The effect of permanent dipole moments of adsorbates upon I-V characteristics of a bilayer tunneling junction between self-assembled monolayers on an Au(111) substrate and a gold tip.
It is important to understand an electronic property of an interface between an organic material and a metal electrode. In the present work, we measured current-voltage (I-V) curves of self-assembled monolayers (SAMs) on Au(111) using a conducting atomic force microscope (AFM) with chemically modified Au-coated AFM tips. This contact resulted in a bilayer junction between the Au(111) substrate covered with one SAM and the Au-coated tip with the other SAM. An alkanethiol (octanethiol) and benzenemethanethiols with various terminal groups (-H, -CH(3), -Cl, -CF(3)) were used as the adsorbates. The shapes of the I-V curves depended on the terminal groups. This phenomenon was attributed to the change in the work function of gold due to different permanent dipole moments of the terminal groups.
Senda
T
T
Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
Wakamatsu
S
S
Nakasa
A
A
Akiba
U
U
Fujihira
M
M