Deposition-rate dependence of granular size distribution in Cu aggregate on liquid substrate studied by atomic force microscopy

Abstract

In this article, we report an atomic force microscopy study on the microstructure and the deposition-rate dependence of granular size distribution in copper (Cu) ramified aggregates on a liquid substrate. This study shows that the ramified Cu aggregates are composed of Gaussian size distribution granules, which form immediately after the Cu atoms are deposited. The interesting phenomenon is that the mean diameter Φ_m of the granules exponentially decays and approaches a stable value Φ_c with an increase in the deposition rate f. The granular mean diameter Φ_m slightly changes with the time interval Δt during which the film is kept in the vacuum chamber, owing to the large diffusion coefficient of the Cu granules on the liquid substrates. The experimental behavior strongly depends on the properties of the liquid substrate.

Keywords:

• Cu granules
• liquid substrates
• atomic force microscopy

Acknowledgements

The authors thank Gao-Xiang Ye, Bo Yang, and A-Gen Xia for their useful discussions and technical assistance. Financial support from the National Natural Science Foundation of China (grant nos 10802083 and 10902104) and the Zhejiang Provincial Natural Science Foundation (grant nos Y6090542 and Y6090589) are gratefully acknowledged.