Silicon Pillar Arrays Research Articles

Formation of microstructured silicon surfaces by electrochemical etching using colloidal crystal as mask

Silicon disk arrays and silicon pillar arrays with a close-packed configuration having an ordered periodicity were fabricated by the electrochemical etching of a silicon substrate through colloidal crystals used as a mask. The colloidal crystals were directly prepared by the self-assembly of polystyrene particles on a silicon substrate. The transfer of a two-dimensional hexagonal array of colloidal crystals to the silicon substrate could be achieved by the selective electrochemical etching of the exposed silicon surfaces, which were located in interspaces among adjacent particles. The diameter of the tip of the silicon pillars could be controlled easily by changing the anodization conditions, such as current density and period of electrochemical etching.

Low Velocity Quantum Reflection of Bose-Einstein Condensates

We study how interactions affect the quantum reflection of Bose-Einstein condensates. A patterned silicon surface with a square array of pillars resulted in high reflection probabilities. For incident velocities greater than 2.5 mm/s, our observations agreed with single-particle theory. At velocities below 2.5 mm/s, the measured reflection probability saturated near 60% rather than increasing towards unity as predicted by the accepted theoretical model. We extend the theory of quantum reflection to account for the mean-field interactions of a condensate which suppresses quantum reflection at low velocity. The reflected condensates show collective excitations as recently predicted.

Process integration and development of inverted photonic crystal arrays

A processing technology has been developed to produce inverted two-dimensional photonic crystal structures by embedding an array of silicon pillars inside a polyimide matrix and releasing this structure from the underlying substrate. The spatial distribution of the high dielectric and low dielectric regions of these structures is inverted compared to the spatial distribution of standard photonic crystal structures produced by etching air holes in a high dielectric slab. Consequently these structures are far more difficult to fabricate. The integration requirements required for developing this technology are discussed along with the processing technology developed to fabricate these devices. An inverted photonic crystal device based on the superprism effect was successfully demonstrated.

Stain etching of silicon pillars and macropores

AbstractWe used a XeCl excimer laser (308 nm, ∼3 J cm–2) and chemically enhanced laser ablation in the presence of SF6 to create arrays of silicon pillars. Etching of these pillars with KOH leads to arrays of macropores whose morphology depends on surface crystallography. Several new stain etchants – containing some combination of HF, NH4HF2, HCl, HNO3, Fe(III), Mn(VII) and water – have been used to cover these structures with a layer of microporous silicon. Both pillars and macropores are black, i.e., exhibit low reflectivity across the visible spectrum. When porosified, pillars exhibit visible photoluminescence whose angular distribution differs from that of planar porous silicon with significantly more intensity at high angles. The peak photoluminescence wavelength depends on the stain etchant composition and exposure to air. The use of metal ions in place of HNO3 in the stain etchant ameliorates the production of gas bubbles and leads to more uniform films. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Non-lithographic method of forming ordered arrays of silicon pillars and macropores

Micrometre-scale Si pillars are formed by chemically enhanced laser ablation using nanosecond excimer laser irradiation of a Si single crystal in the presence of SF6. We demonstrate the importance of precursor holes in determining the positioning of the pillars and show that we can control the initiation of precursor holes by ruling a grating into the Si substrate prior to irradiation. A rule defines an edge from which the laser light diffracts. Near-field amplification of the laser intensity enhances the formation of the precursor holes and aligns them parallel to the rule. The pillars can be thinned and eventually removed by wet chemical etching in aqueous KOH, resulting first in ordered arrays of extremely high aspect ratio pillars (e.g. tens of micrometres in length, with ∼ 10 nm tips) and then macropores. The shape of the macropore is determined by crystallography and the anisotropy of the wet etchant.

Silicon nanoporous pillar array and its surface copper deposition

Silicon nanoporous pillar array (Si-NPA) has been prepared by a hydrothermal etching technique. Using Si-NPA as substrate, a Cu/Si-NPA nanocomposite thin film has been obtained with immersion plating method. Morphological and structural analysis indicates that Si-NPA is a typical structural composite system characterized by a triple hierarchical structure, i. e. the array of micron-sized silicon pillars, the nanopores densely distributed on the surface of the pillars, and the silicon nanocrystallites that constitute the pore walls. Cu/Si-NPA inherits the morphological characteristics of Si-NPA. The compactability of the deposited copper nanoparticles varies alternatively with the local geometrical features of Si-NPA and forms a quasi-periodical pattern. Such an experimental phenomenon is attributed to the velocity dependence of the copper deposition upon the local geometrical features of Si-NPA. These results indicate that Si-NPA might be used as an ideal template for preparing specially patterned, structured or functionalized metal/silicon nanocomposite systems.

Fabrication of nanoscale vertical colloid device architectures

The design, fabrication and preliminary testing of a vertical nanodevice comprising an active region of gold colloidal nanoparticles deposited within a silicon nanopillar architecture is presented. Each step of the fabrication is a parallel process, starting with the production of an array of silicon pillars using natural lithographic techniques. Electrical measurements through a small array of these pillars show linear behaviour in the current–voltage curves, which lead to a pillar resistance value fully commensurate with the known geometry. The results in this paper show the fabrication at each stage, and when combined with characterisation data represent a demonstration of the `proof of principle' of our approach.

Fabrication of nanoscale vertical colloid device architectures

The design, fabrication and preliminary testing of a vertical nanodevice comprising an active region of gold colloidal nanoparticles deposited within a silicon nanopillar architecture is presented. Each step of the fabrication is a parallel process, starting with the production of an array of silicon pillars using natural lithographic techniques. Electrical measurements through a small array of these pillars show linear behaviour in the current–voltage curves, which lead to a pillar resistance value fully commensurate with the known geometry. The results in this paper show the fabrication at each stage, and when combined with characterisation data represent a demonstration of the `proof of principle' of our approach.

Process integration of self-assembled polymer templates into silicon nanofabrication

Self-assembled diblock copolymer thin films are used as sacrificial layers for the transfer of dense nanoscale patterns into more robust materials. We detail the processes used to achieve highly uniform nanoporous dielectric films, high-aspect-ratio nanotextured silicon, silicon nitride dot arrays, silicon pillar arrays, and silicon tip arrays. All techniques are compatible with standard semiconductor fabrication processes. We also discuss the possible applications of each resulting nanometer-scale structure, including high surface area substrates for capacitors and biochips, quantum dot arrays for nonvolatile memories, and silicon pillar arrays for vertical transistors or field-emission displays.

Design and fabrication of colloid-based vertical nanoscale devices

The design and fabrication of a vertical nanodevice with an active region based on gold colloidal nanoparticles deposited on a silicon nanopillar is presented. Devices are fabricated in parallel using natural lithography to create an array of silicon pillars. The nanoscale volume of the active region results from the combination of silicon pillar technology coupled with well controlled vertical processing. The results in this paper show the fabrication procedure at each stage, leading to a structure designed to demonstrate proof of principal of our approach.

Attachment of astroglial cells to microfabricated pillar arrays of different geometries.

We studied the attachment of astroglial cells on smooth silicon and arrays of silicon pillars and wells with various widths and separations. Standard semiconductor industry photolithographic techniques were used to fabricate pillar arrays and wells in single-crystal silicon. The resulting pillars varied in width from 0. 5 to 2.0 micrometer, had interpillar gaps of 1.0-5.0 micrometer, and were 1.0 micrometer in height. Arrays also contained 1.0-micromter-deep wells that were 0.5 micrometer in diameter and separated by 0.5-2.0 micrometer. Fluorescence, reflectance, and confocal light microscopies as well as scanning electron microscopy were used to quantify cell attachment, describe cell morphologies, and study the distribution of cytoskeletal proteins actin and vinculin on surfaces with pillars, wells, and smooth silicon. Seventy percent of LRM55 astroglial cells displayed a preference for pillars over smooth silicon, whereas only 40% preferred the wells to the smooth surfaces. Analysis of variance statistics performed on the data sets yielded values of p > approximately.5 for the comparison between pillar data sets and < approximately.0003 in the comparison between pillar and well data sets. Actin and vinculin distributions were highly polarized in cells found on pillar arrays. Scanning electron microscopy clearly demonstrated that cells made contact with the tops of the pillars and did not reach down into the spaces between pillars even when the interpillar gap was 5.0 microm. These experiments support the use of surface topography to direct the attachment, growth, and morphology of cells. These surfaces can be used to study fundamental cell properties such as cell attachment, proliferation, and gene expression. Such topography might also be used to modify implantable medical devices such as neural implants and lead to future developments in tissue engineering.

UV absorbance measurements of DNA in microplates.

BioTechniquesVol. 28, No. 1 BenchmarksOpen AccessUV Absorbance Measurements of DNA in MicroplatesEvelyn L. McGownEvelyn L. McGown*Address correspondence to Dr. Evelyn L. McGown, Senior Applications Specialist Molecular Devices Corporation, Sunnyvale, CA 94089-1136, USA. Internet: E-mail Address: evelyn_mcgown@moldev.comMolecular Devices Corporation, Sunnyvale, CA, USASearch for more papers by this authorPublished Online:29 Aug 2018https://doi.org/10.2144/00281bm11AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInReddit FiguresReferencesRelatedDetailsCited ByConsiderations when using microplates and Neubauer counting chamber in ecotoxicity tests on microplasticsMarine Pollution Bulletin, Vol. 170Toward QbD Process Understanding on DNA Vaccine Purification Using Design of Experiment12 May 2021 | Frontiers in Bioengineering and Biotechnology, Vol. 9Process Characterization by Definitive Screening Design Approach on DNA Vaccine Production15 October 2020 | Frontiers in Bioengineering and Biotechnology, Vol. 8Ultra-Low Coverage Sequencing as the Most Accurate Library Quantification Method Prior to Target Sequencing14 October 2019 | Molecular Genetics, Microbiology and Virology, Vol. 34, No. 2Surface Modification of Silicon Pillar Arrays To Enhance Fluorescence Detection of Uranium and DNA27 October 2017 | ACS Omega, Vol. 2, No. 10Metabolism and disposition of 2-methoxy-4-nitroaniline in male and female Harlan Sprague Dawley rats and B6C3F 1 /N mice23 June 2012 | Xenobiotica, Vol. 42, No. 12Greiner Bio-One UV-Star® Microplates for UV/VIS of Nucleic Acids and Proteins3 April 2018 | BioTechniques, Vol. 52, No. 5 Vol. 28, No. 1 Follow us on social media for the latest updates Metrics Downloaded 657 times History Published online 29 August 2018 Published in print January 2000 Information© 2018 Author(s)PDF download