Kaliappan Muthukumar, Roser Valenti, Harald O. Jeschke
Electron beam induced deposition (EBID) is a direct write process in which nanostructures are grown on a substrate by decomposing the adsorbed organometallic precursors with a focused electron beam. In this study we use first principles molecular dynamics simulations to investigate the fundamentals of the EBID growth process by comparing the behaviour of two carbonyl precursors (W(CO)6 and Co2(CO)8) on two different SiO2 surfaces (fully hydroxylated (FOH) and partially hydroxylated (POH)) that represent realistic EBID conditions. These precursors are commonly used to obtain tungsten and cobalt composites. Our 20 ps simulations illustrate that these precursors are stable and mobile on the FOH-SiO2 surfaces behaving similar to the gas phase molecules. However, they fragment on POH-SiO2 surfaces upon their interaction with the surface-active sites and tend to remain localized on their bonding sites. Apart from changes in orientation, they show no tendency to reform back to the parent precursor molecule. We also compare the vibrations of these adsorbed species by computing their power spectrum from the trajectory with the available experimental data.
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http://arxiv.org/abs/1306.2567
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