Introducing a single silicon nanowire with a known orientation and dimensions to a specific layout location constitutes a major challenge. The challenge becomes even more formidable, if one chooses to realize the task in a monolithic fashion with an extreme topography, a characteristic of microsystems. The need for such a monolithic integration is fueled by the recent surge in the use of silicon nanowires as functional building blocks in various electromechanical and optoelectronic applications. This challenge is addressed in this work by introducing a top-down, silicon-on-insulator technology. The technology provides a pathway for obtaining well-controlled silicon nanowires along with the surrounding microscale features up to a three-order-of-magnitude scale difference. A two-step etching process is developed, where the first shallow etch defines a nanoscale protrusion on the wafer surface. After applying a conformal protection on the protrusion, a deep etch step is carried out forming the surrounding microscale features. A minimum nanowire cross-section of 35 nm by 168 nm is demonstrated in the presence of an etch depth of 10 μm. Nanowire cross-sectional features are characterized via transmission electron microscopy and linked to specific process steps. The technology allows control on all dimensional aspects along with the exact location and orientation of the silicon nanowire. The adoption of the technology in the fabrication of micro and nanosystems can potentially lead to a significant reduction in process complexity by facilitating direct access to the nanowire during surface processes such as contact formation and doping.
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http://dx.doi.org/10.1088/0957-4484/27/9/095303 | DOI Listing |
Chem Commun (Camb)
January 2025
Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China.
We fabricated flexible, three-dimensional (3D) ordered silicon nanowire (SiNW) arrays decorated with high-density silver nanoparticles (AgNPs) for the sensitive and reproducible detection of pesticide residues. These sensors demonstrated a detection limit of 10 M for methyl parathion (MPT) on curved surfaces.
View Article and Find Full Text PDFAnal Chem
December 2024
School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Conventional wearable flexible sensing systems typically comprise three components: a flexible substrate that contacts the skin, a signal processing module, and a signal output module. These components function relatively independently, resulting in a complex system that lacks sufficient integration. Therefore, developing an integrated wearable flexible sensing system by combining the flexible substrate, the signal processing module, and the signal output module not only enhances performance and comfort, but also reduces manufacturing costs and the risk of failure.
View Article and Find Full Text PDFNanomaterials (Basel)
November 2024
Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
This study explores the hydrogen generation potential via water-splitting reactions under UV-vis radiation by using a synergistic assembly of ZnO nanoparticles integrated with MoS, single-walled carbon nanotubes (SWNTs), and crystalline silicon nanowires (SiNWs) to create the MoS-SiNWs-SWNTs@ZnONPs nanocomposites. A comparative analysis of MoS synthesized through chemical and physical exfoliation methods revealed that the chemically exfoliated MoS exhibited superior performance, thereby being selected for all subsequent measurements. The nanostructured materials demonstrated exceptional surface characteristics, with specific surface areas exceeding 300 m g.
View Article and Find Full Text PDFNanomaterials (Basel)
November 2024
Faculty of Physics, St. Petersburg State University, Universitetskaya Emb. 13B, 199034 St. Petersburg, Russia.
This study investigates the growth of gallium arsenide nanowires, using lead as a catalyst. Typically, nanowires are grown through the vapor-solid-liquid mechanism, where a key factor is the reduction in the nucleation barrier beneath the catalyst droplet. Arsenic exhibits limited solubility in conventional catalysts; however, this research explores an alternative scenario in which lead serves as a solvent for arsenic, while gallium and lead are immiscible liquids.
View Article and Find Full Text PDFGallium nitride-based nanowires (NWs) overcome heteroepitaxy limits, enabling GaN-on-silicon devices, and offer high sensitivity for detection, sensing, and photocatalysis. Additional nanowire coating enhances their performance, protects against photoadsorption, and enables control over structural and optical properties. In this work, we investigate core-shell GaN-(Al/Hf)O nanowires, which meet the aforementioned expectations.
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