AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP26
Desorption Induced Change in Surface Stress of Self-assembly Alkanethiol Monolayer on Gold

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: A.N. Itakura, National Research Institute for Metals, Japan
Authors: A.N. Itakura, National Research Institute for Metals, Japan
T. Narushima, University of Tsukuba, Japan
M. Kitajima, National Research Institute for Metals, Japan
R. Berger, IBM SSD GmbH, Germany
Correspondent: Click to Email
Self-assembled monolayers such as alkanethiol, -HS-(CH@sub 2@)@sub n-1@-CH@sub 3@ for n=4,6,8,12, on metal surface have been well studied because they have potential use in the wide range of technological applications such as molecular recognition and nanofabrication. The alkanethiol monolayer on gold induces a compressive surface stress during the self-assembly and the saturation value of the compressive stress is directly proportional to the alkyl chain length. There are few papers on the stress induced by the desorption. Here we present the evolution of surface stress during adsorption and desorption of self-assembly alkanethiol monolayers (SAM). The adsorption of SAM (n=12) produces a compressive stress of 0.18 N/m in air. An exposure to an argon plasma, in a UHV system, induces a rapid decrease of the compressive stress. This is because of the desorption of SAM, and if the adsorption and desorption are a reversible reaction then the final stress should be zero. But actually, the final value of the stress is tensile : -0.12 N/m. After the stress experiment we examined the surface with Auger electron microscope and detected S remaining on the surface. It suggests that the removing of dodecanethiol is not as a molecule but a part of alkyl chain which is cut from adsorbed molecule. The tensile stress should be due to the remaining part.