Fabrication of periodic arrays of needle-like Si nanowires on (001)Si and their enhanced field emission characteristics

Cheng, Sheng-Tzong; Lin, Hao; Huang, Yuheng; Yang, Shicheng

doi:10.1039/c7ra03733c

Cited by 13 publications

(11 citation statements)

References 45 publications

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“…By adopting the anisotropic, isotropic RIE or both with SiO 2 masks, the top of the Si nanopillars is etched faster than the bottom side resulting in the narrowed tip of the structures ( Figure 3 c,d) [ 70 ]. Besides, Cheng et al successfully produced the needle-like Si nanowires on Si(001) substrate by introducing multiple Ag-nanoparticle catalytic etching/removal (ACER) cycle process [ 71 ]. Unlike the tapering method on Si substrate, a different tapering technique was proposed using Ti/Cr/Ti hybrid mask for sacrificial etching to create tapered nanowires on a GaAs substrate [ 72 ].…”

Section: Fabrication Techniquesmentioning

confidence: 99%

Recent Advances in Vertically Aligned Nanowires for Photonics Applications

2020

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Over the past few decades, nanowires have arisen as a centerpiece in various fields of application from electronics to photonics, and, recently, even in bio-devices. Vertically aligned nanowires are a particularly decent example of commercially manufacturable nanostructures with regard to its packing fraction and matured fabrication techniques, which is promising for mass-production and low fabrication cost. Here, we track recent advances in vertically aligned nanowires focused in the area of photonics applications. Begin with the core optical properties in nanowires, this review mainly highlights the photonics applications such as light-emitting diodes, lasers, spectral filters, structural coloration and artificial retina using vertically aligned nanowires with the essential fabrication methods based on top-down and bottom-up approaches. Finally, the remaining challenges will be briefly discussed to provide future directions.

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Section: Fabrication Techniquesmentioning

confidence: 99%

Recent Advances in Vertically Aligned Nanowires for Photonics Applications

2020

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“…As shown in Fig. 1(b), the ACE processes are performed with these MACE-fabricated Si nanowires to make the nanowires having pencil-like sharpened tip ends for their enhanced light trapping 3,6,22–24 . The ACE process involves reduction of Ag ions (Eq.…”

Section: Resultsmentioning

confidence: 99%

“…3) and oxidation and etching of Si atoms (Eqs. 4 and 5) and these redox reactions are proceeded selectively on reactive Si atoms of sharp edges or Si nano-sized grains of the nanowires 8,18,22 . Ag nanoparticles are grown on the Si nanowire surface during the reduction and completely removed from the Si surface completely in the HNO 3 solution.…”

Section: Resultsmentioning

confidence: 99%

“…The ACE process to taper MACE-fabricated Si nanowires was then performed by repeating processes of reducing AgNO 3 to Ag nanoparticles on tip ends of the nanowires in the mixed solution of HF and AgNO 3 and removing reduced Ag nanoparticles from the nanowire surfaces in the diluted HNO 3 solution. For each cycle of the ACE process, the concentration of HF in the HF and AgNO 3 solution was fixed to 2.0 M while that of AgNO 3 was increased by 0.1 mM from 0.4 to 1.0 mM for each cycle 8,22 .…”

Section: Methodsmentioning

confidence: 99%

“…Surfaces of MACE-fabricated Si nanowires are highly porous and their tips are covered with lots of Si nano-sized grains which could be easily oxidized during and after the MACE process. The formation and oxidization of the Si nano-sized grains on the nanowire surfaces are strongly affected by etching procedures and conditions 8,18,20–22 , contributing in significant increases in PL intensities of the nanowires 9,17 . These Si nano-sized grains and their interfaces can be completely removed from the nanowire surface by selective etching of reactive Si atoms with the anisotropic chemical etching (ACE).…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Surface Properties of Light-Trapping Si Nanowires Using Synergetic Effects of Metal-Assisted and Anisotropic Chemical Etchings

Jeong

Hong

Jung

et al. 2019

Sci Rep

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Metal-assisted chemical etching (MACE) has been widely explored for developing silicon (Si)-based energy and optical devices with its benefits for low-cost and large-area fabrication of Si nanostructures of high aspect ratios. Surface structures and properties of Si nanostructures fabricated through MACE are significantly affected by experimental and environmental conditions of etchings. Herein, we showed that surfaces and interfacial energy states of fabricated Si nanowires can be critically affected by oxidants of MACE etching solutions. Surfaces of fabricated Si nanowires are porous and their tips are fully covered with lots of Si nano-sized grains. Strongly increased photoluminescence (PL) intensities, compared to that of the crystalline Si substrate, are observed for MACE-fabricated Si nanowires due to interfacial energy states of Si and SiOx of Si nano-sized grains. These Si grains can be completely removed from the nanowires by an additional etching process of the anisotropic chemical etching (ACE) of Si to taper the nanowires and enhance light trapping of the nanowires. Compared with the MACE-fabricated Si nanowires, ACE-fabricated tapered Si nanowires have similar Raman and PL spectra to those of the crystalline Si substrate, indicating the successful removal of Si grains from the nanowire surfaces by the ACE process.

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Well‐Defined Nanostructures for Electrochemical Energy Conversion and Storage

Adekoya

et al. 2020

Advanced Energy Materials

134

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existing energy supply systems mainly based on fossil fuels, the performance of the clean energy (conversion and storage) devices/systems has to be significantly improved. The electrochemical energy conversion and storage usually involves many intricate chemical reactions and physical interactions at the surface and inside of electrodes/electrolytes, and the kinetics and transport behaviors of different carriers (e.g., electrons, holes, ions, molecules) are closely associated with the materials selected for electrodes as well as the structures of electrodes. To this point, material design and structure design for electrodes have been the research focuses for improving the electrochemical performance of energy conversion and storage, which both have gained high attention from academia and industry.Along with researches for finding advanced electrode materials, much recent research efforts have been made for electrode structure design and engineering, especially when traditional macro-scale structured electrodes are showing limitations of achieving satisfying performance for energy conversion and storage. Among these efforts, electrode nanostructuring has been demonstrated as a promising way for realizing highperformance electrochemical energy conversion and storage, which attributes the distinct features of nanostructured materials differing from their bulk material counterparts. The high surface-to-volume ratios of nanostructures give large electrochemical surface areas with much more exposed atoms and hence improve the performance per unit electrode area and/or Electrochemical energy conversion and storage play crucial roles in meeting the increasing demand for renewable, portable, and affordable power supplies for society. The rapid development of nanostructured materials provides an alternative route by virtue of their unique and promising effects emerging at nanoscale. In addition to finding advanced materials, structure design and engineering of electrodes improves the electrochemical performance and the resultant commercial competitivity. Regarding the structural engineering, controlling the geometrical parameters (i.e., size, shape, heteroarchitecture, and spatial arrangement) of nanostructures and thus forming well-defined nanostructure (WDN) electrodes have been the central aspects of investigations and practical applications. This review discusses the fundamental aspects and concept of WDNs for energy conversion and storage, with a strong emphasis on illuminating the relationship between the structural characteristics and the resultant electrochemical superiorities. Key strategies for actualizing well-defined features in nanostructures are summarized. Electrocatalysis and photoelectrocatalysis (for energy conversion) as well as metal-ion batteries and supercapacitors (for energy storage) are selected to illustrate the superiorities of WDNs in electrochemical reactions and charge carrier transportation. Finally, conclusions and perspectives regarding future research, development, and applications of WDNs...

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Fabrication of periodic arrays of needle-like Si nanowires on (001)Si and their enhanced field emission characteristics

Abstract: We report here the fabrication and field emission properties of highly-ordered, vertically-aligned tapered Si nanostructure arrays on (001)Si.

Cited by 13 publications

References 45 publications

Recent Advances in Vertically Aligned Nanowires for Photonics Applications

Recent Advances in Vertically Aligned Nanowires for Photonics Applications

Enhanced Surface Properties of Light-Trapping Si Nanowires Using Synergetic Effects of Metal-Assisted and Anisotropic Chemical Etchings

Well‐Defined Nanostructures for Electrochemical Energy Conversion and Storage

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