Lateral interactions in organic functionalization of semiconductor surfaces
- As the size scale of current electronic devices is reaching a fundamental physical limit, new and innovative materials solutions are required for continuous progress of semiconductor technologies. Moreover, the development of nanotechnologies comprised of nanoscale materials is burgeoning in various fields. Nanomaterials often show completely different properties compared to their bulk, dominated by surfaces or interfaces. Given the importance of these interfaces, organic functionalization of semiconductor surfaces, or direct attachment of organic molecules, is a topic of increasing interest. By creating interfaces between inorganic and organic functionalities, we may be able to tune the properties of the surface with the versatility and tailorability of organic molecules. In order to utilize organic functionalization in such applications, a deep understanding of the adsorption of the molecules on the surfaces is necessary. In this work, we focus on the fundamental aspects of the adsorption chemistry of organic molecules on a semiconductor surface, and on the lateral interactions between the adsorbed molecules. We explore several molecules' adsorption chemistry on the Ge(100)-2×1 surface. Experimental techniques such as infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption, in addition to theoretical methods including density functional theory calculations and Monte Carlo simulations, are utilized. The strongest interaction that drives the adsorption of the molecules on the surface is local bond formation between the molecules and "dimers" of the Ge(100)-2×1 surface, such as C-dative bonding of isocyanides, dissociative adsorption of phenols, and cycloaddition of nitrobenzene. However, weaker lateral interactions between the adsorbates or between adsorbates and the surface are also present, and they significantly affect the adsorption of the molecules, especially at higher coverages of the adsorbates. In studies of adsorption of small molecules that interact with one dimer, we observe a coverage-dependant spectral shift of tert-butyl isocyanide, and explain self-assembly of methanol and ethylene that had been reported in the literature. Slightly larger molecules can interact with other neighboring dimers: we show that phenol undergoes a shift in molecular orientation due to non-covalent adsorbate-surface interactions, and we determine that coverage-dependent evolution of dual and single adsorption products of benzenediols originates from inter-adsorbate interactions. Overall, this dissertation provides new insights toward the organic functionalization of semiconductor surfaces.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Chemical Engineering.
|Nørskov, Jens K
|Nørskov, Jens K
|Statement of responsibility
|Submitted to the Department of Chemical Engineering.
|Thesis (Ph.D.)--Stanford University, 2014.
- © 2014 by Bonggeun Shong
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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