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

TL;DR

This study investigates the electrical conductivity of tungsten-based electron beam induced deposits during growth, irradiation, and air exposure, revealing non-linear growth behavior and conductivity changes due to electron tunneling and post-irradiation effects.

Contribution

It provides in situ measurements of conductivity during growth and exposure, and elucidates the mechanisms of electron transport and degradation in W-based deposits.

Findings

Conductivity increases non-linearly during initial growth.

Post-growth conductivity decreases logarithmically over time.

Electron post-irradiation enhances electrical conductivity.

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 non-linearly, independent of 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, sigma 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.