Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 35: CE: Low-dimensional Systems - Materials 3
TT 35.18: Talk
Wednesday, March 16, 2011, 19:00–19:15, HSZ 301
Tuning the electrical properties of Pt-based granular metals prepared by focused electron beam induced deposition — •Roland Sachser, Fabrizio Porrati, Christian H. Schwalb, and Michael Huth — Physikalisches Institut, Goethe-Universität, D-60438 Frankfurt am Main, Germany
We investigated granular metals which have been prepared by focused electron beam induced deposition (FEBID) using the precursor trimethyl(methylcyclopentadienyl)platinum. Microstructural changes of the matrix caused by additional electron beam irradiation after the deposition process lead to an increase of the tunnel coupling between the metallic particles and thus allow a continuous tuning from insulating to metallic behavior with increasing irradiation dose. Transport measurements in the range from 2 K to 260 K were performed on a set of samples which had been exposed to different irradiation doses. For samples with low irradiation dose Efros-Shklowski variable range hopping is observed. Longer irradiated samples show instead a logarithmic conductivity versus temperature dependence over a wide range, e. g. from about 7 K to 260 K for an irradiation dose of 4.4·105 C/m2. Applying a recent theoretical model [1] on this specific sample gives characteristic values for the dimensionless tunnel coupling strength, which is expected close to the metal insulator transition. The observed logarithmic temperature dependence of the conductivity is also predicted by this theory. For much higher irradiation doses we observe a metallic behavior with a positive temperature coefficient of the resistance.
[1] I. S. Beloborodov et al., Rev. Mod. Phys. 79, 469 (2007)