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Silicon Nanowire Arrays (silicon + nanowire_array)
Selected AbstractsLarge-Area Silver-Coated Silicon Nanowire Arrays for Molecular Sensing Using Surface-Enhanced Raman Spectroscopy,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2008Baohua Zhang Abstract A new and facile method to prepare large-area silver-coated silicon nanowire arrays for surface-enhanced Raman spectroscopy (SERS)-based sensing is introduced. High-quality silicon nanowire arrays are prepared by a chemical etching method and used as a template for the generation of SERS-active silver-coated silicon nanowire arrays. The morphologies of the silicon nanowire arrays and the type of silver-plating solution are two key factors determining the magnitude of SERS signal enhancement and the sensitivity of detection; they are investigated in detail for the purpose of optimization. The optimized silver-coated silicon nanowire arrays exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability, and reproducibility. Their further applications in rapidly detecting molecules relating to human health and safety are discussed. A 10 s data acquisition time is capable of achieving a limit of detection of approximately 4,×,10,6M calcium dipicolinate (CaDPA), a biomarker for anthrax. This value is 1/15 the infectious dose of spores (6,×,10,5,M required), revealing that the optimized silver-coated silicon nanowire arrays as SERS-based ultrasensitive sensors are extremely suitable for detecting Bacillus anthracis spores. [source] Bottom-Imprint Method for VSS Growth of Epitaxial Silicon Nanowire Arrays with an Aluminium CatalystADVANCED MATERIALS, Issue 46 2009Zhang Zhang A bottom-imprint method to fabricate high-quality Si [100] nanowire arrays is described (see figure). This new approach combines the functions of a highly ordered anodic aluminum oxide (AAO) template that acts as both a stamp and a template. Vertically aligned, Al-catalyzed Si nanowire (NW) arrays are grown epitaxially on the Si substrate with a narrow size distribution. [source] Morphological Control of Single-Crystalline Silicon Nanowire Arrays near Room Temperature,ADVANCED MATERIALS, Issue 20 2008Chia-Yun Chen Control of the orientation, diameter, and length of silicon nanowires (SiNWs) is achieved in large-scale single-crystalline SiNW arrays fabricated by a statistical electroless metal deposition technique. Taguchi methods are employed to optimize the diameter control and to understand the influence of all processing factors on the growth. The ,100, directions are found to be the preferred crystallographic orientation of the growing SiNWs (see figure). [source] Titelbild: Supersensitive Detection of Explosives by Silicon Nanowire Arrays (Angew. Chem.ANGEWANDTE CHEMIE, Issue 38 201038/2010) TNT und andere Explosivstoffe werden in Luft durch Anordnungen von Siliciumnanodrähten erkannt, die mit Monoschichten eines elektronenreichen Aminosilans modifiziert sind. F. Patolsky et,al. beschreiben diese Funktionseinheiten in ihrer Zuschrift auf S.,6982,ff.: Die elektronenarmen Moleküle des Explosivstoffs werden über einen Ladungstransfer an die Monoschicht gebunden, was einen schnellen und markierungsfreien Nachweis der Explosivstoffe bis hinab zu 0.1-femtomolarer Konzentration (1×10,6,ppt) ermöglicht. Bildgestaltung durch Tremani. [source] Supersensitive Detection of Explosives by Silicon Nanowire Arrays,ANGEWANDTE CHEMIE, Issue 38 2010Yoni Engel Chip als Spürnase: Empfindlicher denn je lassen sich Explosivstoffe mit Siliciumnanodraht-Feldeffekttransistor-Sensoranordnungen nachweisen, die mit Monoschichten eines elektronenreichen Aminosilans modifiziert sind und Komplexe mit den Analyten bilden (siehe Bild). Diese Nano-,Spürnasen" bemerken TNT-Konzentrationen von nur 1×10,6,ppt und sind somit Spürhunden und allen anderen bekannten Nachweismethoden für Explosivstoffe überlegen. [source] Synthesis and Photoelectrochemical Study of Vertically Aligned Silicon Nanowire Arrays,ANGEWANDTE CHEMIE, Issue 51 2009Guangbi Yuan Photoelektroden aus Drähtchen: Parallele Siliciumnanodrähte wurden chemisch synthetisiert und auf die Umwandlung von Sonnenenergie hin geprüft. Experimente belegen, dass solche Nanodrahtanordnungen durch langsames Wachstum aufgebaut werden können. In photoelektrochemischen Untersuchungen erwiesen sich die Nanodrähte als vielversprechende Kandidaten für effiziente Solarzellen. [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Large-Area Silver-Coated Silicon Nanowire Arrays for Molecular Sensing Using Surface-Enhanced Raman Spectroscopy,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2008Baohua Zhang Abstract A new and facile method to prepare large-area silver-coated silicon nanowire arrays for surface-enhanced Raman spectroscopy (SERS)-based sensing is introduced. High-quality silicon nanowire arrays are prepared by a chemical etching method and used as a template for the generation of SERS-active silver-coated silicon nanowire arrays. The morphologies of the silicon nanowire arrays and the type of silver-plating solution are two key factors determining the magnitude of SERS signal enhancement and the sensitivity of detection; they are investigated in detail for the purpose of optimization. The optimized silver-coated silicon nanowire arrays exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability, and reproducibility. Their further applications in rapidly detecting molecules relating to human health and safety are discussed. A 10 s data acquisition time is capable of achieving a limit of detection of approximately 4,×,10,6M calcium dipicolinate (CaDPA), a biomarker for anthrax. This value is 1/15 the infectious dose of spores (6,×,10,5,M required), revealing that the optimized silver-coated silicon nanowire arrays as SERS-based ultrasensitive sensors are extremely suitable for detecting Bacillus anthracis spores. [source] Top-down processed silicon nanowire transistor arrays for biosensingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2009Xuan Thang Vu Abstract We describe the fabrication, electrical and electrochemical characterization of silicon nanowire arrays, which were processed in a top-down approach using combined nanoimprint lithography and wet chemical etching. We used the top silicon layer as contact line and observed an influence of implantation and subsequent annealing of these lines to the device performance. In addition we found a subthreshold slope dependence on wire size. When operated in a liquid environment, wires can be utilized as pH sensors. We characterized the pH sensitivity in the linear range and in the subthreshold operation regime. As a first proof-of-principle experiment for the later use of the sensors in bioassays, we monitored the buildup of polyelectrolyte multilayers on the wire surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||