Benzoic and aliphatic carboxylic acid monomolecular layers on oxidized GaAs surface as a tool for two-dimensional photonic crystal infiltration

The possibility of using surface-adsorbed monolayers on oxidized GaAs single crystals is investigated to explore liquid crystal (LC) wettability and alignment. A technological process is developed to chemically activate the GaAs surface with a view to perform the infiltration of tunable two-dimensional (2-D) photonic crystals with LC materials. We demonstrate a vapor growth method to fabricate self-organized monolayers of carboxylated derivatives on plasma-activated surfaces. Our monolayers strongly increase the wettability of liquid crystal surfaces and may be helpful in achieving the infiltration of 2-D GaAs photonic crystals. Two types of molecular families were studied in this work: benzoic acids and fatty acids, Para-substituted benzoic acids with a wide range of electrical dipoles allow adsorption to be followed by measuring the surface potential of the grafted substrates using the Kelvin probe technique. These model compounds yield important information on the grafting conditions and the stability of the layers. Surface-adsorbed fatty acids are well-known to produce hydrophobic surfaces. The water contact angles measured on modified GaAs surfaces are equivalent to the ones measured on classical alkanethiol layers on gold.

Published in:
Langmuir, 20, 26, 11428
American Chemical Society, Columbus, OH 43210-3337, United States
Compilation and indexing terms, Copyright 2006 Elsevier Inc. All rights reserved
Photonic crystals
Crystal infiltration
Benzoic acids
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 Record created 2007-04-03, last modified 2018-03-17

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