Dresden 2009 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 28: Nanoengineered Thin Films I
DS 28.2: Vortrag
Donnerstag, 26. März 2009, 09:45–10:00, GER 37
Transient electrical conductivity of W-based deposits during growth, relaxation and exposure to air — •Fabrizio Porrati, Roland Sachser, and Michael Huth — Johann Wolfgang Goethe University, Frankfurt am Main, Germany
W-based granular metals have been prepared by electron beam induced deposition from the tungsten-hexacarbonyl, W(CO)6, precursor. In situ electrical conductivity measurements have been performed to monitor the growth process and to investigate the behavior of the deposit by electron beam post irradiation and by exposure to air. During the first part of the growth process, the electrical conductivity grows with the cube of time, σ∼ t3, independently from the electron beam parameters. This behavior is interpreted as the result of the increase of the W-particles diameter. Once the growth process is terminated, the electrical conductivity decreases with the logarithm of time, σ∼ ln(t). Temperature dependence conductivity measurements of the deposits reveal that the electrical transport takes place through two parallel channels: either by means of variable-range-hopping within the carbonaceous matrix or by electron tunneling between W-metal grains. After venting the electron microscope the electrical conductivity of the deposits shows a degradation behavior, which depends on the composition. Electron post-irradiation increases the electrical conductivity of the deposits, which can be attributed to the increase of charge carriers from the breakage of the carbon-carbon bonds in the matrix.