METAL OVERLAYERS ON SELF-ORGANIZED MOLECULAR ASSEMBLIES .4. ION-SCATTERING SPECTROSCOPY OF THE AG/CH3 INTERFACE

Ion scattering spectroscopy (ISS) of vacuum deposited Ag on octadecanethiol (ODT, HS(CH2)17CH3) organized molecular assemblies (OMAs) provides a means of studying interfacial structure at metal/organic interfaces under controlled conditions. The OMAs were self-assembled onto gold films on silicon (100) substrates. ISS compositional depth profiles of the Ag/CH3 interface were performed at a number of temperatures between 113 and 293 K. Results from these experiments show clearly that Ag penetrates rapidly through ODT above approximately 200 K. The changes in ISS Ag peak intensities as a function of time and temperature provide evidence for the formation of Ag clusters at the ODT/Au interface after penetration of Ag. Changes in deposition rate between 0.003 and 0.015 nm/s yielded little difference in corresponding ISS depth profiles. Over a range of ion beam current densities from 0.06 to 2.0 muA/cm2, scaled compositional depth profiles were found to be comparable within experimental error.