Self-assembling monolayer
The self-assembled monolayer (Engl. Self-assembled monolayer , SAM) is an important part of nanotechnology . A self-organizing monolayer forms spontaneously when surface-active or organic substances are immersed in a solution or suspension . Suitable substances are, for. B. alkanethiols , alkyl trichlorosilanes and fatty acids . These form simple monolayers with a high internal order on metals such as gold , silver , platinum and copper as well as graphite and silicon . In general, the formation of ordered layers is only observed on terraces of the single crystals; a different behavior is observed at defects such as step dislocations . Surfaces treated in this way are stable in air for months. In contrast to conventional coating processes such as chemical vapor deposition (engl. Chemical vapor deposition , CVD) have SAM is a defined thickness, nm, depending on the molecule in the range of 0.1 up to a few nanometers. The sensitivity of organic layers to reactive gas can be made visible with the help of scanning tunneling microscopy . Because of this possible reactivity, organic monolayers are often examined in an ultra-high vacuum .
In semiconductor technology , the self-assembling monolayer is used for surface stabilization and tailor-made functionalization of electrodes . Depending on the length of the alkyl chains used, the permeability and the charge transfer rate are influenced. The field of application of SAM-modified electrodes is very broad. Among other things, the technology of the self-organizing monolayer is used in the electrochemical scanning tunneling microscope , in cell examinations, sensor technology and in nanoelectronics .
credentials
- ↑ Thomas Waldmann, Daniela Künzel, Harry E. Hoster, Axel Groß, R. Jürgen Behm: Oxidation of an Organic Adlayer: A Bird's Eye View . In: Journal of the American Chemical Society . tape 134 , no. 21 , May 30, 2012, p. 8817-8822 , doi : 10.1021 / ja302593v .