Au particle deposition onto self-assembled monolayers of thiol and dithiol molecules

Abstract

Gold depositions on self-assembled monolayers (SAMs) of thiol (HS(CH 2) 7CH 3) and dithiol (HS(CH 2) n SH, n=6, 8, 10) molecules were investigated by a scanning tunneling microscope in air. In the case of thiols, evaporated gold atoms were found to penetrate and form monoatomic height islands under the SAMs. On the contrary, gold deposition onto the dithiols resulted in the formation of the gold particles on top of the SAMs. Each Au particle is estimated to have ∼200 atoms and this size is independent of Au coverage, at least below 1 ML. The electrical properties such as Coulomb blockade were also studied by scanning tunneling spectroscopy.