Cooperative Reaction of Hydrogen-Networked Water Molecules at the SiC-H2O2 Solution Interface: Microscopic Insights from Ab Initio Molecular Dynamics
T Morishita and M Kayanuma and T Nakamura and T Kato, JOURNAL OF PHYSICAL CHEMISTRY C, 126, 12441-12449 (2022).
Interest in silicon carbide (SiC) has grown steadily over the years because of its fascinating properties for power electronic devices. Chemical mechanical polishing (CMP) with aqueous oxidant solutions has been a key approach for obtaining efficient machining of SiC surfaces; however, little is known about the chemical reactions at the SiC-aqueous solution interface. Here, we demonstrate using ab initio molecular dynamics simulations that water molecules are highly reactive on both the Si-terminated (0001) and C-terminated (000 (1) over bar) faces of SiC surfaces in contact with a hydrogen peroxide solution. Cooperative hydrogen transfer is found to accelerate the reaction at the SiC- solution interface, which occurs not only on the Si-terminated face but also on the C-terminated face in contrast to previous calculations. We also find that the reaction of a hydrogen peroxide molecule proceeds differently on the Si- and C-terminated faces, which may account for the different oxidation rates of these surfaces. The present results provide new insights into the initial stage of SiC oxidation, particularly by CMP with aqueous oxidant solutions.
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