Various DLC films with thicknesses of about 100 nm were grown using mass separated ion beam deposition (MSIBD) on highly conducting Si and Ni substrates. After deposition the films were irradiated with 1 GeV ²³⁸U ions with fluences between 10⁹ and 10¹¹ ions/cm². Due to their high electronic energy loss of about 30 keV/nm the swift heavy ions graphitize the predominantly (80 %) sp³-bound carbon film along their trajectories yielding conducting nanowires embedded in an insulating matrix. Using atomic force microscopy (AFM) with conducting cantilevers and applied bias voltage the presence of conducting tracks was confirmed and their conductivities were determined to be several orders of magnitude higher than of the host matrix. Temperature dependent electrical measurements were performed on the irradiated samples at 300 K - 10 K with fields up to 5 V/µm. We will discuss the results with respect to contact resistances and possible one-dimensional conduction mechanisms within the tracks.