Nanotechnology 2009-05-13

The transient electrical conductivity of W-based electron-beam-induced deposits during growth, irradiation and exposure to air.

F Porrati, R Sachser, M Huth

Index: Nanotechnology 20(19) , 195301, (2009)

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Abstract

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 under electron beam post-irradiation and by exposure to air. During the first part of the growth process, the electrical conductivity grows nonlinearly, independent of the electron beam parameters. This behavior is interpreted as the result of the increase of the W-particle's diameter. Once the growth process is terminated, the electrical conductivity decreases with the logarithm of time, sigma approximately ln(t). Temperature-dependent conductivity measurements of the deposits reveal that the electrical transport takes place by means of electron tunneling either between W-metal grains or between grains and trap sites in the matrix. 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.