We have synthesized RuO2 and MnO2 thin films under identical growth conditions using reactive DC sputtering. Strikingly different morphologies, namely, the formation of RuO2 nanorods and faceted, nanocrystalline MnO2, are observed. To identify the underlying mechanisms, we have carried out density functional theory based molecular dynamics simulations of the growth of one monolayer. Ru and O2 molecules are preferentially adsorbed at their respective RuO2 ideal surface sites. This is consistent with the close to defect free growth observed experimentally. In contrast, Mn penetrates the MnO2 surface reaching the third subsurface layer and remains at this deep interstitial site 3.10 Å below the pristine surface, resulting in atomic scale decomposition of MnO2. Due to this atomic scale decomposition, MnO2 may have to be renucleated during growth, which is consistent with experiments.

You do not currently have access to this content.