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Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium

The development of hybrid electronic devices relies in large part on the integration of (bio)organic materials and inorganic semiconductors through a stable interface that permits efficient electron transport and protects underlying substrates from oxidative degradation. Group IV semiconductors can...

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Autores principales: Bowers, Carleen M., Toone, Eric J., Clark, Robert L., Shestopalov, Alexander A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MyJove Corporation 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369651/
https://www.ncbi.nlm.nih.gov/pubmed/22214997
http://dx.doi.org/10.3791/3478
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author Bowers, Carleen M.
Toone, Eric J.
Clark, Robert L.
Shestopalov, Alexander A.
author_facet Bowers, Carleen M.
Toone, Eric J.
Clark, Robert L.
Shestopalov, Alexander A.
author_sort Bowers, Carleen M.
collection PubMed
description The development of hybrid electronic devices relies in large part on the integration of (bio)organic materials and inorganic semiconductors through a stable interface that permits efficient electron transport and protects underlying substrates from oxidative degradation. Group IV semiconductors can be effectively protected with highly-ordered self-assembled monolayers (SAMs) composed of simple alkyl chains that act as impervious barriers to both organic and aqueous solutions. Simple alkyl SAMs, however, are inert and not amenable to traditional patterning techniques. The motivation for immobilizing organic molecular systems on semiconductors is to impart new functionality to the surface that can provide optical, electronic, and mechanical function, as well as chemical and biological activity. Microcontact printing (μCP) is a soft-lithographic technique for patterning SAMs on myriad surfaces.(1-9) Despite its simplicity and versatility, the approach has been largely limited to noble metal surfaces and has not been well developed for pattern transfer to technologically important substrates such as oxide-free silicon and germanium. Furthermore, because this technique relies on the ink diffusion to transfer pattern from the elastomer to substrate, the resolution of such traditional printing is essentially limited to near 1 μm.(10-16) In contrast to traditional printing, inkless μCP patterning relies on a specific reaction between a surface-immobilized substrate and a stamp-bound catalyst. Because the technique does not rely on diffusive SAM formation, it significantly expands the diversity of patternable surfaces. In addition, the inkless technique obviates the feature size limitations imposed by molecular diffusion, facilitating replication of very small (<200 nm) features.(17-23) However, up till now, inkless μCP has been mainly used for patterning relatively disordered molecular systems, which do not protect underlying surfaces from degradation. Here, we report a simple, reliable high-throughput method for patterning passivated silicon and germanium with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The technique utilizes a preformed NHS-reactive bilayered system on oxide-free silicon and germanium. The NHS moiety is hydrolyzed in a pattern-specific manner with a sulfonic acid-modified acrylate stamp to produce chemically distinct patterns of NHS-activated and free carboxylic acids. A significant limitation to the resolution of many μCP techniques is the use of PDMS material which lacks the mechanical rigidity necessary for high fidelity transfer. To alleviate this limitation we utilized a polyurethane acrylate polymer, a relatively rigid material that can be easily functionalized with different organic moieties. Our patterning approach completely protects both silicon and germanium from chemical oxidation, provides precise control over the shape and size of the patterned features, and gives ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules. The approach is general and applicable to other technologically-relevant surfaces.
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spelling pubmed-33696512012-06-08 Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium Bowers, Carleen M. Toone, Eric J. Clark, Robert L. Shestopalov, Alexander A. J Vis Exp Bioengineering The development of hybrid electronic devices relies in large part on the integration of (bio)organic materials and inorganic semiconductors through a stable interface that permits efficient electron transport and protects underlying substrates from oxidative degradation. Group IV semiconductors can be effectively protected with highly-ordered self-assembled monolayers (SAMs) composed of simple alkyl chains that act as impervious barriers to both organic and aqueous solutions. Simple alkyl SAMs, however, are inert and not amenable to traditional patterning techniques. The motivation for immobilizing organic molecular systems on semiconductors is to impart new functionality to the surface that can provide optical, electronic, and mechanical function, as well as chemical and biological activity. Microcontact printing (μCP) is a soft-lithographic technique for patterning SAMs on myriad surfaces.(1-9) Despite its simplicity and versatility, the approach has been largely limited to noble metal surfaces and has not been well developed for pattern transfer to technologically important substrates such as oxide-free silicon and germanium. Furthermore, because this technique relies on the ink diffusion to transfer pattern from the elastomer to substrate, the resolution of such traditional printing is essentially limited to near 1 μm.(10-16) In contrast to traditional printing, inkless μCP patterning relies on a specific reaction between a surface-immobilized substrate and a stamp-bound catalyst. Because the technique does not rely on diffusive SAM formation, it significantly expands the diversity of patternable surfaces. In addition, the inkless technique obviates the feature size limitations imposed by molecular diffusion, facilitating replication of very small (<200 nm) features.(17-23) However, up till now, inkless μCP has been mainly used for patterning relatively disordered molecular systems, which do not protect underlying surfaces from degradation. Here, we report a simple, reliable high-throughput method for patterning passivated silicon and germanium with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The technique utilizes a preformed NHS-reactive bilayered system on oxide-free silicon and germanium. The NHS moiety is hydrolyzed in a pattern-specific manner with a sulfonic acid-modified acrylate stamp to produce chemically distinct patterns of NHS-activated and free carboxylic acids. A significant limitation to the resolution of many μCP techniques is the use of PDMS material which lacks the mechanical rigidity necessary for high fidelity transfer. To alleviate this limitation we utilized a polyurethane acrylate polymer, a relatively rigid material that can be easily functionalized with different organic moieties. Our patterning approach completely protects both silicon and germanium from chemical oxidation, provides precise control over the shape and size of the patterned features, and gives ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules. The approach is general and applicable to other technologically-relevant surfaces. MyJove Corporation 2011-12-16 /pmc/articles/PMC3369651/ /pubmed/22214997 http://dx.doi.org/10.3791/3478 Text en Copyright © 2011, Journal of Visualized Experiments http://creativecommons.org/licenses/by-nc/2.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits non-commercial use, distribution, and reproduction, provided the original work is properly cited.
spellingShingle Bioengineering
Bowers, Carleen M.
Toone, Eric J.
Clark, Robert L.
Shestopalov, Alexander A.
Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title_full Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title_fullStr Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title_full_unstemmed Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title_short Soft Lithographic Functionalization and Patterning Oxide-free Silicon and Germanium
title_sort soft lithographic functionalization and patterning oxide-free silicon and germanium
topic Bioengineering
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369651/
https://www.ncbi.nlm.nih.gov/pubmed/22214997
http://dx.doi.org/10.3791/3478
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