Atomic force microscopy characterization and lithography of cu-ligated mercaptoalkanoic acid "molecular ruler" multilayers
Document Type
Article
Publication Date
7-1-2014
Abstract
Hybrid chemical patterning strategies that combine the sophistication of lithography with the intrinsic precision of molecular self-assembly are of broad interest for applications including nanoelectronics and bioactive surfaces. This approach is exemplified by the molecular-ruler process where the sequential deposition of mercaptoalkanoic acid molecules and coordinated metal ions is integrated with conventional lithographic techniques to fabricate registered, nanometer-scale spacings. Herein, we illustrate the capabilities of atomic force microscopy characterization and lithography to investigate the morphology, quality, and local thickness of Cu-ligated mercaptohexadecanoic acid multilayers on Au{111} substrates. These multilayers are a key component utilized in the molecular-ruler process. The rich and varied topographic features of each layer are investigated via contact-mode atomic force microscopy. Using nanoshaving, an atomic force microscopy lithographic strategy that reveals the underlying Au{111} substrate via tip-induced desorption of a molecular film, the local thicknesses of these multilayers are ascertained; these thicknesses are consistent with the anticipated heights for Cu-ligated mercaptohexadecanoic acid multilayers as well as previous ensemble surface analytical measurements. By regulating the force set point utilized during nanoshaving, the upper layer of a Cu-ligated mercaptohexadecanoic acid bilayer is removed, revealing the carboxyl moiety of the lower mercaptohexadecanoic acid layer. This selective nanoshaving demonstrates a simple and practical means to generate three-dimensional multilayers and to reveal buried chemical functionalities within metal-ligated multilayers. © 2014 American Chemical Society.
Publication Title
Langmuir
Volume
30
Issue
25
First Page
7447
Last Page
7455
Digital Object Identifier (DOI)
10.1021/la501645w
ISSN
07437463
E-ISSN
15205827
Citation Information
Drexler, Moore, K. B., Causey, C. P., & Mullen, T. J. (2014). Atomic Force Microscopy Characterization and Lithography of Cu-Ligated Mercaptoalkanoic Acid “Molecular Ruler” Multilayers. Langmuir, 30(25), 7447–7455. https://doi.org/10.1021/la501645w