X-RAY PHOTOELECTRON-SPECTROSCOPY ANALYSIS OF THE COPPER ARACHIDIC ACID ORGANIZED MOLECULAR ASSEMBLY INTERFACE - CHARGING PHENOMENA

Interactions of evaporated copper with the methyl terminated surfaces of self-assembled monolayers of arachidic acid were studied with x-ray photoelectron spectroscopy (XPS). The arachidic acid [CH3(CH2)19COOH] organized molecular assemblies (OMAs) were self-assembled on native oxide grown on freshly prepared 200 nm thick aluminum films on single crystal silicon wafers. XPS spectra were acquired as a function of evaporated copper thickness. Charging shifts of up to 0.84 eV were observed for the C(1s), O(1s), and Cu(2p) photoemission lines during evaporation of up to 4.0 nm of copper. The thickness of the organized molecular assemblies (OMA) is approximately 2.7 nm on the native oxide surface, yielding a total thickness for the oxide/OMA stack of 6-7 nm.