Nickelocene adsorption and decomposition on single crystal surfaces

Surface reactivity and possible decomposition are expected to play a large role in the surface chemistry of nickelocene, thereby affecting its usefulness as a precursor for the chemical vapor deposition of nickel. Nickelocene adsorption and decomposition have been studied with x-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and high-resolution electron energy loss spectroscopy (HREELS) on the Ag(100), Ni(100), NiO(100), and Si(111)-7 x 7 single crystal surfaces. Adsorption on the relatively inert Ag(100) surface is initially molecular at 175 K, with decomposition to nickel and cyclopentadienyl occurring at 225 K. Disproportionation of the adsorbed cyclopentadienyl to desorbing cyclopentadiene and residual surface carbon begins at 400 K. Decomposition of nickelocene is observed immediately upon adsorption on the Ni(100) and NiO(100) surfaces at 135 K. However, not only are the ligands, separated from the metallocene metal center, but the ligands themselves are decomposed immediately upon adsorption at 135 K. The Ni(100) surface results in nickelocene decomposition into acetylene and other carbon-carbon triple bond containing fragments, while decomposition on the NiO(100) surface results in ethylene and other vinylic products. Adsorption on the semiconducting Si(111) surface is molecular at 100 K. Partial dehydrogenation begins at 400 K and decomposition to various hydrocarbon fragments is observed at 800 K. The results presented in this thesis clearly show that surface reactivity affects not only the temperature at which metal-ligand bond cleavage occurs, but also the ultimate fate of the ligands. The ramifications of these findings towards the application of nickelocene as a selective-area chemical vapor deposition source are also discussed