शीतल Lithographic functionalization और ऑक्साइड मुक्त patterning सिलिकॉन और जर्मेनियम
Summary
यहाँ हम ऑक्साइड मुक्त patterning छोटे अणुओं और प्रोटीन के साथ नमूनों substrates के सिलिकॉन जर्मेनियम और प्रतिक्रियाशील जैविक monolayers के साथ और प्रदर्शन functionalization के लिए एक सरल विधि का वर्णन. दृष्टिकोण पूरी तरह से रासायनिक ऑक्सीकरण से सतहों की रक्षा, सुविधा आकारिकी पर सटीक नियंत्रण प्रदान करता है, और रासायनिक भेदभाव पैटर्न के लिए तैयार पहुँच प्रदान करता है है.
Abstract
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.
Protocol
Discussion
प्रस्तुत प्रोटोकॉल या मसिही बिना स्याही का microcontact मुद्रण के फार्म का है कि सार्वभौमिक किसी भी साधारण अच्छी तरह का आदेश दिया monolayers का समर्थन करने में सक्षम सब्सट्रेट करने के लिए लागू किया जा सकता है. इस विधि में, एक टिकट immobilized उत्प्रेरक इसी कार्य समूहों असर सतह पर एक पैटर्न स्थानान्तरण. क्योंकि इस प्रक्रिया स्टाम्प से स्याही हस्तांतरण पर नहीं भरोसा करने के लिए पारंपरिक और प्रतिक्रियाशील μCP वाचाल संकल्प सीमा सतह obviated है, nanoscale वस्तुओं की दिनचर्या के निर्माण की अनुमति है. एक प्राथमिक अत्यधिक आदेश दिया आणविक प्रणाली का समावेश ऑक्सीकरण नुकसान से अंतर्निहित अर्धचालक की पूरी सुरक्षा प्रदान करता है. उसी समय, विधि एक माध्यमिक प्रतिक्रियाशील overlayer का उपयोग करके भारी प्रतिक्रियाशील समूहों के स्थिरीकरण का समर्थन करता है, प्रणाली एक साथ दोनों संरक्षण और functionalization प्राप्त है.
तकनीक स्थिर कार्बन सतह बांड के गठन के साथ शुरू होता है रासायनिक आभ्यांतरिक primar के लिए अनुमति देता हैy monolayer जो ऑक्साइड गठन के लिए एक प्रभावी बाधा के रूप में कार्य करता है. एक माध्यमिक प्रतिक्रियाशील overlayer का गठन टर्मिनल एनएचएस कार्यात्मक समूहों है कि रासायनिक और जैविक moieties की एक किस्म के लिए लगाव अंक के रूप में सेवा प्रदान करता है. यह स्थिर bilayered आणविक प्रणाली बाद हमारे उत्प्रेरक μCP दृष्टिकोण का उपयोग नमूनों है. इस अध्ययन में प्रस्तुत दृष्टिकोण जैविक और जैविक सामग्री का एक व्यापक रेंज के साथ patterning अर्धचालक substrates के लिए एक सामान्य तरीका प्रदान करता है. महंगी, जटिल इंस्ट्रूमेंटेशन के बिना नमूनों जैविक अर्धचालक इंटरफेस बनाने की क्षमता इलेक्ट्रॉनिक्स, नैनो, जैव रसायन और बायोफिज़िक्स जैसे क्षेत्रों में अनेक अवसर प्रदान करता है.
Disclosures
The authors have nothing to disclose.
Acknowledgements
हम NSF पुरस्कार CMMI 1000724 की वित्तीय सहायता स्वीकार करते हैं.
Materials
| Name of the reagent | Company/model |
|---|---|
| XPS spectrometer | Kratos Axis Ultra |
| Atomic force microscope | Veeco D3100 |
| SEM-FEG microscope | FEI XL30 |
| Fluorescent microscope | Zeiss Axio Imager |
| Heatblock | VWR |
| Vacuum pump | Boc Edwards |
| Water purification system | Millipore |
| TESP silicon probes | Veeco |
| Silicon | |
| Pressure Vials | Chemglass |
| Vacuum manifold | Chemglass |
| UV Lamp | UVP |
| Stamp Material | See references 20 and 18 |
| PFTE syringe filters | VWR |
| Nano Strip | Cyantek |
| HCl | Sigma |
| Ethanol | Sigma |
| Acetone | Sigma |
| HF | Sigma |
| Chlorobenzene | Sigma |
| PCl5 | Sigma |
| Propenyl Magnesium Chloride | Sigma |
| Octyl Magnesium Chloride | Sigma |
| Carbon TetraChloride | Sigma |
| Boc protected ethylenediamine | Sigma |
| TFA | Sigma |
| Sodium 2-mercaptoethanesulfonate | Sigma |
| 4N HCl solution in dioxane | Sigma |
| Lysine-N,N-diacetic acid | Sigma |
| Et3N | Sigma |
| DMF | Sigma |
| NiSO4 | Sigma |
| NaP | Sigma |
| NaCl | Sigma |
| imidazole | Sigma |
| PBS | Sigma |
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