Area selective OMCVD of gold and palladium on self-assembled organic monolayers : Control of nucleation sites

Abstract
The area selective organometallic chemical vapor deposition (OMCVD) of gold and palladium onto self-assembled monolayers (SAMs) of 4'-functionalized long chain alkanethiols and 4'-functionalized biphenylthiols was investigated. Trimethylphosphine-methylgold (Me₃PAuMe) and cyclopentadienyl-allyl-palladium (Cp(allyl)Pd) were used as organometallic precursors. X-ray photoelectron spectroscopy (XPS) revealed that in both cases nucleation occurs selectively only on thiol terminated surfaces even at very mild conditions whereas nucleation is inhibited on methyl- and hydroxy-terminated SAMs. It has been shown that it is possible to control the number of gold clusters per area by depositing gold onto mixed SAMs consisting of biphenylthiol and 4'-biphenyldithiol with varying molar ratios.