Preparations of an inorganic-framework proton exchange nanochannel membrane

Science.gov (United States)

Yan, X. H.; Jiang, H. R.; Zhao, G.; Zeng, L.; Zhao, T. S.

2016-09-01

In this work, a proton exchange membrane composed of straight and aligned proton conducting nanochannels is developed. Preparation of the membrane involves the surface sol-gel method assisted with a through-hole anodic aluminum oxide (AAO) template to form the framework of the PEM nanochannels. A monomolecular layer (SO3Hsbnd (CH2)3sbnd Sisbnd (OCH3)3) is subsequently added onto the inner surfaces of the nanochannels to shape a proton-conducting pathway. Straight nanochannels exhibit long range order morphology, contributing to a substantial improvement in the proton mobility and subsequently proton conductivity. In addition, the nanochannel size can be altered by changing the surface sol-gel condition, allowing control of the active species/charge carrier selectivity via pore size exclusion. The proton conductivity of the nanochannel membrane is reported as high as 11.3 mS cm-1 at 70 °C with a low activation energy of 0.21 eV (20.4 kJ mol-1). First-principle calculations reveal that the activation energy for proton transfer is impressively low (0.06 eV and 0.07 eV) with the assistance of water molecules.

Electrophoresis in nanochannels: brief review and speculation

Directory of Open Access Journals (Sweden)

Santiago Juan G

2006-11-01

Full Text Available Abstract The relevant physical phenomena that dominate electrophoretic transport of ions and macromolecules within long, thin nanochannels are reviewed, and a few papers relevant to the discussion are cited. Sample ion transport through nanochannels is largely a function of their interaction with electric double layer. For small ions, this coupling includes the net effect of the external applied field, the internal field of the double layer, and the non-uniform velocity of the liquid. Adsorption/desorption kinetics and the effects of surface roughness may also be important in nanochannel electrophoresis. For macromolecules, the resulting motion is more complex as there is further coupling via steric interactions and perhaps polarization effects. These complex interactions and coupled physics represent a valuable opportunity for novel electrophoretic and chromatographic separations.

Capillarity Induced Negative Pressure of Water Plugs in Nanochannels

NARCIS (Netherlands)

Tas, Niels Roelof; Mela, P.; Kramer, Tobias; Berenschot, Johan W.; van den Berg, Albert

2003-01-01

We have found evidence that water plugs in hydrophilic nanochannels can be at significant negative pressure due to tensile capillary forces. The negative pressure of water plugs in nanochannels induces bending of the thin channel capping layer, which results in a visible curvature of the liquid

Helium retention in krypton ion pre-irradiated nanochannel W film

Science.gov (United States)

Qin, Wenjing; Ren, Feng; Zhang, Jian; Dong, Xiaonan; Feng, Yongjin; Wang, Hui; Tang, Jun; Cai, Guangxu; Wang, Yongqiang; Jiang, Changzhong

2018-02-01

Nanochannel tungsten (W) film is a promising candidate as an alternative to bulk W for use in fusion applications. In previous work it has been shown to have good radiation resistance under helium (He) irradiation. To further understand the influence of the irradiation-induced displacement cascade damage on helium retention behaviour in a fusion environment, in this work, nanochannel W film and bulk W were pre-irradiated by 800 keV Kr2+ ions to the fluence of 2.6  ×  1015 ions cm-2 and subsequently irradiated by 40 keV He+ ions to the fluence of 5  ×  1017 ions cm-2. The Kr2+ ion pre-irradiation greatly increases helium retention in the form of small clusters and retards the formation of large clusters. It can effectively inhibit surface helium blistering under high temperature annealing. Compared with bulk W, no cracks were found in the nanochannel W film post-irradiated by He+ ions at high fluence. The release of helium from the nanochannel W film is more than one order of magnitude higher than that of bulk W whether they are irradiated by single He+ ions or sequentially irradiated by Kr2+ and He+ ions. Moreover, swelling of the bulk W is more serious than that of the nanochannel film. Therefore, nanochannel W film has a higher radiation tolerance performance in the synergistic irradiation.

Electrokinetic energy conversion efficiency of viscoelastic fluids in a polyelectrolyte-grafted nanochannel.

Science.gov (United States)

Jian, Yongjun; Li, Fengqin; Liu, Yongbo; Chang, Long; Liu, Quansheng; Yang, Liangui

2017-08-01

In order to conduct extensive investigation of energy harvesting capabilities of nanofluidic devices, we provide analytical solutions for streaming potential and electrokinetic energy conversion (EKEC) efficiency through taking the combined consequences of soft nanochannel, a rigid nanochannel whose surface is covered by charged polyelectrolyte layer, and viscoelastic rheology into account. The viscoelasticity of the fluid is considered by employing the Maxwell constitutive model when the forcing frequency of an oscillatory driving pressure flow matches with the inverse of the relaxation time scale of a typical viscoelastic fluid. We compare the streaming potential and EKEC efficiency with those of a rigid nanochannel, having zeta potential equal to the electrostatic potential at the solid-polyelectrolyte interface of the soft nanochannels. Within the present selected parameter ranges, it is shown that the different peaks of maximal streaming potential and EKEC efficiency for the rigid nanochannel are larger than those for the soft nanochannel when forcing frequencies of the driving pressure gradient are close to resonating frequencies. However, more enhanced streaming potential and EKEC efficiency for a soft nanochannel can be found in most of the regions away from these resonant frequencies. Moreover, the influence of several dimensionless parameters on EKEC efficiency is discussed in detail. Finally, within the given parametric regions, the maximum efficiency at some resonant frequency obtained in present analysis is about 25%. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface Effect on Oil Transportation in Nanochannel: a Molecular Dynamics Study.

Science.gov (United States)

Zheng, Haixia; Du, Yonggang; Xue, Qingzhong; Zhu, Lei; Li, Xiaofang; Lu, Shuangfang; Jin, Yakang

2017-12-01

In this work, we investigate the dynamics mechanism of oil transportation in nanochannel using molecular dynamics simulations. It is demonstrated that the interaction between oil molecules and nanochannel has a great effect on the transportation properties of oil in nanochannel. Because of different interactions between oil molecules and channel, the center of mass (COM) displacement of oil in a 6-nm channel is over 30 times larger than that in a 2-nm channel, and the diffusion coefficient of oil molecules at the center of a 6-nm channel is almost two times more than that near the channel surface. Besides, it is found that polarity of oil molecules has the effect on impeding oil transportation, because the electrostatic interaction between polar oil molecules and channel is far larger than that between nonpolar oil molecules and channel. In addition, channel component is found to play an important role in oil transportation in nanochannel, for example, the COM displacement of oil in gold channel is very few due to great interaction between oil and gold substrate. It is also found that nano-sized roughness of channel surface greatly influences the speed and flow pattern of oil. Our findings would contribute to revealing the mechanism of oil transportation in nanochannels and therefore are very important for design of oil extraction in nanochannels.

DNA confinement in nanochannels: physics and biological applications

DEFF Research Database (Denmark)

Reisner, Walter; Pedersen, Jonas Nyvold; Austin, Robert H

2012-01-01

in nanochannels, creating a linear unscrolling of the genome along the channel for analysis. We will first review the fundamental physics of DNA nanochannel confinement—including the effect of varying ionic strength—and then discuss recent applications of these systems to genomic mapping. Apart from the intense...... direct assessment of the genome in its native state). In this review, we will discuss how the information contained in genomic-length single DNA molecules can be accessed via physical confinement in nanochannels. Due to self-avoidance interactions, DNA molecules will stretch out when confined...... biological interest in extracting linear sequence information from elongated DNA molecules, from a physics view these systems are fascinating as they enable probing of single-molecule conformation in environments with dimensions that intersect key physical length-scales in the 1 nm to 100μm range. (Some...

Sustained Administration of Hormones Exploiting Nanoconfined Diffusion through Nanochannel Membranes

Directory of Open Access Journals (Sweden)

Thomas Geninatti

2015-08-01

Full Text Available Implantable devices may provide a superior means for hormone delivery through maintaining serum levels within target therapeutic windows. Zero-order administration has been shown to reach an equilibrium with metabolic clearance, resulting in a constant serum concentration and bioavailability of released hormones. By exploiting surface-to-molecule interaction within nanochannel membranes, it is possible to achieve a long-term, constant diffusive release of agents from implantable reservoirs. In this study, we sought to demonstrate the controlled release of model hormones from a novel nanochannel system. We investigated the delivery of hormones through our nanochannel membrane over a period of 40 days. Levothyroxine, osteocalcin and testosterone were selected as representative hormones based on their different molecular properties and structures. The release mechanisms and transport behaviors of these hormones within 3, 5 and 40 nm channels were characterized. Results further supported the suitability of the nanochannels for sustained administration from implantable platforms.

Electrokinetic Analysis of Energy Harvest from Natural Salt Gradients in Nanochannels.

Science.gov (United States)

He, Yuhui; Huang, Zhuo; Chen, Bowei; Tsutsui, Makusu; Shui Miao, Xiang; Taniguchi, Masateru

2017-10-13

The Gibbs free energy released during the mixing of river and sea water has been illustrated as a promising source of clean and renewable energy. Reverse electrodialysis (RED) is one major strategy to gain electrical power from this natural salinity, and recently by utilizing nanochannels a novel mode of this approach has shown improved power density and energy converting efficiency. In this work, we carry out an electrokinetic analysis of the work extracted from RED in the nanochannels. First, we outline the exclusion potential effect induced by the inhomogeneous distribution of extra-counterions along the channel axis. This effect is unique in nanochannel RED and how to optimize it for energy harvesting is the central topic of this work. We then discuss two important indexes of performance, which are the output power density and the energy converting efficiency, and their dependence on the nanochannel parameters such as channel material and geometry. In order to yield maximized output electrical power, we propose a device design by stepwise usage of the saline bias, and the lengths of the nanochannels are optimized to achieve the best trade-off between the input thermal power and the energy converting efficiency.

Numerical study of power generation by reverse electrodialysis in ion-selective nanochannels

International Nuclear Information System (INIS)

Kim, Dong Kwon

2011-01-01

In this article, ion-selective nanochannels are numerically studied to investigate the power generation capability of a concentration gradient in conjunction with reverse electrodialysis. The generation of power from the nanochannel when it is placed between two reservoirs containing sodium chloride solutions with different concentrations is investigated. The current-potential characteristics of the nanochannel were calculated by solving the Poisson equation and the Nernst-Planck equation. The effects of engineering parameters on the power generation density are investigated

Numerical study of power generation by reverse electrodialysis in ion-selective nanochannels

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Kwon [Ajou University, Suwon (Korea, Republic of)

2011-01-15

In this article, ion-selective nanochannels are numerically studied to investigate the power generation capability of a concentration gradient in conjunction with reverse electrodialysis. The generation of power from the nanochannel when it is placed between two reservoirs containing sodium chloride solutions with different concentrations is investigated. The current-potential characteristics of the nanochannel were calculated by solving the Poisson equation and the Nernst-Planck equation. The effects of engineering parameters on the power generation density are investigated.

Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

Science.gov (United States)

Chen, Shih-Yung; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi; Wang, Yuh-Lin

2011-09-01

Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

International Nuclear Information System (INIS)

Chen, Shih-Yung; Wang, Yuh-Lin; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi

2011-01-01

Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

Nanochannel Device with Embedded Nanopore: a New Approach for Single-Molecule DNA Analysis and Manipulation

Science.gov (United States)

Zhang, Yuning; Reisner, Walter

2013-03-01

Nanopore and nanochannel based devices are robust methods for biomolecular sensing and single DNA manipulation. Nanopore-based DNA sensing has attractive features that make it a leading candidate as a single-molecule DNA sequencing technology. Nanochannel based extension of DNA, combined with enzymatic or denaturation-based barcoding schemes, is already a powerful approach for genome analysis. We believe that there is revolutionary potential in devices that combine nanochannels with embedded pore detectors. In particular, due to the fast translocation of a DNA molecule through a standard nanopore configuration, there is an unfavorable trade-off between signal and sequence resolution. With a combined nanochannel-nanopore device, based on embedding a pore inside a nanochannel, we can in principle gain independent control over both DNA translocation speed and sensing signal, solving the key draw-back of the standard nanopore configuration. We demonstrate that we can optically detect successful translocation of DNA from the nanochannel out through the nanopore, a possible method to 'select' a given barcode for further analysis. In particular, we show that in equilibrium DNA will not escape through an embedded sub-persistence length nanopore, suggesting that the pore could be used as a nanoscale window through which to interrogate a nanochannel extended DNA molecule. Furthermore, electrical measurements through the nanopore are performed, indicating that DNA sensing is feasible using the nanochannel-nanopore device.

Ultra-high-aspect-orthogonal and tunable three dimensional polymeric nanochannel stack array for BioMEMS applications

Science.gov (United States)

Heo, Joonseong; Kwon, Hyukjin J.; Jeon, Hyungkook; Kim, Bumjoo; Kim, Sung Jae; Lim, Geunbae

2014-07-01

Nanofabrication technologies have been a strong advocator for new scientific fundamentals that have never been described by traditional theory, and have played a seed role in ground-breaking nano-engineering applications. In this study, we fabricated ultra-high-aspect (~106 with O(100) nm nanochannel opening and O(100) mm length) orthogonal nanochannel array using only polymeric materials. Vertically aligned nanochannel arrays in parallel can be stacked to form a dense nano-structure. Due to the flexibility and stretchability of the material, one can tune the size and shape of the nanochannel using elongation and even roll the stack array to form a radial-uniformly distributed nanochannel array. The roll can be cut at discretionary lengths for incorporation with a micro/nanofluidic device. As examples, we demonstrated ion concentration polarization with the device for Ohmic-limiting/overlimiting current-voltage characteristics and preconcentrated charged species. The density of the nanochannel array was lower than conventional nanoporous membranes, such as anodic aluminum oxide membranes (AAO). However, accurate controllability over the nanochannel array dimensions enabled multiplexed one microstructure-on-one nanostructure interfacing for valuable biological/biomedical microelectromechanical system (BioMEMS) platforms, such as nano-electroporation.Nanofabrication technologies have been a strong advocator for new scientific fundamentals that have never been described by traditional theory, and have played a seed role in ground-breaking nano-engineering applications. In this study, we fabricated ultra-high-aspect (~106 with O(100) nm nanochannel opening and O(100) mm length) orthogonal nanochannel array using only polymeric materials. Vertically aligned nanochannel arrays in parallel can be stacked to form a dense nano-structure. Due to the flexibility and stretchability of the material, one can tune the size and shape of the nanochannel using elongation and even

Dielectric, ferroelectric, and thermodynamic properties of silicone oil modified PVDF films for energy storage application

Energy Technology Data Exchange (ETDEWEB)

Luo, Bingcheng; Wang, Xiaohui, E-mail: wxh@tsinghua.edu.cn, E-mail: llt-dms@mail.tsinghua.edu.cn; Li, Longtu, E-mail: wxh@tsinghua.edu.cn, E-mail: llt-dms@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Sun, Hui [Aero-Engine Control System Institute, Aviation Industry Corporation of China, Jiangsu, Wuxi 214063 (China)

2016-06-13

Silicone oil modified poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) films were fabricated by the blending, casting, and hot-molding methods. The dielectric constant was increased for the 7.4 wt. % and 17.0 wt. % silicone oil modified P(VDF-HFP) films, while the dielectric loss for all blend films are decreased. D-E loops of 7.4 wt. % and 17.0 wt. % silicone oil modified P(VDF-HFP) films become slimmer than the pristine P(VDF-HFP) films. The maximum discharged energy density of 10.3 J/cm{sup 3} was obtained in 7.4 wt. % silicone oil modified P(VDF-HFP) films at the external electric field of 398 kV/mm. The Gibbs energy, miscibility, and phase behavior of binary mixture of P(VDF-HFP) silicone oil were investigated using molecular simulations and the extended Flory–Huggins model revealing favorable interactions and compatibility between P(VDF-HFP) and silicone oil.

Effects of water-channel attractions on single-file water permeation through nanochannels

International Nuclear Information System (INIS)

Xu, Yousheng; Zheng, Youqu; Tian, Xingling; Lv, Mei; He, Bing; Deng, Maolin; Xiu, Peng; Tu, Yusong

2016-01-01

Single-file transportation of water across narrow nanochannels such as carbon nanotubes has attracted much attention in recent years. Such permeation can be greatly affected by the water-channel interactions; despite some progress, this issue has not been fully explored. Herein we use molecular dynamics simulations to investigate the effects of water-channel attractions on occupancy, translational (transportation) and orientational dynamics of water inside narrow single-walled carbon nanotubes (SWNTs). We use SWNTs as the model nanochannels and change the strength of water-nanotube attractions to mimic the changes in the hydrophobicity/polarity of the nanochannel. We investigate the dependence of water occupancy inside SWNTs on the water-channel attraction and identify the corresponding threshold values for drying states, wetting-drying transition states, and stably wetting states. As the strength of water-channel attractions increases, water flow increases rapidly first, and then decreases gradually; the maximal flow occurs in the case where the nanochannel is predominately filled with the 1D water wire but with a small fraction of ‘empty states’, indicating that appropriate empty-filling (drying-wetting) switching can promote water permeation. This maximal flow is unexpected, since in traditional view, the stable and tight hydrogen-bonding network of the water wire is the prerequisite for high permeability of water. The underlying mechanism is discussed from an energetic perspective. In addition, the effect of water-channel attractions on reorientational dynamics of the water wire is studied, and a negative correlation between the flipping frequency of water wire and the water-channel attraction is observed. The underlying mechanism is interpreted in term of the axial total dipole moment of inner water molecules. This work would help to better understand the effects of water-channel attractions on wetting properties of narrow nanochannels, and on single

Transient response of nonideal ion-selective microchannel-nanochannel devices

Science.gov (United States)

Leibowitz, Neta; Schiffbauer, Jarrod; Park, Sinwook; Yossifon, Gilad

2018-04-01

We report evidence of variation in ion selectivity of a fabricated microchannel-nanochannel device resulting in the appearance of a distinct local maximum in the overlimiting chronopotentiometric response. In this system consisting of shallow microchannels joined by a nanochannel, viscous shear at the microchannel walls suppresses the electro-osmotic instability and prevents any associated contribution to the nonmonotonic response. Thus, this response is primarily electrodiffusive. Numerical simulations indicate that concentration polarization develops not only within the microchannel but also within the nanochannel itself, with a local voltage maximum in the chronopotentiometric response correlated with interfacial depletion and having the classic i-2 Sands time dependence. Furthermore, the occurrence of the local maxima is correlated with the change in selectivity due to internal concentration polarization. Understanding the transient nonideal permselective response is essential for obtaining fundamental insight and for optimizing efficient operation of practical fabricated nanofluidic and membrane devices.

Resolving Overlimiting Current Mechanisms in Microchannel-Nanochannel Interface Devices

Science.gov (United States)

Yossifon, Gilad; Leibowitz, Neta; Liel, Uri; Schiffbauer, Jarrod; Park, Sinwook

2015-11-01

We present results demonstrating the space charge-mediated transition between classical, diffusion-limited current and surface-conduction dominant over-limiting currents in a shallow micro-nanochannel device. The extended space charge layer develops at the depleted micro-nanochannel entrance at high current and is correlated with a distinctive maximum in the dc resistance. Experimental results for a shallow surface-conduction dominated system are compared with theoretical models, allowing estimates of the effective surface charge at high voltage to be obtained. Further, we extend the study to microchannels of moderate to large depths where the role of various electro-convection mechanisms becomes dominant. In particular, electro-osmotic of the second kind and electro-osmotic instability (EOI) which competes each other at geometrically heterogeneous (e.g. undulated nanoslot interface, array of nanoslots) nanoslot devices. Also, these effects are also shown to be strongly modulated by the non-ideal permselectivity of the nanochannel.

Concerted orientation induced unidirectional water transport through nanochannels.

Science.gov (United States)

Wan, Rongzheng; Lu, Hangjun; Li, Jinyuan; Bao, Jingdong; Hu, Jun; Fang, Haiping

2009-11-14

The dynamics of water inside nanochannels is of great importance for biological activities as well as for the design of molecular sensors, devices, and machines, particularly for sea water desalination. When confined in specially sized nanochannels, water molecules form a single-file structure with concerted dipole orientations, which collectively flip between the directions along and against the nanotube axis. In this paper, by using molecular dynamics simulations, we observed a net flux along the dipole-orientation without any application of an external electric field or external pressure difference during the time period of the particular concerted dipole orientations of the molecules along or against the nanotube axis. We found that this unique special-directional water transportation resulted from the asymmetric potential of water-water interaction along the nanochannel, which originated from the concerted dipole orientation of the water molecules that breaks the symmetry of water orientation distribution along the channel within a finite time period. This finding suggests a new mechanism for achieving high-flux water transportation, which may be useful for nanotechnology and biological applications.

Microstructure and hardness evolution of nanochannel W films irradiated by helium at high temperature

Science.gov (United States)

Qin, Wenjing; Wang, Yongqiang; Tang, Ming; Ren, Feng; Fu, Qiang; Cai, Guangxu; Dong, Lan; Hu, Lulu; Wei, Guo; Jiang, Changzhong

2018-04-01

Plasma facing materials (PFMs) face one of the most serious challenges in fusion reactors, including unprecedented harsh environment such as 14.1 MeV neutron and transmutation gas irradiation at high temperature. Tungsten (W) is considered to be one of the most promising PFM, however, virtually insolubility of helium (He) in W causes new material issues such as He bubbles and W "fuzz" microstructure. In our previous studies, we presented a new strategy using nanochannel structure designed in the W film to increase the releasing of He atoms and thus to minimize the He nucleation and "fuzz" formation behavior. In this work, we report the further study on the diffusion of He atoms in the nanochannel W films irradiated at a high temperature of 600 °C. More specifically, the temperature influences on the formation and growth of He bubbles, the lattice swelling, and the mechanical properties of the nanochannel W films were investigated. Compared with the bulk W, the nanochannel W films possessed smaller bubble size and lower bubble areal density, indicating that noticeable amounts of He atoms have been released out along the nanochannels during the high temperature irradiations. Thus, with lower He concentration in the nanochannel W films, the formation of the bubble superlattice is delayed, which suppresses the lattice swelling and reduces hardening. These aspects indicate the nanochannel W films have better radiation resistance even at high temperature irradiations.

Compressing a confined DNA: from nano-channel to nano-cavity

Science.gov (United States)

Sakaue, Takahiro

2018-06-01

We analyze the behavior of a semiflexible polymer confined in nanochannel under compression in axial direction. Key to our discussion is the identification of two length scales; the correlation length ξ of concentration fluctuation and what we call the segregation length . These length scales, while degenerate in uncompressed state in nanochannel, generally split as upon compression, and the way they compete with the system size during the compression determines the crossover from quasi-1D nanochannel to quasi-0D nanocavity behaviors. For a flexible polymer, the story becomes very simple, which corresponds to a special limit of our description, but a much richer behavior is expected for a semiflexible polymer relevant to DNA in confined spaces. We also briefly discuss the dynamical properties of the compressed polymer.

DNA barcoding via counterstaining with AT/GC sensitive ligands in injection-molded all-polymer nanochannel devices

DEFF Research Database (Denmark)

Østergaard, Peter Friis; Matteucci, Marco; Reisner, Walter

2013-01-01

Nanochannel technology, coupled with a suitable DNA labeling chemistry, is a powerful approach for performing high-throughput single-molecule mapping of genomes. Yet so far nanochannel technology has remained inaccessible to the broader research community due to high fabrication cost and/or requi......Nanochannel technology, coupled with a suitable DNA labeling chemistry, is a powerful approach for performing high-throughput single-molecule mapping of genomes. Yet so far nanochannel technology has remained inaccessible to the broader research community due to high fabrication cost and...... AT and GC variation along DNA sequences....

Microstructural evolution of nanochannel CrN films under ion irradiation at elevated temperature and post-irradiation annealing

Science.gov (United States)

Tang, Jun; Hong, Mengqing; Wang, Yongqiang; Qin, Wenjing; Ren, Feng; Dong, Lan; Wang, Hui; Hu, Lulu; Cai, Guangxu; Jiang, Changzhong

2018-03-01

High-performance radiation tolerance materials are crucial for the success of future advanced nuclear reactors. In this paper, we present a further investigation that the "vein-like" nanochannel films can enhance radiation tolerance under ion irradiation at high temperature and post-irradiation annealing. The chromium nitride (CrN) nanochannel films with different nanochannel densities and the compact CrN film are chosen as a model system for these studies. Microstructural evolution of these films were investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Elastic Recoil Detection (ERD) and Grazing Incidence X-ray Diffraction (GIXRD). Under the high fluence He+ ion irradiation at 500 °C, small He bubbles with low bubble densities are observed in the irradiated nanochannel CrN films, while the aligned large He bubbles, blistering and texture reconstruction are found in the irradiated compact CrN film. For the heavy Ar2+ ion irradiation at 500 °C, the microstructure of the nanochannel CrN RT film is more stable than that of the compact CrN film due to the effective releasing of defects via the nanochannel structure. Under the He+ ion irradiation and subsequent annealing, compared with the compact film, the nanochannel films have excellent performance for the suppression of He bubble growth and possess the strong microstructural stability. Basing on the analysis on the sizes and number densities of bubbles as well as the concentrations of He retained in the nanochannel CrN films and the compact CrN film under different experimental conditions, potential mechanism for the enhanced radiation tolerance are discussed. Nanochannels play a crucial role on the release of He/defects under ion irradiation. We conclude that the tailored "vein-like" nanochannel structure may be used as advanced radiation tolerance materials for future nuclear reactors.

1-D nanochannels fabricated in polyimide

NARCIS (Netherlands)

Eijkel, Jan C.T.; Bomer, Johan G.; Tas, Niels Roelof; van den Berg, Albert

2004-01-01

A simple method using spin-deposition and sacrificial layer etching is used to fabricate all-polyimide nanochannels (100 and 500 nm channel height). Channels are characterized using spontaneous capillary filling with water, ethanol and isopropanol, and with electroosmotic flow. The channels can be

Lithography-free centimeter-long nanochannel fabrication method using an electrospun nanofiber array

International Nuclear Information System (INIS)

Park, Suk Hee; Shin, Hyun-Jun; Lee, Sangyoup; Kim, Yong-Hwan; Yang, Dong-Yol; Lee, Jong-Chul

2012-01-01

Novel cost-effective methods for polymeric and metallic nanochannel fabrication have been demonstrated using an electrospun nanofiber array. Like other electrospun nanofiber-based nanofabrication methods, our system also showed high throughput as well as cost-effective performances. Unlike other systems, however, our fabrication scheme provides a pseudo-parallel nanofiber array a few centimeters long at a speed of several tens of fibers per second based on our unique inclined-gap fiber collecting system. Pseudo-parallel nanofiber arrays were used either directly for the PDMS molding process or for the metal lift-off process followed by the SiO 2 deposition process to produce the nanochannel array. While the PDMS molding process was a simple fabrication based on one-step casting, the metal lift-off process followed by SiO 2 deposition allowed finetuning on height and width of nanogrooves down to subhundred nanometers from a few micrometers. Nanogrooves were covered either with cover glass or with PDMS slab and nanochannel connectivity was investigated with a fluorescent dye. Also, nanochannel arrays were used to investigate mobility and conformations of λ-DNA. (paper)

Rheology behaviour of modified silicone-dammar as a natural resin coating

Science.gov (United States)

Zakaria, Rosnah; Ahmad, Azizah Hanom

2015-08-01

Modified silicone-dammar (SD) was prepared by various weight percent from 5 - 45 wt% of dammar added. The n-value (viscosity index) of silicone with 5 and 10 % were turn to be 1.6 and 1.3 of viscosity index. While 15, 20, 25 and 30 wt% of dammar added gave 0.7, 0.3, 0.2 and 0.1 of viscosity index. On the other hand, 35, 40 and 45 wt% of dammar gave a fixed value of viscosity index of 0.03. This n-value shows the dispersion quality of paint mixture indicates that the modified silicone-dammar was followed the Bingham's Model. The rheology measurement of SD mixture was analysed by plotting ln shear stress vs shear rate value. Analysis of the graph showed a Bingham plastic model with regression R2 equivalent to 0.99. The linear viscoelastic behaviour of SD samples increased in parallel with increasing dammar content indicate that the suspension of dammar in silicone resin could flow steadily with time giving a pseudoplastic behaviour.

Polymer chain alignment and transistor properties of nanochannel-templated poly(3-hexylthiophene) nanowires

Science.gov (United States)

Oh, Seungjun; Hayakawa, Ryoma; Pan, Chengjun; Sugiyasu, Kazunori; Wakayama, Yutaka

2016-08-01

Nanowires of semiconducting poly(3-hexylthiophene) (P3HT) were produced by a nanochannel-template technique. Polymer chain alignment in P3HT nanowires was investigated as a function of nanochannel widths (W) and polymer chain lengths (L). We found that the ratio between chain length and channel width (L/W) was a key parameter as regards promoting polymer chain alignment. Clear dichroism was observed in polarized ultraviolet-visible (UV-Vis) absorption spectra only at a ratio of approximately L/W = 2, indicating that the L/W ratio must be optimized to achieve uniaxial chain alignment in the nanochannel direction. We speculate that an appropriate L/W ratio is effective in confining the geometries and conformations of polymer chains. This discussion was supported by theoretical simulations based on molecular dynamics. That is, the geometry of the polymer chains, including the distance and tilting angles of the chains in relation to the nanochannel surface, was dominant in determining the longitudinal alignment along the nanochannels. Thus prepared highly aligned polymer nanowire is advantageous for electrical carrier transport and has great potential for improving the device performance of field-effect transistors. In fact, a one-order improvement in carrier mobility was observed in a P3HT nanowire transistor.

Pressure calculations in nanochannel gas flows

NARCIS (Netherlands)

Kim, J.H.; Frijns, A.J.H.; Nedea, S.V.; Steenhoven, van A.A.; Frijns, A.J.H.; Valougeorgis, D.; Colin, S.; Baldas, L.

2012-01-01

In this research, pressure driven flow within a nanochannel is studied for argon in rarefied gas states. A Molecular Dynamics simulation is used to resolve the density and stress variations. Normal stress calculations are based on Irving-Kirkwood method, which divides the stress tensor into its

Science of Water Leaks: Validated Theory for Moisture Flow in Microchannels and Nanochannels.

Science.gov (United States)

Lei, Wenwen; Fong, Nicole; Yin, Yongbai; Svehla, Martin; McKenzie, David R

2015-10-27

Water is ubiquitous; the science of its transport in micro- and nanochannels has applications in electronics, medicine, filtration, packaging, and earth and planetary science. Validated theory for water vapor and two-phase water flows is a "missing link"; completing it enables us to define and quantify flow in a set of four standard leak configurations with dimensions from the nanoscale to the microscale. Here we report the first measurements of water vapor flow rates through four silica microchannels as a function of humidity, including under conditions when air is present as a background gas. An important finding is that the tangential momentum accommodation coefficient (TMAC) is strongly modified by surface layers of adsorbed water molecules, in agreement with previous work on the TMAC for nitrogen molecules impacting a silica surface in the presence of moisture. We measure enhanced flow rates for two-phase flows in silica microchannels driven by capillary filling. For the measurement of flows in nanochannels we use heavy water mass spectrometry. We construct the theory for the flow rates of the dominant modes of water transport through each of the four standard configurations and benchmark it against our new measurements in silica and against previously reported measurements for nanochannels in carbon nanotubes, carbon nanopipes, and porous alumina. The findings show that all behavior can be described by the four standard leak configurations and that measurements of leak behavior made using other molecules, such as helium, are not reliable. Single-phase water vapor flow is overestimated by a helium measurement, while two-phase flows are greatly underestimated for channels larger than 100 nm or for all channels when boundary slip applies, to an extent that depends on the slip length for the liquid-phase flows.

Applicability of Donnan equilibrium theory at nanochannel-reservoir interfaces.

Science.gov (United States)

Tian, Huanhuan; Zhang, Li; Wang, Moran

2015-08-15

Understanding ionic transport in nanochannels has attracted broad attention from various areas in energy and environmental fields. In most pervious research, Donnan equilibrium has been applied widely to nanofluidic systems to obtain ionic concentration and electrical potential at channel-reservoir interfaces; however, as well known that Donnan equilibrium is derived from classical thermodynamic theories with equilibrium assumptions. Therefore the applicability of the Donnan equilibrium may be questionable when the transport at nanochannel-reservoir interface is strongly non-equilibrium. In this work, the Poisson-Nernst-Planck model for ion transport is numerically solved to obtain the exact distributions of ionic concentration and electrical potential. The numerical results are quantitatively compared with the Donnan equilibrium predictions. The applicability of Donnan equilibrium is therefore justified by changing channel length, reservoir ionic concentration, surface charge density and channel height. The results indicate that the Donnan equilibrium is not applicable for short nanochannels, large concentration difference and wide openings. A non-dimensional parameter, Q factor, is proposed to measure the non-equilibrium extent and the relation between Q and the working conditions is studied in detail. Copyright © 2015 Elsevier Inc. All rights reserved.

Horseradish peroxidase-modified porous silicon for phenol monitoring

Energy Technology Data Exchange (ETDEWEB)

Kermad, A., E-mail: amina_energetique@yahoo.fr [Unité de Recherche Matériaux et Energies Renouvelables (URMER), Département de Physique, Faculté des Sciences, Université Abou Baker Belkaid, B.P. 119, Tlemcen 13000 (Algeria); Sam, S., E-mail: Sabrina.sam@polytechnique.edu [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), 02 Bd. Frantz-Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Ghellai, N., E-mail: na_ghellai@yahoo.fr [Unité de Recherche Matériaux et Energies Renouvelables (URMER), Département de Physique, Faculté des Sciences, Université Abou Baker Belkaid, B.P. 119, Tlemcen 13000 (Algeria); Khaldi, K., E-mail: Khadidjaphy@yahoo.fr [Unité de Recherche Matériaux et Energies Renouvelables (URMER), Département de Physique, Faculté des Sciences, Université Abou Baker Belkaid, B.P. 119, Tlemcen 13000 (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), 02 Bd. Frantz-Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria)

2013-11-01

Highlights: • Horseradish peroxidase enzyme (HRP) was covalently immobilized on porous silicon (PSi) surface. • Multistep strategy was used allowing the maintaining of the enzymatic activity of the immobilized enzyme. • Direct electron transfer has occurred between the immobilized enzyme and the surface. • Electrochemical measurements showed a response of HRP-modified PSi toward phenol in the presence of H{sub 2}O{sub 2}. -- Abstract: In this study, horseradish peroxidase enzyme (HRP) was covalently immobilized on porous silicon (PSi) surface using multistep strategy. First, acid terminations were generated on hydrogenated PSi surface by thermal hydrosilylation of undecylenic acid. Then, the carboxyl-terminated monolayer was transformed to active ester (succinimidyl ester) using N-hydroxysuccinimide (NHS) in the presence of the coupling agent N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC). Subsequently, the enzyme was anchored on the surface via an amidation reaction. The structure of the PSi layers was observed by scanning electron microscopy (SEM). Infrared spectroscopy (FTIR) and contact angle measurements confirmed the efficiency of the modification at each step of the functionalization. Cyclic voltammetry was recorded using the HRP-modified PSi as working electrode. The results show that the enzymatic activity of the immobilized HRP is preserved and in the presence of hydrogen peroxide, the enzyme oxidizes phenolic molecules which were subsequently reduced at the modified-PSi electrode.

Horseradish peroxidase-modified porous silicon for phenol monitoring

International Nuclear Information System (INIS)

Kermad, A.; Sam, S.; Ghellai, N.; Khaldi, K.; Gabouze, N.

2013-01-01

Highlights: • Horseradish peroxidase enzyme (HRP) was covalently immobilized on porous silicon (PSi) surface. • Multistep strategy was used allowing the maintaining of the enzymatic activity of the immobilized enzyme. • Direct electron transfer has occurred between the immobilized enzyme and the surface. • Electrochemical measurements showed a response of HRP-modified PSi toward phenol in the presence of H 2 O 2 . -- Abstract: In this study, horseradish peroxidase enzyme (HRP) was covalently immobilized on porous silicon (PSi) surface using multistep strategy. First, acid terminations were generated on hydrogenated PSi surface by thermal hydrosilylation of undecylenic acid. Then, the carboxyl-terminated monolayer was transformed to active ester (succinimidyl ester) using N-hydroxysuccinimide (NHS) in the presence of the coupling agent N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC). Subsequently, the enzyme was anchored on the surface via an amidation reaction. The structure of the PSi layers was observed by scanning electron microscopy (SEM). Infrared spectroscopy (FTIR) and contact angle measurements confirmed the efficiency of the modification at each step of the functionalization. Cyclic voltammetry was recorded using the HRP-modified PSi as working electrode. The results show that the enzymatic activity of the immobilized HRP is preserved and in the presence of hydrogen peroxide, the enzyme oxidizes phenolic molecules which were subsequently reduced at the modified-PSi electrode

Selective and lithography-independent fabrication of 20 nm nano-gap electrodes and nano-channels for nanoelectrofluidics applications

International Nuclear Information System (INIS)

Zhang, J Y; Wang, X F; Wang, X D; Fan, Z C; Li, Y; Ji, An; Yang, F H

2010-01-01

A new method has been developed to selectively fabricate nano-gap electrodes and nano-channels by conventional lithography. Based on a sacrificial spacer process, we have successfully obtained sub-100-nm nano-gap electrodes and nano-channels and further reduced the dimensions to 20 nm by shrinking the sacrificial spacer size. Our method shows good selectivity between nano-gap electrodes and nano-channels due to different sacrificial spacer etch conditions. There is no length limit for the nano-gap electrode and the nano-channel. The method reported in this paper also allows for wafer scale fabrication, high throughput, low cost, and good compatibility with modern semiconductor technology.

Hydronium-dominated ion transport in carbon-dioxide-saturated electrolytes at low salt concentrations in nanochannels

DEFF Research Database (Denmark)

Pennathur, Sumita; Kristensen, Jesper; Crumrine, Andrew

2011-01-01

the surface reaction equilibrium constant for silica/hydronium reactions. The model describes our experimental data with aqueous potassium chloride solutions in 165-nm-high silica nanochannels well, and furthermore, by comparing model predictions with measurements in bulk and in nanochannels with hydrochloric...

Experimental investigation of flow and slip transition in nanochannels

Science.gov (United States)

Li, Zhigang; Li, Long; Mo, Jingwen

2014-11-01

Flow slip in nanochannels is sought in many applications, such as sea water desalination and molecular separation, because it can enhance fluid transport, which is essential in nanofluidic systems. Previous findings about the slip length for simple fluids at the nanoscale appear to be controversial. Some experiments and simulations showed that the slip length is independent of shear rate, which agrees with the prediction of classic slip theories. However, there is increasing work showing that slip length is shear rate dependent. In this work, we experimentally investigate the Poiseuille flows in nanochannels. It is found that the flow rate undergoes a transition between two linear regimes as the shear rate is varied. The transition indicates that the non-slip boundary condition is valid at low shear rate. When the shear rate is larger than a critical value, slip takes place and the slip length increases linearly with increasing shear rate before approaching a constant value. The results reported in this work can help advance the understanding of flow slip in nanochannels. This work was supported by the Research Grants Council of the Hong Kong Special Administrative Region under Grant Nos. 615710 and 615312. J. Mo was partially supported by the Postgraduate Scholarship through the Energy Program at HKUST.

Bioinspired smart asymmetric nanochannel membranes.

Science.gov (United States)

Zhang, Zhen; Wen, Liping; Jiang, Lei

2018-01-22

Bioinspired smart asymmetric nanochannel membranes (BSANM) have been explored extensively to achieve the delicate ionic transport functions comparable to those of living organisms. The abiotic system exhibits superior stability and robustness, allowing for promising applications in many fields. In view of the abundance of research concerning BSANM in the past decade, herein, we present a systematic overview of the development of the state-of-the-art BSANM system. The discussion is focused on the construction methodologies based on raw materials with diverse dimensions (i.e. 0D, 1D, 2D, and bulk). A generic strategy for the design and construction of the BSANM system is proposed first and put into context with recent developments from homogeneous to heterogeneous nanochannel membranes. Then, the basic properties of the BSANM are introduced including selectivity, gating, and rectification, which are associated with the particular chemical and physical structures. Moreover, we summarized the practical applications of BSANM in energy conversion, biochemical sensing and other areas. In the end, some personal opinions on the future development of the BSANM are briefly illustrated. This review covers most of the related literature reported since 2010 and is intended to build up a broad and deep knowledge base that can provide a solid information source for the scientific community.

Field-effect pH Control in Nanochannels

NARCIS (Netherlands)

Veenhuis, R.B.H.; van der Wouden, E.J.; van Nieuwkasteele, Jan William; van den Berg, Albert; Eijkel, Jan C.T.; Kim, Tae Song; Lee, Yoon-Sik; Chung, Taek-Dong; Jeon, Noo Li; Lee, Sang-Hoon; Suh, Kaph-Yang; Choo, Jaebum; Kim, Yong-Kweon

2009-01-01

We demonstrate a novel capacitive method to change the pH in nanochannels. The device employs metal electrodes outside an insulating channel wall to change the electrical double layer potential by the field effect (‘voltage gating’). We demonstrate that this potential change is accompanied by a

Drag reduction in silica nanochannels induced by graphitic wall coatings

Science.gov (United States)

Wagemann, Enrique; Walther, J. H.; Zambrano, Harvey A.

2017-11-01

Transport of water in hydrophilic nanopores is of significant technological and scientific interest. Water flow through hydrophilic nanochannels is known to experience enormous hydraulic resistance. Therefore, drag reduction is essential for the development of highly efficient nanofluidic devices. In this work, we propose the use of graphitic materials as wall coatings in hydrophilic silica nanopores. Specifically, by conducting atomistic simulations, we investigate the flow inside slit and cylindrical silica channels with walls coated with graphene (GE) layers and carbon nanotubes (CNTs), respectively. We develop realistic force fields to simulate the systems of interest and systematically, compare flow rates in coated and uncoated nanochannels under different pressure gradients. Moreover, we assess the effect that GE and CNT translucencies to wettability have on water hydrodynamics in the nanochannels. The influence of channel size is investigated by systematically varying channel heights and nanopore diameters. In particular, we present the computed water density and velocity profiles, volumetric flow rates, slip lengths and flow enhancements, to clearly demonstrate the drag reduction capabilities of graphitic wall coatings. We wish to thank partial funding from CRHIAM Conicyt/ Fondap Project 15130015 and computational support from DTU and NLHPC (Chile).

Self-organized titanium oxide nano-channels for resistive memory application

Energy Technology Data Exchange (ETDEWEB)

Barman, A.; Saini, C. P.; Dhar, S.; Kanjilal, A., E-mail: aloke.kanjilal@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201 314 (India); Sarkar, P. [Department of Physics, National Institute of Technology, Silchar, Assam 788 010 (India); Satpati, B.; Bhattacharyya, S. R. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Kabiraj, D.; Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2015-12-14

Towards developing next generation scalable TiO{sub 2}-based resistive switching (RS) memory devices, the efficacy of 50 keV Ar{sup +}-ion irradiation to achieve self-organized nano-channel based structures at a threshold fluence of 5 × 10{sup 16} ions/cm{sup 2} at ambient temperature is presented. Although x-ray diffraction results suggest the amorphization of as-grown TiO{sub 2} layers, detailed transmission electron microscopy study reveals fluence-dependent evolution of voids and eventual formation of self-organized nano-channels between them. Moreover, gradual increase of TiO/Ti{sub 2}O{sub 3} in the near surface region, as monitored by x-ray photoelectron spectroscopy, establishes the upsurge in oxygen deficient centers. The impact of structural and chemical modification on local RS behavior has also been investigated by current-voltage measurements in conductive atomic force microscopy, while memory application is manifested by fabricating Pt/TiO{sub 2}/Pt/Ti/SiO{sub 2}/Si devices. Finally, the underlying mechanism of our experimental results has been analyzed and discussed in the light of oxygen vacancy migration through nano-channels.

Electricity resonance-induced fast transport of water through nanochannels.

Science.gov (United States)

Kou, Jianlong; Lu, Hangjun; Wu, Fengmin; Fan, Jintu; Yao, Jun

2014-09-10

We performed molecular dynamics simulations to study water permeation through a single-walled carbon nanotube with electrical interference. It was found that the water net flux across the nanochannel is greatly affected by the external electrical interference, with the maximal net flux occurred at an electrical interference frequency of 16670 GHz being about nine times as high as the net flux at the low or high frequency range of (80,000 GHz). The above phenomena can be attributed to the breakage of hydrogen bonds as the electrical interference frequency approaches to the inherent resonant frequency of hydrogen bonds. The new mechanism of regulating water flux across nanochannels revealed in this study provides an insight into the water transportation through biological water channels and has tremendous potential in the design of high-flux nanofluidic systems.

Molecular dynamic simulation of Ar-Kr mixture across a rough walled nanochannel: Velocity and temperature profiles

International Nuclear Information System (INIS)

Pooja,; Ahluwalia, P. K.; Pathania, Y.

2015-01-01

This paper presents the results from a molecular dynamics simulation of mixture of argon and krypton in the Poiseuille flow across a rough walled nanochannel. The roughness effect on liquid nanoflows has recently drawn attention The computational software used for carrying out the molecular dynamics simulations is LAMMPS. The fluid flow takes place between two parallel plates and is bounded by horizontal rough walls in one direction and periodic boundary conditions are imposed in the other two directions. Each fluid atom interacts with other fluid atoms and wall atoms through Leenard-Jones (LJ) potential with a cut off distance of 5.0. To derive the flow a constant force is applied whose value is varied from 0.1 to 0.3 and velocity profiles and temperature profiles are noted for these values of forces. The velocity profile and temperature profiles are also looked at different channel widths of nanochannel and at different densities of mixture. The velocity profile and temperature profile of rough walled nanochannel are compared with that of smooth walled nanochannel and it is concluded that mean velocity increases with increase in channel width, force applied and decrease in density also with introduction of roughness in the walls of nanochannel mean velocity again increases and results also agree with the analytical solution of a Poiseuille flow

Light-Induced Local Heating for Thermophoretic Manipulation of DNA in Polymer Micro- and Nanochannels

DEFF Research Database (Denmark)

Thamdrup, Lasse Højlund; Larsen, Niels Bent; Kristensen, Anders

2010-01-01

We present a method for making polymer chips with a narrow-band near-infrared absorber layer that enables light-induced local heating of liquids inside fluidic micro- and nanochannels fabricated by thermal imprint in polymethyl methacrylate. We have characterized the resulting liquid temperature...... profiles in microchannels using the temperature dependent fluorescence of the complex [Ru(bpy)3]2+. We demonstrate thermophoretic manipulation of individual YOYO-1 stained T4 DNA molecules inside micro- and nanochannels....

Slip flow in graphene nanochannels

DEFF Research Database (Denmark)

. Kannam, Sridhar; Billy, Todd; Hansen, Jesper Schmidt

2011-01-01

We investigate the hydrodynamic boundary condition for simple nanofluidic systems such as argon and methane flowing in graphene nanochannels using equilibrium molecular dynamics simulations (EMD) in conjunction with our recently proposed method [J. S. Hansen, B. D. Todd, and P. J. Daivis, Phys. Rev....... E 84, 016313 (2011)10.1103/PhysRevE.84.016313]. We first calculate the fluid-graphene interfacial friction coefficient, from which we can predict the slip length and the average velocity of the first fluid layer close to the wall (referred to as the slip velocity). Using direct nonequilibrium...

Diffusion transport of nanoparticles at nanochannel boundaries

International Nuclear Information System (INIS)

Mahadevan, T. S.; Milosevic, M.; Kojic, M.; Hussain, F.; Kojic, N.; Serda, R.; Ferrari, M.; Ziemys, A.

2013-01-01

The manipulation of matter at the nanoscale has unleashed a great potential for engineering biomedical drug carriers, but the transport of nanoparticles (NPs) under nanoscale confinement is still poorly understood. Using colloidal physics to describe NP interactions, we have computationally studied the passive transport of NPs using experimentally relevant conditions from bulk into a nanochannel of 60–90 nm height. NP size, channel height, and the Debye length are comparable so that changes in nanoscale dimensions may induce substantial changes in NP transport kinetics. We show that subtle changes in nanochannel dimensions may alter the energy barrier by about six orders of magnitude resulting in different NP penetration depths and diffusion mechanisms: ballistic, first-order and quasi zero-order transport regimes. The analysis of NP diffusion by continuum methods reveals that apparent diffusivity is reduced by decreasing channel size. The continuum finite element (FE) numerical method reproduced the colloidal model results only when surface interactions were accounted for. These results give a new insight into NP passive transport at the boundaries of nanoconfined domains, and have implications on the design of nanoscale fluidics and NP systems for biomedical and engineering applications.

Perspectives on continuum flow models for force-driven nano-channel liquid flows

Science.gov (United States)

Beskok, Ali; Ghorbanian, Jafar; Celebi, Alper

2017-11-01

A phenomenological continuum model is developed using systematic molecular dynamics (MD) simulations of force-driven liquid argon flows confined in gold nano-channels at a fixed thermodynamic state. Well known density layering near the walls leads to the definition of an effective channel height and a density deficit parameter. While the former defines the slip-plane, the latter parameter relates channel averaged density with the desired thermodynamic state value. Definitions of these new parameters require a single MD simulation performed for a specific liquid-solid pair at the desired thermodynamic state and used for calibration of model parameters. Combined with our observations of constant slip-length and kinematic viscosity, the model accurately predicts the velocity distribution and volumetric and mass flow rates for force-driven liquid flows in different height nano-channels. Model is verified for liquid argon flow at distinct thermodynamic states and using various argon-gold interaction strengths. Further verification is performed for water flow in silica and gold nano-channels, exhibiting slip lengths of 1.2 nm and 15.5 nm, respectively. Excellent agreements between the model and the MD simulations are reported for channel heights as small as 3 nm for various liquid-solid pairs.

Reversible photoluminescence in spiropyran-modified porous silicon

International Nuclear Information System (INIS)

Lee, Chen-Yu; Hu, Chih-Hsuan; Cheng, Sheng-Lin; Chu, Chih-Chien; Hsiao, Vincent K.S.

2015-01-01

Spiropyran-modified porous silicon (spiro-PS) was used for the first time as an organic–inorganic hybrid material by using reversible photoluminescence (PL). Before spiropyran modification, the peak wavelength from PS was approximately 600 nm. Subsequent spiropyran modification strongly quenched the PL intensity, from 15,000 to 2000 counts. However, under UV light irradiation, the PL intensity from spiro-PS was increased gradually to 20,000 counts because of the photoinduced ring opening from a colorless spiropyran (SP-form) to a colored merocyanine (MC-form). Furthermore, the resulting peak wavelength of the PL of an MC–PS sample red-shifted from 600 to 650 nm, and the PL intensity was higher than that of unmodified PS. Because the fluorescence emission band (500–700 nm) of PS substantially overlapped the absorption band (500–700 nm) of the MC-form of spiropyran, the energy transfer from the PS (donor) to the open-ring-state MC-form (acceptor) occurs efficiently. The intensity of the PL from spiro-PS can be reversibly modulated using a heat stimulus. The current demonstrations have potential in reversible solid-state lighting or data storage applications. - Highlights: • Spiropyran-modified porous silicon (spiro-PS) was used for the first time as an organic–inorganic hybrid material with reversible photoluminescence (PL). • UV light irradiation make PL intensity from spiro-PS increased due to the photo-induced ring opening process. • The energy transfer from the PS (donor) to the open-ring state of spiropyran (acceptor) was to be efficient due to the fluorescence emission band of PS substantially overlapped with the absorption band of the ring-opened spiro. • The intensity of the PL from spiro-PS can be reversibly modulated using a heat stimulus

End-functional silicone coupling agent modified PEO/P(VDF-HFP)/SiO2 nanocomposite polymer electrolyte DSSC

International Nuclear Information System (INIS)

Zhang Jing; Yang Ying; Wu Sujuan; Xu Sheng; Zhou Conghua; Hu Hao; Chen Bolei; Xiong Xiaodong; Sebo, Bobby; Han Hongwei; Zhao Xingzhong

2008-01-01

The end-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS for short) was used to modify the PEO/P(VDF-HFP)/SiO 2 nanocomposite polymer electrolyte (CPE) and the different amounts of DTMS modification effects were studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains (-C 12 H 25 ) chemically engineered on the SiO 2 nanoparticles, and formed a Si-O-Si cross-linked network in the new nanocomposite polymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionic conductivity and the connection with the photoanode and counter electrode. However, much higher content of the DTMS modification changed the conformation of the polymer network and reduced the ionic movement. Compared with the performance (3.84%) of the original DSSC, the DSSC with functional silicone coupling agent modified CPE (DTMS:SiO 2 = 2:1, mol ratio) exhibited improved J sc (7.94 mA cm -2 ), V oc (0.624 V) and optimal efficiency (5.2%) (measured at AM1.5, light intensity of 58.4 mW cm -2 ). The V oc of the silicone coupling agent modified polymer electrolyte DSSC is obviously improved, which is mainly due to that the hydrophobic alkyl chain end groups formed an insulating layer that retarded the electron recombination at the TiO 2 nanoporous photoanode/polymer electrolyte interface. The DTMS:SiO 2 = 2:1 modified CPE type DSSC exhibited a performance of 6.42% at a light intensity of 32.1 mW cm -2 and 4.94% at 99.2 mW cm -2

Modified porous silicon for electrochemical sensor of para-nitrophenol

International Nuclear Information System (INIS)

Belhousse, S.; Belhaneche-Bensemra, N.; Lasmi, K.; Mezaache, I.; Sedrati, T.; Sam, S.; Tighilt, F.-Z.; Gabouze, N.

2014-01-01

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10 −8 M to the 3 × 10 −4 M

Cathodoluminescence study of anodic nanochannel alumina

Energy Technology Data Exchange (ETDEWEB)

Guo, Q.X. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan)]. E-mail: guoq@cc.saga-u.ac.jp; Hachiya, Y. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Tanaka, T. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Nishio, M. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Ogawa, H. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan)

2006-07-15

Nanochannel alumina (NCA) templates with highly ordered pore arrays were prepared by anodizing pure aluminum foil in acid solutions. Cathodoluminescence measurements reveal that a blue emission band appears at around 2.8 eV and its energy position depends on measurement temperature and pore size of NCA. The shift of the blue emission band energy with temperature is ascribed to the variations of electron-phonon interactions. X-ray absorption near-edge fine structure results show that the blue emission band shift with pore size is due to the local environment change of atoms in NCA.

Modified silicone sling assisted temporalis muscle transfer in the management of lagophthalmos

Directory of Open Access Journals (Sweden)

Ramesh C Gupta

2014-01-01

Full Text Available Aim : To evaluate the efficacy of modified temporalis muscle transfer (TMT by silicone sling for the management of paralytic lagophthalmos. Settings and Design: Prospective interventional study. Materials and Methods : Ten patients of lagophthalmos due to facial palsy underwent modified TMT using silicone sling. The patients were followed-up for a period of 3 months. Palpebral aperture in primary gaze and during eye closure were assessed both pre- and postoperatively along with problems associated with lagophthalmos like exposure keratopathy and lacrimation. Statistical Analysis : Paired t-test was applied to measure the statistical outcome. Results : Eight patients achieved full correction of lagophthalmos with no lid gap on closing the eye. The mean (standard deviation (SD lid gap on eye closure was 7.7 (0.86 mm preoperatively, 0.5 (0.47 mm at 1 st postoperative day, and 0.7 (0.75 mm at 3 rd month. There was a reduction in mean lid gap on eye closure of 7 mm at 3 months (P < 0.0001 which is highly significant. The mean (SD vertical interpalpebral distance during primary gaze was 12.05 (1.12 mm preoperatively, 10 (0.94 mm at 1 st postoperative day, and 10.35 (1.08 mm at 3 rd month. There was a reduction in mean vertical inter palpebral distance of 1.7 mm at 3 months (P = 0.001 which is significant. Exposure keratitis decreased in five out of six patients at 3 months. Conclusion : Modified TMT by silicone sling is a useful procedure with lesser morbidity and good outcomes for the treatment of paralytic lagophthalmos due to long standing facial palsy.

Silicon microneedle formation using modified mask designs based on convex corner undercut

Science.gov (United States)

Wilke, N.; Morrissey, A.

2007-02-01

In this work, we present microneedle fabrication using the mechanism of silicon convex corner undercutting for modified etch masks in aqueous KOH solution (29% KOH, 79 °C). The presented modified mask designs include three different shapes, as well as different compensation structures applied to a square mask shape. We have found that square mask shapes present an optimum needle structure in contrast to circular or diamond shapes. The use of compensation structures facilitates an increase in needle density of 33-50% over that otherwise achieved.

Molecular Dynamics Simulation of Binary Fluid in a Nanochannel

International Nuclear Information System (INIS)

Mullick, Shanta; Ahluwalia, P. K.; Pathania, Y.

2011-01-01

This paper presents the results from a molecular dynamics simulation of binary fluid (mixture of argon and krypton) in the nanochannel flow. The computational software LAMMPS is used for carrying out the molecular dynamics simulations. Binary fluids of argon and krypton with varying concentration of atom species were taken for two densities 0.65 and 0.45. The fluid flow takes place between two parallel plates and is bounded by horizontal walls in one direction and periodic boundary conditions are imposed in the other two directions. To drive the flow, a constant force is applied in one direction. Each fluid atom interacts with other fluid atoms and wall atoms through Week-Chandler-Anderson (WCA) potential. The velocity profile has been looked at for three nanochannel widths i.e for 12σ, 14σ and 16σ and also for the different concentration of two species. The velocity profile of the binary fluid predicted by the simulations agrees with the quadratic shape of the analytical solution of a Poiseuille flow in continuum theory.

Nanoimprinted polymer chips for light induced local heating of liquids in micro- and nanochannels

DEFF Research Database (Denmark)

Thamdrup, Lasse Højlund; Pedersen, Jonas Nyvold; Flyvbjerg, Henrik

2010-01-01

A nanoimprinted polymer chip with a thin near-infrared absorber layer that enables light-induced local heating (LILH) of liquids inside micro- and nanochannels is presented. An infrared laser spot and corresponding hot-spot could be scanned across the device. Large temperature gradients yield...... a 785 nm laser diode was focused from the backside of the chip to a spot diameter down to 5 ..m in the absorber layer, yielding a localized heating (Gaussian profile) and large temperature gradients in the liquid in the nanochannels. A laser power of 38 mW yielded a temperature of 40°C in the center...

Concentration Polarization in Translocation of DNA through Nanopores and Nanochannels

NARCIS (Netherlands)

Das, S.; Dubsky, P.; van den Berg, Albert; Eijkel, Jan C.T.

2012-01-01

In this Letter we provide a theory to show that high-field electrokinetic translocation of DNA through nanopores or nanochannels causes large transient variations of the ionic concentrations in front and at the back of the DNA due to concentration polarization (CP). The CP causes strong local

Microspectroscopic analysis of green fluorescent proteins infiltrated into mesoporous silica nanochannels

NARCIS (Netherlands)

Ma, Yujie; Rajendran, Prayanka; Blum, Christian; Cesa, Yanina; Gartmann, Nando; Brühwiler, Dominik; Subramaniam, Vinod

2011-01-01

The infiltration of enhanced green fluorescent protein (EGFP) into nanochannels of different diameters in mesoporous silica particles was studied in detail by fluorescence microspectroscopy at room temperature. Silica particles from the MCM-41, ASNCs and SBA-15 families possessing nanometer-sized

Modified porous silicon for electrochemical sensor of para-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Belhousse, S., E-mail: all_samia_b@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Belhaneche-Bensemra, N., E-mail: nbelhaneche@yahoo.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Lasmi, K., E-mail: kahinalasmi@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Mezaache, I., E-mail: lyeso_44@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sedrati, T., E-mail: tarek_1990m@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sam, S., E-mail: Sabrina.sam@polytechnique.edu [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Tighilt, F.-Z., E-mail: mli_zola@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria)

2014-11-15

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10{sup −8} M to the 3 × 10{sup −4}M.

Effect of silica particles modified by in-situ and ex-situ methods on the reinforcement of silicone rubber

International Nuclear Information System (INIS)

Song, Yingze; Yu, Jinhong; Dai, Dan; Song, Lixian; Jiang, Nan

2014-01-01

Highlights: • In-situ and ex-situ methods were applied to modify silica particles. • In-situ method was more beneficial to preparing silica particles with high BET surface area. • Silicone rubber filled with in-situ modified silica exhibits excellent mechanical and thermal properties. - Abstract: In-situ and ex-situ methods were applied to modify silica particles in order to investigate their effects on the reinforcement of silicone rubber. Surface area and pore analyzer, laser particle size analyzer, Fourier-transform infrared spectroscopy (FTIR), contact-angle instrument, and transmission electron microscope (TEM) were utilized to investigate the structure and properties of the modified silica particles. Dynamic mechanical thermal analyzer (DMTA) was employed to characterize the vulcanizing behavior and mechanical properties of the composites. Thermogravimetric analysis (TGA) was performed to test the thermal stability of the composites. FTIR and contact angle analysis indicated that silica particles were successfully modified by these two methods. The BET surface area and TEM results reflected that in-situ modification was more beneficial to preparing silica particles with irregular shape and higher BET surface area in comparison with ex-situ modification. The DMTA and TGA data revealed that compared with ex-situ modification, the in-situ modification produced positive influence on the reinforcement of silicone rubber

The Electrochemical Stability in NaCl Solution of Nanotubes and Nanochannels Elaborated on a New Ti-20Zr-5Ta-2Ag Alloy

Directory of Open Access Journals (Sweden)

Claudiu Constantin Manole

2015-01-01

Full Text Available Nanotubular and nanochannels structures were fabricated via anodizing on a new alloy Ti-20Zr-8Ta-2Ag. A continuous coating of connected tubes/channels can be observed in the SEM micrographs forming tubular structures with diameters in hundreds of nm, as well as smaller tubes, with diameters in tens of nm. In the case of nanochannels structure, the diameters are smaller and wall thicknesses significantly thinner than in nanotubes. Wettability measurements indicate a decrease of contact angles in both cases of nanotubes and nanochannels, but the increase of hydrophilic character is more significant in the case of nanochannels. The Tafel procedure and electrochemical impedance spectroscopy tests performed in NaCl 0.9% solution indicate a better stability for the nanostructured surfaces compared to untreated alloy, the surface with nanochannels offering higher corrosion resistance. Spectral UV-VIS determination has confirmed Ag metallic presence, opening the door for applications not only in tissue engineering but for water splitting and the photoreduction of CO2 as well.

Distribution of trace elements in a modified and grain refined aluminium-silicon hypoeutectic alloy.

Science.gov (United States)

Faraji, M; Katgerman, L

2010-08-01

The influence of modifier and grain refiner on the nucleation process of a commercial hypoeutectic Al-Si foundry alloy (A356) was investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis technique (EPMA). Filtering was used to improve the casting quality; however, it compromised the modification of silicon. Effect of filtering on strontium loss was also studied using the afore-mentioned techniques. EPMA was used to trace the modifying and grain refining agents inside matrix and eutectic Si. This was to help understanding mechanisms of nucleation and modification in this alloy. Using EPMA, the negative interaction of Sr and Al3TiB was closely examined. In modified structure, it was found that the maximum point of Sr concentration was in line with peak of silicon; however, in case of just 0.1wt% added Ti, the peak of Ti concentration was not in line with aluminium, (but it was close to Si peak). Furthermore, EPMA results showed that using filter during casting process lowered the strontium content, although produced a cleaner melt. (c) 2010 Elsevier Ltd. All rights reserved.

Streaming current and wall dissolution over 48h in silica nanochannels

DEFF Research Database (Denmark)

Andersen, Mathias Bækbo; Bruus, Henrik; Bardhan, Jaydeep P.

2011-01-01

We present theoretical and experimental studies of the streaming current induced by a pressure-driven flow in long, straight, electrolyte-filled nanochannels. The theoretical work builds on our recent one-dimensional model of electro-osmotic and capillary flow, which self-consistently treats both...

Fabrication of fluidic devices with 30 nm nanochannels by direct imprinting

DEFF Research Database (Denmark)

Cuesta, Irene Fernandez; Palmarelli, Anna Laura; Liang, Xiaogan

2011-01-01

In this work, we propose an innovative approach to the fabrication of a complete micro/nano fluidic system, based on direct nanoimprint lithography. The fabricated device consists of nanochannels connected to U-shaped microchannels by triangular tapered inlets, and has four large reservoirs for l...

Stretching DNA in polymer nanochannels fabricated by thermal imprint in PMMA

DEFF Research Database (Denmark)

Thamdrup, Lasse Højlund; Klukowska, A.; Kristensen, Anders

2008-01-01

. The stamp is compatible with molecular vapor deposition ( MVD), used for applying a durable chlorosilane based antistiction coating, and allows for imprint up to a temperature of 270 degrees C. The extension of YOYO-1 stained T4 GT7 bacteriophage DNA inside the PMMA nanochannels has been experimentally...

Thermodynamics, electrostatics, and ionic current in nanochannels grafted with pH-responsive end-charged polyelectrolyte brushes.

Science.gov (United States)

Chen, Guang; Das, Siddhartha

2017-03-01

In this paper, we study the thermodynamics, electrostatics, and an external electric field driven ionic current in a pH-responsive, end-charged polyelectrolyte (PE) brush grafted nanochannel. By employing a mean field theory, we unravel a highly nonintuitive interplay of pH and electrolyte salt concentration in dictating the height of the end-charged PE brush. Larger pH or weak hydrogen ion concentration leads to maximum ionization of the charge-producing group-as a consequence, the resulting the electric double layer (EDL) energy get maximized causing a maximum deviation of the brush height from the value (d 0 ) of the uncharged brush. This deviation may result in enhancement or lowering of the brush height as compared to d 0 depending on whether the PE end locates lower or higher than h/2 (h is the nanochannel half height) and the salt concentration. Subsequently, we use this combined PE-brush-configuration-EDL-electrostatics framework to compute the ionic current in the nanochannel. We witness that the ionic current for smaller pH is much larger despite the corresponding magnitude of the EDL electrostatic potential being much smaller-this stems from the presence of a much larger concentration of H+ ions at small pH and the fact that H+ ions have very large mobilities. In fact, this ionic current shows a steep variation with pH that can be useful in exploring new designs for applications involving quantification and characterization of ionic current in PE-brush-grafted nanochannels. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multifunctional Core-Shell and Nano-channel Design for Nano-sized Thermo-sensor

Science.gov (United States)

2015-04-01

based on the filling of metals into a nanochannel design. Particularly, different metal alloys with tunable metlingpoints were used to created...nanowires in nanopores of anodic aluminium oxide by mechanical pressure injection. These nanowires inside AAO channels can behave as effective thermal

Slip divergence of water flow in graphene nanochannels: the role of chirality

DEFF Research Database (Denmark)

Wagemann, Enrique; Oyarzua, Elton; Walther, Jens Honore

2017-01-01

Graphene has attracted considerable attention due to its characteristics as a 2D material and its fascinating properties, providing a potential building block for nanofabrication. In nanochannels the solid-liquid interface plays a non-negligible role in determining the fluid dynamics. Therefore, ...

Crystal orientation of PEO confined within the nanorod templated by AAO nanochannels.

Science.gov (United States)

Liu, Chien-Liang; Chen, Hsin-Lung

2018-06-18

The orientation of poly(ethylene oxide) (PEO) crystallites developed in the nanochannels of anodic aluminum oxide (AAO) membrane has been investigated. PEO was filled homogeneously into the nanochannels in the melt state, and the crystallization confined within the PEO nanorod thus formed was allowed to take place subsequently at different temperatures. The effects of PEO molecular weight (MPEO), crystallization temperature (Tc) and AAO channel diameter (DAAO) on the crystal orientation attained in the nanorod were revealed by 2-D wide angle X-ray scattering (WAXS) patterns. In the nanochannels with DAAO = 23 nm, the crystallites formed from PEO with the lowest MPEO (= 3400 g mol-1) were found to adopt a predominantly perpendicular orientation with the crystalline stems aligning normal to the channel axis irrespective of Tc (ranging from -40 to 20 °C). Increasing MPEO or decreasing Tc tended to induce the development of the tilt orientation characterized by the tilt of the (120) plane by 45° from the channel axis. In the case of the highest MPEO (= 95 000 g mol-1) studied, both perpendicular and tilt orientations coexisted irrespective of Tc. Coexistent orientation was always observed in the channels with a larger diameter (DAAO = 89 nm) irrespective of MPEO and Tc. Compared with the previous results of the crystal orientation attained in nanotubes templated by the preferential wetting of the channel walls by PEO, the window of the perpendicular crystal orientation in the nanorod was much narrower due to its weaker confinement effect imposed on the crystal growth than that set by the nanotube.

Effect of the meniscus contact angle during early regimes of spontaneous imbibition in nanochannels

DEFF Research Database (Denmark)

Karna, Nabin Kumar; Oyarzua, Elton; Walther, Jens Honore

2016-01-01

study, large scale atomistic simulations are conducted to investigate capillary imbibition of water in slit silica nanochannels with heights between 4 and 18 nm. We find that the meniscus contact angle remains constant during the inertial regime and its value depends on the height of the channel. We...... also find that the meniscus velocity computed at the channel entrance is related to the particular value of the meniscus contact angle. Moreover, during the subsequent visco-inertial regime, as the influence of viscosity increases, the meniscus contact angle is found to be time dependent for all...... the channels under study. Furthermore, we propose an expression for the time evolution of the dynamic contact angle in nanochannels which, when incorporated into Bosanquet's equation, satisfactorily explains the initial capillary rise....

Probing electron density across Ar{sup +} irradiation-induced self-organized TiO{sub 2−x} nanochannels for memory application

Energy Technology Data Exchange (ETDEWEB)

Barman, A.; Saini, C. P.; Ghosh, S. K.; Dhar, S.; Kanjilal, A., E-mail: aloke.kanjilal@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314 (India); Sarkar, P. K.; Roy, A. [Department of Physics, National Institute of Technology, Silchar, Assam 788010 (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

2016-06-13

The variation of electron density in TiO{sub 2−x} nanochannels, exhibiting resistive switching phenomenon, produced by Ar{sup +} ion-irradiation at the threshold fluence of 5 × 10{sup 16} ions/cm{sup 2} is demonstrated by X-ray reflectivity (XRR). The transmission electron microscopy reveals the formation of nanochannels, while the energy dispersive X-ray spectroscopy confirms Ti enrichment near the surface due to ion-irradiation, in consistent with the increase in electron density by XRR measurements. Such a variation in Ti concentration indicates the evolution of oxygen vacancies (OVs) along the TiO{sub 2−x} nanochannels, and thus paves the way to explain the operation and performance of the Pt/TiO{sub 2−x}/Pt-based memory devices via OV migration.

Radiation-induced evolution of austenite matrix in silicon-modified AISI 316 alloys

International Nuclear Information System (INIS)

Garner, F.A.; Brager, H.R.

1980-01-01

The microstructures of a series of silicon-modified AISI 316 alloys irradiated to fast neutron fluences of about 2-3 and 10 x 10 22 n/cm 2 (E > 0.1 MeV at temperatures ranging from 400 0 C to 600 0 C have been examined. The irradiation of AISI 316 leads to an extensive repartition of several elements, particularly nickel and silicon, between the matrix and various precipitate phases. The segregation of nickel at void and grain boundary surfaces at the expense of other faster-diffusing elements is a clear indication that one of the mechanisms driving the microchemical evolution is the Inverse Kirkendall effect. There is evidence that at one sink this mechanism is in competition with the solute drag process associated with interstitial gradients

Structure and band gap determination of irradiation-induced amorphous nano-channels in LiNbO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sachan, R., E-mail: sachanr@ornl.gov; Pakarinen, O. H.; Chisholm, M. F. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Liu, P. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China); Patel, M. K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Zhang, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Wang, X. L. [School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China); Weber, W. J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2015-04-07

The irradiation of lithium niobate with swift heavy ions results in the creation of amorphous nano-sized channels along the incident ion path. These nano-channels are on the order of a hundred microns in length and could be useful for photonic applications. However, there are two major challenges in these nano-channels characterization: (i) it is difficult to investigate the structural characteristics of these nano-channels due to their very long length and (ii) the analytical electron microscopic analysis of individual ion track is complicated due to electron beam sensitive nature of lithium niobate. Here, we report the first high resolution microscopic characterization of these amorphous nano-channels, widely known as ion-tracks, by direct imaging them at different depths in the material, and subsequently correlating the key characteristics with electronic energy loss of ions. Energetic Kr ions ({sup 84}Kr{sup 22} with 1.98 GeV energy) are used to irradiate single crystal lithium niobate with a fluence of 2 × 10{sup 10} ions/cm{sup 2}, which results in the formation of individual ion tracks with a penetration depth of ∼180 μm. Along the ion path, electron energy loss of the ions, which is responsible for creating the ion tracks, increases with depth under these conditions in LiNbO{sub 3}, resulting in increases in track diameter of a factor of ∼2 with depth. This diameter increase with electronic energy loss is consistent with predictions of the inelastic thermal spike model. We also show a new method to measure the band gap in individual ion track by using electron energy-loss spectroscopy.

Novel epoxy-silicone thermolytic transparent packaging adhesives chemical modified by ZnO nanowires for HB LEDs

International Nuclear Information System (INIS)

He Ying; Wang Junan; Pei Changlong; Song Jizhong; Zhu Di; Chen Jie

2010-01-01

A novel high transparent thermolytic epoxy-silicone for high-brightness light-emitting diode (HB-LED) is introduced, which was synthesized by polymerization using silicone matrix via diglycidyl ether bisphenol-A epoxy resin (DGEBA) as reinforcing agent, and filling ZnO nanowires to modify thermal conductivity and control refractive index of the hybrid material. The interactions of ZnO nanowires with polymers are mediated by the ligands attached to the nanoparticles. Thus, the ligands markedly influence the properties of ZnO nanowires/epoxy-silicone composites. The refractive indices of the prepared hybrid adhesives can be tuned by the ZnO nanowires from 1.4711 to 1.5605. Light transmittance can be increased by 20% from 80 to 95%. The thermal conductivity of the transparent packaging adhesives is 0.89-0.90 W/mK.

Detection of DNA of genetically modified maize by a silicon nanowire field-effect transistor

International Nuclear Information System (INIS)

Pham, Van Binh; Tung Pham, Xuan Thanh; Duong Dang, Ngoc Thuy; Tuyen Le, Thi Thanh; Tran, Phu Duy; Nguyen, Thanh Chien; Nguyen, Van Quoc; Dang, Mau Chien; Tong, Duy Hien; Van Rijn, Cees J M

2011-01-01

A silicon nanowire field-effect transistor based sensor (SiNW-FET) has been proved to be the most sensitive and powerful device for bio-detection applications. In this paper, SiNWs were first fabricated by using our recently developed deposition and etching under angle technique (DEA), then used to build up the complete SiNW device based biosensor. The fabricated SiNW biosensor was used to detect DNA of genetically modified maize. As the DNA of the genetically modified maize has particular DNA sequences of 35S promoter, we therefore designed 21 mer DNA oligonucleotides, which are used as a receptor to capture the transferred DNA of maize. In our work, the SiNW biosensor could detect DNA of genetically modified maize with concentrations down to about 200 pM

Radiation cured and monomer modified silicon elastomers

International Nuclear Information System (INIS)

Eldred, R.J.

1979-01-01

A method is described for the production of a tear resistant silicone elastomer, which has improved elongation properties. This elastomer is the radiation induced reaction product of a noncured methyl vinyl silicone resin (VMQ) and uniformly dispersed therein a blend of a polyfunctional acrylic crosslinking monomer and a filler

Positronium in the AEgIS experiment: study on its emission from nanochanneled samples and design of a new apparatus for Rydberg excitations

CERN Document Server

Di Noto, Lea

This experimental thesis has been done in the framework of AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy), an experiment installed at CERN, whose primary goal is the measurement of the Earth's gravitational acceleration on anti-hydrogen. The antiatoms will be produced by the charge exchange reaction, where a cloud of Ps in Rydberg states interacts with cooled trapped antiprotons. Since the charge exchange cross section depends on Ps velocity and quantum number, the velocity distribution of Ps emitted by a positron-positronium converter as well as its excitation in Rydberg states have to be studied and optimized. In this thesis Ps cooling and emission into vacuum from nanochannelled silicon targets was studied by performing Time of Flight measurements with a dedicated apparatus conceived to receive the slow positron beam as produced at the Trento laboratory or at the NEPOMUC facility at Munich. Measurements were done by varying the positron implantation energy, the sample temperature and ...

The fabrication of silicon nanostructures by focused-ion-beam implantation and TMAH wet etching

International Nuclear Information System (INIS)

Sievilae, Paeivi; Chekurov, Nikolai; Tittonen, Ilkka

2010-01-01

Local gallium implantation of silicon by a focused ion beam (FIB) has been used to create a mask for anisotropic tetramethylammonium hydroxide (TMAH) wet etching. The dependence of the etch stop properties of gallium-doped silicon on the implanted dose has been investigated and a dose of 4 x 10 13 ions cm -2 has been determined to be the threshold value for achieving observable etching resistance. Only a thin, approx. 50 nm, surface layer is found to be durable enough to serve as a mask with a high selectivity of at least 2000:1 between implanted and non-implanted areas. The combined FIB-TMAH process has been used to generate various types of 3D nanostructures including nanochannels separated by thin vertical sidewalls with aspect ratios up to 1:30, ultra-narrow (approx. 25 nm) freestanding bridges and cantilevers, and gratings with a resolution of 20 lines μm -1 .

Hydronium-dominated ion transport in carbon-dioxide-saturated electrolytes at low salt concentrations in nanochannels

DEFF Research Database (Denmark)

Lund Jensen, Kristian; Kristensen, Jesper Toft; Crumrine, Andrew Michael

2011-01-01

the nanochannel conductance at low salt concentrations and identify a conductance minimum before saturation at a value independent of salt concentration in the dilute limit. Via the Poisson-Boltzmann equation, our model self-consistently couples chemical-equilibrium dissociation models of the silica wall...

Amine-modified hyaluronic acid-functionalized porous silicon nanoparticles for targeting breast cancer tumors

Science.gov (United States)

Almeida, Patrick V.; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Kaasalainen, Martti; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A.

2014-08-01

Active targeting of nanoparticles to receptor-overexpressing cancer cells has great potential for enhancing the cellular uptake of nanoparticles and for reducing fast clearance of the nanoparticles from the body. Herein, we present a preparation method of a porous silicon (PSi)-based nanodelivery system for breast cancer targeting, by covalently conjugating a synthesized amide-modified hyaluronic acid (HA+) derived polymer on the surface of undecylenic acid-modified thermally hydrocarbonized PSi (UnTHCPSi) nanoparticles. The resulting UnTHCPSi-HA+ nanoparticles showed relatively small size, reduced polydispersibility, high biocompatibility, improved colloidal and human plasma stability, as well as enhanced cellular interactions and internalization. Moreover, we demonstrated that the enhanced cellular association of UnTHCPSi-HA+ relies on the capability of the conjugated HA+ to bind and consequently target CD44 receptors expressed on the surface of breast cancer cells, thus making the HA+-functionalized UnTHCPSi nanoparticles a suitable and promising nanoplatform for the targeting of CD44-overexpressing breast tumors and for drug delivery.Active targeting of nanoparticles to receptor-overexpressing cancer cells has great potential for enhancing the cellular uptake of nanoparticles and for reducing fast clearance of the nanoparticles from the body. Herein, we present a preparation method of a porous silicon (PSi)-based nanodelivery system for breast cancer targeting, by covalently conjugating a synthesized amide-modified hyaluronic acid (HA+) derived polymer on the surface of undecylenic acid-modified thermally hydrocarbonized PSi (UnTHCPSi) nanoparticles. The resulting UnTHCPSi-HA+ nanoparticles showed relatively small size, reduced polydispersibility, high biocompatibility, improved colloidal and human plasma stability, as well as enhanced cellular interactions and internalization. Moreover, we demonstrated that the enhanced cellular association of Un

Platelet Lysate-Modified Porous Silicon Microparticles for Enhanced Cell Proliferation in Wound Healing Applications.

Science.gov (United States)

Fontana, Flavia; Mori, Michela; Riva, Federica; Mäkilä, Ermei; Liu, Dongfei; Salonen, Jarno; Nicoletti, Giovanni; Hirvonen, Jouni; Caramella, Carla; Santos, Hélder A

2016-01-13

The new frontier in the treatment of chronic nonhealing wounds is the use of micro- and nanoparticles to deliver drugs or growth factors into the wound. Here, we used platelet lysate (PL), a hemoderivative of platelets, consisting of a multifactorial cocktail of growth factors, to modify porous silicon (PSi) microparticles and assessed both in vitro and ex vivo the properties of the developed microsystem. PL-modified PSi was assessed for its potential to induce proliferation of fibroblasts. The wound closure-promoting properties of the microsystem were then assessed in an in vitro wound healing assay. Finally, the PL-modified PSi microparticles were evaluated in an ex vivo experiment over human skin. It was shown that PL-modified PSi microparticles were cytocompatible and enhanced the cell proliferation in different experimental settings. In addition, this microsystem promoted the closure of the gap between the fibroblast cells in the wound healing assay, in periods of time comparable with the positive control, and induced a proliferation and regeneration process onto the human skin in an ex vivo experiment. Overall, our results show that PL-modified PSi microparticles are suitable microsystems for further development toward applications in the treatment of chronic nonhealing wounds.

Direct bonding of ALD Al₂O₃ to silicon nitride thin films

DEFF Research Database (Denmark)

Laganà, Simone; Mikkelsen, E. K.; Marie, Rodolphe

2017-01-01

microscopy (TEM) by improving low temperature annealing bonding strength when using atomic layer deposition of aluminum oxide. We have investigated and characterized bonding of Al2O3-SixNy (low stress silicon rich nitride) and Al2O3-Si3N4 (stoichiometric nitride) thin films annealed from room temperature up......O3 can be bonded to. Preliminary tests demonstrating a well-defined nanochannel system with-100 nm high channels successfully bonded and tests against leaks using optical fluorescence technique and transmission electron microscopy (TEM) characterization of liquid samples are also reported. Moreover...

Nanochannel Electroporation as a Platform for Living Cell Interrogation in Acute Myeloid Leukemia.

Science.gov (United States)

Zhao, Xi; Huang, Xiaomeng; Wang, Xinmei; Wu, Yun; Eisfeld, Ann-Kathrin; Schwind, Sebastian; Gallego-Perez, Daniel; Boukany, Pouyan E; Marcucci, Guido I; Lee, Ly James

2015-12-01

A living cell interrogation platform based on nanochannel electroporation is demonstrated with analysis of RNAs in single cells. This minimally invasive process is based on individual cells and allows both multi-target analysis and stimulus-response analysis by sequential deliveries. The unique platform possesses a great potential to the comprehensive and lysis-free nucleic acid analysis on rare or hard-to-transfect cells.

Small-angle X-ray scattering investigations of biomolecular confinement, loading, and release from liquid-crystalline nanochannel assemblies

Czech Academy of Sciences Publication Activity Database

Angelova, A.; Angelov, Borislav; Garamus, V. M.; Couvreur, P.; Lesieur, S.

2012-01-01

Roč. 3, č. 3 (2012), s. 445-457 ISSN 1948-7185 Institutional research plan: CEZ:AV0Z40500505 Keywords : nanochannels * biomolecular nanostructures * SAXS Subject RIV: CD - Macromolecular Chemistry Impact factor: 6.585, year: 2012

High Current Ionic Diode Using Homogeneously Charged Asymmetric Nanochannel Network Membrane.

Science.gov (United States)

Choi, Eunpyo; Wang, Cong; Chang, Gyu Tae; Park, Jungyul

2016-04-13

A high current ionic diode is achieved using an asymmetric nanochannel network membrane (NCNM) constructed by soft lithography and in situ self-assembly of nanoparticles with uniform surface charge. The asymmetric NCNM exhibits high rectified currents without losing a rectification ratio because of its ionic selectivity gradient and differentiated electrical conductance. Asymmetric ionic transport is analyzed with diode-like I-V curves and visualized via fluorescent dyes, which is closely correlated with ionic selectivity and ion distribution according to variation of NCNM geometries.

Application of methane as a gaseous modifier for the determination of silicon using electrothermal atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Heinrich, Hans-Joachim, E-mail: hans-joachim.heinrich@bam.de; Kipphardt, Heinrich

2012-04-15

For determination of silicon in aqueous solutions by electrothermal atomic absorption spectrometry methane/argon mixtures as a gaseous modifier were applied during the pyrolysis step to improve the analytical performance. The beneficial effects observed on thermal stabilization, signal enhancement and shape of absorbance signals were attributed to the thermal decomposition products of methane, which were hydrogen and carbon black (soot). Using a 5% CH{sub 4} mixture with argon, the optimized pyrolysis and atomization temperatures were 1350 Degree-Sign C and 2450 Degree-Sign C, respectively. A flushing step following the pyrolysis was mandatory to avoid background absorption and accelerated deposition of pyrolytic graphite. Characteristic masses of 50 and 30 pg were obtained for standard transversely heated graphite atomizer (THGA) tubes and end-capped THGA tubes, respectively, which were lower than with other previously applied modifiers. A limit of detection of 0.2 {mu}g L{sup -1} (3 s, n = 10) has been obtained. In addition, this gaseous modifier did not contribute to contamination which often was significant when a liquid modifier solution was co-injected. The proposed method has been applied to the determination of silicon in ultrapure water, nitric and hydrochloric acids. - Highlights: Black-Right-Pointing-Pointer CH{sub 4}/Ar gas mixtures act as new modifier in the determination of Si using ET AAS. Black-Right-Pointing-Pointer CH{sub 4} improved thermal stabilization, atomization efficiency and signal shape of Si. Black-Right-Pointing-Pointer Optimum performance by addition of 5% CH{sub 4} during pyrolysis at 1350 Degree-Sign C. Black-Right-Pointing-Pointer Gaseous modifier does not contribute to blank values. Black-Right-Pointing-Pointer Optimized method suitable for determination of Si in ultrapure reagents.

Structure and dynamics of water confined in a graphene nanochannel under gigapascal high pressure: dependence of friction on pressure and confinement.

Science.gov (United States)

Yang, Lei; Guo, Yanjie; Diao, Dongfeng

2017-05-31

Recently, water flow confined in nanochannels has become an interesting topic due to its unique properties and potential applications in nanofluidic devices. The trapped water is predicted to experience high pressure in the gigapascal regime. Theoretical and experimental studies have reported various novel structures of the confined water under high pressure. However, the role of this high pressure on the dynamic properties of water has not been elucidated to date. In the present study, the structure evolution and interfacial friction behavior of water constrained in a graphene nanochannel were investigated via molecular dynamics simulations. Transitions of the confined water to different ice phases at room temperature were observed in the presence of lateral pressure at the gigapascal level. The friction coefficient at the water/graphene interface was found to be dependent on the lateral pressure and nanochannel height. Further theoretical analyses indicate that the pressure dependence of friction is related to the pressure-induced change in the structure of water and the confinement dependence results from the variation in the water/graphene interaction energy barrier. These findings provide a basic understanding of the dynamics of the nanoconfined water, which is crucial in both fundamental and applied science.

Reactivity study of silicon electrode modified by grafting using electrochemical reduction of diazonium salts

International Nuclear Information System (INIS)

Kaiber, A.; Cherkkaoui, M.; Chazalviel, J.N.

2015-01-01

The use of the hydrogenated surface of silicon is hampered by its chemical instability by surface oxidation. The researchers have attempted to modify this surface by direct grafting through the establishment of covalent silicon-carbon bonds from the reaction of chemical species on the surface. Different grafting methods can be implemented for the preparation of grafted surfaces. The choice of an electrochemical reaction allows fast grafting from the hydrogenated surface. We studied the formation of a phenyl layer by electrochemical reduction of aryl diazonium salts (BF4-,+N2-ph-OCH3) on a p-Si-H (111) electrode in an aqueous medium (0.05M H/sub 2/SO/sub 4/ + 0.05M HF). The grafting of an organic layer by reduction is confirmed by the observation of a cyclic voltammetry peak around -0.3V/SCE. In-situ infrared spectroscopy (IR) analysis allows to identify the chemical functions present on the grafted surface, allowing a direct monitoring of the grafting reaction. (author)

Electroosmotic Flow in Mixed Polymer Brush-Grafted Nanochannels

Directory of Open Access Journals (Sweden)

Qianqian Cao

2016-12-01

Full Text Available Mixed polymer brush-grafted nanochannels—where two distinct species of polymers are alternately grafted on the inner surface of nanochannels—are an interesting class of nanostructured hybrid materials. By using a coarse-grained molecular dynamics simulation method, we are able to simulate the electrokinetic transport dynamics of the fluid in such nanochannels as well as the conformational behaviors of the mixed polymer brush. We find that (1 the brush adopts vertically-layered and longitudinally-separated structures due to the coupling of electroosmotic flow (EOF and applied electric field; (2 the solvent quality affects the brush conformations and the transport properties of the EOF; (3 the EOF flux non-monotonically depends on the grafting density, although the EOF velocity in the central region of the channel monotonically depends on the grafting density.

Eavesdropping on spin waves inside the domain-wall nanochannel via three-magnon processes

Science.gov (United States)

Zhang, Beining; Wang, Zhenyu; Cao, Yunshan; Yan, Peng; Wang, X. R.

2018-03-01

One recent breakthrough in the field of magnonics is the experimental realization of reconfigurable spin-wave nanochannels formed by a magnetic domain wall with a width of 10-100 nm [Wagner et al., Nat. Nano. 11, 432 (2016), 10.1038/nnano.2015.339]. This remarkable progress enables an energy-efficient spin-wave propagation with a well-defined wave vector along its propagating path inside the wall. In the mentioned experiment, a microfocus Brillouin light scattering spectroscopy was taken in a line-scans manner to measure the frequency of the bounded spin wave. Due to their localization nature, the confined spin waves can hardly be detected from outside the wall channel, which guarantees the information security to some extent. In this work, we theoretically propose a scheme to detect/eavesdrop on the spin waves inside the domain-wall nanochannel via nonlinear three-magnon processes. We send a spin wave (ωi,ki) in one magnetic domain to interact with the bounded mode (ωb,kb) in the wall, where kb is parallel with the domain-wall channel defined as the z ̂ axis. Two kinds of three-magnon processes, i.e., confluence and splitting, are expected to occur. The confluence process is conventional: conservation of energy and momentum parallel with the wall indicates a transmitted wave in the opposite domain with ω (k ) =ωi+ωb and (ki+kb-k ) .z ̂=0 , while the momentum perpendicular to the domain wall is not necessary to be conserved due to the nonuniform internal field near the wall. We predict a stimulated three-magnon splitting (or "magnon laser") effect: the presence of a bound magnon propagating along the domain wall channel assists the splitting of the incident wave into two modes, one is ω1=ωb,k1=kb identical to the bound mode in the channel, and the other one is ω2=ωi-ωb with (ki-kb-k2) .z ̂=0 propagating in the opposite magnetic domain. Micromagnetic simulations confirm our theoretical analysis. These results demonstrate that one is able to uniquely

Atomic and electronic structures of novel silicon surface structures

Energy Technology Data Exchange (ETDEWEB)

Terry, J.H. Jr.

1997-03-01

The modification of silicon surfaces is presently of great interest to the semiconductor device community. Three distinct areas are the subject of inquiry: first, modification of the silicon electronic structure; second, passivation of the silicon surface; and third, functionalization of the silicon surface. It is believed that surface modification of these types will lead to useful electronic devices by pairing these modified surfaces with traditional silicon device technology. Therefore, silicon wafers with modified electronic structure (light-emitting porous silicon), passivated surfaces (H-Si(111), Cl-Si(111), Alkyl-Si(111)), and functionalized surfaces (Alkyl-Si(111)) have been studied in order to determine the fundamental properties of surface geometry and electronic structure using synchrotron radiation-based techniques.

Analytical and Experimental Evaluation of Joining Silicon Carbide to Silicon Carbide and Silicon Nitride to Silicon Nitride for Advanced Heat Engine Applications Phase II

Energy Technology Data Exchange (ETDEWEB)

Sundberg, G.J.

1994-01-01

Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joins were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).

A novel vertical fan-out platform based on an array of curved anodic alumina nanochannels

International Nuclear Information System (INIS)

Liu, Chih-Yi; Lai, Ming-Yu; Tsai, Kun-Tong; Chang, Hsuan-Hao; Wang, Yuh-Lin; He, Jr-Hau; Shiue, Jessie

2013-01-01

Focused ion beam lithography and a two-step anodization have been combined to fabricate a vertical fan-out platform containing an array of unique probes. Each probe comprises three anodic alumina nanochannels with a fan-out arrangement. The lithography is used to pattern an aluminum sheet with a custom-designed array of triangular ‘cells’ whose apexes are composed of nanoholes. The nanoholes grow into straight nanochannels under proper voltage in the first-step anodization. The second step uses a doubled voltage to induce lateral repulsion among the nanochannels’ growth fronts originating in the same cell. Therefore, the fronts fan out. The repulsion roots in the inter-front distance being shorter than the naturally favoured length, which increases with anodization voltage. The fan-out evolution continues until the growth fronts originating in all the cells evolve into a close-packed two-dimensional hexagonal lattice whose spacing is identical to the favoured one. The chemical and physical mechanisms behind the fan-out fabrication are discussed. This novel fan-out platform facilitates probing and handling of many signals from different areas on a sample’s surface and is therefore promising for applications in detection and manipulation at the nanoscale level. (paper)

Effect of the meniscus contact angle during early regimes of spontaneous imbibition in nanochannels.

Science.gov (United States)

Karna, Nabin Kumar; Oyarzua, Elton; Walther, Jens H; Zambrano, Harvey A

2016-11-30

Nanoscale capillarity has been extensively investigated; nevertheless, many fundamental questions remain open. In spontaneous imbibition, the classical Lucas-Washburn equation predicts a singularity as the fluid enters the channel consisting of an anomalous infinite velocity of the capillary meniscus. Bosanquet's equation overcomes this problem by taking into account fluid inertia predicting an initial imbibition regime with constant velocity. Nevertheless, the initial constant velocity as predicted by Bosanquet's equation is much greater than those observed experimentally. In the present study, large scale atomistic simulations are conducted to investigate capillary imbibition of water in slit silica nanochannels with heights between 4 and 18 nm. We find that the meniscus contact angle remains constant during the inertial regime and its value depends on the height of the channel. We also find that the meniscus velocity computed at the channel entrance is related to the particular value of the meniscus contact angle. Moreover, during the subsequent visco-inertial regime, as the influence of viscosity increases, the meniscus contact angle is found to be time dependent for all the channels under study. Furthermore, we propose an expression for the time evolution of the dynamic contact angle in nanochannels which, when incorporated into Bosanquet's equation, satisfactorily explains the initial capillary rise.

Functionalization of silicon oxide using supercritical fluid deposition of 3,4-epoxybutyltrimethoxysilane for the immobilization of amino-modified oligonucleotide

Energy Technology Data Exchange (ETDEWEB)

Rull, Jordi [Université Grenoble Alpes, Grenoble F38000 (France); CEA, LETI, MINATEC Campus, Grenoble Cedex 9 F38054 (France); CEA, iRTSV, LCBM, Grenoble 38054 (France); CNRS, UMR 5249, Grenoble (France); Nonglaton, Guillaume, E-mail: guillaume.nonglaton@cea.fr [Université Grenoble Alpes, Grenoble F38000 (France); CEA, LETI, MINATEC Campus, Grenoble Cedex 9 F38054 (France); Costa, Guillaume; Fontelaye, Caroline [Université Grenoble Alpes, Grenoble F38000 (France); CEA, LETI, MINATEC Campus, Grenoble Cedex 9 F38054 (France); Marchi-Delapierre, Caroline; Ménage, Stéphane [Université Grenoble Alpes, Grenoble F38000 (France); CEA, iRTSV, LCBM, Grenoble 38054 (France); CNRS, UMR 5249, Grenoble (France); Marchand, Gilles [Université Grenoble Alpes, Grenoble F38000 (France); CEA, LETI, MINATEC Campus, Grenoble Cedex 9 F38054 (France)

2015-11-01

Graphical abstract: - Highlights: • First example of grafting of 3,4-epoxybutyltrimethoxysilane (EBTMOS) onto silicon oxide by supercritical fluid deposition. • Extraordinary efficiency of the supercritical fluid deposition for the grafting of the EBTMOS compared with the conventional solution or vapor phase methodologies. • Demonstration of the efficiency of this functionalization process for the immobilization of amino-modified oligonucleotides. - Abstract: The functionalization of silicon oxide based substrates using silanes is generally performed through liquid phase methodologies. These processes involve a huge quantity of potentially toxic solvents and present some important disadvantages for the functionalization of microdevices or porous materials, for example the low diffusion. To overcome this drawback, solvent-free methodologies like molecular vapor deposition (MVD) or supercritical fluid deposition (SFD) have been developed. In this paper, the deposition process of 3,4-epoxybutyltrimethoxysilane (EBTMOS) on silicon oxide using supercritical carbon dioxide (scCO{sub 2}) as a solvent is studied for the first time. The oxirane ring of epoxy silanes readily reacts with amine group and is of particular interest for the grafting of amino-modified oligonucleotides or antibodies for diagnostic application. Then the ability of this specific EBTMOS layer to react with amine functions has been evaluated using the immobilization of amino-modified oligonucleotide probes. The presence of the probes is revealed by fluorescence using hybridization with a fluorescent target oligonucleotide. The performances of SFD of EBTMOS have been optimized and then compared with the dip coating and molecular vapor deposition methods, evidencing a better grafting efficiency and homogeneity, a lower reaction time in addition to the eco-friendly properties of the supercritical carbon dioxide. The epoxysilane layers have been characterized by surface enhanced ellipsometric

Electronic band-gap modified passive silicon optical modulator at telecommunications wavelengths.

Science.gov (United States)

Zhang, Rui; Yu, Haohai; Zhang, Huaijin; Liu, Xiangdong; Lu, Qingming; Wang, Jiyang

2015-11-13

The silicon optical modulator is considered to be the workhorse of a revolution in communications. In recent years, the capabilities of externally driven active silicon optical modulators have dramatically improved. Self-driven passive modulators, especially passive silicon modulators, possess advantages in compactness, integration, low-cost, etc. Constrained by a large indirect band-gap and sensitivity-related loss, the passive silicon optical modulator is scarce and has been not advancing, especially at telecommunications wavelengths. Here, a passive silicon optical modulator is fabricated by introducing an impurity band in the electronic band-gap, and its nonlinear optics and applications in the telecommunications-wavelength lasers are investigated. The saturable absorption properties at the wavelength of 1.55 μm was measured and indicates that the sample is quite sensitive to light intensity and has negligible absorption loss. With a passive silicon modulator, pulsed lasers were constructed at wavelengths at 1.34 and 1.42 μm. It is concluded that the sensitive self-driven passive silicon optical modulator is a viable candidate for photonics applications out to 2.5 μm.

High-efficient solar cells with porous silicon

International Nuclear Information System (INIS)

Migunova, A.A.

2002-01-01

It has been shown that the porous silicon is multifunctional high-efficient coating on silicon solar cells, modifies its surface and combines in it self antireflection and passivation properties., The different optoelectronic effects in solar cells with porous silicon were considered. The comparative parameters of uncovered photodetectors also solar cells with porous silicon and other coatings were resulted. (author)

Surface Coating of Gypsum-Based Molds for Maxillofacial Prosthetic Silicone Elastomeric Material: The Surface Topography.

Science.gov (United States)

Khalaf, Salah; Ariffin, Zaihan; Husein, Adam; Reza, Fazal

2015-07-01

This study aimed to compare the surface roughness of maxillofacial silicone elastomers fabricated in noncoated and coated gypsum materials. This study was also conducted to characterize the silicone elastomer specimens after surfaces were modified. A gypsum mold was coated with clear acrylic spray. The coated mold was then used to produce modified silicone experimental specimens (n = 35). The surface roughness of the modified silicone elastomers was compared with that of the control specimens, which were prepared by conventional flasking methods (n = 35). An atomic force microscope (AFM) was used for surface roughness measurement of silicone elastomer (unmodified and modified), and a scanning electron microscope (SEM) was used to evaluate the topographic conditions of coated and noncoated gypsum and silicone elastomer specimens (unmodified and modified) groups. After the gypsum molds were characterized, the fabricated silicone elastomers molded on noncoated and coated gypsum materials were evaluated further. Energy-dispersive X-ray spectroscopy (EDX) analysis of gypsum materials (noncoated and coated) and silicone elastomer specimens (unmodified and modified) was performed to evaluate the elemental changes after coating was conducted. Independent t test was used to analyze the differences in the surface roughness of unmodified and modified silicone at a significance level of p SEM analysis results showed evident differences in surface smoothness. EDX data further revealed the presence of the desired chemical components on the surface layer of unmodified and modified silicone elastomers. Silicone elastomers with lower surface roughness of maxillofacial prostheses can be obtained simply by coating a gypsum mold. © 2014 by the American College of Prosthodontists.

Analysis of single quantum-dot mobility inside 1D nanochannel devices

Science.gov (United States)

Hoang, H. T.; Segers-Nolten, I. M.; Tas, N. R.; van Honschoten, J. W.; Subramaniam, V.; Elwenspoek, M. C.

2011-07-01

We visualized individual quantum dots using a combination of a confining nanochannel and an ultra-sensitive microscope system, equipped with a high numerical aperture lens and a highly sensitive camera. The diffusion coefficients of the confined quantum dots were determined from the experimentally recorded trajectories according to the classical diffusion theory for Brownian motion in two dimensions. The calculated diffusion coefficients were three times smaller than those in bulk solution. These observations confirm and extend the results of Eichmann et al (2008 Langmuir 24 714-21) to smaller particle diameters and more narrow confinement. A detailed analysis shows that the observed reduction in mobility cannot be explained by conventional hydrodynamic theory.

Analysis of single quantum-dot mobility inside 1D nanochannel devices

International Nuclear Information System (INIS)

Hoang, H T; Tas, N R; Van Honschoten, J W; Elwenspoek, M C; Segers-Nolten, I M; Subramaniam, V

2011-01-01

We visualized individual quantum dots using a combination of a confining nanochannel and an ultra-sensitive microscope system, equipped with a high numerical aperture lens and a highly sensitive camera. The diffusion coefficients of the confined quantum dots were determined from the experimentally recorded trajectories according to the classical diffusion theory for Brownian motion in two dimensions. The calculated diffusion coefficients were three times smaller than those in bulk solution. These observations confirm and extend the results of Eichmann et al (2008 Langmuir 24 714-21) to smaller particle diameters and more narrow confinement. A detailed analysis shows that the observed reduction in mobility cannot be explained by conventional hydrodynamic theory.

Dimensional stability of wood-plastic composites reinforced with potassium methyl siliconate modified fiber and sawdust made from beetle-killed trees

Science.gov (United States)

Cheng Piao; Zhiyong Cai; Nicole M. Stark; Charles J. Montezun

2014-01-01

Wood fromtwovarieties of beetle-killed trees was used to fabricate wood–plastic composites. Loblolly pine and lodgepole pine beetle-killed trees were defibrated mechanically and thermomechanically, respectively, into fiber. Fiber and sawdust produced from the trees were modified with potassium methyl siliconate (PMS) and injection-molded into fiber/sawdust reinforced...

Modification of porous silicon rugate filters through thiol-yne photochemistry

International Nuclear Information System (INIS)

Soeriyadi, Alexander H.; Zhu, Ying; Gooding, J. Justin; Reece, Peter

2014-01-01

Porous silicon (PSi) has a considerable potential as biosensor platform. In particular, the ability to modify the surface chemistry of porous silicon is of interest. Here we present a generic method to modify the surface of porous silicon through thiol-yne photochemistry initiated by a radical initiator. Firstly, a freshly etched porous silicon substrate is modified through thermal hydrosilylation with 1,8-nonadiyne to passivate the surface and introduce alkyne functionalities. The alkyne functional surface could then be further reacted with thiol species in the presence of a radical initiator and UV light. Functionalization of the PSi rugate filter is followed with optical reflectivity measurements as well as high resolution X-ray photoelectron spectroscopy (XPS)

Molecular Dynamics and Monte Carlo simulations resolve apparent diffusion rate differences for proteins confined in nanochannels

Energy Technology Data Exchange (ETDEWEB)

Tringe, J.W., E-mail: tringe2@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA (United States); Ileri, N. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA (United States); Department of Chemical Engineering & Materials Science, University of California, Davis, CA (United States); Levie, H.W. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA (United States); Stroeve, P.; Ustach, V.; Faller, R. [Department of Chemical Engineering & Materials Science, University of California, Davis, CA (United States); Renaud, P. [Swiss Federal Institute of Technology, Lausanne, (EPFL) (Switzerland)

2015-08-18

Highlights: • WGA proteins in nanochannels modeled by Molecular Dynamics and Monte Carlo. • Protein surface coverage characterized by atomic force microscopy. • Models indicate transport characteristics depend strongly on surface coverage. • Results resolve of a four orders of magnitude difference in diffusion coefficient values. - Abstract: We use Molecular Dynamics and Monte Carlo simulations to examine molecular transport phenomena in nanochannels, explaining four orders of magnitude difference in wheat germ agglutinin (WGA) protein diffusion rates observed by fluorescence correlation spectroscopy (FCS) and by direct imaging of fluorescently-labeled proteins. We first use the ESPResSo Molecular Dynamics code to estimate the surface transport distance for neutral and charged proteins. We then employ a Monte Carlo model to calculate the paths of protein molecules on surfaces and in the bulk liquid transport medium. Our results show that the transport characteristics depend strongly on the degree of molecular surface coverage. Atomic force microscope characterization of surfaces exposed to WGA proteins for 1000 s show large protein aggregates consistent with the predicted coverage. These calculations and experiments provide useful insight into the details of molecular motion in confined geometries.

Robotic UV-Vis apparatus for long-term characterization of drug release from nanochannels

International Nuclear Information System (INIS)

Geninatti, T; Grattoni, A; Small, E

2014-01-01

Reliable monitoring of the kinetics of molecular release from drug delivery devices is crucial for their therapeutic success. Commercially available UV-Vis spectrophotometers provide reliable quantification of analyte concentrations directly correlated to the absorbance of fluids. However, they are not suitable for long-term measurements requiring high frequency of sampling from a large number of replicates and continuous fluid mixing, all of which are necessary for evaluation of drug delivery devices. To address this need, we developed a novel robotic apparatus serially connected to a commercial UV-Vis spectrophotometer. The robotic apparatus enables us to automatically and reliably acquire long-term data for up to 48 samples with high frequency of measurements and independent magnetic stirring. We equipped the robotic apparatus with independent connectors that allowed us to apply an electric potential to each sample for electrokinetic studies. The apparatus repeatability and accuracy was demonstrated in comparison to a commercial UV-Vis spectrophotometer. The system was successfully employed to characterize the diffusion kinetics of acetone and doxorubicin through nanochannel membranes (nDS) designed for long-term drug delivery. Dendritic fullerene 1 was used to show that the robotic apparatus routes the electric potential to nanochannel membranes enabling us to investigate the actively controlled release of molecules. Our results demonstrate that the robotic apparatus could widely broaden the range of applications of UV-Vis spectrophotometry, especially in the case of large sample processing and for long-term diffusive and electrokinetic studies in drug delivery. (technical design note)

Effect of meniscus constact angle during early regimes of spontaneous capillarity in nanochannels

DEFF Research Database (Denmark)

Karna, N.K.; Oyarzua, Elton; Walther, Jens Honore

2016-01-01

4 and 18 nm. We alsofind that the meniscus contact angle remains constant during the inertial regime and its value depends upon the height of the channel. We also find that the meniscus velocity computed at the channel entrance is related to the particular value of themeniscus contact angle....... Moreover, after the inertial regime, the meniscus contactangle is found to be time dependent for all the channels under study. We propose an expression for the time evolution of the dynamic contact angle in nanochannels which, when incorporated in Bosanquets equation, satisfactorily explains the initial...

Correlation between inter-spin interaction and molecular dynamics of organic radicals in organic 1D nanochannels

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Hirokazu [Department of Chemistry, College of Humanities and Sciences, Nihon University 3-25-40, Sakura-jo-sui, Setagaya-ku, Tokyo, 156-8550 (Japan)

2015-12-31

One-dimensional (1D) molecular chains of 4-substituted-2,2,6,6-tetramethyl-1-piperidinyloxyl (4-X-TEMPO) radicals were constructed in the crystalline 1D nanochannels of 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) used as a template. The ESR spectra of CLPOT inclusion compounds (ICs) using 4-X-TEMPO were examined on the basis of spectral simulation using EasySpin program package for simulating and fitting ESR spectra. The ESR spectra of [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC were isotropic in the total range of temperatures. The peak-to-peak line width (ΔB{sub pp}) became monotonically narrower from 2.8 to 1.3 mT with increase in temperature in the range of 4.2–298 K. The effect of the rotational diffusion motion of TEMPO radicals in the CLPOT nanochannels for the inter-spin interaction of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC was found to be smaller than the case of [(TPP){sub 2}−(TEMPO){sub 1.0}] IC (TPP = tris(o-phenylenedioxy)cyclotriphosphazene) reported in our previous study. The ΔB{sub pp} of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC in the whole range of temperatures was much narrower than the estimation to be based on the Van Vleck’s formula for the second moment of the rigid lattice model where the electron spin can be considered as fixed; 11 mT of Gaussian line-width component. This suggests the possibility of exchange narrowing in the 1D organic-radical chains of the [(CLPOT){sub 2}-(TEMPO){sub 1.0}] IC. On the other hand, the ESR spectra of [(CLPOT){sub 2}-(MeO-TEMPO){sub 0.41}] IC (MeO-TEMPO = 4-methoxy-TEMPO) were reproduced by a superposition of major broad isotropic adsorption line and minor temperature-dependent modulated triplet component. This suggests that the IC has the part of 1D organic-radical chains and MeO-TEMPO molecules isolated in the CLPOT nanochannels.

Hybrid method coupling molecular dynamics and Monte Carlo simulations to study the properties of gases in microchannels and nanochannels

NARCIS (Netherlands)

Nedea, S.V.; Frijns, A.J.H.; Steenhoven, van A.A.; Markvoort, Albert. J.; Hilbers, P.A.J.

2005-01-01

We combine molecular dynamics (MD) and Monte Carlo (MC) simulations to study the properties of gas molecules confined between two hard walls of a microchannel or nanochannel. The coupling between MD and MC simulations is introduced by performing MD near the boundaries for accuracy and MC in the bulk

Intermediate Bandgap Solar Cells From Nanostructured Silicon

Energy Technology Data Exchange (ETDEWEB)

Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

Porous Anodic Aluminum Oxide with Serrated Nanochannels

Science.gov (United States)

Li, Dongdong; Zhao, Liang; Lu, Jia G.

2010-03-01

Self-assembled nanoporous anodic aluminum oxide (AAO) membrane with straight channels has long been an important tool in synthesizing highly ordered and vertically aligned quasi-1D nanostructures for various applications. Recently shape-selective nanomaterials have been achieved using AAO as a template. It is envisioned that nanowires with multi-branches will significantly increase the active functional sites for applications as sensors, catalysts, chemical cells, etc. Here AAO membranes with serrated nanochannels have been successfully fabricated via a two-step annodization method. The serrated channels with periodic intervals are aligned at an angle of ˜25^circ along the stem channels. The formation of the serrated channels is attributed to the evolution of oxygen gas bubbles and the resulted plastic deformation in oxide membrane. In order to reveal the inside channel structure, Platinum are electrodeposited into the AAO template. The as-synthesized serrated Pt nanowires demonstrate a superior electrocatalytic activity. This is attributed to the enhanced electric field strength around serrated tips as shown in the electric field simulation by COMOSL. Moreover, hierarchical serrated/straight hybrid structures can be constructed using this simple and novel self assembly technique.

Diamond deposition on siliconized stainless steel

International Nuclear Information System (INIS)

Alvarez, F.; Reinoso, M.; Huck, H.; Rosenbusch, M.

2010-01-01

Silicon diffusion layers in AISI 304 and AISI 316 type stainless steels were investigated as an alternative to surface barrier coatings for diamond film growth. Uniform 2 μm thick silicon rich interlayers were obtained by coating the surface of the steels with silicon and performing diffusion treatments at 800 deg. C. Adherent diamond films with low sp 2 carbon content were deposited on the diffused silicon layers by a modified hot filament assisted chemical vapor deposition (HFCVD) method. Characterization of as-siliconized layers and diamond coatings was performed by energy dispersive X-ray analysis, scanning electron microscopy, X-ray diffraction and Raman spectroscopy.

In vitro assessment of biopolymer-modified porous silicon microparticles for wound healing applications.

Science.gov (United States)

Mori, Michela; Almeida, Patrick V; Cola, Michela; Anselmi, Giulia; Mäkilä, Ermei; Correia, Alexandra; Salonen, Jarno; Hirvonen, Jouni; Caramella, Carla; Santos, Hélder A

2014-11-01

The wound healing stands as very complex and dynamic process, aiming the re-establishment of the damaged tissue's integrity and functionality. Thus, there is an emerging need for developing biopolymer-based composites capable of actively promoting cellular proliferation and reconstituting the extracellular matrix. The aims of the present work were to prepare and characterize biopolymer-functionalized porous silicon (PSi) microparticles, resulting in the development of drug delivery microsystems for future applications in wound healing. Thermally hydrocarbonized PSi (THCPSi) microparticles were coated with both chitosan and a mixture of chondroitin sulfate/hyaluronic acid, and subsequently loaded with two antibacterial model drugs, vancomycin and resveratrol. The biopolymer coating, drug loading degree and drug release behavior of the modified PSi microparticles were evaluated in vitro. The results showed that both the biopolymer coating and drug loading of the THCPSi microparticles were successfully achieved. In addition, a sustained release was observed for both the drugs tested. The viability and proliferation profiles of a fibroblast cell line exposed to the modified THCPSi microparticles and the subsequent reactive oxygen species (ROS) production were also evaluated. The cytotoxicity and proliferation results demonstrated less toxicity for the biopolymer-coated THCPSi microparticles at different concentrations and time points comparatively to the uncoated counterparts. The ROS production by the fibroblasts exposed to both uncoated and biopolymer-coated PSi microparticles showed that the modified PSi microparticles did not induce significant ROS production at the concentrations tested. Overall, the biopolymer-based PSi microparticles developed in this study are promising platforms for wound healing applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of air on water capillary flow in silica nanochannels

DEFF Research Database (Denmark)

Zambrano, Harvey; Walther, Jens Honore; Oyarzua, Elton

2013-01-01

, with the fabrication of microsystems integrated by nanochannels, a thorough understanding of the transport of fluids in nanoconfinement is required for a successful operation of the functional parts of such devices. In this work, Molecular Dynamics simulations are conducted to study the spontaneous imbibition of water...... in sub 10 nm silica channels. The capillary filling speed is computed in channels subjected to different air pressures. In order to describe the interactions between the species, an effective force field is developed, which is calibrated by reproducing the water contact angle. The results show...... that the capillary filling speed qualitatively follows the classical Washburn model, however, quantitatively it is lower than expected. Furthermore, it is observed that the deviations increase as air pressure is higher. We attribute the deviations to amounts of air trapped at the silica-water interface which leads...

Modified tube gastropexy using a mushroom-tipped silicone catheter for management of gastric dilatation-volvulus in dogs.

Science.gov (United States)

Belch, A; Rubinos, C; Barnes, D C; Nelissen, P

2017-02-01

To report the short- and long-term complications and clinical outcomes of a cohort of dogs managed for gastric dilatation-volvulus using a modified right-sided tube gastropexy technique. Retrospective case series. Of 31 dogs treated, 29 (93·5%) had an excellent short-term outcome, and gastric dilatation-volvulus did not recur in any dog. Twenty-six dogs (84%) were initially fed via the gastrostomy tube postoperatively; three (9·7%) suffered a major complication including septic peritonitis (n=1), and premature tube removal (n=2). Fourteen dogs (45·1%) had minor complications including mild, self-limiting discharge from the stoma site in 13. Modified tube gastropexy using a mushroom-tipped silicone catheter is an effective and safe surgical method for the management of gastric dilatation-volvulus. The gastrostomy tube allowed early enteral feeding and easy administration of medications, including gastroprotectants. © 2017 British Small Animal Veterinary Association.

A novel self-embrittling strippable coating for radioactive decontamination based on silicone modified styrene-acrylic emulsion

Science.gov (United States)

Wang, Jing; Wang, Jianhui; Zheng, Li; Li, Jian; Cui, Can; Lv, Linmei

2017-03-01

Silicone modified styrene-acrylic emulsion and butyl acrylate were used as a main film-forming agent and an additive respectively to synthesize a self-embrittling strippable coating. The doping mass-ratio of butyl acrylate was adjusted at 0, 5%, 10%, 15%, 20%, and the results indicated the optimized doping ratio was 10%. Ca(OH)2 was used to promote the coating film self-embrittling at a moderate doping mass-ratio of 20%. The synthesized coating’s coefficients of α and β decontamination on concrete, marble, glass and stainless steel surfaces were both greater than 85%, which indicated the synthesized coating is a promising cleaner for radioactive decontamination.

Displacement damage analysis and modified electrical equivalent circuit for electron and photon-irradiated silicon solar cells

Science.gov (United States)

Arjhangmehr, Afshin; Feghhi, Seyed Amir Hossein

2014-10-01

Solar modules and arrays are the conventional energy resources of space satellites. Outside the earth's atmosphere, solar panels experience abnormal radiation environments and because of incident particles, photovoltaic (PV) parameters degrade. This article tries to analyze the electrical performance of electron and photon-irradiated mono-crystalline silicon (mono-Si) solar cells. PV cells are irradiated by mono-energetic electrons and poly-energetic photons and immediately characterized after the irradiation. The mean degradation of the maximum power (Pmax) of silicon solar cells is presented and correlated using the displacement damage dose (Dd) methodology. This method simplifies evaluation of cell performance in space radiation environments and produces a single characteristic curve for Pmax degradation. Furthermore, complete analysis of the results revealed that the open-circuit voltage (Voc) and the filling factor of mono-Si cells did not significantly change during the irradiation and were independent of the radiation type and fluence. Moreover, a new technique is developed that adapts the irradiation-induced effects in a single-cell equivalent electrical circuit and adjusts its elements. The "modified circuit" is capable of modeling the "radiation damage" in the electrical behavior of mono-Si solar cells and simplifies the designing of the compensation circuits.

Electrokinetics of nanochannels and porous membranes with dynamic surface charges

DEFF Research Database (Denmark)

Andersen, Mathias Bækbo

. Notably, we find that the conductance minimum is mainly caused by hydronium ions, and in our case almost exclusively due to carbonic acid generated from the dissolution of CO2 from the atmosphere. We carry out delicate experiments and measure the conductance of silica nanochannels as a function...... and consider strong out-of-equilibrium transport across the membrane. Our model predicts large pH variations in the electrodialysis system that in turn lowers the ion-selectivity of the membrane by protonation reactions. This opens up for significant over-limiting current. We use our model to investigate...... procedure that requires much attention to the comparability between the conditions in the model and in the experiment. Finally, we make a small digression and study induced-charge electro-osmosis (ICEO) and the validity of common EO slip formulae as a function of a finite Debye screening length...

A nanoscale bio-inspired light-harvesting system developed from self-assembled alkyl-functionalized metallochlorin nano-aggregates

Science.gov (United States)

Ocakoglu, Kasim; Joya, Khurram S.; Harputlu, Ersan; Tarnowska, Anna; Gryko, Daniel T.

2014-07-01

Self-assembled supramolecular organization of nano-structured biomimetic light-harvesting modules inside solid-state nano-templates can be exploited to develop excellent light-harvesting materials for artificial photosynthetic devices. We present here a hybrid light-harvesting system mimicking the chlorosomal structures of the natural photosynthetic system using synthetic zinc chlorin units (ZnChl-C6, ZnChl-C12 and ZnChl-C18) that are self-aggregated inside the anodic aluminum oxide (AAO) nano-channel membranes. AAO nano-templates were modified with a TiO2 matrix and functionalized with long hydrophobic chains to facilitate the formation of supramolecular Zn-chlorin aggregates. The transparent Zn-chlorin nano-aggregates inside the alkyl-TiO2 modified AAO nano-channels have a diameter of ~120 nm in a 60 μm length channel. UV-Vis studies and fluorescence emission spectra further confirm the formation of the supramolecular ZnChl aggregates from monomer molecules inside the alkyl-functionalized nano-channels. Our results prove that the novel and unique method can be used to produce efficient and stable light-harvesting assemblies for effective solar energy capture through transparent and stable nano-channel ceramic materials modified with bio-mimetic molecular self-assembled nano-aggregates.Self-assembled supramolecular organization of nano-structured biomimetic light-harvesting modules inside solid-state nano-templates can be exploited to develop excellent light-harvesting materials for artificial photosynthetic devices. We present here a hybrid light-harvesting system mimicking the chlorosomal structures of the natural photosynthetic system using synthetic zinc chlorin units (ZnChl-C6, ZnChl-C12 and ZnChl-C18) that are self-aggregated inside the anodic aluminum oxide (AAO) nano-channel membranes. AAO nano-templates were modified with a TiO2 matrix and functionalized with long hydrophobic chains to facilitate the formation of supramolecular Zn-chlorin aggregates. The

Colloidal characterization of silicon nitride and silicon carbide

Science.gov (United States)

Feke, Donald L.

1986-01-01

The colloidal behavior of aqueous ceramic slips strongly affects the forming and sintering behavior and the ultimate mechanical strength of the final ceramic product. The colloidal behavior of these materials, which is dominated by electrical interactions between the particles, is complex due to the strong interaction of the solids with the processing fluids. A surface titration methodology, modified to account for this interaction, was developed and used to provide fundamental insights into the interfacial chemistry of these systems. Various powder pretreatment strategies were explored to differentiate between true surface chemistry and artifacts due to exposure history. The colloidal behavior of both silicon nitride and carbide is dominated by silanol groups on the powder surfaces. However, the colloid chemistry of silicon nitride is apparently influenced by an additional amine group. With the proper powder treatments, silicon nitride and carbide powder can be made to appear colloidally equivalent. The impact of these results on processing control will be discussed.

Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

Science.gov (United States)

Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

2015-06-03

On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

Science.gov (United States)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

Chitosan-modified porous silicon microparticles for enhanced permeability of insulin across intestinal cell monolayers.

Science.gov (United States)

Shrestha, Neha; Shahbazi, Mohammad-Ali; Araújo, Francisca; Zhang, Hongbo; Mäkilä, Ermei M; Kauppila, Jussi; Sarmento, Bruno; Salonen, Jarno J; Hirvonen, Jouni T; Santos, Hélder A

2014-08-01

Porous silicon (PSi) based particulate systems are emerging as an important drug delivery system due to its advantageous properties such as biocompatibility, biodegradability and ability to tailor the particles' physicochemical properties. Here, annealed thermally hydrocarbonized PSi (AnnTHCPSi) and undecylenic acid modified AnnTHCPSi (AnnUnTHCPSi) microparticles were developed as a PSi-based platform for oral delivery of insulin. Chitosan (CS) was used to modify the AnnUnTHCPSi microparticles to enhance the intestinal permeation of insulin. Surface modification with CS led to significant increase in the interaction of PSi microparticles with Caco-2/HT-29 cell co-culture monolayers. Compared to pure insulin, the CS-conjugated microparticles significantly improved the permeation of insulin across the Caco-2/HT-29 cell monolayers, with ca. 20-fold increase in the amount of insulin permeated and ca. 7-fold increase in the apparent permeability (P(app)) value. Moreover, among all the investigated particles, the CS-conjugated microparticles also showed the highest amount of insulin associated with the mucus layer and the intestinal Caco-2 cells and mucus secreting HT-29 cells. Our results demonstrate that CS-conjugated AnnUnTHCPSi microparticles can efficiently enhance the insulin absorption across intestinal cells, and thus, they are promising microsystems for the oral delivery of proteins and peptides across the intestinal cell membrane. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fabrication and Modification of Nanoporous Silicon Particles

Science.gov (United States)

Ferrari, Mauro; Liu, Xuewu

2010-01-01

Silicon-based nanoporous particles as biodegradable drug carriers are advantageous in permeation, controlled release, and targeting. The use of biodegradable nanoporous silicon and silicon dioxide, with proper surface treatments, allows sustained drug release within the target site over a period of days, or even weeks, due to selective surface coating. A variety of surface treatment protocols are available for silicon-based particles to be stabilized, functionalized, or modified as required. Coated polyethylene glycol (PEG) chains showed the effective depression of both plasma protein adsorption and cell attachment to the modified surfaces, as well as the advantage of long circulating. Porous silicon particles are micromachined by lithography. Compared to the synthesis route of the nanomaterials, the advantages include: (1) the capability to make different shapes, not only spherical particles but also square, rectangular, or ellipse cross sections, etc.; (2) the capability for very precise dimension control; (3) the capacity for porosity and pore profile control; and (4) allowance of complex surface modification. The particle patterns as small as 60 nm can be fabricated using the state-of-the-art photolithography. The pores in silicon can be fabricated by exposing the silicon in an HF/ethanol solution and then subjecting the pores to an electrical current. The size and shape of the pores inside silicon can be adjusted by the doping of the silicon, electrical current application, the composition of the electrolyte solution, and etching time. The surface of the silicon particles can be modified by many means to provide targeted delivery and on-site permanence for extended release. Multiple active agents can be co-loaded into the particles. Because the surface modification of particles can be done on wafers before the mechanical release, asymmetrical surface modification is feasible. Starting from silicon wafers, a treatment, such as KOH dipping or reactive ion

Vibrational Spectroscopy of Chemical Species in Silicon and Silicon-Rich Nitride Thin Films

Directory of Open Access Journals (Sweden)

Kirill O. Bugaev

2012-01-01

Full Text Available Vibrational properties of hydrogenated silicon-rich nitride (SiN:H of various stoichiometry (0.6≤≤1.3 and hydrogenated amorphous silicon (a-Si:H films were studied using Raman spectroscopy and Fourier transform infrared spectroscopy. Furnace annealing during 5 hours in Ar ambient at 1130∘C and pulse laser annealing were applied to modify the structure of films. Surprisingly, after annealing with such high-thermal budget, according to the FTIR data, the nearly stoichiometric silicon nitride film contains hydrogen in the form of Si–H bonds. From analysis of the FTIR data of the Si–N bond vibrations, one can conclude that silicon nitride is partly crystallized. According to the Raman data a-Si:H films with hydrogen concentration 15% and lower contain mainly Si–H chemical species, and films with hydrogen concentration 30–35% contain mainly Si–H2 chemical species. Nanosecond pulse laser treatments lead to crystallization of the films and its dehydrogenization.

Porous Silicon Hydrogen Sensor at Room Temperature: The Effect of Surface Modification and Noble Metal Contacts

Directory of Open Access Journals (Sweden)

Jayita KANUNGO

2009-04-01

Full Text Available Porous silicon (PS was fabricated by anodization of p-type crystalline silicon of resistivity 2-5 Ω cm. After formation, the PS surface was modified by the solution containing noble metal like Pd. Pd-Ag catalytic contact electrodes were deposited on porous silicon and on p-Silicon to fabricate Pd-Ag/PS/p-Si/Pd-Ag sensor structure to carry out the hydrogen sensing experiments. The Sensor was exposed to 1% hydrogen in nitrogen as carrier gas at room temperature (270C. Pd modified sensor showed minimum fluctuations and consistent performance with 86% response, response time and recovery time of 24 sec and 264 sec respectively. The stability experiments were studied for both unmodified and Pd modified sensor structures for a period of about 24 hours and the modified sensors showed excellent durability with no drift in response behavior.

Temperature effects on the electrohydrodynamic and electrokinetic behaviour of ion-selective nanochannels

International Nuclear Information System (INIS)

Wood, Jeffery A; Benneker, Anne M; Lammertink, Rob G H

2016-01-01

A non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations is used to study the influence of heating effects in the form of Joule heating and viscous dissipation and imposed temperature gradients on a microchannel/nanochannel system. The system is solved numerically under various cases in order to determine the influence of temperature-related effects on ion-selectivity, flux and fluid flow profiles, as well as coupling between these phenomena. It is demonstrated that for a larger reservoir system, the effects of Joule heating and viscous dissipation only become relevant for higher salt concentrations and electric field strengths than are compatible with ion-selectivity due to Debye layer overlap. More interestingly, it is shown that using different temperature reservoirs can have a strong influence on ion-selectivity, as well as the induced electrohydrodynamic flows. (paper)

Influence of nanometric silicon carbide on phenolic resin composites ...

Indian Academy of Sciences (India)

Abstract. This paper presents a preliminary study on obtaining and characterization of phenolic resin-based com- posites modified with nanometric silicon carbide. The nanocomposites were prepared by incorporating nanometric silicon carbide (nSiC) into phenolic resin at 0.5, 1 and 2 wt% contents using ultrasonication to ...

Forging Fast Ion Conducting Nanochannels with Swift Heavy Ions: The Correlated Role of Local Electronic and Atomic Structure

Energy Technology Data Exchange (ETDEWEB)

Sachan, Ritesh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Material Science and Technology Division; Cooper, Valentino R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Material Science and Technology Division; Liu, Bin [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Aidhy, Dilpuneet S. [Univ. of Wyoming, Laramie, WY (United States). Dept. of Mechanical Engineering; Voas, Brian K. [Iowa State Univ., Ames, IA (United States). Dept. of Materials Science and Engineering; Lang, Maik [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Ou, Xin [Chinese Academy of Sciences (CAS), Shanghai (China). State Key Lab. of Functional Material for Informatics; Trautmann, Christina [GSI Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany); Technical Univ. of Darmstadt (Germany). Dept. of Materials Science; Zhang, Yanwen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Material Science and Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Chisholm, Matthew F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Material Science and Technology Division; Weber, William J. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Material Science and Technology Division

2016-12-19

Atomically disordered oxides have attracted significant attention in recent years due to the possibility of enhanced ionic conductivity. However, the correlation between atomic disorder, corresponding electronic structure, and the resulting oxygen diffusivity is not well understood. The disordered variants of the ordered pyrochlore structure in gadolinium titanate (Gd₂Ti₂O₇) are seen as a particularly interesting prospect due to intrinsic presence of a vacant oxygen site in the unit atomic structure, which could provide a channel for fast oxygen conduction. In this paper, we provide insights into the subangstrom scale on the disordering-induced variations in the local atomic environment and its effect on the electronic structure in high-energy ion irradiation-induced disordered nanochannels, which can be utilized as pathways for fast oxygen ion transport. With the help of an atomic plane-by-plane-resolved analyses, the work shows how the presence of various types of TiO_x polyhedral that exist in the amorphous and disordered crystalline phase modify the electronic structures relative to the ordered pyrochlore phase in Gd₂Ti₂O₇. Finally, the correlated molecular dynamics simulations on the disordered structures show a remarkable enhancement in oxygen diffusivity as compared with ordered pyrochlore lattice and make that a suitable candidate for applications requiring fast oxygen conduction.

Fabrication of self-enclosed nanochannels based on capillary-pressure balance mechanism

Science.gov (United States)

Kou, Yu; Sang, Aixia; Li, Xin; Wang, Xudi

2017-10-01

Polymer-based micro/nano fluidic devices are becoming increasingly important to biological applications and fluidic control. In this paper, we propose a self-enclosure method for the fabrication of large-area nanochannels without external force by using a capillary-pressure balance mechanism. The melt polymer coated on the nanogrooves fills into the trenches inevitably and the air in the trenches is not excluded but compressed, which leads to an equilibrium state between pressure of the trapped air and capillary force of melt polymer eventually, resulting in the channels’ formation. A pressure balance model was proposed to elucidate the unique self-sealing phenomenon and the criteria for the design and construction of sealed channels was discussed. According to the bonding mechanism investigated using the volume of fluid (VOF) simulation and experiments, we can control the dimension of sealed channels by varying the baking condition. This fabrication technique has great potential for low-cost and mass production of polymeric-based micro/nano fluidic devices.

Ultra-high optical responsivity of semiconducting asymmetric nano-channel diodes for photon detection

Science.gov (United States)

Akbas, Y.; Plecenik, T.; Durina, P.; Plecenik, A.; Jukna, A.; Wicks, G.; Sobolewski, Roman

2017-05-01

The asymmetric nano-channel diode (ANCD) is the 2-dimensional electron gas (2DEG) semiconductor nanodevice that, unlike a conventional diode, relies on the device nanostructure and field-controlled transport in a ballistic nanometerwidth channel instead of barriers to develop its asymmetric, diode-like current-voltage (I-V) characteristics. We focus on ANCD optoelectronic properties, and demonstrate that the devices can act as very sensitive, single-photon-level, visiblelight photodetectors. Our test structures consist of 2-μm-long and 230-nm-wide channels and were fabricated using electron-beam lithography on a GaAs/AlGaAs heterostructure with a 2DEG layer, followed by reactive ion etching. The I-V curves were collected by measuring the transport current under the voltage-source biasing condition, both in the dark and under light illumination. The experiments were conducted inside a cryostat, in a temperature range from 300 K to 78 K. As an optical excitation, we used a 800-nm-wavelength, generated by a commercial Ti:sapphire laser operated either at a quasi-continuous-wave mode or as a source of 100-fs-wide pulses. The impact of the light illumination was very clear, and at low temperatures we observed a significant photocurrent Iph 0.25 μA at temperature 78 K for the incident optical power as low as 1 nW, with a limited dark-current background. The magnitude of the device optical responsivity increased linearly with the decrease of the optical power, reaching for 1-nW optical excitation the value as high as 400 A/W at room temperature and >800 A/W at 78K. The physics of the photoresponse gain mechanism in the ANCD arises from a vast disparity between the sub-picosecond transit time of photo-excited electrons travelling in the 2DEG nanochannel and the up to microsecond lifetime of photo-excited holes pushed towards the device substrate.

Reduce chest pain using modified silicone fluted drain tube for chest drainage after video-assisted thoracic surgery (VATS) lung resection.

Science.gov (United States)

Li, Xin; Hu, Bin; Miao, Jinbai; Li, Hui

2016-02-01

The aim of this study was to assess the feasibility, efficacy and safety of a modified silicone fluted drain tube after video-assisted thoracic surgery (VATS) lung resection. The prospective randomized study included 50 patients who underwent VATS lung resection between March 2015 and June 2015. Eligible patients were randomized into two groups: experimental group (using the silicone fluted drain tubes for chest drainage) and control group (using standard drain tubes for chest drainage). The volume and characteristics of drainage, postoperative (PO) pain scores and hospital stay were recorded. All patients received standard care during hospital admission. In accordance with the exit criteria, three patients were excluded from study. The remaining 47 patients included in the final analysis were divided into two groups: experiment group (N=24) and control group (N=23). There was no significant difference between the two groups in terms of age, sex, height, weight, clinical diagnosis and type of surgical procedure. There was a trend toward less PO pain in experimental group on postoperative day (POD) 1, with a statistically significant difference. Patients in experimental group had a reduced occurrence of fever [temperature (T) >37.4 °C] compared to the control group. The silicone fluted drain tube is feasible and safe and may relieve patient PO pain and reduce occurrence of fever without the added risk of PO complications.

A nanoscale bio-inspired light-harvesting system developed from self-assembled alkyl-functionalized metallochlorin nano-aggregates

KAUST Repository

Ocakoǧlu, Kasim; Joya, Khurram Saleem; Harputlu, Ersan; Tarnowska, Anna; Gryko, Daniel T.

2014-01-01

Self-assembled supramolecular organization of nano-structured biomimetic light-harvesting modules inside solid-state nano-templates can be exploited to develop excellent light-harvesting materials for artificial photosynthetic devices. We present here a hybrid light-harvesting system mimicking the chlorosomal structures of the natural photosynthetic system using synthetic zinc chlorin units (ZnChl-C6, ZnChl-C12 and ZnChl-C 18) that are self-aggregated inside the anodic aluminum oxide (AAO) nano-channel membranes. AAO nano-templates were modified with a TiO2 matrix and functionalized with long hydrophobic chains to facilitate the formation of supramolecular Zn-chlorin aggregates. The transparent Zn-chlorin nano-aggregates inside the alkyl-TiO2 modified AAO nano-channels have a diameter of ∼120 nm in a 60 μm length channel. UV-Vis studies and fluorescence emission spectra further confirm the formation of the supramolecular ZnChl aggregates from monomer molecules inside the alkyl-functionalized nano-channels. Our results prove that the novel and unique method can be used to produce efficient and stable light-harvesting assemblies for effective solar energy capture through transparent and stable nano-channel ceramic materials modified with bio-mimetic molecular self-assembled nano-aggregates. © 2014 the Partner Organisations.

Studies of pulsed laser melting and rapid solidification using amorphous silicon

International Nuclear Information System (INIS)

Lowndes, D.H.; Wood, R.F.

1984-06-01

Pulsed-laser melting of ion implantation-amorphized silicon layers, and subsequent solidification were studied. Measurements of the onset of melting of amorphous silicon layers and of the duration of melting, and modified melting model calculations demonstrated that the thermal conductivity, K/sub a/, of amorphous silicon is very low (K/sub a/ approx. = 0.02 W/cm-K). K/sub a/ is also the dominant parameter determining the dynamical response of amorphous silicon to pulsed laser radiation. TEM indicates that bulk (volume) nucleation occurs directly from the highly undercooled liquid silicon that can be prepared by pulsed laser melting of amorphous silicon layers at low laser energy densities. A modified thermal melting model is presented. The model calculations demonstrate that the release of latent heat by bulk nucleation occurring during the melt-in process is essential to obtaining agreement with observed depths of melting. These calculations also show that this release of latent heat accompanying bulk nucleation can result in the existence of buried molten layers of silicon in the interior of the sample after the surface has solidified. The bulk nucleation implies that the liquid-to-amorphous phase transition (produced using picosecond or uv nanosecond laser pulses) cannot be explained using purely thermodynamic considerations

Release of low molecular weight silicones and platinum from silicone breast implants.

Science.gov (United States)

Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

1997-12-01

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was

Electrical properties of pressure quenched silicon by thermal spraying

International Nuclear Information System (INIS)

Tan, S.Y.; Gambino, R.J.; Sampath, S.; Herman, H.

2007-01-01

High velocity thermal spray deposition of polycrystalline silicon film onto single crystal substrates, yields metastable high pressure forms of silicon in nanocrystalline form within the deposit. The phases observed in the deposit include hexagonal diamond-Si, R-8, BC-8 and Si-IX. The peculiar attribute of this transformation is that it occurs only on orientation silicon substrate. The silicon deposits containing the high pressure phases display a substantially higher electrical conductivity. The resistivity profile of the silicon deposit containing shock induced metastable silicon phases identified by X-ray diffraction patterns. The density of the pressure induced polymorphic silicon is higher at deposit/substrate interface. A modified two-layer model is presented to explain the resistivity of the deposit impacted by the pressure induced polymorphic silicon generated by the thermal spraying process. The pressure quenched silicon deposits on the p - silicon substrate, with or without metastable phases, display the barrier potential of about 0.72 eV. The measured hall mobility value of pressure quenched silicon deposits is in the range of polycrystalline silicon. The significance of this work lies in the fact that the versatility of thermal spray may enable applications of these high pressure forms of silicon

High Efficiency, Low Cost Solar Cells Manufactured Using 'Silicon Ink' on Thin Crystalline Silicon Wafers

Energy Technology Data Exchange (ETDEWEB)

Antoniadis, H.

2011-03-01

Reported are the development and demonstration of a 17% efficient 25mm x 25mm crystalline Silicon solar cell and a 16% efficient 125mm x 125mm crystalline Silicon solar cell, both produced by Ink-jet printing Silicon Ink on a thin crystalline Silicon wafer. To achieve these objectives, processing approaches were developed to print the Silicon Ink in a predetermined pattern to form a high efficiency selective emitter, remove the solvents in the Silicon Ink and fuse the deposited particle Silicon films. Additionally, standard solar cell manufacturing equipment with slightly modified processes were used to complete the fabrication of the Silicon Ink high efficiency solar cells. Also reported are the development and demonstration of a 18.5% efficient 125mm x 125mm monocrystalline Silicon cell, and a 17% efficient 125mm x 125mm multicrystalline Silicon cell, by utilizing high throughput Ink-jet and screen printing technologies. To achieve these objectives, Innovalight developed new high throughput processing tools to print and fuse both p and n type particle Silicon Inks in a predetermined pat-tern applied either on the front or the back of the cell. Additionally, a customized Ink-jet and screen printing systems, coupled with customized substrate handling solution, customized printing algorithms, and a customized ink drying process, in combination with a purchased turn-key line, were used to complete the high efficiency solar cells. This development work delivered a process capable of high volume producing 18.5% efficient crystalline Silicon solar cells and enabled the Innovalight to commercialize its technology by the summer of 2010.

Novel Protic Ionic Liquid Composite Membranes with Fast and Selective Gas Transport Nanochannels for Ethylene/Ethane Separation.

Science.gov (United States)

Dou, Haozhen; Jiang, Bin; Xiao, Xiaoming; Xu, Mi; Tantai, Xiaowei; Wang, Baoyu; Sun, Yongli; Zhang, Luhong

2018-04-25

Protic ionic liquids (PILs) were utilized for the fabrication of composite membranes containing silver salt as the C 2 H 4 transport carrier to perform C 2 H 4 /C 2 H 6 separation for the first time. The intrinsic nanostructures of PILs were adopted to construct fast and selective C 2 H 4 transport nanochannels. The investigation of structure-performance relationships of composite membranes suggested that transport nanochannels (polar domains of PILs) could be tuned by the sizes of cations, which greatly manipulated activity of the carrier and determined the separation performances of membranes. The role of different carriers in the facilitated transport was studied, which revealed that the PILs were good solvents for dissolution and activation of the carrier due to their hydrogen bond networks and waterlike properties. The operating conditions of separation process were investigated systemically and optimized, confirming C 2 H 4 /C 2 H 6 selectivity was enhanced with the increase of silver salt concentration, the flow rate of sweep gas, and the feed ratio of C 2 H 4 to C 2 H 6 , as well as the decrease of the transmembrane pressure and operating temperature. Furthermore, the composite membranes exhibited long-term stability and obtained very competitive separation performances compared with other results. In summary, PIL composite membranes, which possess good long-term stability, high C 2 H 4 /C 2 H 6 selectivity, and excellent C 2 H 4 permeability, may have a good perspective in industrial C 2 H 4 /C 2 H 6 separation.

Enhanced NO2 sensing characteristics of Au modified porous silicon/thorn-sphere-like tungsten oxide composites

Science.gov (United States)

Yuan, Lin; Hu, Ming; Wei, Yulong; Ma, Wenfeng

2016-12-01

The thorn-sphere-like tungsten oxide (WO3) made up by 1D nanorods has been successfully synthesized through hydrothermal method on the Au-modified porous silicon (PS) substrates with seed-layer induction. By using XRD, EDS, FESEM and TEM techniques, we tested and verified that the crystal structure and morphology evolution of WO3 hierarchical nanostructure on the Au-modified PS strongly depend on the Au-sputtering time and hydrothermal reaction time. In addition, by comparing the NO2-sensing properties of the prepared products, we found that the 10 s-Au decorated PS/WO3-3 h (sputtering Au for 10 s and hydrothermal reaction for 3 h) composites sensor behaving as a typical p-type semiconductor and operating at room temperature (RT) exhibits high sensitivity and response characteristics even to ppb-level NO2, which makes this kind of sensor a competitive candidate for NO2-sensing applications. Moreover, the enhanced response may not only due to the high specific surface area but the Au nanoparticles acting as promoters for the spillover effect and forming metal-semiconductor heterojunctions with the PS and WO3. The transmission of electrons and holes in the heterogeneous interface generated among PS, WO3 and Au is proposed to illustrate the p-type response mechanism.

Promising silicones modified with cationic biocides for the development of antimicrobial medical devices.

Science.gov (United States)

Ghamrawi, Sarah; Bouchara, Jean-Philippe; Tarasyuk, Oksana; Rogalsky, Sergiy; Lyoshina, Lyudmila; Bulko, Olga; Bardeau, Jean-François

2017-06-01

We have tested silicones containing 2% or 5% of the cationic biocides polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS), 1-octyl-3-methylimidazolium tetrafluoroborate (OMIM-BF 4 ) or 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF 4 ) against the major relevant bacterial and yeast species in health care-associated infections (HCAI). Study conducted according to the international standard ISO 22196 revealed that silicones containing 2% or 5% DMIM-BF 4 or 5% PHMG-DBS presented the highest antimicrobial activity, leading to a logarithmic growth reduction of 3.03 to 6.46 and 3.65 to 4.85 depending on the bacterial or fungal species. Heat-pretreated silicones containing 2% DMIM-BF 4 kept a high activity, with at least a 3-log reduction in bacterial growth, except against P. aeruginosa where there was only a 1.1-log reduction. After 33days, the release ratio of cationic biocide from silicone films containing 5% of DMIM-BF 4 was found to be 5.6% in pure water and 1.9% in physiological saline solution, respectively. No leaching of PHMG-DBS polymeric biocide was detected under the same conditions. These results demonstrate unambiguously that silicones containing 2% DMIM-BF 4 or 5% PHMG-DBS present high antimicrobial activity, as well as high leaching resistance and therefore may be good candidates for the development of safer medical devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Microstructure and nanomechanical properties of Fe+ implanted silicon

International Nuclear Information System (INIS)

Nunes, B.; Magalhães, S.; Franco, N.; Alves, E.; Colaço, R.

2013-01-01

Silicon wafers were implanted with iron ions at different fluences (from 5 × 10 15 up to 2 × 10 17 cm −2 ), followed by annealing treatments at temperatures from 550 °C to 1000 °C, aiming at evaluating the nanomechanical response of the samples and its relation with the microstructural features and characteristics of the modified layer. After implantation, a homogeneous amorphous layer with a thickness between 200 nm and 270 nm is formed, without damaging the surface smoothness neither introducing surface defects. After annealing, recrystallization and formation of nanometric precipitates of iron silicides is observed, with the corresponding changes in the hardness and stiffness of the modified layer. These results indicate that ion implantation of silicon followed by annealing at proper temperatures, can be an alternative route to be deeper explored in what concerns the precise control of the microstructure and, thus, the improvement of nanomechanical properties of silicon.

Osseointegrated silicone finger prosthesis using dental implants: a renovated technique.

Science.gov (United States)

Vinnakota, Dileep Nag; Sankar, V Vijay; Chirumamilla, Naveen; Reddy, V Vamsikrishna

2014-11-01

In clinical practice, we come across patients with traumatically amputated or congenitally missing partial or complete fingers that can be restored using microsurgical replantation or transplantation procedures. However, in some cases this might not be possible due to systemic or local factors and the lost or missing part has to be replaced prosthetically to offer psychological and functional wellbeing. These prostheses can be constructed with various materials like acrylics or silicone retained with the help of auxiliary aids. However, these prostheses cause some hindrance in performing functions like writing, typing, etc. The aim of the present trial was to ameliorate the existing design of implant supported finger prosthesis. Distal phalange of middle finger replaced with implant supported silicone finger prosthesis is modified by utilizing a metal framework to support silicone material to improve rigidity while working. We could achieve a good function, esthetics and tactile sensibility with this modified design. Whenever, feasible this design can improve the performance and patients feel a deep sense of satisfaction and improved self-esteem with this modified prosthesis.

Voltage-Controlled Reconfigurable Spin-Wave Nanochannels and Logic Devices

Science.gov (United States)

Rana, Bivas; Otani, YoshiChika

2018-01-01

Propagating spin waves (SWs) promise to be a potential information carrier in future spintronics devices with lower power consumption. Here, we propose reconfigurable nanochannels (NCs) generated by voltage-controlled magnetic anisotropy (VCMA) in an ultrathin ferromagnetic waveguide for SW propagation. Numerical micromagnetic simulations are performed to demonstrate the confinement of magnetostatic forward volumelike spin waves in NCs by VCMA. We demonstrate that the NCs, with a width down to a few tens of a nanometer, can be configured either into a straight or curved structure on an extended SW waveguide. The key advantage is that either a single NC or any combination of a number of NCs can be easily configured by VCMA for simultaneous propagation of SWs either with the same or different wave vectors according to our needs. Furthermore, we demonstrate the logic operation of a voltage-controlled magnonic xnor and universal nand gate and propose a voltage-controlled reconfigurable SW switch for the development of a multiplexer and demultiplexer. We find that the NCs and logic devices can even be functioning in the absence of the external-bias magnetic field. These results are a step towards the development of all-voltage-controlled magnonic devices with an ultralow power consumption.

Ternary and quaternary nanocomposites based on polystyrene, SBS, organically modified clay and silicone-polyether

International Nuclear Information System (INIS)

Kaneko, Manuela L.Q.A.; Lourenco, Emerson; Paiva, Raphael E.F.; Felisberti, Maria I.; Yoshida, Inez V.P.

2009-01-01

This work aims the study of toughened nanocomposites based on polystyrene (PS), poly(styrene-b-butadiene-b-styrene) (SBS), organically modified clay (C20A) and silicone-polyether, PDMS-POE. The intercalation of the copolymer PDMS-POE into the clay galleries increased the interlamellar distance, improving the exfoliation of the clay during the extrusion process of the materials. C20A/PDMS-POE nanocomposite, MC20A, was prepared by mechanical mixture using 1:1 wt% ratio. MC20A was incorporated into PS and PS/SBS blends using an extruder. The materials were characterized by X-ray diffraction and stress-strain mechanical tests. MC20A/PS/SBS, prepared by extrusion, showed an increase in the interlamellar distance, suggesting the intercalation of PS or SBS into the clay galleries. The PDMSPOE acted as a 'plasticizer' for PS and PS/SBS blend. However, this effect was not reverted by the clay addition. On the contrary, the 'plasticizer' effect was intensified by the clay maybe due to the slip characteristics of PDMS-POE associated with the lamella orientation. (author)

Micropatterned arrays of porous silicon: toward sensory biointerfaces.

Science.gov (United States)

Flavel, Benjamin S; Sweetman, Martin J; Shearer, Cameron J; Shapter, Joseph G; Voelcker, Nicolas H

2011-07-01

We describe the fabrication of arrays of porous silicon spots by means of photolithography where a positive photoresist serves as a mask during the anodization process. In particular, photoluminescent arrays and porous silicon spots suitable for further chemical modification and the attachment of human cells were created. The produced arrays of porous silicon were chemically modified by means of a thermal hydrosilylation reaction that facilitated immobilization of the fluorescent dye lissamine, and alternatively, the cell adhesion peptide arginine-glycine-aspartic acid-serine. The latter modification enabled the selective attachment of human lens epithelial cells on the peptide functionalized regions of the patterns. This type of surface patterning, using etched porous silicon arrays functionalized with biological recognition elements, presents a new format of interfacing porous silicon with mammalian cells. Porous silicon arrays with photoluminescent properties produced by this patterning strategy also have potential applications as platforms for in situ monitoring of cell behavior.

Sponge-like reduced graphene oxide/silicon/carbon nanotube composites for lithium ion batteries

Science.gov (United States)

Fang, Menglu; Wang, Zhao; Chen, Xiaojun; Guan, Shiyou

2018-04-01

Three-dimensional sponge-like reduced graphene oxide/silicon/carbon nanotube composites were synthesized by one-step hydrothermal self-assembly using silicon nanoparticles, graphene oxide and amino modified carbon nanotubes to develop high-performance anode materials of lithium ion batteries. Scanning electron microscopy and transmission electron microscopy images show the structure of composites that Silicon nanoparticles are coated with reduced graphene oxide while amino modified carbon nanotubes wrap around the reduced graphene oxide in the composites. When applied to lithium ion battery, these composites exhibit high initial specific capacity of 2552 mA h/g at a current density of 0.05 A/g. In addition, reduced graphene oxide/silicon/carbon nanotube composites also have better cycle stability than bare Silicon nanoparticles electrode with the specific capacity of 1215 mA h/g after 100 cycles. The three-dimension sponge-like structure not only ensures the electrical conductivity but also buffers the huge volume change, which has broad potential application in the field of battery.

Fabrication of nanochannels on polyimide films using dynamic plowing lithography

Science.gov (United States)

Stoica, Iuliana; Barzic, Andreea Irina; Hulubei, Camelia

2017-12-01

Three distinct polyimide films were analyzed from the point of view of their morphology in order to determine if their surface features can be adapted for applications where surface anisotropy is mandatory. Channels of nanometric dimensions were created on surface of the specimens by using a less common atomic force microscopy (AFM) method, namely Dynamic Plowing Lithography (DPL). The changes generated by DPL procedure were monitored through the surface texture and other functional parameters, denoting the surface orientation degree and also bearing and fluid retention properties. The results revealed that in the same nanolithography conditions, the diamine and dianhydride moieties have affected the characteristics of the nanochannels. This was explained based on the aliphatic/aromatic nature of the monomers and the backbone flexibility. The reported data are of great importance in designing custom nanostructures with enhanced anisotropy on surface of polyimide films for liquid crystal orientation or guided cell growth purposes. At the end, to track the effect of the nanolithography process on the tip sharpness, degradation and contamination, the blind tip reconstruction was performed on AFM probe, before and after lithography experiments, using TGT1 test grating AFM image.

A numerical model for simulating electroosmotic micro- and nanochannel flows under non-Boltzmann equilibrium

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyoungjin; Kwak, Ho Sang [School of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho, Gumi, Gyeongbuk 730-701 (Korea, Republic of); Song, Tae-Ho, E-mail: kimkj@kumoh.ac.kr, E-mail: hskwak@kumoh.ac.kr, E-mail: thsong@kaist.ac.kr [Department of Mechanical, Aerospace and Systems Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong, Yuseong, Daejeon 305-701 (Korea, Republic of)

2011-08-15

This paper describes a numerical model for simulating electroosmotic flows (EOFs) under non-Boltzmann equilibrium in a micro- and nanochannel. The transport of ionic species is represented by employing the Nernst-Planck equation. Modeling issues related to numerical difficulties are discussed, which include the handling of boundary conditions based on surface charge density, the associated treatment of electric potential and the evasion of nonlinearity due to the electric body force. The EOF in the entrance region of a straight channel is examined. The numerical results show that the present model is useful for the prediction of the EOFs requiring a fine resolution of the electric double layer under either the Boltzmann equilibrium or non-equilibrium. Based on the numerical results, the correlation between the surface charge density and the zeta potential is investigated.

Novel silicone elastomer formulations for DEAPs

DEFF Research Database (Denmark)

Skov, Anne Ladegaard; Vudayagiri, Sindhu; Benslimane, Mohamed

2013-01-01

We demonstrate that the force output and work density of polydimethylsiloxane (PDMS) based dielectric elastomer transducers can be significantly enhanced by the addition of high permittivity titanium dioxide nanoparticles which was also shown by Stoyanov et al[1] for pre-stretched elastomers...... and by Carpi et al for RTV silicones[2]. Furthermore the elastomer matrix is optimized to give very high breakdown strengths. We obtain an increase in the dielectric permittivity of a factor of approximately 2 with a loading of 12% TiO2 particles compared to the pure modified silicone elastomer with breakdown...

Preparation and properties of bisphenol-F based boron-phenolic resin/modified silicon nitride composites and their usage as binders for grinding wheels

International Nuclear Information System (INIS)

Lin, Chun-Te; Lee, Hsun-Tsing; Chen, Jem-Kun

2015-01-01

Highlights: • Bisphenol-F based boron-phenolic resins (B-BPF) with B−O bonds were synthesized. • The modified silicon nitride (m-SiN) was well dispersed and adhered in the B-BPF. • B-BPF/m-SiN composites have good thermal resistance and mechanical properties. • The grinding wheels bound by B-BPF/m-SiN have excellent grinding quality. - Abstract: In this study, phenolic resins based on bisphenol-F (BPF) were synthesized. Besides, ammonium borate was added in the synthesis process of BPF to form the bisphenol-F based boron-phenolic resins (B-BPF). The glass transition temperature, thermal resistance, flexural strength and hardness of B-BPF are respectively higher than those of BPF. This is due to the presence of new cross-link B−O bonds in the B-BPF. In addition, the 3-aminopropyltriethoxysilane modified silicon nitride powders (m-SiN) were fully mixed with B-BPF to form the B-BPF/m-SiN composites. The thermal resistance and mechanical properties of the B-BPF/m-SiN are promoted by the well-dispersed and well-adhered m-SiN in these novel polymer/ceramics composites. The results of grinding experiments indicate that the grinding wheels bound by the B-BPF/m-SiN have better grinding quality than those bound by the BPF. Thus the B-BPF/m-SiN composites are better binding media than the BPF resins

Effects of nanostructurized silicon on proliferation of stem and cancer cell.

Science.gov (United States)

Osminkina, L A; Luckyanova, E N; Gongalsky, M B; Kudryavtsev, A A; Gaydarova, A Kh; Poltavtseva, R A; Kashkarov, P K; Timoshenko, V Yu; Sukhikh, G T

2011-05-01

In vitro experiments showed that stem and cancer cells retained their viability on the surface of porous silicon with 10-100 nm nanostructures, but their proliferation was inhibited. Silicon nanoparticles of 100 nm in size obtained by mechanical grinding of porous silicon films or crystal silicon plates in a concentration below 1 mg/ml in solution did not modify viability and proliferation of mouse fibroblast and human laryngeal cancer cells. Additional ultrasonic exposure of cancer cells in the presence of 1 mg/ml silicon nanoparticles added to nutrient medium led to complete destruction of cells or to the appearance of membrane defects blocking their proliferation and initiating their apoptotic death.

Silicon carbide modified carbon materials. Formation of nanocrystalline SiC from thermochemical processes in the system coal tar pitch/poly(carbosilane)

Energy Technology Data Exchange (ETDEWEB)

Czosnek, C.; Janik, J.F.; Olejniczak, Z. [Stanislaw Staszic University of Mining & Meterology, AGH, Krakow (Poland)

2002-12-01

Poly(carbosilane) or PCS, (-CH{sub 2}-SiH(CH{sub 3})-){sub n}, is used as a Si-bearing precursor in combination with a coal tar pitch to study thermally induced transformations toward SiC-modified carbon composites. Following mixing of the components in the molten pitch at 160{sup o}C, the mixture is heated under argon atmosphere at 500{sup o}C yielding a solid carbonizate that is further subjected to separate pyrolysis experiments at 1300{sup o}C or 1650{sup o}C. At temperatures up to 500{sup o}C, the PCS reacts with suitable pitch components as well as undergoing decomposition reactions. At higher temperatures, clusters of prevailingly nanocrystalline beta-SiC are confirmed after the 1650{sup o}C pyrolysis step with indications that the formation of the compound starts at 1300{sup o}C. Si-29 MAS NMR, XRD, FT-IR, XPS, and elemental analysis are used to characterize each pyrolysis step, especially, from the viewpoint of transformation of silicon species to silicon carbide in the carbon matrix evolved from the pitch.

Structural and elastic properties of porous silicon

Energy Technology Data Exchange (ETDEWEB)

Matthai, C C [Department of Physics and Astronomy, University of Wales College of Cardiff, Cardiff CF2 3YB (United Kingdom); Gavartin, J L [Department of Physics and Astronomy, University of Wales College of Cardiff, Cardiff CF2 3YB (United Kingdom); Cafolla, A A [Department of Physics, Dublin City University, Dublin (Ireland)

1995-01-15

We have implemented a modified diffusion-limited aggregation model to simulate the porous silicon structure obtained by electrochemical dissolution. The resulting fractal structures were fully equilibrated using the molecular dynamics method. An analysis of the relaxed structure shows it to be quite stable with the presence of one-, two- and three-coordinated atoms as well as the four-coordinated atoms found in bulk silicon. It is suggested that the different substructures or nanocrystals might be responsible for the observed photoluminescence. ((orig.))

Tunable photoluminescence of porous silicon by liquid crystal infiltration

International Nuclear Information System (INIS)

Ma Qinglan; Xiong Rui; Huang Yuanming

2011-01-01

The photoluminescence (PL) of porous silicon films has been investigated as a function of the amount of liquid crystal molecules that are infiltrated into the constricted geometry of the porous silicon films. A typical nematic liquid crystal 4-pentyl-4'-cyanobiphenyl was employed in our experiment as the filler to modify the PL of porous silicon. It is found that the originally red PL of porous silicon films can be tuned to blue by simply adjusting the amount of liquid crystal molecules in the microchannels of the porous films. The chromaticity coordinates are calculated for the recorded PL spectra. The mechanism of the tunable PL is discussed. Our results have demonstrated that the luminescent properties of porous silicon films can be efficiently tuned by liquid crystal infiltration. - Highlights: → Liquid crystal infiltration can tune the photoluminescence of porous silicon. → Red emission of porous silicon can be switched to blue by the infiltration. → Chromaticity coordinates are calculated for the tuned emissions. → White emission is realized for porous silicon by liquid crystal infiltration.

A Brillouin scattering study of the effect of chemical passivation on the elastic properties of porous silicon

Science.gov (United States)

Fan, H. J.; Kuok, M. H.; Ng, S. C.; Boukherroub, R.; Lockwood, D. J.

2002-07-01

Brillouin scattering has been performed to probe acoustic waves in porous silicon films that have been chemically modified with either 1-decene, decyl aldehyde, undecylenic acid, or ethyl undecylenate. The shift in the frequencies of acoustic modes in the passivated porous silicon samples, relative to those in freshly prepared porous silicon, is different for different chemical modifiers. The magnitude of the frequency shift is qualitatively correlated with the change, caused by the passivation, in the average densities and elastic constants of the samples.

Suppression of ion conductance by electro-osmotic flow in nano-channels with weakly overlapping electrical double layers

Directory of Open Access Journals (Sweden)

Yang Liu

2016-08-01

Full Text Available This theoretical study investigates the nonlinear ionic current-voltage characteristics of nano-channels that have weakly overlapping electrical double layers. Numerical simulations as well as a 1-D mathematical model are developed to reveal that the electro-osmotic flow (EOF interplays with the concentration-polarization process and depletes the ion concentration inside the channels, thus significantly suppressing the channel conductance. The conductance may be restored at high electrical biases in the presence of recirculating vortices within the channels. As a result of the EOF-driven ion depletion, a limiting-conductance behavior is identified, which is intrinsically different from the classical limiting-current behavior.

Movable MEMS Devices on Flexible Silicon

KAUST Repository

Ahmed, Sally

2013-05-05

Flexible electronics have gained great attention recently. Applications such as flexible displays, artificial skin and health monitoring devices are a few examples of this technology. Looking closely at the components of these devices, although MEMS actuators and sensors can play critical role to extend the application areas of flexible electronics, fabricating movable MEMS devices on flexible substrates is highly challenging. Therefore, this thesis reports a process for fabricating free standing and movable MEMS devices on flexible silicon substrates; MEMS flexure thermal actuators have been fabricated to illustrate the viability of the process. Flexure thermal actuators consist of two arms: a thin hot arm and a wide cold arm separated by a small air gap; the arms are anchored to the substrate from one end and connected to each other from the other end. The actuator design has been modified by adding etch holes in the anchors to suit the process of releasing a thin layer of silicon from the bulk silicon substrate. Selecting materials that are compatible with the release process was challenging. Moreover, difficulties were faced in the fabrication process development; for example, the structural layer of the devices was partially etched during silicon release although it was protected by aluminum oxide which is not attacked by the releasing gas . Furthermore, the thin arm of the thermal actuator was thinned during the fabrication process but optimizing the patterning and etching steps of the structural layer successfully solved this problem. Simulation was carried out to compare the performance of the original and the modified designs for the thermal actuators and to study stress and temperature distribution across a device. A fabricated thermal actuator with a 250 μm long hot arm and a 225 μm long cold arm separated by a 3 μm gap produced a deflection of 3 μm before silicon release, however, the fabrication process must be optimized to obtain fully functioning

Resistivity distribution of silicon single crystals using codoping

Science.gov (United States)

Wang, Jong Hoe

2005-07-01

Numerous studies including continuous Czochralski method and double crucible technique have been reported on the control of macroscopic axial resistivity distribution in bulk crystal growth. The simple codoping method for improving the productivity of silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. Wang [J. Crystal Growth 275 (2005) e73] demonstrated using numerical analysis and by experimental results that the axial specific resistivity distribution can be modified in melt growth of silicon crystals and relatively uniform profile is possible by B-P codoping method. In this work, the basic characteristic of 8 in silicon single crystal grown using codoping method is studied and whether proposed method has advantage for the silicon crystal growth is discussed.

Controlled ion-beam transformation of silicon bipolar microwave power transistor's characteristics

International Nuclear Information System (INIS)

Solodukha, V.A.; Snitovskij, Yu.P.

2015-01-01

In this article, a method for changing the silicon bipolar microwave power transistor's characteristics in a direct and deliberate manner by modifying the chemical composition at the molybdenum - silicon boundary, the electro-physical properties of molybdenum - silicon contacts, and the electrophysical characteristics of transistor structure areas by the phosphorus ions irradiation of generated ohmic molybdenum - silicon contacts to the transistor emitters is proposed for the first time. The possibilities of this method are investigated and confirmed experimentally. (authors)

Grafting of functionalized polymer on porous silicon surface using Grignard reagent

Science.gov (United States)

Tighilt, F.-Z.; Belhousse, S.; Sam, S.; Hamdani, K.; Lasmi, K.; Chazalviel, J. N.; Gabouze, N.

2017-11-01

Recently, considerable attention has been paid to the manipulation and the control of the physicochemical properties of porous silicon surfaces because of their crucial importance to the modern microelectronics industry. Hybrid structures consisting of deposited polymer on porous silicon surfaces are important to applications in microelectronics, photovoltaics and sensors (Ensafi et al., 2016; Kashyout et al., 2015; Osorio et al.; 2015; Hejjo et al., 2002) [1-4]. In many cases, the polymer can provide excellent mechanical and chemical protection of the substrate, changes the electrochemical interface characteristics of the substrate, and provides new ways to the functionalization of porous silicon surfaces for molecular recognition and sensing. In this work, porous silicon surface was modified by anodic treatment in ethynylmagnesium bromide electrolyte leading to the formation of a polymeric layer bearing some bromine substituents. Subsequently, the formed polymer is functionalized with amine molecules containing functional groups (carboxylic acid or pyridine) by a substitution reaction between bromine sites and amine groups (Hofmann reaction). The chemical composition of the modified porous silicon surfaces was investigated and the grafting of polymeric chains and functional groups on the porous silicon surface was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) which displayed the principal characteristic peaks attributed to the different functional groups. Furthermore, the surface of the material was examined by scanning electron microscopy (SEM).

Rapid detection of structural variation in a human genome using nanochannel-based genome mapping technology

DEFF Research Database (Denmark)

Cao, Hongzhi; Hastie, Alex R.; Cao, Dandan

2014-01-01

mutations; however, none of the current detection methods are comprehensive, and currently available methodologies are incapable of providing sufficient resolution and unambiguous information across complex regions in the human genome. To address these challenges, we applied a high-throughput, cost......-effective genome mapping technology to comprehensively discover genome-wide SVs and characterize complex regions of the YH genome using long single molecules (>150 kb) in a global fashion. RESULTS: Utilizing nanochannel-based genome mapping technology, we obtained 708 insertions/deletions and 17 inversions larger...... fosmid data. Of the remaining 270 SVs, 260 are insertions and 213 overlap known SVs in the Database of Genomic Variants. Overall, 609 out of 666 (90%) variants were supported by experimental orthogonal methods or historical evidence in public databases. At the same time, genome mapping also provides...

Modified genetic algorithms to model cluster structures in medium-size silicon clusters

International Nuclear Information System (INIS)

Bazterra, Victor E.; Ona, Ofelia; Caputo, Maria C.; Ferraro, Marta B.; Fuentealba, Patricio; Facelli, Julio C.

2004-01-01

This paper presents the results obtained using a genetic algorithm (GA) to search for stable structures of medium size silicon clusters. In this work the GA uses a semiempirical energy function to find the best cluster structures, which are further optimized using density-functional theory. For small clusters our results agree well with previously reported structures, but for larger ones different structures appear. This is the case of Si 36 where we report a different structure, with significant lower energy than those previously found using limited search approaches on common structural motifs. This demonstrates the need for global optimization schemes when searching for stable structures of medium-size silicon clusters

Inverse Raman scattering in silicon: A free-carrier enhanced effect

International Nuclear Information System (INIS)

Solli, D. R.; Koonath, P.; Jalali, B.

2009-01-01

Stimulated Raman scattering has been harnessed to produce the first silicon lasers and amplifiers. The Raman effect can also produce intensity-dependent nonlinear loss through a corollary process, inverse Raman scattering (IRS). This process has never been observed in a semiconductor. We demonstrate IRS in silicon--a process that is substantially modified by optically generated free carriers--achieving attenuation levels >15 dB with a pump intensity of 4 GW/cm 2 . Surprisingly, free-carrier absorption, the detrimental effect that generally suppresses nonlinear effects in silicon, actually facilitates IRS by delaying the onset of contamination from coherent anti-Stokes Raman scattering. Silicon-based IRS could be a valuable tool for chip-scale signal processing.

Surface functionalization of HF-treated silicon nanowires

Indian Academy of Sciences (India)

Administrator

place when silicon nanowires reacted with 2,2,2-trifluoroethyl acrylate, and reductive deposition reaction occurred in the ... detection of fM level of protein. 14 and DNA. 15 ... surfaces can be easily modified to act as both elec- tron-transfer ...

High-performance RF coil inductors on silicon

Energy Technology Data Exchange (ETDEWEB)

Malba, V.; Young, D.; Ou, J.J.; Bernhardt, A.F.; Boser, B.E.

1998-03-01

Strong demand for wireless communication devices has motivated research directed toward monolithic integration of transceivers. The fundamental electronic component least compatible with silicon integrated circuits is the inductor, although a number of inductors are required to implement oscillators, filters and matching networks in cellular devices. Spiral inductors have been integrated into the silicon IC metallization sequence but have not performed adequately due to coupling to the silicon which results in parasitic capacitance and loss. We have, for the first time, fabricated three dimensional coil inductors on silicon which have significantly lower capacitive coupling and loss and which now exceed the requirements of potential applications. Quality factors of 30 at 1 GHz have been measured in single turn devices and Q > 16 in 2 and 4 turn devices. The reduced Q for multiturn devices appears to be related to eddy currents in outer turns generated by magnetic fields from current in neighboring turns. Higher Q values significantly in excess of 30 are anticipated using modified coil designs.

Intravitreal properties of porous silicon photonic crystals

Science.gov (United States)

Cheng, L; Anglin, E; Cunin, F; Kim, D; Sailor, M J; Falkenstein, I; Tammewar, A; Freeman, W R

2009-01-01

Aim To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery. Methods A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology. Results No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles). Conclusion The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases. PMID:18441177

Development of low-cost silicon crystal growth techniques for terrestrial photovoltaic solar energy conversion

Science.gov (United States)

Zoutendyk, J. A.

1976-01-01

Because of the growing need for new sources of electrical energy, photovoltaic solar energy conversion is being developed. Photovoltaic devices are now being produced mainly from silicon wafers obtained from the slicing and polishing of cylindrically shaped single crystal ingots. Inherently high-cost processes now being used must either be eliminated or modified to provide low-cost crystalline silicon. Basic to this pursuit is the development of new or modified methods of crystal growth and, if necessary, crystal cutting. If silicon could be grown in a form requiring no cutting, a significant cost saving would potentially be realized. Therefore, several techniques for growth in the form of ribbons or sheets are being explored. In addition, novel techniques for low-cost ingot growth and cutting are under investigation.

Soft chemical synthesis of silicon nanosheets and their applications

Energy Technology Data Exchange (ETDEWEB)

Nakano, Hideyuki; Ikuno, Takashi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

2016-12-15

Two-dimensional silicon nanomaterials are expected to show different properties from those of bulk silicon materials by virtue of surface functionalization and quantum size effects. Since facile fabrication processes of large area silicon nanosheets (SiNSs) are required for practical applications, a development of soft chemical synthesis route without using conventional vacuum processes is a challenging issue. We have recently succeeded to prepare SiNSs with sub-nanometer thicknesses by exfoliating layered silicon compounds, and they are found to be composed of crystalline single-atom-thick silicon layers. In this review, we present the synthesis and modification methods of SiNSs. These SiNSs have atomically flat and smooth surfaces due to dense coverage of organic moieties, and they are easily self-assembled in a concentrated state to form a regularly stacked structure. We have also characterized the electron transport properties and the electronic structures of SiNSs. Finally, the potential applications of these SiNSs and organic modified SiNSs are also reviewed.

Palladium modified porous silicon as multi-functional MALDI chip for serum peptide detection.

Science.gov (United States)

Li, Xiao; Chen, Xiaoming; Tan, Jie; Liang, Xiao; Wu, Jianmin

2017-02-14

Interest in using mesoporous materials for peptidomic research has increased recently. The present study reports a new type of matrix assisted laser desorption/ionization (MALDI) plate derived from electrochemically etched porous silicon (PSi) whose surface was modified with palladium nanoparticles (PdNPs). Owing to the well-tailored pore size and the molecular filtration effect of the PSi, peptides in serum samples can be selectively captured and enriched in the pore channel, thereby eliminating the interference from large proteins in subsequent MALDI-MS detection. On the other hand, the PdNPs with localized surface plasmon resonance (LSPR) effect can help to enhance the efficiency of energy absorption in the UV region. Meanwhile, the charge separation effect between the PSi semiconductor and PdNPs also can be applied to promote the accumulation of positive charges on PdNPs, resulting in an improvement in laser desorption/ionization (LDI) efficiency under positive linear detection mode. The interplay among these unique properties of PSi and PdNPs can synergistically increase the overall sensitivity in serum peptide detection. Using this technology, serum sample can be directly detected on the PSi-PdNPs chip without complicated pretreatment process. Therefore, a high fidelity serum peptide fingerprint can be acquired in a high throughput way. With the assistance of statistical analysis, colorectal cancer patients and healthy people can be accurately distinguished based on the serum peptide fingerprints.

EDITORIAL: Special issue on silicon photonics

Science.gov (United States)

Reed, Graham; Paniccia, Mario; Wada, Kazumi; Mashanovich, Goran

2008-06-01

The technology now known as silicon photonics can be traced back to the pioneering work of Soref in the mid-1980s (see, for example, Soref R A and Lorenzo J P 1985 Electron. Lett. 21 953). However, the nature of the research conducted today, whilst it builds upon that early work, is unrecognizable in terms of technology metrics such as device efficiency, device data rate and device dimensions, and even in targeted applications areas. Today silicon photonics is still evolving, and is enjoying a period of unprecedented attention in terms of research focus. This has resulted in orders-of-magnitude improvement in device performance over the last few years to levels many thought were impossible. However, despite the existence of the research field for more than two decades, silicon is still regarded as a 'new' optical material, one that is being manipulated and modified to satisfy the requirements of a range of applications. This is somewhat ironic since silicon is one of the best known and most thoroughly studied materials, thanks to the electronics industry that has made silicon its material of choice. The principal reasons for the lack of study of this 'late developer' are that (i) silicon is an indirect bandgap material and (ii) it does not exhibit a linear electro-optic (Pockels) effect. The former condition means that it is difficult to make a laser in silicon based on the intrinsic performance of the material, and consequently, in recent years, researchers have attempted to modify the material to artificially engineer the conditions for lasing to be viable (see, for example, the review text, Jalali B et al 2008 Silicon Lasers in Silicon Photonics: The State of the Art ed G T Reed (New York: Wiley)). The latter condition means that optical modulators are intrinsically less efficient in silicon than in some other materials, particularly when targeting the popular telecommunications wavelengths around 1.55 μm. Therefore researchers have sought alternative

Cyclodextrin-Modified Porous Silicon Nanoparticles for Efficient Sustained Drug Delivery and Proliferation Inhibition of Breast Cancer Cells.

Science.gov (United States)

Correia, Alexandra; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Almeida, Sérgio; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2015-10-21

Over the past decade, the potential of polymeric structures has been investigated to overcome many limitations related to nanosized drug carriers by modulating their toxicity, cellular interactions, stability, and drug-release kinetics. In this study, we have developed a successful nanocomposite consisting of undecylenic acid modified thermally hydrocarbonized porous silicon nanoparticles (UnTHCPSi NPs) loaded with an anticancer drug, sorafenib, and surface-conjugated with heptakis(6-amino-6-deoxy)-β-cyclodextrin (HABCD) to show the impact of the surface polymeric functionalization on the physical and biological properties of the drug-loaded nanoparticles. Cytocompatibility studies showed that the UnTHCPSi-HABCD NPs were not toxic to breast cancer cells. HABCD also enhanced the suspensibility and both the colloidal and plasma stabilities of the UnTHCPSi NPs. UnTHCPSi-HABCD NPs showed a significantly increased interaction with breast cancer cells compared to bare NPs and also sustained the drug release. Furthermore, the sorafenib-loaded UnTHCPSi-HABCD NPs efficiently inhibited cell proliferation of the breast cancer cells.

Quercetin-Based Modified Porous Silicon Nanoparticles for Enhanced Inhibition of Doxorubicin-Resistant Cancer Cells.

Science.gov (United States)

Liu, Zehua; Balasubramanian, Vimalkumar; Bhat, Chinmay; Vahermo, Mikko; Mäkilä, Ermei; Kemell, Marianna; Fontana, Flavia; Janoniene, Agne; Petrikaite, Vilma; Salonen, Jarno; Yli-Kauhaluoma, Jari; Hirvonen, Jouni; Zhang, Hongbo; Santos, Hélder A

2017-02-01

One of the most challenging obstacles in nanoparticle's surface modification is to achieve the concept that one ligand can accomplish multiple purposes. Upon such consideration, 3-aminopropoxy-linked quercetin (AmQu), a derivative of a natural flavonoid inspired by the structure of dopamine, is designed and subsequently used to modify the surface of thermally hydrocarbonized porous silicon (PSi) nanoparticles. This nanosystem inherits several advanced properties in a single carrier, including promoted anticancer efficiency, multiple drug resistance (MDR) reversing, stimuli-responsive drug release, drug release monitoring, and enhanced particle-cell interactions. The anticancer drug doxorubicin (DOX) is efficiently loaded into this nanosystem and released in a pH-dependent manner. AmQu also effectively quenches the fluorescence of the loaded DOX, thereby allowing the use of the nanosystem for monitoring the intracellular drug release. Furthermore, a synergistic effect with the presence of AmQu is observed in both normal MCF-7 and DOX-resistant MCF-7 breast cancer cells. Due to the similar structure as dopamine, AmQu may facilitate both the interaction and internalization of PSi into the cells. Overall, this PSi-based platform exhibits remarkable superiority in both multifunctionality and anticancer efficiency, making this nanovector a promising system for anti-MDR cancer treatment. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface modification of silicon wafer by grafting zwitterionic polymers to improve its antifouling property

Science.gov (United States)

Sun, Yunlong; Chen, Changlin; Xu, Heng; Lei, Kun; Xu, Guanzhe; Zhao, Li; Lang, Meidong

2017-10-01

Silicon (111) wafer was modified by triethoxyvinylsilane containing double bond as an intermedium, and then P4VP (polymer 4-vinyl pyridine) brush was "grafted" onto the surface of silicon wafer containing reactive double bonds by adopting the "grafting from" way and Si-P4VP substrate (silicon wafer grafted by P4VP) was obtained. Finally, P4VP brush of Si-P4VP substrate was modified by 1,3-propanesulfonate fully to obtain P4VP-psl brush (zwitterionic polypyridinium salt) and the functional Si-P4VP-psl substrate (silicon wafer grafted by zwitterionic polypyridinium salt based on polymer 4-vinyl pyridine) was obtained successfully. The antifouling property of the silicon wafer, the Si-P4VP substrate and the Si-P4VP-psl substrate was investigated by using bovine serum albumin, mononuclear macrophages (RAW 264.7) and Escherichia coli (E. coli) ATTC25922 as model bacterium. The results showed that compared with the blank sample-silicon wafer, the Si-P4VP-psl substrate had excellent anti-adhesion ability against bovine serum albumin, cells and bacterium, due to zwitterionic P4VP-psl brush (polymer 4-vinyl pyridine salt) having special functionality like antifouling ability on biomaterial field.

Distribution of distances between DNA barcode labels in nanochannels close to the persistence length

Science.gov (United States)

Reinhart, Wesley F.; Reifenberger, Jeff G.; Gupta, Damini; Muralidhar, Abhiram; Sheats, Julian; Cao, Han; Dorfman, Kevin D.

2015-02-01

We obtained experimental extension data for barcoded E. coli genomic DNA molecules confined in nanochannels from 40 nm to 51 nm in width. The resulting data set consists of 1 627 779 measurements of the distance between fluorescent probes on 25 407 individual molecules. The probability density for the extension between labels is negatively skewed, and the magnitude of the skewness is relatively insensitive to the distance between labels. The two Odijk theories for DNA confinement bracket the mean extension and its variance, consistent with the scaling arguments underlying the theories. We also find that a harmonic approximation to the free energy, obtained directly from the probability density for the distance between barcode labels, leads to substantial quantitative error in the variance of the extension data. These results suggest that a theory for DNA confinement in such channels must account for the anharmonic nature of the free energy as a function of chain extension.

Progress in Studies on Carbon and Silicon Carbide Nanocomposite Materials

International Nuclear Information System (INIS)

Xiao, P.; Chen, J.; Xian-feng, X.

2010-01-01

Silicon carbide nanofiber and carbon nanotubes are introduced. The structure and application of nanotubers (nanofibers) in carbon/carbon composites are emphatically presented. Due to the unique structure of nanotubers (nanofibers), they can modify the microstructure of pyrocarbon and induce the deposition of pyrocarbon with high text in carbon/carbon composites. So the carbon/carbon composites modified by CNT/CNF have more excellent properties.

Characterization of silicon- and carbon-based composite anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Khomenko, Volodymyr G.; Barsukov, Viacheslav Z.

2007-01-01

In recent years development of active materials for negative electrodes has been of great interest. Special attention has been focused on the active materials possessing higher reversible capacity than that of conventional graphite. In the present work the electrochemical performance of some carbon/silicon-based materials has been analyzed. For this purpose various silicon-based composites were prepared using such carbon materials as graphite, hard carbon and graphitized carbon black. An analysis of charging-discharging processes at electrodes based on different carbon materials has shown that graphite modified with silicon is the most promising anode material. It has also been revealed that the irreversible capacity mainly depends on the content of Si. An optimum content of Si has been determined with taking into account that high irreversible capacity is not suitable for practical application in lithium-ion batteries. This content falls within the range of 8-10 wt%. The reversible capacity of graphite modified with 8 wt% carbon-coated Si was as high as 604 mAh g -1 . The irreversible capacity loss with this material was as low as 8.1%. The small irreversible capacity of the material allowed developing full lithium-ion rechargeable cells in the 2016 coin cell configuration. Lithium-ion batteries based on graphite modified with silicon show gravimetric and volumetric specific energy densities which are higher by approximately 20% than those for a lithium-ion battery based on natural graphite

Non-Gaussian Distribution of DNA Barcode Extension In Nanochannels Using High-throughput Imaging

Science.gov (United States)

Sheats, Julian; Reinhart, Wesley; Reifenberger, Jeff; Gupta, Damini; Muralidhar, Abhiram; Cao, Han; Dorfman, Kevin

2015-03-01

We present experimental data for the extension of internal segments of highly confined DNA using a high-­throughput experimental setup. Barcode­-labeled E. coli genomic DNA molecules were imaged at a high areal density in square nanochannels with sizes ranging from 40 nm to 51 nm in width. Over 25,000 molecules were used to obtain more than 1,000,000 measurements for genomic distances between 2,500 bp and 100,000 bp. The distribution of extensions has positive excess kurtosis and is skew­ left due to weak backfolding in the channel. As a result, the two Odijk theories for the chain extension and variance bracket the experimental data. We compared to predictions of a harmonic approximation for the confinement free energy and show that it produces a substantial error in the variance. These results suggest an inherent error associated with any statistical analysis of barcoded DNA that relies on harmonic models for chain extension. Present address: Department of Chemical and Biological Engineering, Princeton University.

Testbeam studies of silicon microstrip sensor architectures modified to facilitate detector module mass production

CERN Document Server

Poley, Anne-luise; The ATLAS collaboration

2016-01-01

For the High Luminosity Upgrade of the LHC, the Inner Detector of the ATLAS detector will be replaced by an all-silicon tracker, consisting of pixel and strip sensor detector modules. Silicon strip sensors are being developed to meet both the tracking requirements in a high particle density environment and constraints imposed by the construction process. Several thousand wire bonds per module, connecting sensor strips and readout channels, need to be produced with high reliability and speed, requiring wire bond pads of sufficient size on each sensor strip. These sensor bond pads change the local sensor architecture and the resulting electric field and thus alter the sensor performance. These sensor regions with bond pads, which account for up to 10 % of a silicon strip sensor, were studied using both an electron beam at DESY and a micro-focused X-ray beam at the Diamond Light Source. This contribution presents measurements of the effective strip width in sensor regions where the structure of standard parallel...

Bioconjugate functionalization of thermally carbonized porous silicon using a radical coupling reaction†

Science.gov (United States)

Sciacca, Beniamino; Alvarez, Sara D.; Geobaldo, Francesco; Sailor, Michael J.

2011-01-01

The high stability of Salonen’s thermally carbonized porous silicon (TCPSi) has attracted attention for environmental and biochemical sensing applications, where corrosion-induced zero point drift of porous silicon-based sensor elements has historically been a significant problem. Prepared by the high temperature reaction of porous silicon with acetylene gas, the stability of this silicon carbide-like material also poses a challenge—many sensor applications require a functionalized surface, and the low reactivity of TCPSi has limited the ability to chemically modify its surface. This work presents a simple reaction to modify the surface of TCPSi with an alkyl carboxylate. The method involves radical coupling of a dicarboxylic acid (sebacic acid) to the TCPSi surface using a benzoyl peroxide initiator. The grafted carboxylic acid species provides a route for bioconjugate chemical modification, demonstrated in this work by coupling propylamine to the surface carboxylic acid group through the intermediacy of pentafluorophenol and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC). The stability of the carbonized porous Si surface, both before and after chemical modification, is tested in phosphate buffered saline solution and found to be superior to either hydrosilylated (with undecylenic acid) or thermally oxidized porous Si surfaces. PMID:20967329

Slim edges in double-sided silicon 3D detectors

International Nuclear Information System (INIS)

Povoli, M; Dalla Betta, G-F; Bagolini, A; Boscardin, M; Giacomini, G; Vianello, E; Zorzi, N

2012-01-01

Minimization of the insensitive edge area is one of the key requirements for silicon radiation detectors to be used in future silicon trackers. In 3D detectors this goal can be achieved with the active edge, at the expense of a high fabrication process complexity. In the framework of the ATLAS 3D sensor collaboration, we produced modified 3D silicon sensors with a double-sided technology. While this approach is not suitable to obtain active edges, because it does not use a support wafer, it allows for a new type of edge termination, the slim edge. In this paper we report on the development of the slim edge, from numerical simulations to design and testing, proving that it works effectively without increasing the fabrication complexity of silicon 3D detectors, and that it could be further optimized to reduce the insensitive edge region to less than 100 μm.

Cluster-assisted nucleation of silicon phase in hypoeutectic Al–Si alloy with further inoculation

International Nuclear Information System (INIS)

Zhang, Yong; Zheng, Hongliang; Liu, Yue; Shi, Lei; Xu, Rongfu; Tian, Xuelei

2014-01-01

The paper discusses the responses of eutectic silicon and eutectic cells in Al–10Si alloy upon inoculation with an Al–10Si–2Fe master alloy. The further inoculation hardly destroys the modification effect of Sr but significantly refines the eutectic cells in Sr-modified samples, while in unmodified samples, it stimulates the occurrences of polyhedral silicon particles and divorced eutectic. Thermal analysis, scanning electron microscopy, (high-resolution) transmission electron microscopy and scanning and transmission electron microscopy have been used to elucidate the underlying mechanism. A cluster-assisted nucleation mechanism responsible for the enhanced nucleation of silicon phase upon inoculation is proposed. Icosahedral (AlFeSi) clusters are speculated to evolve from the added Al–10Si–2Fe master alloy in Al–10Si melt, around which aggregations of silicon atoms form. Through a series of structural evolutions, these clusters transform into precursors of a silicon crystal. The subsequent formation of silicon particles is achieved by the agglomerations and attachments of these precursors and individual silicon atoms. This hypothesis is further consolidated by the increased characteristic temperatures of eutectic and the anomalous appearance of a high density of nanoscale particles, as well as the abnormal disappearance of Sr-induced twins in further inoculated silicon particles. The increased characteristic temperatures are strong indications of the enhanced nucleation of the silicon phase. The high density of nanoscale particles with an indeterminate crystal structure are the survivors of these precursors. In an Sr-modified and further inoculated sample, the formation of Sr-induced twins is consequently inhibited due to the participation of these precursors during the growth of silicon particles. Furthermore, based on the proposed nucleation mechanism, the dependence of eutectic cell size on Sr level is elucidated in detail

Chemical modification of silicon surfaces for the application in soft lithography

Energy Technology Data Exchange (ETDEWEB)

Gilles, S.

2007-05-15

The objective of this work was to chemically modify silicon surfaces by anchoring functional molecules. A major part was devoted to the investigation and improvement of the self-assembly process of organosilanes on oxidized silicon surfaces. The formation of a release agent layer with perfluorinated alkylsilanes was performed by vapor phase deposition. An advanced vapor phase deposition device, called CASINO device, was built to enhance the qualities of the thin films. It is possible to carry out cleaning and silanization in a closed chamber without exposing the samples to air in between. Thereby surface contamination is avoided. Experiments with the new device were performed following examples given in literature. To optimize the silanization process in the CASINO device, it was also planned to apply heat treatment of the sample during or after the deposition process. Surface layers of thiolterminated and of aminoterminated molecules were investigated as adhesive layer for the linkage of metal structures to silicon surfaces, e.g. Shuttle-Transfer Printing with gold crossbar electrodes. First, thiol- and aminoterminated organosilane SAMs were tested as adhesive layers for gold. The surface modified with thiolterminated silane molecules was further examined. Adhesion was promoted only after heat treatment of a thiolmodified silicon substrate with a gold layer on top. (orig.)

Influence of silicon addition on the mechanical properties and ...

Indian Academy of Sciences (India)

The addition of silicon to low-alloy steel allows to modify the materials' microstructure and thus to improve their ... Graphite supplied by TIMCAL) was added to the mixture powders ... cut into halves using a diamond disk in the Accutom-2 cut-.

Silicon: Potential to Promote Direct and Indirect Effects on Plant Defense Against Arthropod Pests in Agriculture

Science.gov (United States)

Reynolds, Olivia L.; Padula, Matthew P.; Zeng, Rensen; Gurr, Geoff M.

2016-01-01

Silicon has generally not been considered essential for plant growth, although it is well recognized that many plants, particularly Poaceae, have substantial plant tissue concentrations of this element. Recently, however, the International Plant Nutrition Institute [IPNI] (2015), Georgia, USA has listed it as a “beneficial substance”. This reflects that numerous studies have now established that silicon may alleviate both biotic and abiotic stress. This paper explores the existing knowledge and recent advances in elucidating the role of silicon in plant defense against biotic stress, particularly against arthropod pests in agriculture and attraction of beneficial insects. Silicon confers resistance to herbivores via two described mechanisms: physical and biochemical/molecular. Until recently, studies have mainly centered on two trophic levels; the herbivore and plant. However, several studies now describe tri-trophic effects involving silicon that operate by attracting predators or parasitoids to plants under herbivore attack. Indeed, it has been demonstrated that silicon-treated, arthropod-attacked plants display increased attractiveness to natural enemies, an effect that was reflected in elevated biological control in the field. The reported relationships between soluble silicon and the jasmonic acid (JA) defense pathway, and JA and herbivore-induced plant volatiles (HIPVs) suggest that soluble silicon may enhance the production of HIPVs. Further, it is feasible that silicon uptake may affect protein expression (or modify proteins structurally) so that they can produce additional, or modify, the HIPV profile of plants. Ultimately, understanding silicon under plant ecological, physiological, biochemical, and molecular contexts will assist in fully elucidating the mechanisms behind silicon and plant response to biotic stress at both the bi- and tri-trophic levels. PMID:27379104

Silicon: Potential to Promote Direct and Indirect Effects on Plant Defense Against Arthropod Pests in Agriculture.

Science.gov (United States)

Reynolds, Olivia L; Padula, Matthew P; Zeng, Rensen; Gurr, Geoff M

2016-01-01

Silicon has generally not been considered essential for plant growth, although it is well recognized that many plants, particularly Poaceae, have substantial plant tissue concentrations of this element. Recently, however, the International Plant Nutrition Institute [IPNI] (2015), Georgia, USA has listed it as a "beneficial substance". This reflects that numerous studies have now established that silicon may alleviate both biotic and abiotic stress. This paper explores the existing knowledge and recent advances in elucidating the role of silicon in plant defense against biotic stress, particularly against arthropod pests in agriculture and attraction of beneficial insects. Silicon confers resistance to herbivores via two described mechanisms: physical and biochemical/molecular. Until recently, studies have mainly centered on two trophic levels; the herbivore and plant. However, several studies now describe tri-trophic effects involving silicon that operate by attracting predators or parasitoids to plants under herbivore attack. Indeed, it has been demonstrated that silicon-treated, arthropod-attacked plants display increased attractiveness to natural enemies, an effect that was reflected in elevated biological control in the field. The reported relationships between soluble silicon and the jasmonic acid (JA) defense pathway, and JA and herbivore-induced plant volatiles (HIPVs) suggest that soluble silicon may enhance the production of HIPVs. Further, it is feasible that silicon uptake may affect protein expression (or modify proteins structurally) so that they can produce additional, or modify, the HIPV profile of plants. Ultimately, understanding silicon under plant ecological, physiological, biochemical, and molecular contexts will assist in fully elucidating the mechanisms behind silicon and plant response to biotic stress at both the bi- and tri-trophic levels.

Mesoporous Silicon with Modified Surface for Plant Viruses and Their Protein Particle Sensing

Directory of Open Access Journals (Sweden)

Kae Dal Kwack

2008-10-01

Full Text Available Changes in electric parameters of a mesoporous silicon treated by a plasma chemical etching with fluorine and hydrogen ions, under the adsorption of NEPO (Nematodetransmitted Polyhedral plant viruses such as TORSV (Tomato Ringspot Virus, GFLV (Grapevine Fan Leaf Virus and protein macromolecule from TORSV particles are described. The current response to the applied voltage is measured for each virus particle to investigate the material parameters which are sensitive to the adsorbed particles. The peculiar behaviors of the response are modeled by the current-voltage relationship in a MOSFET. This model explains the behavior well and the double gate model of the MOSFET informs that the mesoporous silicon is a highly sensitive means of detecting the viruses in the size range less than 50 nm.

Radiation modification of silicone rubber with glycidylmethacrylate

International Nuclear Information System (INIS)

Segura, Tania; Burillo, Guillermina

2013-01-01

The grafting of glycidilmethacrylate(GMA) was grafted onto silicone rubber (SR) by using the γ-ray pre-irradiation grafting method under different conditions. The effect of reaction time, total dose, reaction temperature and monomer concentration on the graft yield was studied. It was found that the degree of grafting can be controlled by adjusting these parameters. The chemical structure of SR before and after grafting was characterized using FTIR-ATR and SEM–EDS. The analysis revealed that the surface of the SR was uniformly covered by GMA and the cross-section analysis indicated that the grafting occurred in the bulk. Thermogravimetric analysis (TGA) showed that the graft copolymer was more thermally stable than polyglycidylmethacrylate but less stable than SR, and the DSC confirmed that the GMA was grafting onto silicone rubber. - Highlights: • A graft copolymer with silicone rubber was synthesized by gamma pre-irradiation method. • SEM–EDS analysis showed that the surface and the bulk of the new copolymer were grafted. • The thermal properties of the silicone rubber used were modified with grafting. • The new copolymer could be used to immobilize nucleophilic biomolecules

Stable electroluminescence from passivated nano-crystalline porous silicon using undecylenic acid

Science.gov (United States)

Gelloz, B.; Sano, H.; Boukherroub, R.; Wayner, D. D. M.; Lockwood, D. J.; Koshida, N.

2005-06-01

Stabilization of electroluminescence from nanocrystalline porous silicon diodes has been achieved by replacing silicon-hydrogen bonds terminating the surface of nanocrystalline silicon with more stable silicon-carbon (Si-C) bonds. Hydrosilylation of the surface of partially and anodically oxidized porous silicon samples was thermally induced at about 90 °C using various different organic molecules. Devices whose surface have been modified with stable covalent bonds shows no degradation in the EL efficiency and EL output intensity under DC operation for several hours. The enhanced stability can be attributed to the high chemical resistance of Si-C bonds against current-induced surface oxidation associated with the generation of nonradiative defects. Although devices treated with 1-decene exhibit reduced EL efficiency and brightness compared to untreatred devices, other molecules, such as ethyl-undecylenate and particularly undecylenic acid provide stable and more efficient visible electroluminescence at room temperature. Undecylenic acid provides EL brightness as high as that of an untreated device.

Knotting dynamics of DNA chains of different length confined in nanochannels

International Nuclear Information System (INIS)

Suma, Antonio; Micheletti, Cristian; Orlandini, Enzo

2015-01-01

Langevin dynamics simulations are used to characterize the typical mechanisms governing the spontaneous tying, untying and the dynamical evolution of knots in coarse-grained models of DNA chains confined in nanochannels. In particular we focus on how these mechanisms depend on the chain contour length, L c , at a fixed channel width D = 56 nm corresponding to the onset of the Odijk scaling regime where chain backfoldings and hence knots are disfavoured but not suppressed altogether. We find that the lifetime of knots grows significantly with L c , while that of unknots varies to a lesser extent. The underlying kinetic mechanisms are clarified by analysing the evolution of the knot position along the chain. At the considered confinement, in fact, knots are typically tied by local backfoldings of the chain termini where they are eventually untied after a stochastic motion along the chain. Consequently, the lifetime of unknots is mostly controlled by backfoldings events at the chain ends, which is largely independent of L c . The lifetime of knots, instead, increases significantly with L c because knots can, on average, travel farther along the chain before being untied. The observed interplay of knots and unknots lifetimes underpins the growth of the equilibrium knotting probability of longer and longer chains at fixed channel confinement. (paper)

Modification of inkjet printer for polymer sensitive layer preparation on silicon-based gas sensors

Directory of Open Access Journals (Sweden)

Tianjian Li

2015-04-01

Full Text Available Inkjet printing is a versatile, low cost deposition technology with the capabilities for the localized deposition of high precision, patterned deposition in a programmable way, and the parallel deposition of a variety of materials. This paper demonstrates a new method of modifying the consumer inkjet printer to prepare polymer-sensitive layers on silicon wafer for gas sensor applications. A special printing tray for the modified inkjet printer to support a 4-inch silicon wafer is designed. The positioning accuracy of the deposition system is tested, based on the newly modified printer. The experimental data show that the positioning errors in the horizontal direction are negligibly small, while the positioning errors in the vertical direction rise with the increase of the printing distance of the wafer. The method for making suitable ink to be deposited to form the polymer-sensitive layer is also discussed. In the testing, a solution of 0.1 wt% polyvinyl alcohol (PVA was used as ink to prepare a sensitive layer with certain dimensions at a specific location on the surface of the silicon wafer, and the results prove the feasibility of the methods presented in this article.

Magnetic domain walls as reconfigurable spin-wave nano-channels

Science.gov (United States)

Wagner, Kai

Research efforts to utilize spin waves as information carriers for wave based logic in micro- and nano-structured ferromagnetic materials have increased tremendously over the recent years. However, finding efficient means of tailoring and downscaling guided spin-wave propagation in two dimensions, while maintaining energy efficiency and reconfigurability, still remains a delicate challenge. Here we target these challenges by spin-wave transport inside nanometer-scaled potential wells formed along magnetic domain walls. For this, we investigate the magnetization dynamics of a rectangular-like element in a Landau state exhibiting a so called 180° Néel wall along its center. By microwave antennae the rf-excitation is constricted to one end of the domain wall and the spin-wave intensities are recorded by means of Brillouin-Light Scattering microscopy revealing channeled transport. Additional micromagnetic simulations with pulsed as well as cw-excitation are performed to yield further insight into this class of modes. We find several spin-wave modes quantized along the width of the domain wall yet with well defined wave vectors along the wall, exhibiting positive dispersion. In a final step, we demonstrate the flexibility of these spin-wave nano-channels based on domain walls. In contrast to wave guides realised by fixed geometries, domain walls can be easily manipulated. Here we utilize small external fields to control its position with nanometer precision over a micrometer range, while still enabling transport. Domain walls thus, open the perspective for reprogrammable and yet non-volatile spin-wave waveguides of nanometer width. Financial support by the Deutsche Forschungsgemeinschaft within project SCHU2922/1-1 is gratefully acknowledged.

Effect of hydrodynamic slippage on electro-osmotic flow in zeta potential patterned nanochannels

Energy Technology Data Exchange (ETDEWEB)

Datta, S; Choudhary, J N, E-mail: subhra-datta@iitd.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

2013-10-01

The effect of hydrodynamic slippage on the electro-osmotic flow in a nanochannel with thick electrical double layers whose wall surface potential has a periodic axial variation is studied. The equations of Stokes flow are solved exactly with the help of the Navier slip boundary condition and the Debye-Huckel linearization of the equation governing the potential of the electrical double layer. Each periodic cell of the flow field consists of four counter-rotating vortices. The cross-channel profile of the axial velocity at the center of the cell exhibits three extrema and a reversed velocity zone near the channel axis of symmetry. The size of the extrema and that of the reversed velocity zone increases with increase in the degree of slippage. In the limit when the wavelength of axial variation in surface potential is much larger than the channel width, the flow characteristics are interpreted in terms of the lubrication approximation. In the limit when the electrical double layer is much thinner than the channel height, the effect of slip is modeled by a Helmholtz-Smoluchowski apparent slip boundary condition that depends on the pattern wavelength. (paper)

Functionalization of nanochannels by radio-induced grafting polymerization on PET track-etched membranes

International Nuclear Information System (INIS)

Soto Espinoza, S.L.; Arbeitman, C.R.; Clochard, M.C.; Grasselli, M.

2014-01-01

The application of swift-heavy ion bombardment to polymers is a well-established technique to manufacture micro- and nanopores onto polymeric films to obtain porous membranes. A few years ago, it was realized that, during ion bombardment, the high energy deposition along the ion path through the polymer reached cylindrical damage regions corresponding to the core trace and the penumbra. After the etching procedure, there are still enough active sites left in the penumbra that can be used to initiate a polymerization process selectively inside the membrane pores. In this study, we report the grafting polymerization of glycidyl methacrylate onto etched PET foils to obtain functionalized nanochannels. Grafted polymers were labeled with a fluorescent tag and analyzed by different fluorescence techniques such as direct fluorescence, fluorescence microscopy and confocal microscopy. These techniques allowed identifying and quantifying the grafted regions on the polymeric foils. - Highlights: • Irradiated PET foils with swift-heavy ions were etched and grafted in a step-by-step process. • Grafting polymerization was performed on the remaining active sites after etching. • Track-etched PET membranes were fluorescently labeled by chemical functionalization. • Functionalized track-etched PET membranes were analyzed by fluorescence and confocal microscopy

Modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium

Energy Technology Data Exchange (ETDEWEB)

Patakham, Ussadawut [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand); Kajornchaiyakul, Julathep [National Metal and Material Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@kmutt.ac.th [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

2013-10-25

Highlights: •Morphologies and growth of Sc and Sr-modified eutectic silicon resemble those of dendrites. •Crystal orientation of eutectic aluminum depends on growth characteristics of eutectic silicon. •We report strong evidence of the occurrence of an impurity-induced twinning mechanism. -- Abstract: The modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium was studied. The crystallographic orientation relationships between primary dendrites and the eutectic phase of unmodified and modified Al–6Si–0.3 Mg alloys were determined using electron backscatter diffraction (EBSD). The orientation of aluminum modified with scandium in the eutectic phase was different from that of the neighboring primary dendrites. This result implies that eutectic aluminum grows epitaxially from the surrounding primary aluminum dendrites in the unmodified alloy and that eutectic aluminum grows competitively from the surrounding primary aluminum dendrites in the modified alloy. The pole figure maps of eutectic Si in the [1 0 0], [1 1 0] and [1 1 1] axes of the unmodified and Sc-modified alloys were different, suggesting that the eutectic Al and Si crystals in modified alloy growth are more isotropic and cover a larger set of directions. The lattice fringes of Si of the alloys with and without Sc modification were different in the TEM results. The lattice fringes of Si in modified alloy were found to be multiple twins. However, this was not observed in the unmodified alloy. The growth characteristic of eutectic Si crystal in modified alloy suggests the occurrence of multiple twinning reactions and the formation of a high density of twins. This modification mechanism by Sc is explained by the results of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis, which provide strong evidence of the occurrence of the impurity-induced twinning (IIT) mechanism.

Bovine serum albumin adsorption on passivated porous silicon layers

Science.gov (United States)

Lockwood, David; Boukherroub, Rabah

2005-03-01

Hydrogen-terminated porous silicon (pSi) films were fabricated through electrochemical anodization of crystalline Si in HF-based solutions. The pSi-H surface was chemically functionalized by thermal reaction with undecylenic acid to produce an organic monolayer covalently attached to the silicon surface through Si-C bonds and bearing an acid terminal group. Bovine serum albumin (BSA) was then adsorbed onto the modified surface. SEM showed that the porous films were damaged and partially lifted off the Si substrate after a prolonged BSA adsorption. Ellipsometry revealed that the BSA had penetrated ˜ 1.3 micrometers into the porous structure. The film damage results from BSA anchoring itself tightly through strong electrostatic interactions to the acid-covered Si sidewalls. A change in surface tension during BSA film formation then causes the pSi layer to buckle and lift-off the underlying Si substrate. FTIR results from the modified pSi surfaces showed the presence of strong characteristic Amide I, II and III vibrational bands after BSA adsorption.

Hall measurements and grain-size effects in polycrystalline silicon

International Nuclear Information System (INIS)

Ghosh, A.K.; Rose, A.; Maruska, H.P.; Eustace, D.J.; Feng, T.

1980-01-01

The effects of grain size on Hall measurements in polycrystalline silicon are analyzed and interpreted, with some modifications, using the model proposed by Bube. This modified model predicts that the measured effective Hall voltage is composed of components originating from the bulk and space-charge regions. For materials with large grain sizes, the carrier concentration is independent of the intergrain boundary barrier, whereas the mobility is dependent on it. However, for small grains, both the carrier density and mobility depend on the barrier. These predictions are consistent with experimental results of mm-size Wacker and μm-size neutron-transmutation-doped polycrystalline silicon

Photoluminescence and electrical properties of silicon oxide and silicon nitride superlattices containing silicon nanocrystals

International Nuclear Information System (INIS)

Shuleiko, D V; Ilin, A S

2016-01-01

Photoluminescence and electrical properties of superlattices with thin (1 to 5 nm) alternating silicon-rich silicon oxide or silicon-rich silicon nitride, and silicon oxide or silicon nitride layers containing silicon nanocrystals prepared by plasma-enhanced chemical vapor deposition with subsequent annealing were investigated. The entirely silicon oxide based superlattices demonstrated photoluminescence peak shift due to quantum confinement effect. Electrical measurements showed the hysteresis effect in the vicinity of zero voltage due to structural features of the superlattices from SiOa 93 /Si 3 N 4 and SiN 0 . 8 /Si 3 N 4 layers. The entirely silicon nitride based samples demonstrated resistive switching effect, comprising an abrupt conductivity change at about 5 to 6 V with current-voltage characteristic hysteresis. The samples also demonstrated efficient photoluminescence with maximum at ∼1.4 eV, due to exiton recombination in silicon nanocrystals. (paper)

The Influence of Remelting on the Properties of AlSi6Cu4 Alloy Modified by Antimony

OpenAIRE

Medlen D.; Bolibruchova D.

2012-01-01

The paper deals with the problem of multiple remelting influence on AlSi6Cu4 alloy modified by antimony on chosen mechanical characteristics, microstructure and gas content. This foundry alloy is used mostly in automotive industry. Foundry Aluminum-Silicon alloys are also used in number of industrial weight sensitive applications because of their low weight and very good castability and good mechanical properties. Modifiers are usually added to molten aluminum-silicon alloys to refine the eut...

A new semicustom integrated bipolar amplifier for silicon strip detectors

International Nuclear Information System (INIS)

Zimmerman, T.

1989-01-01

The QPA02 is a four channel DC coupled two stage transimpedance amplifier designed at Fermilab on a semicustom linear array (Quickchip 2S) manufactured by Tektronix. The chip was developed as a silicon strip amplifier but may have other applications as well. Each channel consists of a preamplifier and a second stage amplifier/sharper with differential output which can directly drive a transmission line (90 to 140 ohms). External bypass capacitors are the only discrete components required. QPA02 has been tested and demonstrated to be an effective silicon strip amplifier. Other applications may exist which can use this amplifier or a modified version of this amplifier. For example, another design is now in progress for a wire chamber amplifier, QPA03, to be reported later. Only a relatively small effort was required to modify the design and layout for this application. 11 figs

Controlling the Nanoscale Patterning of AuNPs on Silicon Surfaces

Directory of Open Access Journals (Sweden)

Chris J. Allender

2013-03-01

Full Text Available This study evaluates the effectiveness of vapour-phase deposition for creating sub-monolayer coverage of aminopropyl triethoxysilane (APTES on silicon in order to exert control over subsequent gold nanoparticle deposition. Surface coverage was evaluated indirectly by observing the extent to which gold nanoparticles (AuNPs deposited onto the modified silicon surface. By varying the distance of the silicon wafer from the APTES source and concentration of APTES in the evaporating media, control over subsequent gold nanoparticle deposition was achievable to an extent. Fine control over AuNP deposition (AuNPs/μm2 however, was best achieved by adjusting the ionic concentration of the AuNP-depositing solution. Furthermore it was demonstrated that although APTES was fully removed from the silicon surface following four hours incubation in water, the gold nanoparticle-amino surface complex was stable under the same conditions. Atomic force microscopy (AFM and X-ray photoelectron spectroscopy (XPS were used to study these affects.

Optimization of chemical displacement deposition of copper on porous silicon.

Science.gov (United States)

Bandarenka, Hanna; Redko, Sergey; Nenzi, Paolo; Balucani, Marco; Bondarenko, Vitaly

2012-11-01

Copper (II) sulfate was used as a source of copper to achieve uniform distribution of Cu particles deposited on porous silicon. Layers of the porous silicon were formed by electrochemical anodization of Si wafers in a mixture of HF, C3H7OH and deionized water. The well-known chemical displacement technique was modified to grow the copper particles of specific sizes. SEM and XRD analysis revealed that the outer surface of the porous silicon was covered with copper particles of the crystal orientation inherited from the planes of porous silicon skeleton. The copper crystals were found to have the cubic face centering elementary cell. In addition, the traces of Cu2O cubic primitive crystalline phases were identified. The dimensions of Cu particles were determined by the Feret's analysis of the SEM images. The sizes of the particles varied widely from a few to hundreds of nanometers. A phenomenological model of copper deposition was proposed.

Lighting emitting microstructures in porous silicon

International Nuclear Information System (INIS)

Squire, E.

1999-01-01

Experimental and theoretical techniques are used to examine microstructuring effects on the optical properties of single layer, multilayer, single and multiple microcavity structures fabricated from porous silicon. Two important issues regarding the effects of the periodic structuring of this material are discussed. Firstly, the precise role played by this microstructuring, given that the luminescence is distributed throughout the entire structure and the low porosity layers are highly absorbing at short wavelengths. The second issue examined concerns the observed effects on the optical spectra of the samples owing to the emission bandwidth of the material being greater than the optical stopband of the structure. Measurements of the reflectivity and photoluminescence spectra of different porous silicon microstructures are presented and discussed. The results are modelled using a transfer matrix technique. The matrix method has been modified to calculate the optical spectra of porous silicon specifically by accounting for the effects of dispersion, absorption and emission within the material. Layer thickness and porosity gradients have also been included in the model. The dielectric function of the two component layers (i.e. silicon and air) is calculated using the Looyenga formula. This approach can be adapted to suit other porous semiconductors if required. Examination of the experimental results have shown that the emitted light is strongly controlled by the optical modes of the structures. Furthermore, the data display an interplay of a wide variety of effects dependent upon the structural composition. Comparisons made between the experimental and calculated reflectivity and photoluminescence spectra of many different porous silicon microstructures show very good agreement. (author)

Effect of aromatic SAMs molecules on graphene/silicon schottky diode performance

OpenAIRE

Yağmurcukardeş, Nesli; Aydın, Hasan; Can, Mustafa; Yanılmaz, Alper; Mermer, Ömer; Okur, Salih; Selamet, Yusuf

2016-01-01

Au/n-Si/Graphene/Au Schottky diodes were fabricated by transferring atmospheric pressure chemical vapor deposited (APCVD) graphene on silicon substrates. Graphene/n-Si interface properties were improved by using 5-[(3-methylphenyl)(phenyl) amino]isophthalic acid (MePIFA) and 5-(diphenyl)amino]isophthalic acid (DPIFA) aromatic self-assembled monolayer (SAM) molecules. The surface morphologies of modified and non-modified films were investigated by atomic force microscopy and scanning electron ...

Nano-hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

Energy Technology Data Exchange (ETDEWEB)

Sanchez, Alejandra [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Gonzalez, Jerson [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Garcia-Pineres, Alfonso [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica, 2060 (Costa Rica); Montero, Mavis L. [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Centro de Ciencia e Ingenieria en Materiales (CICIMA), Universidad de Costa Rica, 2060 (Costa Rica)

2011-06-15

The properties of porous silicon make it an interesting material for biological applications. However, porous silicon is not an appropriate surface for cell growth. Surface modification is an alternative that could afford a bioactive material. In this work, we report a method to yield materials by modification of the porous silicon surface with hydroxyapatite of nanometric dimensions, produced using an electrochemical process and coated on macroporous silicon substrates by cathodic bias. The chemical nature of the calcium phosphate deposited on the substrates after the experimental process and the amount of cell growth on these surfaces were characterized. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Development of advanced methods for continuous Czochralski growth. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

Science.gov (United States)

Wolfson, R. G.; Sibley, C. B.

1978-01-01

The three components required to modify the furnace for batch and continuous recharging with granular silicon were designed. The feasibility of extended growth cycles up to 40 hours long was demonstrated by a recharge simulation experiment; a 6 inch diameter crystal was pulled from a 20 kg charge, remelted, and pulled again for a total of four growth cycles, 59-1/8 inch of body length, and approximately 65 kg of calculated mass.

Electrochemical characteristics of porous TiO2 encapsulated silicon anode

International Nuclear Information System (INIS)

Jeon, Bup Ju; Lee, Joong Kee

2011-01-01

Graphical abstract: Cycling performances of the TiO 2 coated silicon anode at different catalyst pH values. Display Omitted Highlights: → TiO 2 coated silicon was used as the anode material for lithium batteries. → TiO 2 layer acted as a buffer layer for reducing the volume expansion. → Pore size distribution of TiO 2 coated silicon influenced discharge capacity. → Higher capacity retention was exhibited at pH 10.7. - Abstract: TiO 2 coated silicon, which was prepared by the modified sol-gel method, was employed as the anode material for lithium secondary batteries and the relationship between the diffusivity and electrochemical characteristics was investigated. The results showed that the physical properties of the samples, such as their diffusivity and pore size distribution, enhanced the cycling efficiency of the TiO 2 coated silicon, probably due to the reduction of the side reactions, which may be closely related to the pore size distribution of the TiO 2 coating layer. The pore size of the coating layer plays an important role in retarding the lithium ion diffusion. In the experimental range studied herein, higher capacity retention was exhibited for the TiO 2 coated silicon prepared at pH 10.7.

Superhydrophobic SERS substrates based on silicon hierarchical nanostructures

Science.gov (United States)

Chen, Xuexian; Wen, Jinxiu; Zhou, Jianhua; Zheng, Zebo; An, Di; Wang, Hao; Xie, Weiguang; Zhan, Runze; Xu, Ningsheng; Chen, Jun; She, Juncong; Chen, Huanjun; Deng, Shaozhi

2018-02-01

Silicon nanostructures have been cultivated as promising surface enhanced Raman scattering (SERS) substrates in terms of their low-loss optical resonance modes, facile functionalization, and compatibility with today’s state-of-the-art CMOS techniques. However, unlike their plasmonic counterparts, the electromagnetic field enhancements induced by silicon nanostructures are relatively small, which restrict their SERS sensing limit to around 10-7 M. To tackle this problem, we propose here a strategy for improving the SERS performance of silicon nanostructures by constructing silicon hierarchical nanostructures with a superhydrophobic surface. The hierarchical nanostructures are binary structures consisted of silicon nanowires (NWs) grown on micropyramids (MPs). After being modified with perfluorooctyltriethoxysilane (PFOT), the nanostructure surface shows a stable superhydrophobicity with a high contact angle of ˜160°. The substrate can allow for concentrating diluted analyte solutions into a specific area during the evaporation of the liquid droplet, whereby the analytes are aggregated into a small volume and can be easily detected by the silicon nanostructure SERS substrate. The analyte molecules (methylene blue: MB) enriched from an aqueous solution lower than 10-8 M can be readily detected. Such a detection limit is ˜100-fold lower than the conventional SERS substrates made of silicon nanostructures. Additionally, the detection limit can be further improved by functionalizing gold nanoparticles onto silicon hierarchical nanostructures, whereby the superhydrophobic characteristics and plasmonic field enhancements can be combined synergistically to give a detection limit down to ˜10-11 M. A gold nanoparticle-functionalized superhydrophobic substrate was employed to detect the spiked melamine in liquid milk. The results showed that the detection limit can be as low as 10-5 M, highlighting the potential of the proposed superhydrophobic SERS substrate in

Key Processes of Silicon-On-Glass MEMS Fabrication Technology for Gyroscope Application.

Science.gov (United States)

Ma, Zhibo; Wang, Yinan; Shen, Qiang; Zhang, Han; Guo, Xuetao

2018-04-17

MEMS fabrication that is based on the silicon-on-glass (SOG) process requires many steps, including patterning, anodic bonding, deep reactive ion etching (DRIE), and chemical mechanical polishing (CMP). The effects of the process parameters of CMP and DRIE are investigated in this study. The process parameters of CMP, such as abrasive size, load pressure, and pH value of SF1 solution are examined to optimize the total thickness variation in the structure and the surface quality. The ratio of etching and passivation cycle time and the process pressure are also adjusted to achieve satisfactory performance during DRIE. The process is optimized to avoid neither the notching nor lag effects on the fabricated silicon structures. For demonstrating the capability of the modified CMP and DRIE processes, a z-axis micro gyroscope is fabricated that is based on the SOG process. Initial test results show that the average surface roughness of silicon is below 1.13 nm and the thickness of the silicon is measured to be 50 μm. All of the structures are well defined without the footing effect by the use of the modified DRIE process. The initial performance test results of the resonant frequency for the drive and sense modes are 4.048 and 4.076 kHz, respectively. The demands for this kind of SOG MEMS device can be fulfilled using the optimized process.

Stable electroluminescence from passivated nano-crystalline porous silicon using undecylenic acid

Energy Technology Data Exchange (ETDEWEB)

Gelloz, B.; Sano, H.; Koshida, N. [Dept. Elec. and Elec. Eng., Tokyo Univ. of A and T, Koganei, Tokyo 184-8588 (Japan); Boukherroub, R. [Laboratoire de Physique de la Matiere Condensee, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau (France); Wayner, D.D.M.; Lockwood, D.J. [National Research Council, Ottawa (Canada)

2005-06-01

Stabilization of electroluminescence from nanocrystalline porous silicon diodes has been achieved by replacing silicon-hydrogen bonds terminating the surface of nanocrystalline silicon with more stable silicon-carbon (Si-C) bonds. Hydrosilylation of the surface of partially and anodically oxidized porous silicon samples was thermally induced at about 90 C using various different organic molecules. Devices whose surface have been modified with stable covalent bonds shows no degradation in the EL efficiency and EL output intensity under DC operation for several hours. The enhanced stability can be attributed to the high chemical resistance of Si-C bonds against current-induced surface oxidation associated with the generation of nonradiative defects. Although devices treated with 1-decene exhibit reduced EL efficiency and brightness compared to untreated devices, other molecules, such as ethyl-undecylenate and particularly undecylenic acid provide stable and more efficient visible electroluminescence at room temperature. Undecylenic acid provides EL brightness as high as that of an untreated device. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bactericidal effects of plasma-modified surface chemistry of silicon nanograss

International Nuclear Information System (INIS)

Ostrikov, Kola; Macgregor-Ramiasa, Melanie; Cavallaro, Alex; Ostrikov, Kostya; Vasilev, Krasimir

2016-01-01

The surface chemistry and topography of biomaterials regulate the adhesion and growth of microorganisms in ways that are still poorly understood. Silicon nanograss structures prepared via inductively coupled plasma etching were coated with plasma deposited nanometer-thin polymeric films to produce substrates with controlled topography and defined surface chemistry. The influence of surface properties on Staphylococcus aureus proliferation is demonstrated and explained in terms of nanograss substrate wetting behaviour. With the combination of the nanograss topography; hydrophilic plasma polymer coatings enhanced antimicrobial activity while hydrophobic coatings reduced it. This study advances the understanding of the effects of surface wettability on the bactericidal properties of reactive nano-engineered surfaces. (paper)

Radiation cured silicone rubber articles

International Nuclear Information System (INIS)

DuPont, J.G.; Goodwin, P.A.

1984-01-01

A process for making radiation cured silicone rubber articles is disclosed wherein a hydroxyl-terminated polysilaxane having a molecular weight from about 50,000 to about 2,000,000, optionally modified by mixing with up to 85% of an end-stopped silicone rubber, is mixed with from about 10 to about 70 parts per hundred of rubber of a finely divided silica filler with a particle size in the reinforcing range and other inert fillers as determined by desired final properties; the composition so prepared is formed into the desired shape at room temperature; the article so formed is precured to improve the mechanical properties of the material with which it is made by exposure to ammonia gas, ammonium hydroxide, or to the vapors or solutions of a volatile amine at room temperature; and the precured article is irradiated with high energy electrons or gamma radiation to effect a permanent cure of the material from which the article is formed

A theoretical approach to photosynthetically active radiation silicon sensor

International Nuclear Information System (INIS)

Tamasi, M.J.L.; Martínez Bogado, M.G.

2013-01-01

This paper presents a theoretical approach for the development of low cost radiometers to measure photosynthetically active radiation (PAR). Two alternatives are considered: a) glass optical filters attached to a silicon sensor, and b) dielectric coating on a silicon sensor. The devices proposed are based on radiometers previously developed by the Argentine National Atomic Energy Commission. The objective of this work is to adapt these low cost radiometers to construct reliable instruments for measuring PAR. The transmittance of optical filters and sensor response have been analyzed for different dielectric materials, number of layers deposited, and incidence angles. Uncertainties in thickness of layer deposition were evaluated. - Highlights: • Design of radiometers to measure photosynthetically active radiation • The study has used a filter and a Si sensor to modify spectral response. • Dielectric multilayers on glass and silicon sensor • Spectral response related to different incidence angles, materials and spectra

Report on achievements in fiscal 1999. Development of energy usage rationalizing silicon manufacturing process (Development of manufacturing technology for mass production of silicon for solar cells); 1999 nendo energy shiyo gorika silicon seizo process kaihatsu seika hokokusho. Taiyo denchiyo silicon ryosanka seizo gijutsu no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Discussions were given on manufacture of raw material silicon for solar cells with regard to boron removal, solidification, finishing and refining of metallic impurities, refining of unutilized silicon scraps, and making them into wafers and solar cells after refining. This paper summarizes the achievements in fiscal 1999. With regard to purity deterioration due to contamination by boron containing silica powder generated during the boron removal in the manufacturing process, the facilities were modified resulting in the reduction thereof to 0.04 ppmw or less. Regarding the repetitive use of boron removing crucibles, the experiment identified the possibility of using them for more than three times. In trial fabrication of samples by using the solidification refining and cast integrated process, ingots of 550 mm square and about 300 mm high were obtained, which were sliced into 10-cm square materials for use as wafers. Measurement of the conversion efficiency has resulted in 13% or more which is almost equivalent in the center and edges of the ingot. It was revealed that solar cell wafers may be fabricated by using this process, which can use either the p-type low-resistance silicon scraps or the metallic silicon as the starting material. (NEDO)

Trends in heteroepitaxy of III-Vs on silicon for photonic and photovoltaic applications

Science.gov (United States)

Lourdudoss, Sebastian; Junesand, Carl; Kataria, Himanshu; Metaferia, Wondwosen; Omanakuttan, Giriprasanth; Sun, Yan-Ting; Wang, Zhechao; Olsson, Fredrik

2017-02-01

We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.

Detection of Human Ig G Using Photoluminescent Porous Silicon Interferometer.

Science.gov (United States)

Cho, Bomin; Kim, Seongwoong; Woo, Hee-Gweon; Kim, Sungsoo; Sohn, Honglae

2015-02-01

Photoluminescent porous silicon (PSi) interferometers having dual optical properties, both Fabry-Pérot fringe and photolumincence (PL), have been developed and used as biosensors for detection of Human Immunoglobin G (Ig G). PSi samples were prepared by electrochemical etching of p-type silicon under white light exposure. The surface of PSi was characterized using a cold field emission scanning electron microscope. The sensor system studied consisted of a single layer of porous silicon modified with Protein A. The system was probed with various fragments of aqueous human immunoglobin G (Ig G) analyte. Both reflectivity and PL were simultaneously measured under the exposure of human Ig G. An increase of optical thickness and decrease of PL were obtained under the exposure of human Ig G. Detection limit of 500 fM was observed for the human Ig G.

Silicone metalization

Energy Technology Data Exchange (ETDEWEB)

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2008-12-09

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

Science.gov (United States)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Effects of the Formulations of Silicon-Based Composite Anodes on their Mechanical, Storage, and Electrochemical Properties.

Science.gov (United States)

Assresahegn, Birhanu Desalegn; Bélanger, Daniel

2017-10-23

In this work, the effects of the formulation of silicon-based composite anodes on their mechanical, storage, and electrochemical properties were investigated. The electrode formulation was changed through the use of hydrogenated or modified (through the covalent attachment of a binding additive such as polyacrylic acid) silicon and acetylene black or graphene sheets as conducting additives. A composite anode with a covalently grafted binder had the highest elongation without breakages and strong adhesion to the current collector. These mechanical properties depend significantly on the conductive carbon additive used and the use of graphene sheets instead of acetylene black can improve elongation and adhesion significantly. After 180 days of storage under ambient conditions, the electronic conductivity and discharge capacity of the modified silicon electrode showed much smaller decreases in these properties than those of the hydrogenated silicon composite electrode, indicating that the modification can result in passivation and a constant composition of the active material. Moreover, the composite Si anode has a high packing density. Consequently, thin-film electrodes with very high material loadings can be prepared without decreased electrochemical performance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Human aortic endothelial cell morphology influenced by topography of porous silicon substrates.

Science.gov (United States)

Formentín, Pilar; Catalán, Úrsula; Fernández-Castillejo, Sara; Alba, Maria; Baranowska, Malgorzata; Solà, Rosa; Pallarès, Josep; Marsal, Lluís F

2015-10-01

Porous silicon has received much attention because of its optical properties and for its usefulness in cell-based biosensing, drug delivery, and tissue engineering applications. Surface properties of the biomaterial are associated with cell adhesion and with proliferation, migration, and differentiation. The present article analyzes the behavior of human aortic endothelial cells in macro- and nanoporous collagen-modified porous silicon samples. On both substrates, cells are well adhered and numerous. Confocal microscopy and scanning electron microscopy were employed to study the effects of porosity on the morphology of the cells. On macroporous silicon, filopodia is not observed but the cell spreads on the surface, increasing the lamellipodia surface which penetrates the macropore. On nanoporous silicon, multiple filopodia were found to branch out from the cell body. These results demonstrate that the pore size plays a key role in controlling the morphology and growth rate of human aortic endothelial cells, and that these forms of silicon can be used to control cell development in tissue engineering as well as in basic cell biology research. © The Author(s) 2015.

Oxygen defect processes in silicon and silicon germanium

KAUST Repository

Chroneos, A.

2015-06-18

Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

Oxygen defect processes in silicon and silicon germanium

KAUST Repository

Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlö gl, Udo

2015-01-01

Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

Soft photo structuring of porous silicon in water

Energy Technology Data Exchange (ETDEWEB)

Juan, M.; Bouillard, J.S.; Plain, J.; Bachelot, R.; Adam, P.M.; Lerondel, G.; Royer, P. [ICD - Laboratoire de Nanotechnologie et d' Instrumentation Optique, CNRS FRE 2848, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France)

2007-05-15

We report on local photo-induced patterning of porous silicon in water. Scanning probe microscopy images of the sample surface after illumination show that the emission properties as well as the topography are modified according to the interferometric illumination pattern. Local photo-oxidation is believed to be at the origin of these modifications. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Evaluation of Dimethylformamide (DMF) as an Organic Modifier in ...

African Journals Online (AJOL)

Purpose: Ideal behaviour of mixtures of organic modifier and water is reflected by a linear relationship between refractive index ... of acetone and water as mobile phase. Results: DMF/water mixture behaved ideally across the whole concentration range ... heavy oils, fats or silicone oil and mobile phases containing water.

Detonation Synthesis of Alpha-Variant Silicon Carbide

Science.gov (United States)

Langenderfer, Martin; Johnson, Catherine; Fahrenholtz, William; Mochalin, Vadym

2017-06-01

A recent research study has been undertaken to develop facilities for conducting detonation synthesis of nanomaterials. This process involves a familiar technique that has been utilized for the industrial synthesis of nanodiamonds. Developments through this study have allowed for experimentation with the concept of modifying explosive compositions to induce synthesis of new nanomaterials. Initial experimentation has been conducted with the end goal being synthesis of alpha variant silicon carbide (α-SiC) in the nano-scale. The α-SiC that can be produced through detonation synthesis methods is critical to the ceramics industry because of a number of unique properties of the material. Conventional synthesis of α-SiC results in formation of crystals greater than 100 nm in diameter, outside nano-scale. It has been theorized that the high temperature and pressure of an explosive detonation can be used for the formation of α-SiC in the sub 100 nm range. This paper will discuss in detail the process development for detonation nanomaterial synthesis facilities, optimization of explosive charge parameters to maximize nanomaterial yield, and introduction of silicon to the detonation reaction environment to achieve first synthesis of nano-sized alpha variant silicon carbide.

Silicon epitaxy on textured double layer porous silicon by LPCVD

International Nuclear Information System (INIS)

Cai Hong; Shen Honglie; Zhang Lei; Huang Haibin; Lu Linfeng; Tang Zhengxia; Shen Jiancang

2010-01-01

Epitaxial silicon thin film on textured double layer porous silicon (DLPS) was demonstrated. The textured DLPS was formed by electrochemical etching using two different current densities on the silicon wafer that are randomly textured with upright pyramids. Silicon thin films were then grown on the annealed DLPS, using low-pressure chemical vapor deposition (LPCVD). The reflectance of the DLPS and the grown silicon thin films were studied by a spectrophotometer. The crystallinity and topography of the grown silicon thin films were studied by Raman spectroscopy and SEM. The reflectance results show that the reflectance of the silicon wafer decreases from 24.7% to 11.7% after texturing, and after the deposition of silicon thin film the surface reflectance is about 13.8%. SEM images show that the epitaxial silicon film on textured DLPS exhibits random pyramids. The Raman spectrum peaks near 521 cm -1 have a width of 7.8 cm -1 , which reveals the high crystalline quality of the silicon epitaxy.

Production of electronic grade lunar silicon by disproportionation of silicon difluoride

Science.gov (United States)

Agosto, William N.

1993-01-01

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

The influence of remelting on the properties of AlSi6Cu4 alloy modified by antimony

Directory of Open Access Journals (Sweden)

D. Medlen

2012-01-01

Full Text Available The paper deals with the problem of multiple remelting influence on AlSi6Cu4 alloy modified by antimony on chosen mechanical characteristics, microstructure and gas content. This foundry alloy is used mostly in automotive industry. Foundry Aluminum-Silicon alloys are also used in number of industrial weight sensitive applications because of their low weight and very good castability and good mechanical properties. Modifiers are usually added to molten aluminum-silicon alloys to refine the eutectic phase particle shape and improve the mechanical properties of the final cast products and Al-Si alloys cast properties.

Nanoscale fabrication and characterization of chemically modified silicon surfaces using conductive atomic force microscopy in liquids

Science.gov (United States)

Kinser, Christopher Reagan

This dissertation examines the modification and characterization of hydrogen-terminated silicon surfaces in organic liquids. Conductive atomic force microscope (cAFM) lithography is used to fabricate structures with sub-100 nm line width on H:Si(111) in n-alkanes, 1-alkenes, and 1-alkanes. Nanopatterning is accomplished by applying a positive (n-alkanes and 1-alkenes) or a negative (1-alkanes) voltage pulse to the silicon substrate with the cAFM tip connected to ground. The chemical and kinetic behavior of the patterned features is characterized using AFM, lateral force microscopy, time-of-flight secondary ion mass spectroscopy (TOF SIMS), and chemical etching. Features patterned in hexadecane, 1-octadecene, and undecylenic acid methyl ester exhibited chemical and kinetic behavior consistent with AFM field induced oxidation. The oxide features are formed due to capillary condensation of a water meniscus at the AFM tip-sample junction. A space-charge limited growth model is proposed to explain the observed growth kinetics. Surface modifications produced in the presence of neat 1-dodecyne and 1-octadecyne exhibited a reduced lateral force compared to the background H:Si(111) substrate and were resistant to a hydrofluoric acid etch, characteristics which indicate that the patterned features are not due to field induced oxidation and which are consistent with the presence of the methyl-terminated 1-alkyne bound directly to the silicon surface through silicon-carbon bonds. In addition to the cAFM patterned surfaces, full monolayers of undecylenic acid methyl ester (SAM-1) and undec-10-enoic acid 2-bromoethyl ester (SAM-2) were grown on H:Si(111) substrates using ultraviolet light. The structure and chemistry of the monolayers were characterized using AFM, TOF SIMS, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), X-ray standing waves (XSW), and X-ray fluorescence (XRF). These combined analyses provide evidence that SAM-1 and SAM-2 form dense monolayers

Study on Production of Silicon Nanoparticles from Quartz Sand for Hybrid Solar Cell Applications

Science.gov (United States)

Arunmetha, S.; Vinoth, M.; Srither, S. R.; Karthik, A.; Sridharpanday, M.; Suriyaprabha, R.; Manivasakan, P.; Rajendran, V.

2018-01-01

Nano silicon (nano Si) particles were directly prepared from natural mineral quartz sand and thereafter used to fabricate the hybrid silicon solar cells. Here, in this preparation technique, two process stages were involved. In the first stage, the alkaline extraction and acid precipitation processes were applied on quartz sand to fetch silica nanoparticles. In the second stage, magnesiothermic and modified magnesiothermic reduction reactions were applied on nano silica particles to prepare nano Si particles. The effect of two distinct reduction methodologies on nano Si particle preparation was compared. The magnesiothermic and modified magnesiothermic reductions in the silica to silicon conversion process were studied with the help of x-ray diffraction (XRD) with intent to study the phase changes during the reduction reaction as well as its crystalline nature in the pure silicon phase. The particles consist of a combination of fine particles with spherical morphology. In addition to this, the optical study indicated an increase in visible light absorption and also increases the performance of the solar cell. The obtained nano Si particles were used as an active layer to fabricate the hybrid solar cells (HSCs). The obtained results confirmed that the power conversion efficiency (PCE) of the magnesiothermically modified nano Si cells (1.06%) is much higher as compared to the nano Si cells that underwent magnesiothermic reduction (1.02%). Thus, this confirms the increased PCE of the investigated nano Si solar cell up to 1.06%. It also revealed that nano Si behaved as an electron acceptor and transport material. The present study provided valuable insights and direction for the preparation of nano Si particles from quartz sand, including the influence of process methods. The prepared nano Si particles can be utilized for HSCs and an array of portable electronic devices.

Covalent Surface Modification of Silicon Oxides with Alcohols in Polar Aprotic Solvents.

Science.gov (United States)

Lee, Austin W H; Gates, Byron D

2017-09-05

Alcohol-based monolayers were successfully formed on the surfaces of silicon oxides through reactions performed in polar aprotic solvents. Monolayers prepared from alcohol-based reagents have been previously introduced as an alternative approach to covalently modify the surfaces of silicon oxides. These reagents are readily available, widely distributed, and are minimally susceptible to side reactions with ambient moisture. A limitation of using alcohol-based compounds is that previous reactions required relatively high temperatures in neat solutions, which can degrade some alcohol compounds or could lead to other unwanted side reactions during the formation of the monolayers. To overcome these challenges, we investigate the condensation reaction of alcohols on silicon oxides carried out in polar aprotic solvents. In particular, propylene carbonate has been identified as a polar aprotic solvent that is relatively nontoxic, readily accessible, and can facilitate the formation of alcohol-based monolayers. We have successfully demonstrated this approach for tuning the surface chemistry of silicon oxide surfaces with a variety of alcohol containing compounds. The strategy introduced in this research can be utilized to create silicon oxide surfaces with hydrophobic, oleophobic, or charged functionalities.

DNA analysis by single molecule stretching in nanofluidic biochips

DEFF Research Database (Denmark)

Abad, E.; Juarros, A.; Retolaza, A.

2011-01-01

Imprint Lithography (NIL) technology combined with a conventional anodic bonding of the silicon base and Pyrex cover. Using this chip, we have performed single molecule imaging on a bench-top fluorescent microscope system. Lambda phage DNA was used as a model sample to characterize the chip. Single molecules of λ-DNA......Stretching single DNA molecules by confinement in nanofluidic channels has attracted a great interest during the last few years as a DNA analysis tool. We have designed and fabricated a sealed micro/nanofluidic device for DNA stretching applications, based on the use of the high throughput Nano...... stained with the fluorescent dye YOYO-1 were stretched in the nanochannel array and the experimental results were analysed to determine the extension factor of the DNA in the chip and the geometrical average of the nanochannel inner diameter. The determination of the extension ratio of the chip provides...

Superhydrophobic nanofluidic channels for enhanced electrokinetic conversion

Science.gov (United States)

Checco, Antonio; Al Hossain, Aktaruzzaman; Rahmani, Amir; Black, Charles; Doerk, Gregory; Colosqui, Carlos

2017-11-01

We present current efforts in the development of novel slit nanofluidic channels with superhydrophobic nanostructured surfaces designed to enhance hydrodynamic conductivity and improve selective transport and electrokinetic energy conversion efficiencies (mechanical-electrical energy conversion). The nanochannels are fabricated on silicon wafers using UV lithography, and their internal surface is patterned with conical nanostructures (feature size and spacing 30 nm) defined by block copolymer self-assembly and plasma etching. These nanostructures are rendered superhydrophobic by passivation with a hydrophobic silane monolayer. We experimentally characterize hydrodynamic conductivity, effective zeta potentials, and eletrokinetic flows for the patterned nanochannels, comparing against control channels with bare surfaces. Experimental observations are rationalized using both continuum-based modeling and molecular dynamics simulations. Scientific and technical knowledge produced by this work is particularly relevant for sustainable energy conversion and storage, separation processes and water treatment using nanoporous materials. The ONR Contract # N000141613178 and NSF-CBET award# 1605809.

Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

Science.gov (United States)

Whitman, Pamela K.; Feke, Donald L.

1986-01-01

The effects of various powder treatment strategies on the colloid chemistry of aqueous dispersions of silicon carbide and silicon nitride are examined using a surface titration methodology. Pretreatments are used to differentiate between the true surface chemistry of the powders and artifacts resulting from exposure history. Silicon nitride powders require more extensive pretreatment to reveal consistent surface chemistry than do silicon carbide powders. As measured by titration, the degree of proton adsorption from the suspending fluid by pretreated silicon nitride and silicon carbide powders can both be made similar to that of silica.

Poly(dimethylsiloxane) / tetraethyl orthosilicate modified hydroxyapatite composites: mechanical properties and biocompatibility evaluation

International Nuclear Information System (INIS)

Bareiro, O.; Santos, L. A.

2012-01-01

A composite of poly(dimethylsiloxane)/hydroxyapatite (PDMS/HAp) has been developed and its mechanical properties and biocompatibility were assessed. The processing of the composite involved the surface modification of HAp with 5 or 10 %(wt/wt) tetraethyl orthosilicate (TEOS) solutions, followed by mixing in a two roll open mixer with the silicone. The energy dispersive spectroscopy (EDS) spectra indicated evidence of a silane layer in the HAp modified surface. In tensile property measurement, the PDMS/modified-HAp composite showed higher values of tensile strength (2.41 MPa) and lower elongation at break (73.44 %) than the PDMS/unmodified HAp composite, 2.26 MPa and 365.58 % respectively. In both cases, the composites showed higher values of tensile strength than the original silicone (1.97 MPa). Scanning electron microscopy (SEM) micrographs of the PDMS/unmodified-HAp composite exhibited debonding of the HAp particles from the elastomeric matrix at the fracture surface. On the other hand, HAp particles remained well attached to the matrix in the PDMS/modified-HAp composite. The presence of HAp improved the biocompatibility of the silicone. The soaking of the composites for 7 days in a simulated body fluid (SBF) formed a dense and homogeneous layer of HAp like crystals in the surface of the composites. The surface modification of HAp powders with TEOS solutions formed a strong interface PDMS/HAp, this enhanced the tensile strength of the composite. (author)

Synthesis and characterization of UV-absorbing fluorine-silicone acrylic resin polymer

Science.gov (United States)

Lei, Huibin; He, Deliang; Guo, Yanni; Tang, Yining; Huang, Houqiang

2018-06-01

A series of UV-absorbing fluorine-silicone acrylic resin polymers containing different amount of UV-absorbent were successfully prepared by solution polymerization, with 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate (BHEM), vinyltrimethoxysilane (VTMS) and hexafluorobutyl methacrylate (HFMA) as modifying monomers. The acrylic polymers and the coatings thereof were characterized by Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) absorption spectrum, thermogravimetric analysis (TGA), water contact angle (CA) and Xenon lamp artificial accelerated aging tests. Results indicated that the resin exhibited high UV absorption performance as well as good thermal stability. The hydrophobicity of the coatings was of great improvement because of the bonded fluorine and silicone. Meanwhile, the weather-resistance was promoted through preferably colligating the protective effects of BHEM, organic fluorine and silicone. Also, a fitting formula about the weatherability with the BMHE content was tentatively proposed.

Effect of UV irradiations on the structural and optical features of porous silicon: application in silicon solar cells

International Nuclear Information System (INIS)

Aouida, S.; Saadoun, M.; Boujmil, M.F.; Ben Rabha, M.; Bessaies, B.

2004-01-01

The aim of this paper is to investigate the structural and optical stability of porous silicon layers (PSLs) planned to be used in silicon solar cells technology. The PSLs were prepared by a HNO 3 /HF vapor etching (VE) based method. Fourier transform infrared (FT-IR) spectroscopy shows that fresh VE-based PSLs contain N-H and Si-F bonds related to a ammonium hexafluorosilicate (NH 4 ) 2 SiF 6 minor phase, and conventional Si-H x and Si-O x bonds. Free air exposures of PSLs without and with UV irradiation lead to oxidation or photo-oxidation of the porous layer, respectively. FT-IR characterisation of the PSLs shows that UV irradiations modify the transformation kinetics replacing instable Si-H x by Si-O x or Si-O-H bonds. When fresh PSLs undergo free air oxidation within 7 days, the surface reflectivity decreases from 10 to about 8%, while it drops to about 4% when a 10 min free air UV irradiation is applied. Long periods of free air oxidation do not ensure the reflectivity to be stable, whereas it becomes stable after only 10 min of UV irradiation. This behaviour was explained taking into account the kinetic differences between oxidation with and without UV irradiation. Fresh VE-based PSLs were found to improve efficiently the photovoltaic (PV) characteristics of crystalline silicon solar cells. The passivating action of VE-based PSLs was discussed. An improvement of the PV performances was observed solely for stable oxidized porous silicon (PS) structures obtained from UV irradiations

Specific and selective target detection of supra-genome 21 Mers Salmonella via silicon nanowires biosensor

Science.gov (United States)

Mustafa, Mohammad Razif Bin; Dhahi, Th S.; Ehfaed, Nuri. A. K. H.; Adam, Tijjani; Hashim, U.; Azizah, N.; Mohammed, Mohammed; Noriman, N. Z.

2017-09-01

The nano structure based on silicon can be surface modified to be used as label-free biosensors that allow real-time measurements. The silicon nanowire surface was functionalized using 3-aminopropyltrimethoxysilane (APTES), which functions as a facilitator to immobilize biomolecules on the silicon nanowire surface. The process is simple, economical; this will pave the way for point-of-care applications. However, the surface modification and subsequent detection mechanism still not clear. Thus, study proposed step by step process of silicon nano surface modification and its possible in specific and selective target detection of Supra-genome 21 Mers Salmonella. The device captured the molecule with precisely; the approach took the advantages of strong binding chemistry created between APTES and biomolecule. The results indicated how modifications of the nanowires provide sensing capability with strong surface chemistries that can lead to specific and selective target detection.

Arsenic implantation into polycrystalline silicon and diffusion to silicon substrate

International Nuclear Information System (INIS)

Tsukamoto, K.; Akasaka, Y.; Horie, K.

1977-01-01

Arsenic implantation into polycrystalline silicon and drive-in diffusion to silicon substrate have been investigated by MeV He + backscattering analysis and also by electrical measurements. The range distributions of arsenic implanted into polycrystalline silicon are well fitted to Gaussian distributions over the energy range 60--350 keV. The measured values of R/sub P/ and ΔR/sub P/ are about 10 and 20% larger than the theoretical predictions, respectively. The effective diffusion coefficient of arsenic implanted into polycrystalline silicon is expressed as D=0.63 exp[(-3.22 eV/kT)] and is independent of the arsenic concentration. The drive-in diffusion of arsenic from the implanted polycrystalline silicon layer into the silicon substrate is significantly affected by the diffusion atmosphere. In the N 2 atmosphere, a considerable amount of arsenic atoms diffuses outward to the ambient. The outdiffusion can be suppressed by encapsulation with Si 3 N 4 . In the oxidizing atmosphere, arsenic atoms are driven inward by growing SiO 2 due to the segregation between SiO 2 and polycrystalline silicon, and consequently the drive-in diffusion of arsenic is enhanced. At the interface between the polycrystalline silicon layer and the silicon substrate, arsenic atoms are likely to segregate at the polycrystalline silicon side

Porous silicon: silicon quantum dots for photonic applications

International Nuclear Information System (INIS)

Pavesi, L.; Guardini, R.

1996-01-01

Porous silicon formation and structure characterization are briefly illustrated. Its luminescence properties rae presented and interpreted on the basis of exciton recombination in quantum dot structures: the trap-controlled hopping mechanism is used to describe the recombination dynamics. Porous silicon application to photonic devices is considered: porous silicon multilayer in general, and micro cavities in particular are described. The present situation in the realization of porous silicon LEDs is considered, and future developments in this field of research are suggested. (author). 30 refs., 30 figs., 13 tabs

Micro-architecture embedding ultra-thin interlayer to bond diamond and silicon via direct fusion

Science.gov (United States)

Kim, Jong Cheol; Kim, Jongsik; Xin, Yan; Lee, Jinhyung; Kim, Young-Gyun; Subhash, Ghatu; Singh, Rajiv K.; Arjunan, Arul C.; Lee, Haigun

2018-05-01

The continuous demand on miniaturized electronic circuits bearing high power density illuminates the need to modify the silicon-on-insulator-based chip architecture. This is because of the low thermal conductivity of the few hundred nanometer-thick insulator present between the silicon substrate and active layers. The thick insulator is notorious for releasing the heat generated from the active layers during the operation of devices, leading to degradation in their performance and thus reducing their lifetime. To avoid the heat accumulation, we propose a method to fabricate the silicon-on-diamond (SOD) microstructure featured by an exceptionally thin silicon oxycarbide interlayer (˜3 nm). While exploiting the diamond as an insulator, we employ spark plasma sintering to render the silicon directly fused to the diamond. Notably, this process can manufacture the SOD microarchitecture via a simple/rapid way and incorporates the ultra-thin interlayer for minute thermal resistance. The method invented herein expects to minimize the thermal interfacial resistance of the devices and is thus deemed as a breakthrough appealing to the current chip industry.

Study of modified two incisions silicone oil removal with a 23G transconjunctival sutureless vitrectomy system

Directory of Open Access Journals (Sweden)

Hai-Jun Yang

2015-01-01

Full Text Available AIM:To evaluate the efficacy and safety of silicone oil removal with a 23G transconjunctival sutureless vitrectomy system linked disposable transfusion tube and self-made suction tip. METHODS: The suction tip was made with a 23G infusion tube be cut from the end of the 5mm. It was used to connect the disposable transfusion tube and 23G puncture cannula. The disposable transfusion tube which was cut from the end of the MaiFei's pipe was connected with the effusion box of the vitreous cutter. Intraocular silicone oil was proactive suction and removed through two incisions on pars plana ciliaris with the vitreous cutter suction system. RESULTS: Only 13 cases(9.8%need suture puncture ports in 132 cases in the operation. Operation time was 7-28min. The average operation time was 15.1± 6.2min. In early postoperative, there were 107 cases(81.1%appeared lower intraocular pressure(CONCLUSION: The surgery that silicone oil is removed through two incisions with a 23G transconjunctival sutureless vitrectomy system linked disposable transfusion tube and self-made suction tip has the advantages of safe, effective, fast, economic, and it is worthy of popularization and application in clinical.

Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells.

Science.gov (United States)

Nogay, Gizem; Stuckelberger, Josua; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Niquille, Xavier; Debrot, Fabien; Despeisse, Matthieu; Haug, Franz-Josef; Löper, Philipp; Ballif, Christophe

2016-12-28

The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiC x (p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiC x (p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiC x (p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm -2 on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a V oc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p + /p-wafer full-side-passivated rear-side scheme shown here.

Anisotropic multi-spot DBR porous silicon chip for the detection of human immunoglobin G.

Science.gov (United States)

Cho, Bomin; Um, Sungyong; Sohn, Honglae

2014-07-01

Asymmetric porous silicon multilayer (APSM)-based optical biosensor was developed to specify human Immunoglobin G (Ig G). APSM chip was generated by an electrochemical etching of silicon wafer using an asymmetric electrode configuration in aqueous ethanolic HF solution and constituted with nine arrayed porous silicon multilayer. APSM prepared from anisotropic etching conditions displayed a sharp reflection resonance in the reflectivity spectrum. Each spot displayed single reflection resonance at different wavelengths as a function of the lateral distance from the Pt counter electrode. The sensor system was consisted of the 3 x 3 spot array of APSM modified with protein A. The system was probed with an aqueous human Ig G. Molecular binding and specificity was monitored as a shift in wavelength of reflection resonance.

Effect of organo-clay on the dielectric relaxation response of silicone rubber

International Nuclear Information System (INIS)

Gharavi, N; Razzaghi-Kashani, M; Golshan-Ebrahimi, N

2010-01-01

Dielectric elastomers are light weight, low-cost, highly deformable and fast response smart materials capable of converting electrical energy into mechanical work or vice versa. Silicone rubber is a well-known dielectric elastomer which is used as actuator, and in order to enhance the efficiency of this smart material, compounding of silicone rubber with various fillers can be carried out. The effect of organically modified montmorillonite (OMMT) nano-clay on improvement of dielectric properties, actuation stress and its relaxation response was considered in this study. OMMT was dispersed in room temperature vulcanized (RTV) silicone rubber, and a composite film was cast. Using an in-house actuation set-up, it was shown that the actuation stress for a given electric field intensity is higher for composites than that for pristine silicone rubber. Also, the time-dependent actuation response of the samples was evaluated, and it was shown that the characteristic relaxation time of the actuation stress for composites is less than for the pristine rubber as a result of OMMT addition

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

International Nuclear Information System (INIS)

Liu, Pingsheng; Chen, Qiang; Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong; Shen, Jian

2013-01-01

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

Energy Technology Data Exchange (ETDEWEB)

Liu, Pingsheng [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen, Qiang, E-mail: chem100@nju.edu.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); High Technology Research Institute of Nanjing University, Changzhou 213164 (China); Yuan, Bo; Chen, Mengzhou; Wu, Shishan; Lin, Sicong [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Shen, Jian, E-mail: shenj1957@yahoo.com.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

2013-10-15

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics. Highlights: • Facile surface modification of silicone rubber with functional brushes • Modified SR surfaces have improved resistance to nonspecific protein adsorption. • Modified SR surfaces have excellent resistance to platelet adhesion. • Zwitteironic surface significant improvement in blood compatibility • Could inspire many creative uses of SR based materials for biomedical.

Effect of post-deposition implantation and annealing on the properties of PECVD deposited silicon nitride films

International Nuclear Information System (INIS)

Shams, Q.A.

1988-01-01

Recently it has been shown that memory-quality silicon nitride can be deposited using plasma enhanced chemical vapor deposition (PECVD). Nitrogen implantation and post-deposition annealing resulted in improved memory properties of MNOS devices. The primary objective of the work described here is the continuation of the above work. Silicon nitride films were deposited using argon as the carrier gas and evaluated in terms of memory performance as the charge-trapping layer in the metal-nitride-oxide-silicon (MNOS) capacitor structure. The bonding structure of PECVD silicon nitride was modified by annealing in different ambients at temperatures higher than the deposition temperature. Post-deposition ion implantation was used to introduce argon into the films in an attempt to influence the transfer, trapping, and emission of charge during write/erase exercising of the MNOS devices. Results show that the memory performance of PECVD silicon nitride is sensitive to the deposition parameters and post-deposition processing

Directional Etching of Silicon by Silver Nanostructures

Science.gov (United States)

Sharma, Pradeep; Wang, Yuh-Lin

2011-02-01

We report directional etching of nanostructures (nanochannels and nanotrenches) into the Si(100) substrates in aqueous HF and H2O2 solution by lithographically defined Ag patterns (nanoparticles, nanorods, and nanorings). The Effect of Ag/Si interface oxide on the directional etching has been studied by etching Ag/SiOx/Si samples of known interface oxide thickness. Based on high resolution transmission electron microscopy (HRTEM) imaging and TEM-energy dispersive X-ray (EDX) spectra of the Ag/Si interfaces, we propose that maintenance of the sub-nanometer oxide at the Ag/Si interfaces and Ag-Si interaction are the key factors which regulate the directional etching of Si.

Topological and metric properties of linear and circular DNA chains in nano-slits and nano-channels

Science.gov (United States)

Orlandini, Enzo; Micheletti, Cristian

2014-03-01

Motivated by recent advancements in single DNA molecule experiments, based on nanofluidic devices, we investigate numerically the metric and topological properties of a modelof open and circular DNA chains confined inside nano-slits and nano-channles. The results reveal an interesting characterization of the metric crossover behaviour in terms of the abundance, type and length of occuring knots. In particular we find that the knotting probability is nonmonotonic for increasing confinement and can be largely enhanced or suppressed, compared to the bulk case, by simply varying the slit or channel trasversal dimension. The observed knot population consists of knots that are far simpler than for DNA chains in spherical (i.e. cavities or capsids) confinement. These results suggest that nanoslits and nanochannels can be properly designed to produce open DNA chains hosting simple knots or to sieve DNA rings according to their knotted state. Finally we discuss the implications that the presence of knots may have on the dynamical properties of confined DNA chains such as chain elongation, injection/ejection processes and entanglement relaxation. We acknowledge financial support from the Italian ministry of education, grant PRIN 2010HXAW77.

Electrohydrodynamics in nanochannels coated by mixed polymer brushes: effects of electric field strength and solvent quality

Science.gov (United States)

Cao, Qianqian; Tian, Xiu; You, Hao

2018-04-01

We examine the electrohydrodynamics in mixed polymer brush-coated nanochannels and the conformational dynamics of grafted polymers using molecular dynamics simulations. Charged (A) and neutral polymers (B) are alternately grafted on the channel surfaces. The effects of the electric field strength and solvent quality are addressed in detail. The dependence of electroosmotic flow characteristics and polymer conformational behavior on the solvent quality is influenced due to the change of the electric field strength. The enhanced electric field induces a collapse of the neutral polymer chains which adopt a highly extended conformation along the flow direction. However, the thickness of the charged polymer layer is affected weakly by the electric field, and even a slight swelling is identified for the A-B attraction case, implying the conformational coupling between two polymer species. Furthermore, the charged polymer chains incline entirely towards the electric field direction oppositely to the flow direction. More importantly, unlike the neutral polymer chains, the shape factor of the charged polymer chains, which is used to describe the overall shape of polymer chains, is reduced significantly with increasing the electric field strength, corresponding to a more coiled structure.

The effect of organo-clay on the dielectric properties of silicone rubber

International Nuclear Information System (INIS)

Razzaghi-Kashani, M; Gharavi, N; Javadi, S

2008-01-01

Dielectric elastomers are highly deformable and fast response smart materials capable of actuation under electric fields. Among commercially available dielectric elastomers, silicone rubber can be compounded with different fillers in order to modify its electrical and mechanical properties. To study the effect of organically modified montmorillonite (OMMT) on the dielectric properties of silicone rubber, OMMT was added to this rubber at two levels, 2% and 5%, using two methods, low-shear and high-shear mixing. Composites were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD patterns showed different crystallite structures for silicate platelets in the rubber matrix as a result of the two different mixing methods. In low-shear mixing, the ordered crystallite structure of the clay remains almost unchanged, whereas in high-shear mixing it loses its ordered structure, leading to the disappearance of the diffraction peaks. SEM and AFM micrographs depicted better dispersion and more uniform distribution of the organo-clay under high-shear mixing compared to those obtained by low-shear mixing. The tensile properties also confirmed the different degree of dispersion of the nano-clay resulting from the two different methods of mixing. The dielectric properties of the composites were measured under AC electric fields, and the results were compared with reference silicone rubbers with no OMMT. It was shown that the order of organo-clay layers in the less dispersed structure of the clay imparts an additional ionic polarization and higher dielectric permittivity compared to the case where the clay layers are more dispersed and lost their order. The storage and loss dielectric constants of base silicone rubber increase when it is compounded with OMMT

Modified MIS-structure based on nanoporous silicon with enhanced sensitivity to the hydrogen containing gases

Energy Technology Data Exchange (ETDEWEB)

Gorbanyuk, T.; Evtukh, A.; Litovchenko, V.; Solntsev, V. [Institute of Semiconductor Physics, Kiev (Ukraine)

2008-07-01

The gas sensitivity of metal-insulator-semiconductor (MIS)-structures based on nanoporous silicon with active electrodes from palladium/tungsten oxide composite has been studied. It was found that the using of palladium/tungsten oxide composite (instead of thin palladium film) leads to enhanced sensitivity of MIS structures to hydrogen sulphide in air. The mechanism of this phenomenon has been established. The enhanced H{sub 2}S sensitivity is explained in the following way. The microparticles of tungsten trioxide inside palladium matrix stimulate the dissociation of hydrogen sulphide molecules, and hydrogen atoms and/or protons flow down to palladium surface, are absorbed by palladium volume, diffuse to palladium/oxidized nanoporous silicon interface. Hydrogen atoms adsorbed at the interface are polarized and give rise to a dipole layer. As a result, the voltage shift of the capacity-voltage (C-V) curve proportional to the measured gas concentration is observed. The surface microstructure of Pd/WO{sub 3} composite was studied by AFM microscopy. The chemical content of the composite film has been investigated by SIMS. It was found that the composite film on nanoporous silicon surface poses the holes with the size about 0.05 {mu}m, the mean separation between tungsten oxide microparticles is 1-2 {mu}m. It also was found that the using of the additional double layer polymer film (polymer film (phthalocyanine zinc)/semicon-ductor film (cadmium sulphide)) on composite film surface leads to the additional enhancement of the gas sensitivity to hydrogen sulphide. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Cell cloning-on-the-spot by using an attachable silicone cylinder.

Science.gov (United States)

Park, Hong Bum; Son, Wonseok; Chae, Dong Han; Lee, Jisu; Kim, Il-Woung; Yang, Woomi; Sung, Jae Kyu; Lim, Kyu; Lee, Jun Hee; Kim, Kyung-Hee; Park, Jong-Il

2016-06-10

Cell cloning is a laboratory routine to isolate and keep particular properties of cultured cells. Transfected or other genetically modified cells can be selected by the traditional microbiological cloning. In addition, common laboratory cell lines are prone to genotypic drift during their continual culture, so that supplementary cloning steps are often required to maintain correct lineage phenotypes. Here, we designed a silicone-made attachable cloning cylinder, which facilitated an easy and bona fide cloning of interested cells. This silicone cylinder was easy to make, showed competent stickiness to laboratory plastics including culture dishes, and hence enabled secure isolation and culture for days of selected single cells, especially, on the spots of preceding cell-plating dishes under microscopic examination of visible cellular phenotypes. We tested the silicone cylinder in the monoclonal subcloning from a heterogeneous population of a breast cancer cell line, MDA-MB-231, and readily established independent MDA-MB-231 subclones showing different sublineage phenotypes. Copyright © 2016 Elsevier Inc. All rights reserved.

Deep level transient spectroscopic investigation of phosphorus-doped silicon by self-assembled molecular monolayers.

Science.gov (United States)

Gao, Xuejiao; Guan, Bin; Mesli, Abdelmadjid; Chen, Kaixiang; Dan, Yaping

2018-01-09

It is known that self-assembled molecular monolayer doping technique has the advantages of forming ultra-shallow junctions and introducing minimal defects in semiconductors. In this paper, we report however the formation of carbon-related defects in the molecular monolayer-doped silicon as detected by deep-level transient spectroscopy and low-temperature Hall measurements. The molecular monolayer doping process is performed by modifying silicon substrate with phosphorus-containing molecules and annealing at high temperature. The subsequent rapid thermal annealing drives phosphorus dopants along with carbon contaminants into the silicon substrate, resulting in a dramatic decrease of sheet resistance for the intrinsic silicon substrate. Low-temperature Hall measurements and secondary ion mass spectrometry indicate that phosphorus is the only electrically active dopant after the molecular monolayer doping. However, during this process, at least 20% of the phosphorus dopants are electrically deactivated. The deep-level transient spectroscopy shows that carbon-related defects are responsible for such deactivation.

Aminopropyl-modified magnesium-phyllosilicates: layered solids with tailored interlayer access and reactivity.

Science.gov (United States)

Ferreira, Ricardo B; da Silva, César R; Pastore, Heloise O

2008-12-16

Despite its wide application, the synthesis of aminopropyl-modified magnesium-phyllosilicates was known only in the case where every silicon atom bore an organic pending group. This paper shows the preparation of aminopropyl-modified talc where tailored amounts of silicon atoms are bound to an aminopropyl group. The decrease in the concentration of the organoamino group leaves a proportional concentration of interlayer SiOH groups that can be used to react with other silylation agents. The amino group reacts with CO2, forming a carbamate functionality; it seems that the presence of this group avoids delamination in water as performed for the parent compound. Bearing in mind that the aminopropyl group can be changed by other groups, the present synthesis strategy demonstrates ways to produce solids with controlled surface properties with interlayer amino and SiOH groups in variable concentrations, allowing formation of several other interlayer functionalities.

Matrix metalloproteinase sensing via porous silicon microcavity devices functionalized with human antibodies

Energy Technology Data Exchange (ETDEWEB)

Martin, Marta; Gergely, Csilla [GES-UMR 5650, CNRS, Universite Montpellier 2, Pl. Eugene Bataillon 34095, Montpellier Cedex 5 (France); Taleb Bendiab, Chakib; Massif, Laurent; Cuisinier, Frederic [EA4203, Faculte d' Odontologie, Universite Montpellier 1, Montpellier Cedex 5 (France); Palestino, Gabriela [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Salvador Nava 6, 78000 San Luis Potosi (Mexico); Agarwal, Vivechana [CIICAP, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col Chamilpa, Cuernavaca, Mor. (Mexico)

2011-06-15

Porous silicon microcavity (PSiMc) structures were used as support material for specific sensing of matrix metalloproteinases (MMPs). For lower concentrations of MMP-8, the structures were tested with two types of functionalization methods. Silanization of the oxidized porous silicon structures, followed by glutaraldehyde chemistry was found to give very inconsistent results. The use of biotinilated bovine serum albumin linked to the naked PSiMc was found to be an alternative method to attach the anti MMP-8 human antibody, previously modified with streptavidin, which was further used to sense MMP-8 (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Gold nanorods-silicone hybrid material films and their optical limiting property

Science.gov (United States)

Li, Chunfang; Qi, Yanhai; Hao, Xiongwen; Peng, Xue; Li, Dongxiang

2015-10-01

As a kind of new optical limiting materials, gold nanoparticles have optical limiting property owing to their optical nonlinearities induced by surface plasmon resonance (SPR). Gold nanorods (GNRs) possess transversal SPR absorption and tunable longitudinal SPR absorption in the visible and near-infrared region, so they can be used as potential optical limiting materials against tunable laser pulses. In this letter, GNRs were prepared using seed-mediated growth method and surface-modified by silica coating to obtain good dispersion in polydimethylsiloxane prepolymers. Then the silicone rubber films doped with GNRs were prepared after vulcanization, whose optical limiting property and optical nonlinearity were investigated. The silicone rubber samples doped with more GNRs were found to exhibit better optical limiting performance.

Geochemistry of silicon isotopes

Energy Technology Data Exchange (ETDEWEB)

Ding, Tiping; Li, Yanhe; Gao, Jianfei; Hu, Bin [Chinese Academy of Geological Science, Beijing (China). Inst. of Mineral Resources; Jiang, Shaoyong [China Univ. of Geosciences, Wuhan (China).

2018-04-01

Silicon is one of the most abundant elements in the Earth and silicon isotope geochemistry is important in identifying the silicon source for various geological bodies and in studying the behavior of silicon in different geological processes. This book starts with an introduction on the development of silicon isotope geochemistry. Various analytical methods are described and compared with each other in detail. The mechanisms of silicon isotope fractionation are discussed, and silicon isotope distributions in various extraterrestrial and terrestrial reservoirs are updated. Besides, the applications of silicon isotopes in several important fields are presented.

Fabrication of Nanostructures Using Self-Assembled Peptides as Templates

DEFF Research Database (Denmark)

Castillo, Jaime

2015-01-01

the advantages of diphenylalanine are explained step by step offering new alternatives to fabricate nanostructures in a simple and rapid way. The chapter is complemented with techniques to manipulate the self-assembled diphenylalanine nanostructures without changing its properties during the manipulation process.......This chapter evaluates the use of a short-aromatic dipeptide, diphenylalanine, as a template in the fabrication of new nanostructures (nanowires, coaxial nanocables, nanochannels) using materials such as silicon, conducting and non-conducting polymers. Diphenylalanine self...

Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

DEFF Research Database (Denmark)

Yu, Liyun; Skov, Anne Ladegaard

2016-01-01

One prominent method of modifying the properties of dielectric elastomers (DEs) is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting...... and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO2) particles were also studied. The best overall performing formulation had 35 wt.% TiO2 nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0...

Electrochemical characterization of carbon coated bundle-type silicon nanorod for anode material in lithium ion secondary batteries

International Nuclear Information System (INIS)

Halim, Martin; Kim, Jung Sub; Choi, Jeong-Gil; Lee, Joong Kee

2015-01-01

Highlights: • Bundle-type silicon nanorods (BSNR) were synthesized by metal assisted chemical etching. • Novel bundle-type nanorods electrode showed self-relaxant characteristics. • The self-relaxant property was enhanced by increasing the silver concentration. • PAA binder enhanced the self-relaxant property of the silicon material. • Carbon coated BSNR (BSNR@C) has evidently provided better cycle performance. - Abstract: Nanostructured silicon synthesis by surface modification of commercial micro-powder silicon was investigated in order to reduce the maximum volume change over cycle. The surface of micro-powder silicon was modified using an Ag metal-assisted chemical etching technique to produce nanostructured material in the form of bundle-type silicon nanorods. The volume change of the electrode using the nanostructured silicon during cycle was investigated using an in-situ dilatometer. Our result shows that nanostructured silicon synthesized using this method showed a self-relaxant characteristic as an anode material for lithium ion battery application. Moreover, binder selection plays a role in enhancing self-relaxant properties during delithiation via strong hydrogen interaction on the surface of the silicon material. The nanostructured silicon was then coated with carbon from propylene gas and showed higher capacity retention with the use of polyacrylic acid (PAA) binder. While the nano-size of the pore diameter control may significantly affect the capacity fading of nanostructured silicon, it can be mitigated via carbon coating, probably due to the prevention of Li ion penetration into 10 nano-meter sized pores

Electrochemical characterization of carbon coated bundle-type silicon nanorod for anode material in lithium ion secondary batteries

Energy Technology Data Exchange (ETDEWEB)

Halim, Martin [Center for Energy Convergence, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Energy and Environmental Engineering, Korea University of Science and Technology, Gwahangno, Yuseong-gu, Daejeon, 305-333 (Korea, Republic of); Kim, Jung Sub [Center for Energy Convergence, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Department of Material Science & Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Choi, Jeong-Gil [Department of Chemical Engineering, Hannam University, 461-1 Junmin-dong, Yusung-gu, Taejon 305-811 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Center for Energy Convergence, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Energy and Environmental Engineering, Korea University of Science and Technology, Gwahangno, Yuseong-gu, Daejeon, 305-333 (Korea, Republic of)

2015-04-15

Highlights: • Bundle-type silicon nanorods (BSNR) were synthesized by metal assisted chemical etching. • Novel bundle-type nanorods electrode showed self-relaxant characteristics. • The self-relaxant property was enhanced by increasing the silver concentration. • PAA binder enhanced the self-relaxant property of the silicon material. • Carbon coated BSNR (BSNR@C) has evidently provided better cycle performance. - Abstract: Nanostructured silicon synthesis by surface modification of commercial micro-powder silicon was investigated in order to reduce the maximum volume change over cycle. The surface of micro-powder silicon was modified using an Ag metal-assisted chemical etching technique to produce nanostructured material in the form of bundle-type silicon nanorods. The volume change of the electrode using the nanostructured silicon during cycle was investigated using an in-situ dilatometer. Our result shows that nanostructured silicon synthesized using this method showed a self-relaxant characteristic as an anode material for lithium ion battery application. Moreover, binder selection plays a role in enhancing self-relaxant properties during delithiation via strong hydrogen interaction on the surface of the silicon material. The nanostructured silicon was then coated with carbon from propylene gas and showed higher capacity retention with the use of polyacrylic acid (PAA) binder. While the nano-size of the pore diameter control may significantly affect the capacity fading of nanostructured silicon, it can be mitigated via carbon coating, probably due to the prevention of Li ion penetration into 10 nano-meter sized pores.

Silicon heterojunction transistor

International Nuclear Information System (INIS)

Matsushita, T.; Oh-uchi, N.; Hayashi, H.; Yamoto, H.

1979-01-01

SIPOS (Semi-insulating polycrystalline silicon) which is used as a surface passivation layer for highly reliable silicon devices constitutes a good heterojunction for silicon. P- or B-doped SIPOS has been used as the emitter material of a heterojunction transistor with the base and collector of silicon. An npn SIPOS-Si heterojunction transistor showing 50 times the current gain of an npn silicon homojunction transistor has been realized by high-temperature treatments in nitrogen and low-temperature annealing in hydrogen or forming gas

Enhanced performance of solar cells with optimized surface recombination and efficient photon capturing via anisotropic-etching of black silicon

International Nuclear Information System (INIS)

Chen, H. Y.; Peng, Y.; Hong, M.; Zhang, Y. B.; Cai, Bin; Zhu, Y. M.; Yuan, G. D.; Zhang, Y.; Liu, Z. Q.; Wang, J. X.; Li, J. M.

2014-01-01

We report an enhanced conversion efficiency of femtosecond-laser treated silicon solar cells by surface modification of anisotropic-etching. The etching improves minority carrier lifetime inside modified black silicon area substantially; moreover, after the etching, an inverted pyramids/upright pyramids mixed texture surface is obtained, which shows better photon capturing capability than that of conventional pyramid texture. Combing of these two merits, the reformed solar cells show higher conversion efficiency than that of conventional pyramid textured cells. This work presents a way for fabricating high performance silicon solar cells, which can be easily applied to mass-production

Selective Adsorption of Nano-bio materials and nanostructure fabrication on Molecular Resists Modified by proton beam irradiation

International Nuclear Information System (INIS)

Lee, H. W.; Kim, H. S.; Kim, S. M.

2008-04-01

The purpose of this research is the fabrication of nanostructures on silicon substrate using proton beam and selectively adsorption of bio-nano materials on the patterned substrate. Recently, the miniaturization of the integrated devices with fine functional structures was intensively investigated, based on combination of nanotechnology (NT), biotechnology (BT) and information technology (IT). Because of the inherent limitation in optical lithography, large variety of novel patterning technologies were evolved to construct nano-structures onto a substrate. Atomic force microscope-based nanolithography has readily formed sub-50 nm patterns by the local modification of a substrate using a probe with a curvature of 10 nm. The surface property was regarded as one of the most important factors for AFM-based nanolithography as well as for other novel nanolithographies. The molecular thin films such as a self-assembled monolayer or a polymer resist layer have been used as an alternative to modifying the surface property. Although proton or ion beam irradiation has been used as an efficient tool to modify the physical, chemical and electrical properties of a surface, the nano-patterning on the substrate or the molecular film modified with the beam irradiation has hardly been studied at both home and abroad. The selective adsorption of nano-bio materials such as carbon nanotubes and proteins on the patterns would contribute to developing the integrated devices. The polystyrene nanoparticles (400 nm) were arrayed on al silicon surface using nanosphere lithography and the various nanopatterns were fabricated by proton beam irradiation on the polystyrene nanoparticles arrayed silicon surface. We obtained the two different nanopatterns such as polymer nanoring patterns and silicon oxide patterns on the same silicon substrate. The polymer nanoring patterns formed by the crosslinkage of polystyrene when proton beam was irradiated at the triangular void spaces that are enclosed by

DNA immobilization on polymer-modified Si surface by controlling pH

International Nuclear Information System (INIS)

Demirel, Goekcen Birlik; Caykara, Tuncer

2009-01-01

A novel approach based on polymer-modified Si surface as DNA sensor platforms is presented. The polymer-modified Si surface was prepared by using 3-(methacryloxypropyl)trimethoxysilane [γ-MPS] and poly(acrylamide) [PAAm]. Firstly, a layer of γ-MPS was formed on the hydroxylated silicon surface as a monolayer and then modified with different molecular weight of PAAm to form polymer-modified surface. The polymer-modified Si surface was used for dsDNA immobilization. All steps about formation of layer structure were characterized by ellipsometry, atomic force microscopy (AFM), attenuated total reflectance Fourier transformed infrared (ATR-FTIR), and contact angle (CA) measurements. We found that in this case the amount of dsDNA immobilized onto the surface was dictated by the electrostatic interaction between the substrate surface and the DNA. Our results thus demonstrated that DNA molecules could be immobilized differently onto the polymer-modified support surface via electrostatic interactions.

Silicon surface biofunctionalization with dopaminergic tetrahydroisoquinoline derivatives

Energy Technology Data Exchange (ETDEWEB)

Lucena-Serrano, A.; Lucena-Serrano, C.; Contreras-Cáceres, R.; Díaz, A.; Valpuesta, M. [Dep. Química Orgánica, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga (Spain); Cai, C. [Dep. Chemistry, University of Houston, Houston, TX 77204-5003 (United States); López-Romero, J.M., E-mail: jmromero@uma.es [Dep. Química Orgánica, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga (Spain)

2016-01-01

Graphical abstract: - Highlights: • Two dopaminergic tetrahydroisoquinolines (THI) were synthesized. • Vinyl-terminated THI incorporated onto the H−Si(1 1 1) substrates via a hydrosilylation. • The highest yield in coverage was obtained in DMSO, at 4 h of irradiation and 0.1 mbar of vacuum. • Alkynyl-terminated Si surface was produced for incorporation of azide-THI by click reaction. • Best yields on grafted molecule were obtained by click reaction in absence of ascorbic acid. - Abstract: In this work we grafted vinyl- and azido-terminated tetrahydroisoquinolines (compounds 1 and 2, respectively) onto H−Si(1 1 1) silicon wafers obtaining highly stable modified surfaces. A double bond was incorporated into the tetrahydroisoquinoline structure of 1 to be immobilized by a light induced hydrosilylation reaction on hydrogen-terminated Si(1 1 1). The best results were obtained employing a polar solvent (DMSO), rather than a non-polar solvent (toluene). The azide derivative 2 was grafted onto alkenyl-terminated silicon substrates with copper-catalyzed azide-alkyne cycloaddition (CuAAC). Atomic force microscopy (AFM), contact angle goniometry (CA) and X-ray photoemission spectroscopy (XPS) were used to demonstrate the incorporation of 1 and 2 into the surfaces, study the morphology of the modified surfaces and to calculate the yield of grafting and surface coverage. CA measurements showed the increase in the surface hydrophobicity when 1 or 2 were incorporated into the surface. Moreover, compounds 1 and 2 were prepared starting from 1-(p-nitrophenyl)tetrahydroisoquinoline 3 under smooth conditions and in good yields. The structures of 1 and 2 were designed with a reduced A-ring, two substituents at positions C-6 and C-7, an N-methyl group and a phenyl moiety at C-1 in order to provide a high affinity against dopaminergic receptors. Moreover, O-demethylation of 1 was carried out once it was adsorbed onto the surface by treatment with BBr{sub 3}. The method

Vertical integration of high-Q silicon nitride microresonators into silicon-on-insulator platform.

Science.gov (United States)

Li, Qing; Eftekhar, Ali A; Sodagar, Majid; Xia, Zhixuan; Atabaki, Amir H; Adibi, Ali

2013-07-29

We demonstrate a vertical integration of high-Q silicon nitride microresonators into the silicon-on-insulator platform for applications at the telecommunication wavelengths. Low-loss silicon nitride films with a thickness of 400 nm are successfully grown, enabling compact silicon nitride microresonators with ultra-high intrinsic Qs (~ 6 × 10(6) for 60 μm radius and ~ 2 × 10(7) for 240 μm radius). The coupling between the silicon nitride microresonator and the underneath silicon waveguide is based on evanescent coupling with silicon dioxide as buffer. Selective coupling to a desired radial mode of the silicon nitride microresonator is also achievable using a pulley coupling scheme. In this work, a 60-μm-radius silicon nitride microresonator has been successfully integrated into the silicon-on-insulator platform, showing a single-mode operation with an intrinsic Q of 2 × 10(6).

Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

Science.gov (United States)

Pradeepkumar, Aiswarya; Zielinski, Marcin; Bosi, Matteo; Verzellesi, Giovanni; Gaskill, D. Kurt; Iacopi, Francesca

2018-06-01

Heteroepitaxial 3C-SiC films on silicon substrates are of technological interest as enablers to integrate the excellent electrical, electronic, mechanical, thermal, and epitaxial properties of bulk silicon carbide into well-established silicon technologies. One critical bottleneck of this integration is the establishment of a stable and reliable electronic junction at the heteroepitaxial interface of the n-type SiC with the silicon substrate. We have thus investigated in detail the electrical and transport properties of heteroepitaxial cubic silicon carbide films grown via different methods on low-doped and high-resistivity silicon substrates by using van der Pauw Hall and transfer length measurements as test vehicles. We have found that Si and C intermixing upon or after growth, particularly by the diffusion of carbon into the silicon matrix, creates extensive interstitial carbon traps and hampers the formation of a stable rectifying or insulating junction at the SiC/Si interface. Although a reliable p-n junction may not be realistic in the SiC/Si system, we can achieve, from a point of view of the electrical isolation of in-plane SiC structures, leakage suppression through the substrate by using a high-resistivity silicon substrate coupled with deep recess etching in between the SiC structures.

Fluorescence and thermoluminescence in silicon oxide films rich in silicon

International Nuclear Information System (INIS)

Berman M, D.; Piters, T. M.; Aceves M, M.; Berriel V, L. R.; Luna L, J. A.

2009-10-01

In this work we determined the fluorescence and thermoluminescence (TL) creation spectra of silicon rich oxide films (SRO) with three different silicon excesses. To study the TL of SRO, 550 nm of SRO film were deposited by Low Pressure Chemical Vapor Deposition technique on N-type silicon substrates with resistivity in the order of 3 to 5 Ω-cm with silicon excess controlled by the ratio of the gases used in the process, SRO films with Ro= 10, 20 and 30 (12-6% silicon excess) were obtained. Then, they were thermally treated in N 2 at high temperatures to diffuse and homogenize the silicon excess. In the fluorescence spectra two main emission regions are observed, one around 400 nm and one around 800 nm. TL creation spectra were determined by plotting the integrated TL intensity as function of the excitation wavelength. (Author)

Coating of silicone with mannoside-PAMAM dendrimers to enhance formation of non-pathogenic Escherichia coli biofilms against colonization of uropathogens.

Science.gov (United States)

Zhu, Zhiling; Yu, Fei; Chen, Haoqing; Wang, Jun; Lopez, Analette I; Chen, Quan; Li, Siheng; Long, Yuyu; Darouiche, Rabih O; Hull, Richard A; Zhang, Lijuan; Cai, Chengzhi

2017-12-01

Bacterial interference using non-pathogenic Escherichia coli 83972 is a novel strategy for preventing catheter-associated urinary tract infection (CAUTI). Crucial to the success of this strategy is to establish a high coverage and stable biofilm of the non-pathogenic bacteria on the catheter surface. However, this non-pathogenic strain is sluggish to form biofilms on silicone as the most widely used material for urinary catheters. We have addressed this issue by modifying the silicone catheter surfaces with mannosides that promote the biofilm formation, but the stability of the non-pathogenic biofilms challenged by uropathogens over long-term remains a concern. Herein, we report our study on the stability of the non-pathogenic biofilms grown on propynylphenyl mannoside-modified silicone. The result shows that 94% non-pathogenic bacteria were retained on the modified silicone under >0.5 Pa shear stress. After being challenged by three multidrug-resistant uropathogenic isolates in artificial urine for 11 days, large amounts (>4 × 10 6  CFU cm -2 ) of the non-pathogenic bacteria remained on the surfaces. These non-pathogenic biofilms reduced the colonization of the uropathogens by >3.2-log. In bacterial interference, the non-pathogenic Escherichia coli strains are sluggish to form biofilms on the catheter surfaces, due to rapid removal by urine flow. We have demonstrated a solution to this bottleneck by pre-functionalization of mannosides on the silicone surfaces to promote E. coli biofilm formation. A pre-conjugated high affinity propynylphenyl mannoside ligand tethered to the nanometric amino-terminated poly(amido amine) (PAMAM) dendrimer is used for binding to a major E. coli adhesin FimH. It greatly improves the efficiency for the catheter modification, the non-pathogenic biofilm coverage, as well as the (long-term) stability for prevention of uropathogen infections. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Buried oxide layer in silicon

Science.gov (United States)

Sadana, Devendra Kumar; Holland, Orin Wayne

2001-01-01

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Hydroxyapatites enriched in silicon – Bioceramic materials for biomedical and pharmaceutical applications

Directory of Open Access Journals (Sweden)

Katarzyna Szurkowska

2017-08-01

Full Text Available Hydroxyapatite (Ca10(PO46(OH2, abbreviated as HA plays a crucial role in implantology, dentistry and bone surgery. Due to its considerable similarity to the inorganic fraction of the mineralized tissues (bones, enamel and dentin, it is used as component in many bone substitutes, coatings of metallic implants and dental materials. Biomaterial engineering often takes advantage of HA capacity for partial ion substitution because the incorporation of different ions in the HA structure leads to materials with improved biological or physicochemical properties. The objective of the work is to provide an overview of current knowledge about apatite materials substituted with silicon ions. Although the exact mechanism of action of silicon in the bone formation process has not been fully elucidated, research has shown beneficial effects of this element on bone matrix mineralization as well as on collagen type I synthesis and stabilization. The paper gives an account of the functions of silicon in bone tissue and outlines the present state of research on synthetic HA containing silicate ions (Si-HA. Finally, methods of HA production as well as potential and actual applications of HA materials modified with silicon ions are discussed.

Periodic patterning of silicon by direct nanosecond laser interference ablation

International Nuclear Information System (INIS)

Tavera, T.; Pérez, N.; Rodríguez, A.; Yurrita, P.; Olaizola, S.M.; Castaño, E.

2011-01-01

The production of periodic structures in silicon wafers by four-beam is presented. Because laser interference ablation is a single-step and cost-effective process, there is a great technological interest in the fabrication of these structures for their use as antireflection surfaces. Three different laser fluences are used to modify the silicon surface (0.8 J cm -2 , 1.3 J cm -2 , 2.0 J cm -2 ) creating bumps in the rim of the irradiated area. Laser induced periodic surface structures (LIPSS), in particular micro and nano-ripples, are also observed. Measurements of the reflectivity show a decrease in the reflectance for the samples processed with a laser fluence of 2.0 J cm -2 , probably caused by the appearance of the nano-ripples in the structured area, while bumps start to deteriorate.

Ion beam studied of silicon oxynitride and silicon nitroxide thin layers

International Nuclear Information System (INIS)

Oude Elferink, J.B.

1989-01-01

In this the processes occurring during high temperature treatments of silicon oxynitride and silicon oxide layers are described. Oxynitride layers with various atomic oxygen to nitrogen concentration ration (O/N) are considered. The high energy ion beam techniques Rutherford backscattering spectroscopy, elastic recoil detection and nuclear reaction analysis have been used to study the layer structures. A detailed discussion of these ion beam techniques is given. Numerical methods used to obtain quantitative data on elemental compositions and depth profiles are described. The electrical compositions and depth profiles are described. The electrical properties of silicon nitride films are known to be influenced by the behaviour of hydrogen in the film during high temperature anneling. Investigations of the behaviour of hydrogen are presented. Oxidation of silicon (oxy)nitride films in O 2 /H 2 0/HCl and nitridation of silicon dioxide films in NH 3 are considered since oxynitrides are applied as an oxidation mask in the LOCOS (Local oxidation of silicon) process. The nitridation of silicon oxide layers in an ammonia ambient is considered. The initial stage and the dependence on the oxide thickness of nitrogen and hydrogen incorporation are discussed. Finally, oxidation of silicon oxynitride layers and of silicon oxide layers are compared. (author). 76 refs.; 48 figs.; 1 tab

Assessment of the effect of silicon on antioxidant enzymes in cotton plants by multivariate analysis.

Science.gov (United States)

Alberto Moldes, Carlos; Fontão de Lima Filho, Oscar; Manuel Camiña, José; Gabriela Kiriachek, Soraya; Lia Molas, María; Mui Tsai, Siu

2013-11-27

Silicon has been extensively researched in relation to the response of plants to biotic and abiotic stress, as an element triggering defense mechanisms which activate the antioxidant system. Furthermore, in some species, adding silicon to unstressed plants modifies the activity of certain antioxidant enzymes participating in detoxifying processes. Thus, in this study, we analyzed the activity of antioxidant enzymes in leaves and roots of unstressed cotton plants fertilized with silicon (Si). Cotton plants were grown in hydroponic culture and added with increasing doses of potassium silicate; then, the enzymatic activity of catalase (CAT), guaiacol peroxidase (GPOX), ascorbate peroxidase (APX), and lipid peroxidation were determined. Using multivariate analysis, we found that silicon altered the activity of GPOX, APX, and CAT in roots and leaves of unstressed cotton plants, whereas lipid peroxidation was not affected. The analysis of these four variables in concert showed a clear differentiation among Si treatments. We observed that enzymatic activities in leaves and roots changed as silicon concentration increased, to stabilize at 100 and 200 mg Si L(-1) treatments in leaves and roots, respectively. Those alterations would allow a new biochemical status that could be partially responsible for the beneficial effects of silicon. This study might contribute to adjust the silicon application doses for optimal fertilization, preventing potential toxic effects and unnecessary cost.

GRANULATION TRIALS OF WASTE THE DUST SILICON CARBIDE FOR UTILIZATION IN METALLURGY

Directory of Open Access Journals (Sweden)

Gabriel Borowski

2016-09-01

Full Text Available The article presents the results of laboratory granulation tests of dust silicon carbide and the results of research on the selection of the binder and the properties of the granules obtained. The research material was a waste of the silicon carbide powder with a high fragmentation, mixed with a cement or an organic modified starch specimen. Six tests were performed in a disc granulator with 100 cm in diameter. In each series of trial specified: the type and share of the binder, the diameter of the granules, tenderness, type of structure and mechanical properties. Good granules of silicon carbide obtained with the addition of cement binder with 4% of the mass fraction and at least 24 hours of seasoning. The binder should be added twice by powdering, first in a stirred granulator, and again after manufacture. It was found that the resulting granules may be used as a replacement of ferrosilicon in the process of steelmaking.

Nonlinear silicon photonics

Science.gov (United States)

Tsia, Kevin K.; Jalali, Bahram

2010-05-01

An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

Study on immobilizations of ovine anti-human IgG and MCAb against EHF on radiation-modified silicone films

International Nuclear Information System (INIS)

Guo Jinhui; Ha Hongfei; Zhang Yuhua

1990-01-01

Films of silicone (silastic) were grafted by monomer acrylamide vis γ-radiation technology and then the ovine anti-human IgG, Epidemic hemorrhagic fever (EHF)-MCAb were immobilized on the silastic-AAM films with different grafting yields passthrough associate reactions. Measruements of relationships between grafting yields. Contents of immobilized antibodies and immunoactivities for immobilized silastic-AAM films were performed by using 125 I method ELISA method was used to measure the immunoactivities for the immobilized monoantibody. The results showed that the antibodies used can be immobilized on radiation-grafted silicone films and this immobilization method has its potential significance in clinical practice

Study on immobilizations of ovine anti-human IgG and MCAb against EHF on radiation-modified silicone films

Energy Technology Data Exchange (ETDEWEB)

Jinhui, Guo; Hongfei, Ha; Yuhua, Zhang [Beijing Univ., BJ (China). Dept. of Technical Physics

1990-08-01

Films of silicone (silastic) were grafted by monomer acrylamide vis {gamma}-radiation technology and then the ovine anti-human IgG, Epidemic hemorrhagic fever (EHF)-MCAb were immobilized on the silastic-AAM films with different grafting yields passthrough associate reactions. Measruements of relationships between grafting yields. Contents of immobilized antibodies and immunoactivities for immobilized silastic-AAM films were performed by using {sup 125}I method ELISA method was used to measure the immunoactivities for the immobilized monoantibody. The results showed that the antibodies used can be immobilized on radiation-grafted silicone films and this immobilization method has its potential significance in clinical practice.

Modification of Al-Si (13%) alloy using different modifiers

International Nuclear Information System (INIS)

Ikram, N.; Raza, M.R.; Ahmad, R.

2007-01-01

During present research work LM 13 aluminium silicon alloy was prepared using high purity aluminium ingot and various master alloys of AI-Si, AI-Cu, AI-Ni, AIFe, AI-Mn and AI-Mg. A gas fired crucible pit type furnace was used to prepare various heats of LM 13 alloy. Degassing procedure was carried out by using perforated bell type plunger using the degassing tablet. Modification was performed by plunging the modifier at the bottom of the crucible containing the molten metal. Three types of modifiers sodium salt, metallic sodium and strontium in the form of AI-Sr master alloy were used in order to evaluate the microstructure and tensile properties of the alloy. Degassed, unmodified and modified test samples for metallurgical testing purposes were prepared according to the standard procedures. (author)

Production of Solar Grade (SoG) Silicon by Refining Liquid Metallurgical Grade (MG) Silicon: Final Report, 19 April 2001; FINAL

International Nuclear Information System (INIS)

Khattack, C. P.; Joyce, D. B.; Schmid, F.

2001-01-01

This report summarizes the results of the developed technology for producing SoG silicon by upgrading MG silicon with a cost goal of$20/kg in large-scale production. A Heat Exchanger Method (HEM) furnace originally designed to produce multicrystalline ingots was modified to refine molten MG silicon feedstock prior to directional solidification. Based on theoretical calculations, simple processing techniques, such as gas blowing through the melt, reaction with moisture, and slagging have been used to remove B from molten MG silicon. The charge size was scaled up from 1 kg to 300 kg in incremental steps and effective refining was achieved. After the refining parameters were established, improvements to increase the impurity reduction rates were emphasized. With this approach, 50 kg of commercially available as-received MG silicon was processed for a refining time of about 13 hours. A half life of and lt;2 hours was achieved, and the B concentration was reduced to 0.3 ppma and P concentration to 10 ppma from the original values of 20 to 60 ppma, and all other impurities to and lt;0.1 ppma. Achieving and lt;1 ppma B by this simple refining technique is a breakthrough towards the goal of achieving low-cost SoG silicon for PV applications. While the P reduction process was being optimized, the successful B reduction process was applied to a category of electronics industry silicon scrap previously unacceptable for PV feedstock use because of its high B content (50-400 ppma). This material after refining showed that its B content was reduced by several orders of magnitude, to(approx)1 ppma (0.4 ohm-cm, or about 5x1016 cm-3). NREL's Silicon Materials Research team grew and wafered small and lt;100 and gt; dislocation-free Czochralski (Cz) crystals from the new feedstock material for diagnostic tests of electrical properties, C and O impurity levels, and PV performance relative to similar crystals grown from EG feedstock and commercial Cz wafers. The PV conversion

Liquid phase epitaxial growth of silicon on porous silicon for photovoltaic applications

International Nuclear Information System (INIS)

Berger, S.; Quoizola, S.; Fave, A.; Kaminski, A.; Perichon, S.; Barbier, D.; Laugier, A.

2001-01-01

The aim of this experiment is to grow a thin silicon layer ( 2 atmosphere, and finally LPE silicon growth with different temperature profiles in order to obtain a silicon layer on the sacrificial porous silicon (p-Si). We observed a pyramidal growth on the surface of the (100) porous silicon but the coalescence was difficult to obtain. However, on a p-Si (111) oriented wafer, homogeneous layers were obtained. (orig.)

Nonlinear silicon photonics

Science.gov (United States)

Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

2017-09-01

Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

Transformational silicon electronics

KAUST Repository

Rojas, Jhonathan Prieto

2014-02-25

In today\\'s traditional electronics such as in computers or in mobile phones, billions of high-performance, ultra-low-power devices are neatly integrated in extremely compact areas on rigid and brittle but low-cost bulk monocrystalline silicon (100) wafers. Ninety percent of global electronics are made up of silicon. Therefore, we have developed a generic low-cost regenerative batch fabrication process to transform such wafers full of devices into thin (5 μm), mechanically flexible, optically semitransparent silicon fabric with devices, then recycling the remaining wafer to generate multiple silicon fabric with chips and devices, ensuring low-cost and optimal utilization of the whole substrate. We show monocrystalline, amorphous, and polycrystalline silicon and silicon dioxide fabric, all from low-cost bulk silicon (100) wafers with the semiconductor industry\\'s most advanced high-κ/metal gate stack based high-performance, ultra-low-power capacitors, field effect transistors, energy harvesters, and storage to emphasize the effectiveness and versatility of this process to transform traditional electronics into flexible and semitransparent ones for multipurpose applications. © 2014 American Chemical Society.

Silicon Microspheres Photonics

International Nuclear Information System (INIS)

Serpenguzel, A.

2008-01-01

Electrophotonic integrated circuits (EPICs), or alternatively, optoelectronic integrated circuit (OEICs) are the natural evolution of the microelectronic integrated circuit (IC) with the addition of photonic capabilities. Traditionally, the IC industry has been based on group IV silicon, whereas the photonics industry on group III-V semiconductors. However, silicon based photonic microdevices have been making strands in siliconizing photonics. Silicon microspheres with their high quality factor whispering gallery modes (WGMs), are ideal candidates for wavelength division multiplexing (WDM) applications in the standard near-infrared communication bands. In this work, we will discuss the possibility of using silicon microspheres for photonics applications in the near-infrared

Investigation of the silicon ion density during molecular beam epitaxy growth

CERN Document Server

Eifler, G; Ashurov, K; Morozov, S

2002-01-01

Ions impinging on a surface during molecular beam epitaxy influence the growth and the properties of the growing layer, for example, suppression of dopant segregation and the generation of crystal defects. The silicon electron gun in the molecular beam epitaxy (MBE) equipment is used as a source for silicon ions. To use the effect of ion bombardment the mechanism of generation and distribution of ions was investigated. A monitoring system was developed and attached at the substrate position in the MBE growth chamber to measure the ion and electron densities towards the substrate. A negative voltage was applied to the substrate to modify the ion energy and density. Furthermore the current caused by charge carriers impinging on the substrate was measured and compared with the results of the monitoring system. The electron and ion densities were measured by varying the emission current of the e-gun achieving silicon growth rates between 0.07 and 0.45 nm/s and by changing the voltage applied to the substrate betw...

Tuning the cathodoluminescence of porous silicon films

International Nuclear Information System (INIS)

Biaggi-Labiosa, A.; Fonseca, L.F.; Resto, O.; Balberg, I.

2008-01-01

We have obtained intense cathodoluminescence (CL) emission from electron beam modified porous silicon films by excitation with electrons with kinetic energies below 2 keV. Two types of CL emissions were observed, a stable one and a non-stable one. The first type is obtained in well-oxidized samples and is characterized by a spectral peak that is red shifted with respect to the photoluminescence (PL) peak. The physically interesting and technologically promising CL is however the CL that correlates closely with the PL. Tuning of this CL emission was achieved by controlling the average size of the nanostructure thus showing that the origin of this CL emission is associated with the quantum confinement and the surface chemistry effects that are known to exist in the porous silicon system. We also found that the electron bombardment causes microscale morphological modifications of the films, but the nanoscale features appear to be unchanged. The structural changes are manifested by the increase in the density of the nanoparticles which explains the significant enhancement of the PL that follows the electron irradiation

Production of technical silicon and silicon carbide from rice-husk

Directory of Open Access Journals (Sweden)

A. Z. Issagulov

2014-10-01

Full Text Available In the article there are studied physical and chemical properties of silicon-carbonic raw material – rice-husk, thermophysical characteristics of the process of rice-husk pyrolysis in nonreactive and oxidizing environment; structure and phase composition of products of the rice-husk pyrolysis in interval of temperatures 150 – 850 °С and high temperature pyrolysis in interval of temperatures 900 – 1 500 °С. There are defined the silicon-carbon production conditions, which meet the requirements applicable to charging materials at production of technical silicon and silicon carbide.

Photovoltaic characteristics of porous silicon /(n+ - p) silicon solar cells

International Nuclear Information System (INIS)

Dzhafarov, T.D.; Aslanov, S.S.; Ragimov, S.H.; Sadigov, M.S.; Nabiyeva, A.F.; Yuksel, Aydin S.

2012-01-01

Full text : The purpose of this work is to improve the photovoltaic parameters of the screen-printed silicon solar cells by formation the nano-porous silicon film on the frontal surface of the cell. The photovoltaic characteristics of two type silicon solar cells with and without porous silicon layer were measured and compared. A remarkable increment of short-circuit current density and the efficiency by 48 percent and 20 percent, respectively, have been achieved for PS/(n + - pSi) solar cell comparing to (n + - p)Si solar cell without PS layer

A Long-Range Electric Field Solver for Molecular Dynamics Based on Atomistic-to-Continuum Modeling.

Science.gov (United States)

Templeton, Jeremy A; Jones, Reese E; Lee, Jonathan W; Zimmerman, Jonathan A; Wong, Bryan M

2011-06-14

Understanding charge transport processes at a molecular level is currently hindered by a lack of appropriate models for incorporating nonperiodic, anisotropic electric fields in molecular dynamics (MD) simulations. In this work, we develop a model for including electric fields in MD using an atomistic-to-continuum framework. This framework provides the mathematical and the algorithmic infrastructure to couple finite element (FE) representations of continuous data with atomic data. Our model represents the electric potential on a FE mesh satisfying a Poisson equation with source terms determined by the distribution of the atomic charges. Boundary conditions can be imposed naturally using the FE description of the potential, which then propagate to each atom through modified forces. The method is verified using simulations where analytical solutions are known or comparisons can be made to existing techniques. In addition, a calculation of a salt water solution in a silicon nanochannel is performed to demonstrate the method in a target scientific application in which ions are attracted to charged surfaces in the presence of electric fields and interfering media.

Mass transfer in silicon at deposition of Ti thin films assisted by self ion irradiation

International Nuclear Information System (INIS)

Mikhalkovich, O.M.; Tashlykov, I.S.; Gusakov, V.E.

2011-01-01

In this paper a composite structure, processes of diffusion in Si, modified by means of ion-assisted deposition of coatings in conditions of a self-irradiation are discussed. Rutherford backscattering in combination with a channelling (RBS/Ch) of He + ions and computer program RUMP were applied to investigate an element composition. It is established, that coatings include atoms of metal, hydrogen, carbon, oxygen, silicon. The interstitial Si atoms, generated by radiation effect, diffuse during deposition of thin coating, both in a depth of a wafers, and in coatings. The influence of irradiation of ions Xe+ on diffusion processes in silicon are revealed. (authors)

Performance improvement of silicon solar cells by nanoporous silicon coating

Directory of Open Access Journals (Sweden)

Dzhafarov T. D.

2012-04-01

Full Text Available In the present paper the method is shown to improve the photovoltaic parameters of screen-printed silicon solar cells by nanoporous silicon film formation on the frontal surface of the cell using the electrochemical etching. The possible mechanisms responsible for observed improvement of silicon solar cell performance are discussed.

Reprogramming hMSCs morphology with silicon/porous silicon geometric micro-patterns.

Science.gov (United States)

Ynsa, M D; Dang, Z Y; Manso-Silvan, M; Song, J; Azimi, S; Wu, J F; Liang, H D; Torres-Costa, V; Punzon-Quijorna, E; Breese, M B H; Garcia-Ruiz, J P

2014-04-01

Geometric micro-patterned surfaces of silicon combined with porous silicon (Si/PSi) have been manufactured to study the behaviour of human Mesenchymal Stem Cells (hMSCs). These micro-patterns consist of regular silicon hexagons surrounded by spaced columns of silicon equilateral triangles separated by PSi. The results show that, at an early culture stage, the hMSCs resemble quiescent cells on the central hexagons with centered nuclei and actin/β-catenin and a microtubules network denoting cell adhesion. After 2 days, hMSCs adapted their morphology and cytoskeleton proteins from cell-cell dominant interactions at the center of the hexagonal surface. This was followed by an intermediate zone with some external actin fibres/β-catenin interactions and an outer zone where the dominant interactions are cell-silicon. Cells move into silicon columns to divide, migrate and communicate. Furthermore, results show that Runx2 and vitamin D receptors, both specific transcription factors for skeleton-derived cells, are expressed in cells grown on micropatterned silicon under all observed circumstances. On the other hand, non-phenotypic alterations are under cell growth and migration on Si/PSi substrates. The former consideration strongly supports the use of micro-patterned silicon surfaces to address pending questions about the mechanisms of human bone biogenesis/pathogenesis and the study of bone scaffolds.

Light propagation studies on laser modified waveguides using scanning near-field optical microscopy

DEFF Research Database (Denmark)

Borrise, X.; Berini, Abadal Gabriel; Jimenez, D.

2001-01-01

By means of direct laser writing on Al, a new method to locally modify optical waveguides is proposed. This technique has been applied to silicon nitride waveguides, allowing modifications of the optical propagation along the guide. To study the formed structures, a scanning near-held optical mic...

Simulation of thermo-mechanical effect in bulk-silicon FinFETs

OpenAIRE

Burenkov, Alex; Lorenz, Jürgen

2016-01-01

The thermo-mechanical effect in bulk-silicon FinFETs of the 14 nm CMOS technology node is studied by means of numerical simulation. The electrical performance of such devices is significantly enhanced by the intentional introduction of mechanical stress during the device processing. The thermo-mechanical effect modifies the mechanical stress distribution in active regions of the transistors when they are heated. This can lead to a modification of the electrical performance. Numerical simulati...

Study on structural properties of epitaxial silicon films on annealed double layer porous silicon

International Nuclear Information System (INIS)

Yue Zhihao; Shen Honglie; Cai Hong; Lv Hongjie; Liu Bin

2012-01-01

In this paper, epitaxial silicon films were grown on annealed double layer porous silicon by LPCVD. The evolvement of the double layer porous silicon before and after thermal annealing was investigated by scanning electron microscope. X-ray diffraction and Raman spectroscopy were used to investigate the structural properties of the epitaxial silicon thin films grown at different temperature and different pressure. The results show that the surface of the low-porosity layer becomes smooth and there are just few silicon-bridges connecting the porous layer and the substrate wafer. The qualities of the epitaxial silicon thin films become better along with increasing deposition temperature. All of the Raman peaks of silicon films with different deposition pressure are situated at 521 cm -1 under the deposition temperature of 1100 °C, and the Raman intensity of the silicon film deposited at 100 Pa is much closer to that of the monocrystalline silicon wafer. The epitaxial silicon films are all (4 0 0)-oriented and (4 0 0) peak of silicon film deposited at 100 Pa is more symmetric.

Surface treated fly ash filled modified epoxy composites

Directory of Open Access Journals (Sweden)

Uma Dharmalingam

2015-01-01

Full Text Available Abstract Fly ash, an inorganic alumino silicate has been used as filler in epoxy matrix, but it reduces the mechanical properties due to its poor dispersion and interfacial bonding with the epoxy matrix. To improve its interfacial bonding with epoxy matrix, surface treatment of fly ash was done using surfactant sodium lauryl sulfate and silane coupling agent glycidoxy propyl trimethoxy silane. An attempt is also made to reduce the particle size of fly ash using high pressure pulverizer. To improve fly ash dispersion in epoxy matrix, the epoxy was modified by mixing with amine containing liquid silicone rubber (ACS. The effect of surface treated fly ash with varying filler loadings from 10 to 40% weight on the mechanical, morphological and thermal properties of modified epoxy composites was investigated. The surface treated fly ash was characterized by particle size analyzer and FTIR spectra. Morphological studies of surface treated fly ash filled modified epoxy composites indicate good dispersion of fillers in the modified epoxy matrix and improves its mechanical properties. Impact strength of the surface treated fly ash filled modified epoxy composites show more improvement than unmodified composites.

Investigation of carbon nanotube-containing film on silicon substrates and its tribological behavior

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhiyong [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Cheng, Xianhua, E-mail: xhcheng@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2015-11-15

Highlights: • CNT-containing film was self-assembled on silicon substrates. • CNTs are strongly bonded with the substrates by chemical combination between La and oxygen-containing functional groups. • CNT-containing film has excellent friction reduction, load-carrying capacity and anti-wear ability. - Abstract: Carbon nanotubes (CNTs) were functionalized with Lanthanum (La) modifier and appropriate acid-treatment methods. CNT-containing film was deposited on silicon substrates via a self-assembly process. The formation and microstructure of La treated CNTs and CNT-containing film were characterized by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS) and water contact angle (WCA). Its tribological properties were evaluated with a UMT-2MT reciprocating friction tester. The results show that CNTs were adsorbed on silicon substrates by means of chemically bonding between La and oxygen-containing functional groups. The friction coefficient of the silicon substrates is reduced from 0.87 to 0.12 after the deposition of CNT-containing film on its surface. CNT-containing film shows excellent antiwear, friction reducing ability and load-carrying capacity due to excellent mechanical and self-lubrication properties of CNTs.

Porous silicon photoluminescence modification by colloidal gold nanoparticles: Plasmonic, surface and porosity roles

International Nuclear Information System (INIS)

Mora, M.B. de la; Bornacelli, J.; Nava, R.; Zanella, R.; Reyes-Esqueda, J.A.

2014-01-01

Metal nanoparticles on semiconductors are of interest because of the tunable effect of the surface plasmon resonance on the physical properties of the semiconductor. In this work, colloidal gold nanoparticles obtained by two different methods, with an average size of 6.1±2.0 nm and 5.0±2.0 nm, were added to luminescent porous silicon by drop casting. The gold nanoparticles interact with porous silicon by modifying its optical properties such as photoluminescence. That being said, plasmon effects are not the only to be taken into account; as shown in this work, surface chemical modification and porosity also play a key role in the final performance of photoluminescence of a porous silicon–gold nanoparticle hybrid system. -- Highlights: • A hybrid material consisting of porous silicon and gold nanoparticles was fabricated. • Porous silicon/gold nanoparticle hybrid material was made by drop casting. • Influence of plasmonics, surface chemical modification and porosity on the optical behavior of our material was analyzed. • Porosity is proposed as a parameter control to obtain the best effects on luminescence of the hybrid plasmonic material

Porous silicon photoluminescence modification by colloidal gold nanoparticles: Plasmonic, surface and porosity roles

Energy Technology Data Exchange (ETDEWEB)

Mora, M.B. de la; Bornacelli, J. [Instituto de Física, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Nava, R. [Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Temixco, Morelos 62580 (Mexico); Zanella, R. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Reyes-Esqueda, J.A., E-mail: betarina@gmail.com [Instituto de Física, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico)

2014-02-15

Metal nanoparticles on semiconductors are of interest because of the tunable effect of the surface plasmon resonance on the physical properties of the semiconductor. In this work, colloidal gold nanoparticles obtained by two different methods, with an average size of 6.1±2.0 nm and 5.0±2.0 nm, were added to luminescent porous silicon by drop casting. The gold nanoparticles interact with porous silicon by modifying its optical properties such as photoluminescence. That being said, plasmon effects are not the only to be taken into account; as shown in this work, surface chemical modification and porosity also play a key role in the final performance of photoluminescence of a porous silicon–gold nanoparticle hybrid system. -- Highlights: • A hybrid material consisting of porous silicon and gold nanoparticles was fabricated. • Porous silicon/gold nanoparticle hybrid material was made by drop casting. • Influence of plasmonics, surface chemical modification and porosity on the optical behavior of our material was analyzed. • Porosity is proposed as a parameter control to obtain the best effects on luminescence of the hybrid plasmonic material.

Controlling growth density and patterning of single crystalline silicon nanowires

International Nuclear Information System (INIS)

Chang, Tung-Hao; Chang, Yu-Cheng; Liu, Fu-Ken; Chu, Tieh-Chi

2010-01-01

This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

Electrochemical characteristics of bundle-type silicon nanorods as an anode material for lithium ion batteries

International Nuclear Information System (INIS)

Nguyen, Si Hieu; Lim, Jong Choo; Lee, Joong Kee

2012-01-01

Highlights: ► A metal-assisted chemical etching technique was performed on Si thin films. ► The etching process resulted in the formation of bundle-type Si nanorods. ► The morphology of Si electrodes closely relate to electrochemical characteristics. - Abstract: In order to prepare bundle-type silicon nanorods, a silver-assisted chemical etching technique was used to modify a 1.6 μm silicon thin film, which was deposited on Cu foil by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition. The bundle-type silicon nanorods on Cu foil were employed as anodes for a lithium secondary battery, without further treatment. The electrochemical characteristics of the pristine silicon thin film anodes and the bundle-type silicon nanorod anodes are different from one another. The electrochemical performance of the bundle-type silicon nanorod anodes exceeded that of the pristine Si thin film anodes. The specific capacity of the bundle-type silicon nanorod anodes is much higher than 3000 mAh g −1 at the first charge (Li insertion) cycle. The coulombic efficiency of bundle-type silicon anodes was stable at more than 97%, and the charge capacity remained at 1420 mAh g −1 , even after 100 cycles of charging and discharging. The results from the differential voltage analysis showed a side reaction at around 0.44–0.5 V, and the specific potential of this side reaction decreased after each cycle. The apparent diffusion coefficients of the two anode types were in the range of 10 −13 –10 −16 cm 2 s −1 in the first cycle. In subsequent charge cycles, these values for the silicon thin film anodes and the silicon nanorod bundle anode were approximately 10 −12 –10 −14 and 10 −13 –10 −15 cm 2 s −1 , respectively.

Light emitting structures porous silicon-silicon substrate

International Nuclear Information System (INIS)

Monastyrskii, L.S.; Olenych, I.B.; Panasjuk, M.R.; Savchyn, V.P.

1999-01-01

The research of spectroscopic properties of porous silicon has been done. Complex of photoluminescence, electroluminescence, cathodoluminescence, thermostimulated depolarisation current analyte methods have been applied to study of geterostructures and free layers of porous silicon. Light emitting processes had tendency to decrease. The character of decay for all kinds of luminescence were different

Gelcasting of SiC/Si for preparation of silicon nitride bonded silicon carbide

International Nuclear Information System (INIS)

Xie, Z.P.; Tsinghua University, Beijing,; Cheng, Y.B.; Lu, J.W.; Huang, Y.

2000-01-01

In the present paper, gelcasting of aqueous slurry with coarse silicon carbide(1mm) and fine silicon particles was investigated to fabricate silicon nitride bonded silicon carbide materials. Through the examination of influence of different polyelectrolytes on the Zeta potential and viscosity of silicon and silicon carbide suspensions, a stable SiC/Si suspension with 60 vol% solid loading could be prepared by using polyelectrolyte of D3005 and sodium alginate. Gelation of this suspension can complete in 10-30 min at 60-80 deg C after cast into mold. After demolded, the wet green body can be dried directly in furnace and the green strength will develop during drying. Complex shape parts with near net size were prepared by the process. Effects of the debindering process on nitridation and density of silicon nitride bonded silicon carbide were also examined. Copyright (2000) The Australian Ceramic Society

Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

Science.gov (United States)

Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

2018-05-01

We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

Silicon detectors

International Nuclear Information System (INIS)

Klanner, R.

1984-08-01

The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

FTIR studies of swift silicon and oxygen ion irradiated porous silicon

International Nuclear Information System (INIS)

Bhave, Tejashree M.; Hullavarad, S.S.; Bhoraskar, S.V.; Hegde, S.G.; Kanjilal, D.

1999-01-01

Fourier Transform Infrared Spectroscopy has been used to study the bond restructuring in silicon and oxygen irradiated porous silicon. Boron doped p-type (1 1 1) porous silicon was irradiated with 10 MeV silicon and a 14 MeV oxygen ions at different doses ranging between 10 12 and 10 14 ions cm -2 . The yield of PL in porous silicon irradiated samples was observed to increase considerably while in oxygen irradiated samples it was seen to improve only by a small extent for lower doses whereas it decreased for higher doses. The results were interpreted in view of the relative intensities of the absorption peaks associated with O-Si-H and Si-H stretch bonds

Breast cancer in a patient with silicone breast implants after 13 years.

Science.gov (United States)

Bingham, H G; Copeland, E M; Hackett, R; Caffee, H H

1988-03-01

The patient described in this article is a 45-year-old woman who developed an infiltrating ductal carcinoma in her left breast next to a Silastic mammary implant that had been used for augmentation some 13 years previously. She underwent a modified radical mastectomy and removal of the silicone prosthesis with an axillary lymph node dissection. Twenty-six axillary lymph nodes were negative for metastatic disease. The 165-gram silicone gel prosthesis was surrounded by a thin fibrous capsule with an attached 1-cm carcinoma that did not invade the fibrous capsule. It appeared that the capsule presented a barrier to the invading ductal carcinoma. The fibrous capsule surrounding the Silastic implant may have altered the spread of the breast cancer without being related to its genesis.

Observation of correlation effects in the hopping transport in amorphous silicon

International Nuclear Information System (INIS)

Voegele, V.; Kalbitzer, S.; Boehringer, K.

1985-01-01

Amorphous silicon films have been modified by the implantation of Au or Si ions. The d.c. conductivity, measured between 300 and 15 K, was found to exhibit hopping exponents m which increase with decreasing temperature. Depending on the varied defect densities, m ranges between the limits of 1/4 and 1. These results can be explained by variable-range-hopping theory, if a Coulomb correlation term is included. (author)

One - step nanosecond laser microstructuring, sulfur hyperdoping, and annealing of silicon surfaces in liquid carbondisulfide

Science.gov (United States)

Van Luong, Nguyen; Danilov, P. A.; Ionin, A. A.; Khmel'nitskii, P. A.; Kudryashov, S. I.; Mel'nik, N. N.; Saraeva, I. N.; Смirnov, H. A.; Rudenko, A. A.; Zayarny, D. A.

2017-09-01

We perform a single-shot IR nanosecond laser processing of commercial silicon wafers in ambient air and under a 2 mm thick carbon disulfide liquid layer. We characterize the surface spots modified in the liquid ambient and the spots ablated under the same conditions in air in terms of its surface topography, chemical composition, band-structure modification, and crystalline structure by means of SEM and EDX microscopy, as well as of FT-IR and Raman spectroscopy. These studies indicate that single-step microstructuring and deep (up to 2-3% on the surface) hyperdoping of the crystalline silicon in its submicron surface layer, preserving via pulsed laser annealing its crystallinity and providing high (103 - 104 cm-1) spectrally at near- and mid-IR absorption coefficients, can be obtained in this novel approach, which is very promising for thin - film silicon photovoltaic devices

Bitumen based modified substance

International Nuclear Information System (INIS)

Kostolanyi, P.

1987-01-01

The necessary amounts of tetrahydrosilicic acid and methyl phenyl silicon oil are added to molten bitumen heated to temperatures of 50 to 200 degC. The mixture is thoroughly mixed and let to cool. The structure of the product comes close to gel and its properties (penetration, softening point, workability time, penetration index) may be changed in dependence on the amount of additions and on the time and temperature of heating. The advantage of the thus prepared modified material is its shorter workability time, its ability to bind materials with a certain water content, and its relatively low price. It may be used for fixing and storing low-and medium-level radioactive organic and thickened waste waters. (E.S.)

Annealing temperature dependence of photoluminescent characteristics of silicon nanocrystals embedded in silicon-rich silicon nitride films grown by PECVD

International Nuclear Information System (INIS)

Chao, D.S.; Liang, J.H.

2013-01-01

Recently, light emission from silicon nanostructures has gained great interest due to its promising potential of realizing silicon-based optoelectronic applications. In this study, luminescent silicon nanocrystals (Si–NCs) were in situ synthesized in silicon-rich silicon nitride (SRSN) films grown by plasma-enhanced chemical vapor deposition (PECVD). SRSN films with various excess silicon contents were deposited by adjusting SiH 4 flow rate to 100 and 200 sccm and keeping NH 3 one at 40 sccm, and followed by furnace annealing (FA) treatments at 600, 850 and 1100 °C for 1 h. The effects of excess silicon content and post-annealing temperature on optical properties of Si–NCs were investigated by photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The origins of two groups of PL peaks found in this study can be attributed to defect-related interface states and quantum confinement effects (QCE). Defect-related interface states lead to the photon energy levels almost kept constant at about 3.4 eV, while QCE results in visible and tunable PL emission in the spectral range of yellow and blue light which depends on excess silicon content and post-annealing temperature. In addition, PL intensity was also demonstrated to be highly correlative to the excess silicon content and post-annealing temperature due to its corresponding effects on size, density, crystallinity, and surface passivation of Si–NCs. Considering the trade-off between surface passivation and structural properties of Si–NCs, an optimal post-annealing temperature of 600 °C was suggested to maximize the PL intensity of the SRSN films

Custom-made silicone hand prosthesis: A case study.

Science.gov (United States)

Nayak, S; Lenka, P K; Equebal, A; Biswas, A

2016-09-01

Up to now, a cosmetic glove was the most common method for managing transmetacarpal (TMC) and carpometacarpal (CMC) amputations, but it is devoid of markings and body color. At this amputation level, it is very difficult to fit a functional prosthesis because of the short available length, unsightly shape, grafted skin, contracture and lack of functional prosthetic options. A 30-year-old male came to our clinic with amputation at the 1st to 4th carpometacarpal level and a 5th metacarpal that was projected laterally and fused with the carpal bone. The stump had grafted skin, redness, and an unhealed suture line. He complained of pain projected over the metacarpal and suture area. The clinical team members decided to fabricate a custom-made silicone hand prosthesis to accommodate the stump, protect the grafted skin, improve the hand's appearance and provide some passive function. The custom silicone hand prosthesis was fabricated with modified flexible wires to provide passive interphalangeal movement. Basic training, care and maintenance instructions for the prosthesis were given to the patient. The silicone hand prosthesis was able to restore the appearance of the lost digits and provide some passive function. His pain (VAS score) was reduced. Improvement in activities of daily living was found in the DASH questionnaire and Jebsen-Taylor Hand Function test. A silicone glove is a good option for more distal amputations, as it can accommodate any deformity, protect the skin, enhance the appearance and provide functional assistance. This case study provides a simple method to get passively movable fingers after proximal hand amputation. Copyright © 2016. Published by Elsevier Masson SAS.

Strategies for doped nanocrystalline silicon integration in silicon heterojunction solar cells

Czech Academy of Sciences Publication Activity Database

Seif, J.; Descoeudres, A.; Nogay, G.; Hänni, S.; de Nicolas, S.M.; Holm, N.; Geissbühler, J.; Hessler-Wyser, A.; Duchamp, M.; Dunin-Borkowski, R.E.; Ledinský, Martin; De Wolf, S.; Ballif, C.

2016-01-01

Roč. 6, č. 5 (2016), s. 1132-1140 ISSN 2156-3381 R&D Projects: GA MŠk LM2015087 Institutional support: RVO:68378271 Keywords : microcrystalline silicon * nanocrystalline silicon * silicon heterojunctions (SHJs) * solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.712, year: 2016

Surface modification on silicon with chitosan and biological research

International Nuclear Information System (INIS)

Lue Xiaoying; Cui Wei; Huang Yan; Zhao Yi; Wang Zhigong

2009-01-01

The aim of the present study was to investigate the effect of chitosan modification of silicon (Si) on protein adsorption, cell adhesion and cell proliferation. Chitosan was first immobilized on the Si surface through a (3-aminopropyl)triethoxysilane (APTES) bridge. The surface was then characterized by contact angle measurement, atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDX). The amount of protein adsorbed on the native Si and chitosan-modified Si surface was evaluated by a modified Coomassie brilliant blue (CBB) protein assay. The adhesion and proliferation behavior of L-929 and pc12 cells were then assessed by microscopy and methylthiazoltetrazolium (MTT) tests. The results showed that the chitosan modification could resist protein adsorption and inhibit the adhesion and proliferation of two kinds of cells on Si.

Examination of total cross section resonance structure of niobium and silicon in neutron transmission experiments

Science.gov (United States)

Andrianova, Olga; Lomakov, Gleb; Manturov, Gennady

2017-09-01

The neutron transmission experiments are one of the main sources of information about the neutron cross section resonance structure and effect in the self-shielding. Such kind of data for niobium and silicon nuclides in energy range 7 keV to 3 MeV can be obtained from low-resolution transmission measurements performed earlier in Russia (with samples of 0.027 to 0.871 atom/barn for niobium and 0.076 to 1.803 atom/barn for silicon). A significant calculation-to-experiment discrepancy in energy range 100 to 600 keV and 300 to 800 keV for niobium and silicon, respectively, obtained using the evaluated nuclear data library ROSFOND, were found. The EVPAR code was used for estimation the average resonance parameters in energy range 7 to 600 keV for niobium. For silicon a stochastic optimization method was used to modify the resolved resonance parameters in energy range 300 to 800 keV. The improved ROSFOND evaluated nuclear data files were tested in calculation of ICSBEP integral benchmark experiments.

Periodically poled silicon

Science.gov (United States)

Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Khurgin, Jacob B.; Jalali, Bahram

2010-02-01

Bulk centrosymmetric silicon lacks second-order optical nonlinearity χ(2) - a foundational component of nonlinear optics. Here, we propose a new class of photonic device which enables χ(2) as well as quasi-phase matching based on periodic stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for devices based on χ(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50% based on χ(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature 441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With integrated piezoelectric material, dynamically control of χ(2)nonlinearity in PePSi waveguide may also be achieved. The successful realization of PePSi based devices depends on the strength of the stress induced χ(2) in silicon. Presently, there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We present a simple theoretical model that produces result consistent with prior theoretical works and use this model to identify possible reasons for this discrepancy.

Efficiency Enhancement of Silicon Solar Cells by Porous Silicon Technology

Directory of Open Access Journals (Sweden)

Eugenijus SHATKOVSKIS

2012-09-01

Full Text Available Silicon solar cells produced by a usual technology in p-type, crystalline silicon wafer were investigated. The manufactured solar cells were of total thickness 450 mm, the junction depth was of 0.5 mm – 0.7 mm. Porous silicon technologies were adapted to enhance cell efficiency. The production of porous silicon layer was carried out in HF: ethanol = 1 : 2 volume ratio electrolytes, illuminating by 50 W halogen lamps at the time of processing. The etching current was computer-controlled in the limits of (6 ÷ 14 mA/cm2, etching time was set in the interval of (10 ÷ 20 s. The characteristics and performance of the solar cells samples was carried out illuminating by Xenon 5000 K lamp light. Current-voltage characteristic studies have shown that porous silicon structures produced affect the extent of dark and lighting parameters of the samples. Exactly it affects current-voltage characteristic and serial resistance of the cells. It has shown, the formation of porous silicon structure causes an increase in the electric power created of solar cell. Conversion efficiency increases also respectively to the initial efficiency of cell. Increase of solar cell maximum power in 15 or even more percent is found. The highest increase in power have been observed in the spectral range of Dl @ (450 ÷ 850 nm, where ~ 60 % of the A1.5 spectra solar energy is located. It has been demonstrated that porous silicon technology is effective tool to improve the silicon solar cells performance.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2428

Chiral silicon nanostructures

International Nuclear Information System (INIS)

Schubert, E.; Fahlteich, J.; Hoeche, Th.; Wagner, G.; Rauschenbach, B.

2006-01-01

Glancing angle ion beam assisted deposition is used for the growth of amorphous silicon nanospirals onto [0 0 1] silicon substrates in a temperature range from room temperature to 475 deg. C. The nanostructures are post-growth annealed in an argon atmosphere at various temperatures ranging from 400 deg. C to 800 deg. C. Recrystallization of silicon within the persisting nanospiral configuration is demonstrated for annealing temperatures above 800 deg. C. Transmission electron microscopy and Raman spectroscopy are used to characterize the silicon samples prior and after temperature treatment

In vitro cytotoxicity of maxillofacial silicone elastomers: effect of accelerated aging.

Science.gov (United States)

Bal, Bilge Turhan; Yilmaz, Handan; Aydin, Cemal; Karakoca, Seçil; Yilmaz, Sükran

2009-04-01

The purpose of this in vitro study was to evaluate the cytotoxicity of three maxillofacial silicone elastomers at 24, 48, and 72 h on L-929 cells and to determine the effect of accelerated aging on the cytotoxicity of these silicone elastomers. Disc-shaped test samples of maxillofacial silicone elastomers (Cosmesil, Episil, Multisil) were fabricated according to manufacturers' instructions under aseptic conditions. Samples were then divided into three groups: (1) not aged; (2) aged for 150 h with an accelerated weathering tester; and (3) aged for 300 h. Then the samples were placed in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12) for 24, 48, and 72 h. After the incubation periods, cytotoxicity of the extracts to cultured fibroblasts (L-929) was measured by MTT assay. The degree of cytotoxicity of each sample was determined according to the reference value represented by the cells with a control (culture without sample). Statistical significance was determined by repeated measurement ANOVA (p test (p test materials in each group demonstrated high survival rates in MTT assay (Episil; 93.84%, Multisil; 88.30%, Cosmesil; 87.50%, respectively); however, in all groups, Episil material demonstrated significantly higher cell survival rate after each of the experimental incubation periods (p Accelerated aging for 150 and 300 h had no significant effect on the biocompatibility of maxillofacial silicone elastomers tested (p > 0.05).

N-Type delta Doping of High-Purity Silicon Imaging Arrays

Science.gov (United States)

Blacksberg, Jordana; Hoenk, Michael; Nikzad, Shouleh

2005-01-01

A process for n-type (electron-donor) delta doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays. Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac delta function (impulse function): the dopant is highly concentrated in a very thin layer. Preferably, the dopant is concentrated in one or at most two atomic layers in a crystal plane and, therefore, delta doping is also known as atomic-plane doping. The use of doping to enable detection of high-energy photons and low-energy particles was reported in several prior NASA Tech Briefs articles. As described in more detail in those articles, the main benefit afforded by delta doping of a back-illuminated silicon detector is to eliminate a "dead" layer at the back surface of the silicon wherein high-energy photons and low-energy particles are absorbed without detection. An additional benefit is that the delta-doped layer can serve as a back-side electrical contact. Delta doping of p-type silicon detectors is well established. The development of the present process addresses concerns specific to the delta doping of high-purity silicon detectors, which are typically n-type. The present process involves relatively low temperatures, is fully compatible with other processes used to fabricate the detectors, and does not entail interruption of those processes. Indeed, this process can be the last stage in the fabrication of an imaging detector that has, in all other respects, already been fully processed, including metallized. This process includes molecular-beam epitaxy (MBE) for deposition of three layers, including

Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition.

Science.gov (United States)

Ogawa, Tomohiro; Ezoe, Yuichiro; Moriyama, Teppei; Mitsuishi, Ikuyuki; Kakiuchi, Takuya; Ohashi, Takaya; Mitsuda, Kazuhisa; Putkonen, Matti

2013-08-20

To enhance x-ray reflectivity of silicon micropore optics using dry etching of silicon (111) wafers, iridium coating is tested by use of atomic layer deposition. An iridium layer is successfully formed on sidewalls of tiny micropores with a pore width of 20 μm and depth of 300 μm. The film thickness is ∼20  nm. An enhanced x-ray reflectivity compared to that of silicon is confirmed at Ti Kα 4.51 keV, for what we believe to be the first time, with this type of optics. Some discrepancies from a theoretical reflectivity curve of iridium-coated silicon are noticed at small incident angles <1.3°. When a geometrical shadowing effect due to occultation by a ridge existing on the sidewalls is taken into account, the observed reflectivity becomes well represented by the modified theoretical curve. An estimated surface micro roughness of ∼1  nm rms is consistent with atomic force microscope measurements of the sidewalls.

Protein attachment to silane-functionalized porous silicon: A comparison of electrostatic and covalent attachment.

Science.gov (United States)

Baranowska, Malgorzata; Slota, Agata J; Eravuchira, Pinkie J; Alba, Maria; Formentin, Pilar; Pallarès, Josep; Ferré-Borrull, Josep; Marsal, Lluís F

2015-08-15

Porous silicon (pSi) is a prosperous biomaterial, biocompatible, and biodegradable. Obtaining regularly functionalized pSi surfaces is required in many biotechnology applications. Silane-PEG-NHS (triethoxysilane-polyethylene-glycol-N-hydroxysuccinimide) is useful for single-molecule studies due to its ability to attach to only one biomolecule. We investigate the functionalization of pSi with silane-PEG-NHS and compare it with two common grafting agents: APTMS (3-aminopropylotrimethoxysilane) as electrostatic linker, and APTMS modified with glutaraldehyde as covalent spacer. We show the arrangement of two proteins (collagen and bovine serum albumin) as a function of the functionalization and of the pore size. FTIR is used to demonstrate correct functionalization while fluorescence confocal microscopy reveals that silane-PEG-NHS results in a more uniform protein distribution. Reflection interference spectroscopy (RIfS) is used to estimate the attachment of linker and proteins. The results open a way to obtain homogenous chemical modified silicon supports with a great value in biosensing, drug delivery and cell biology. Copyright © 2015 Elsevier Inc. All rights reserved.

Surface chemistry of a hydrogenated mesoporous p-type silicon

Energy Technology Data Exchange (ETDEWEB)

Media, El-Mahdi, E-mail: belhadidz@tahoo.fr; Outemzabet, Ratiba, E-mail: oratiba@hotmail.com

2017-02-15

of siloxanes/hydroxide, SiO{sub x}, and hydrides, SiH{sub x}, respectively. The results show clearly that the adsorbed species found in the final stage after an electrochemical treatment consist of surface hydrogen and they show also that the surface morphology is different compared to the starting one, which is considered as reference. It is clear that the H-terminated of porous silicon surface is hydrophobic in nature. The hydrophobic character of this surface makes difficult the grafting of a probe which serves to get other molecules; where from the necessity of the presence of a hydrophilic surface on the porous silicon surface. This will facilitate the penetration and the grafting of the molecules probes. So to improve the penetration and the grafting of the organic molecules or the immobilization of the probes on the hydrogenated mesoporous silicon surfaces under wet chemical conditions an intermediate step is required. In this second study, we use the following procedure. After the porosification of the silicon by electrochemical anodisation, the porous SiH layer returns a hydrophobic surface. This stage is a starting point of multistep scheme for the surface modification. The next step is the thermal hydrosilylation in order to have an acidic surface. The acidic surface was then modified by the chains of Poly(ethylene glycol) (PEG) which is a highly investigated polymer for the covalent modification of biological macromolecules and surfaces. The grafting of PEG returns a hydrophilic surface confirmed by the IR results.

Preparation and characterisation of immobilised humic acid on silicon wafer

International Nuclear Information System (INIS)

Szabo, Gy.; Guczi, J.; Telegdi, J.; Pashalidis, I.; Szymczak, W.; Buckau, G.

2005-01-01

Full text of publication follows: The chemistry of the interactions of radionuclides with humic acid needs to be understood in details so that humate-mediated migration of radionuclides through the environment can be predicted. To achieve such a data in microscopic scale, several detective techniques, such as atomic force microscopy (AFM), chemical force microscopy (CFM), nuclear microprobe analysis (NMA) and X-ray photoelectron spectroscopy (XPS) can be used to measure intermolecular forces and to visualize the surface morphology. The main aim of this work was to provide humic material with specific properties in order to study with different spectroscopic techniques, the complexation behaviour of surface bound humic acid in microscopic scale. Namely, humic acid has been immobilised on silicon wafers in order to mimic surface bound humic substances in natural aquatic systems. In this communication, we present a simple protocol to immobilize humic acid on silicon wafer surface. A tri-functional silane reagent 3-amino-propyl-tri-methoxy-silane (APTES) was used to modify the surface of silicon wafers and appeared to be able to strongly attached soluble humic acid through their carboxylic groups to solid support. Characterisation of the surfaces, after any preparation steps, was done by ATR-FTIR, AFM and TOF-SIMS. These methods have proved that the humic acid forms a relatively homogeneous layer on the wafers. Immobilisation of humic acid on silicon wafer was further proved by binding isotherm of Am/Nd. (authors)

Numerical analysis of thermal stress and dislocation density distributions in large size multi-crystalline silicon ingots during the seeded growth process

Science.gov (United States)

Nguyen, Thi Hoai Thu; Chen, Jyh-Chen; Hu, Chieh; Chen, Chun-Hung; Huang, Yen-Hao; Lin, Huang-Wei; Yu, Andy; Hsu, Bruce

2017-06-01

In this study, a global transient numerical simulation of silicon growth from the beginning of the solidification process until the end of the cooling process is carried out modeling the growth of an 800 kg ingot in an industrial seeded directional solidification furnace. The standard furnace is modified by the addition of insulating blocks in the hot zone. The simulation results show that there is a significant decrease in the thermal stress and dislocation density in the modified model as compared to the standard one (a maximal decrease of 23% and 75% along the center line of ingot for thermal stress and dislocation density, respectively). This modification reduces the heating power consumption for solidification of the silicon melt by about 17% and shortens the growth time by about 2.5 h. Moreover, it is found that adjusting the operating conditions of modified model to obtain the lower growth rate during the early stages of the solidification process can lower dislocation density and total heater power.

The chemistry of silicon

CERN Document Server

Rochow, E G; Emeléus, H J; Nyholm, Ronald

1975-01-01

Pergamon Texts in Organic Chemistry, Volume 9: The Chemistry of Silicon presents information essential in understanding the chemical properties of silicon. The book first covers the fundamental aspects of silicon, such as its nuclear, physical, and chemical properties. The text also details the history of silicon, its occurrence and distribution, and applications. Next, the selection enumerates the compounds and complexes of silicon, along with organosilicon compounds. The text will be of great interest to chemists and chemical engineers. Other researchers working on research study involving s

Influence of Silicon-Containing Additives on Concrete Waterproofness Property

Science.gov (United States)

Butakova, M. D.; Saribekyan, S. S.; Mikhaylov, A. V.

2017-11-01

The article studies the influence of silicon-containing additives on the property of the water resistance of concrete samples. It provides a review of the literature on common approaches and technologies improving concrete waterproofness and reinforced concrete structures. Normal hardening samples were obtained on the basis of concretes containing microsilica, aerosil or ash, or the combinations thereof. This research is aimed at the study of the complex modifier effect r on the basis of metakaolin, superplasticizer and silicon containing additives on the property of concrete water resistance. The need to use a superplasticizer to reduce the water-cement ratio and metakaolin as a hardening accelerator along with the set of strength is substantiated. This article describes a part of the results of the experiment conducted to find alternative options for colmatizing expensive additives used in the concreting foundations of private house-building. The implementation of the scientific work will not only clarify this area but will also broaden the knowledge of such additive as aerosol.

Study on the graphene/silicon Schottky diodes by transferring graphene transparent electrodes on silicon

International Nuclear Information System (INIS)

Wang, Xiaojuan; Li, Dong; Zhang, Qichong; Zou, Liping; Wang, Fengli; Zhou, Jun; Zhang, Zengxing

2015-01-01

Graphene/silicon heterostructures present a Schottky characteristic and have potential applications for solar cells and photodetectors. Here, we fabricated graphene/silicon heterostructures by using chemical vapor deposition derived graphene and n-type silicon, and studied the electronic and optoelectronic properties through varying their interface and silicon resistivity. The results exhibit that the properties of the fabricated configurations can be effectively modulated. The graphene/silicon heterostructures with a Si (111) interface and high resistivity show a better photovoltaic behavior and should be applied for high-performance photodetectors. With the combined atomic force microscopy and theoretical analysis, the possible origination is discussed. The work here should be helpful on exploring high-performance graphene/silicon photoelectronics. - Highlights: • Different graphene/silicon heterostructures were fabricated. • Electronic and optoelectronic properties of the heterostructures were studied. • Graphene/silicon heterostructures were further explored for photodetectors.

Study on the graphene/silicon Schottky diodes by transferring graphene transparent electrodes on silicon

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaojuan [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Li, Dong; Zhang, Qichong; Zou, Liping; Wang, Fengli [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Jun, E-mail: zhoujunzhou@tongji.edu.cn [Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Zhang, Zengxing, E-mail: zhangzx@tongji.edu.cn [MOE Key Laboratory of Advanced Micro-structured Materials & Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

2015-10-01

Graphene/silicon heterostructures present a Schottky characteristic and have potential applications for solar cells and photodetectors. Here, we fabricated graphene/silicon heterostructures by using chemical vapor deposition derived graphene and n-type silicon, and studied the electronic and optoelectronic properties through varying their interface and silicon resistivity. The results exhibit that the properties of the fabricated configurations can be effectively modulated. The graphene/silicon heterostructures with a Si (111) interface and high resistivity show a better photovoltaic behavior and should be applied for high-performance photodetectors. With the combined atomic force microscopy and theoretical analysis, the possible origination is discussed. The work here should be helpful on exploring high-performance graphene/silicon photoelectronics. - Highlights: • Different graphene/silicon heterostructures were fabricated. • Electronic and optoelectronic properties of the heterostructures were studied. • Graphene/silicon heterostructures were further explored for photodetectors.

Adsorption of Hydrophobically Modified Polyelectrolytes on Hydrophobic Substrates Adsorption de polyélectrolytes modifiés hydrophobiquement sur les substrats hydrophobes

Directory of Open Access Journals (Sweden)

Mays J. W.

2006-12-01

Full Text Available A series of diblock copolymers, poly (tert-butyl styrene-sodium poly (styrene sulfonate with different molecular weight and percentage of sulfonation have been used to study the effect of polymer structure on its adsorption behavior onto hydrophobically modified silicon wafers. The percentage of the hydrophobic block varies from 3. 6-8. 9%. Previous studies show that salt concentration is very important for the adsorption of such polyelectrolytes onto silica surfaces. Octadecyltriethoxysilane (OTE has been used to modify the silicon wafer which changes the water contact angle from 50° on unmodified silica to 100° to 120°. On this hydrophobic surface, we found that the adsorption of these slightly hydrophobically modified polyelectrolytes is close to the 4/23rd power of salt concentration predicted by a recent model. The grafting density is also consistent with a dependence on the length of the hydrophobic block to the -12/23rd power, and the length of the polyelectrolyte block to the -6/23rd power, predicted by this model. Une série de copolymères à diblocs poly (tert-butyle styrène-sodium (sulfonate de polystyrène de masses moléculaires et pourcentages de sulfonation différents ont été utilisés pour étudier les effets de la structure du polymère sur son pouvoir d'adsorption sur des surfaces de silicium modifiées hydrophobiquement. Le pourcentage du bloc hydrophobe varie de 3,6 à 8,9%. Les études antérieures montrent que la concentration saline est très importante pour l'adsorption de ces polyélectrolytes sur les surfaces de silice. Nous avons utilisé l'octadecyltriéthoxysilane (OTE pour modifier la surface de silicium qui change l'angle de contact de l'eau de 50° sur la silice non modifiée à une valeur comprise entre 100° et 120° sur la silice modifiée. Sur cette surface hydrophobe, nous constatons que l'adsorption de ces polyélectrolytes légèrement modifiés hydrophobiquement est proche de la loi puissance 4

Interaction of human endothelial cells and nickel-titanium materials modified with silicon ions

Energy Technology Data Exchange (ETDEWEB)

Lotkov, Aleksandr I., E-mail: lotkov@ispms.tsc.ru; Kashin, Oleg A., E-mail: okashin@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Kudryavtseva, Yuliya A., E-mail: yulia-k1970@mail.ru; Antonova, Larisa V., E-mail: antonova.la@mail.ru; Matveeva, Vera G., E-mail: matveeva-vg@mail.ru; Sergeeva, Evgeniya A., E-mail: sergeewa.ew@yandex.ru [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, 650002 (Russian Federation); Kudryashov, Andrey N., E-mail: kudryashov@angioline.ru [Angioline Interventional Device Ltd, Novosibirsk, 630090 (Russian Federation)

2015-10-27

The paper studies the influence of chemical and phase compositions of NiTi surface layers modified with Si ions by plasma immersion implantation on their interaction with endothelial cells. It is shown that certain technological modes of Si ion implantation enhance the adhesion, proliferation, and viability of endothelial cells. It is found that the Si-modified NiTi surface is capable of stimulating the formation of capillary-like structures in the cell culture.

PNA-PEG modified silicon platforms as functional bio-interfaces for applications in DNA microarrays and biosensors.

Science.gov (United States)

Cattani-Scholz, Anna; Pedone, Daniel; Blobner, Florian; Abstreiter, Gerhard; Schwartz, Jeffrey; Tornow, Marc; Andruzzi, Luisa

2009-03-09

The synthesis and characterization of two types of silicon-based biofunctional interfaces are reported; each interface bonds a dense layer of poly(ethylene glycol) (PEG(n)) and peptide nucleic acid (PNA) probes. Phosphonate self-assembled monolayers were derivatized with PNA using a maleimido-terminated PEG(45). Similarly, siloxane monolayers were functionalized with PNA using a maleimido-terminated PEG(45) spacer and were subsequently modified with a shorter methoxy-terminated PEG(12) ("back-filling"). The long PEG(45) spacer was used to distance the PNA probe from the surface and to minimize undesirable nonspecific adsorption of DNA analyte. The short PEG(12) "back-filler" was used to provide additional passivation of the surface against nonspecific DNA adsorption. X-ray photoelectron spectroscopic (XPS) analysis near the C 1s and N 1s ionization edges was done to characterize chemical groups formed in the near-surface region, which confirmed binding of PEG and PNA to the phosphonate and silane films. XPS also indicated that additional PEG chains were tethered to the surface during the back-filling process. Fluorescence hybridization experiments were carried out with complementary and noncDNA strands; both phosphonate and siloxane biofunctional surfaces were effective for hybridization of cDNA strands and significantly reduced nonspecific adsorption of the analyte. Spatial patterns were prepared by polydimethylsiloxane (PDMS) micromolding on the PNA-functionalized surfaces; selective hybridization of fluorescently labeled DNA was shown at the PNA functionalized regions, and physisorption at the probe-less PEG-functionalized regions was dramatically reduced. These results show that PNA-PEG derivatized phosphonate monolayers hold promise for the smooth integration of device surface chemistry with semiconductor technology for the fabrication of DNA biosensors. In addition, our results confirm that PNA-PEG derivatized self-assembled carboxyalkylsiloxane films are

Optimization and characterization of biomolecule immobilization on silicon substrates using (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde linker

International Nuclear Information System (INIS)

Gunda, Naga Siva Kumar; Singh, Minashree; Norman, Lana; Kaur, Kamaljit; Mitra, Sushanta K.

2014-01-01

In the present work, we developed and optimized a technique to produce a thin, stable silane layer on silicon substrate in a controlled environment using (3-aminopropyl)triethoxysilane (APTES). The effect of APTES concentration and silanization time on the formation of silane layer is studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy (FTIR). Biomolecules of interest are immobilized on optimized silane layer formed silicon substrates using glutaraldehyde linker. Surface analytical techniques such as ellipsometry, FTIR, contact angle measurement system, and atomic force microscopy are employed to characterize the bio-chemically modified silicon surfaces at each step of the biomolecule immobilization process. It is observed that a uniform, homogenous and highly dense layer of biomolecules are immobilized with optimized silane layer on the silicon substrate. The developed immobilization method is successfully implemented on different silicon substrates (flat and pillar). Also, different types of biomolecules such as anti-human IgG (rabbit monoclonal to human IgG), Listeria monocytogenes, myoglobin and dengue capture antibodies were successfully immobilized. Further, standard sandwich immunoassay (antibody–antigen–antibody) is employed on respective capture antibody coated silicon substrates. Fluorescence microscopy is used to detect the respective FITC tagged detection antibodies bound to the surface after immunoassay.

Optimization and characterization of biomolecule immobilization on silicon substrates using (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde linker

Energy Technology Data Exchange (ETDEWEB)

Gunda, Naga Siva Kumar [Department of Mechanical Engineering, University of Alberta, Edmonton, Canada T6G 2G8 (Canada); Singh, Minashree [Department of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada T6G 1C9 (Canada); Norman, Lana [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada T6G 2V4 (Canada); Kaur, Kamaljit [Department of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada T6G 1C9 (Canada); Mitra, Sushanta K., E-mail: sushanta.mitra@ualberta.ca [Department of Mechanical Engineering, University of Alberta, Edmonton, Canada T6G 2G8 (Canada)

2014-06-01

In the present work, we developed and optimized a technique to produce a thin, stable silane layer on silicon substrate in a controlled environment using (3-aminopropyl)triethoxysilane (APTES). The effect of APTES concentration and silanization time on the formation of silane layer is studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy (FTIR). Biomolecules of interest are immobilized on optimized silane layer formed silicon substrates using glutaraldehyde linker. Surface analytical techniques such as ellipsometry, FTIR, contact angle measurement system, and atomic force microscopy are employed to characterize the bio-chemically modified silicon surfaces at each step of the biomolecule immobilization process. It is observed that a uniform, homogenous and highly dense layer of biomolecules are immobilized with optimized silane layer on the silicon substrate. The developed immobilization method is successfully implemented on different silicon substrates (flat and pillar). Also, different types of biomolecules such as anti-human IgG (rabbit monoclonal to human IgG), Listeria monocytogenes, myoglobin and dengue capture antibodies were successfully immobilized. Further, standard sandwich immunoassay (antibody–antigen–antibody) is employed on respective capture antibody coated silicon substrates. Fluorescence microscopy is used to detect the respective FITC tagged detection antibodies bound to the surface after immunoassay.

Irradiation effects of swift heavy ions on gallium arsenide, silicon and silicon diodes

International Nuclear Information System (INIS)

Bhoraskar, V.N.

2001-01-01

The irradiation effects of high energy lithium, boron, oxygen and silicon ions on crystalline silicon, gallium arsenide, porous silicon and silicon diodes were investigated. The ion energy and fluence were varied over the ranges 30 to 100 MeV and 10 11 to 10 14 ions/cm 2 respectively. Semiconductor samples were characterized with the x-ray fluorescence, photoluminescence, thermally stimulated exo-electron emission and optical reflectivity techniques. The life-time of minority carriers in crystalline silicon was measured with a pulsed electron beam and the lithium depth distribution in GaAs was measured with the neutron depth profiling technique. The diodes were characterized through electrical measurements. The results of optical reflectivity, life-time of minority carriers and photoluminescence show that swift heavy ions induce defects in the surface region of crystalline silicon. In the ion-irradiated GaAs, migration of silicon, oxygen and lithium atoms from the buried region towards the surface was observed, with orders of magnitude enhancement in the diffusion coefficients. Enhancement in the photoluminescence intensity was observed in the GaAs and porous silicon samples that, were irradiated with silicon ions. The trade-off between the turn-off time and the voltage, drop in diodes irradiated with different swift heavy ions was also studied. (author)

Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

Energy Technology Data Exchange (ETDEWEB)

Sundberg, G.J.; Vartabedian, A.M.; Wade, J.A.; White, C.S. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

1994-10-01

The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.

Hydrogen in amorphous silicon

International Nuclear Information System (INIS)

Peercy, P.S.

1980-01-01

The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

A convenient way of manufacturing silicon nanotubes on a silicon substrate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Changchang; Cheng, Heming; Liu, Xiang, E-mail: liuxiang@ahut.edu.cn

2016-07-01

A convenient approach of preparing silicon nanotubes (SiNTs) on a silicon substrate is described in this work in detail. Firstly, a porous silicon (PSi) slice is prepared by a galvanic displacement reaction. Then it is put into aqueous solutions of 20% (w%) ammonium fluoride and 2.5 mM cobalt nitrate for a predetermined time. The cobalt ions are reduced and the resulted cobalt particles are deposited on the PSi slice. After the cobalt particles are removed with 5 M nitric acid a plenty of SiNTs come out and exhibit disorderly on the silicon substrate, which are illustrated by scanning electron microscopy (SEM). The compositions of the SiNTs are examined by energy-dispersive X-ray spectroscopy. Based on the SEM images, a suggested mechanism is put forward to explain the generation of the SiNTs on the PSi substrate. - Highlights: • A facile approach of preparing silicon nano tubes was invented. • The experimental results demonstrated the strong reducibility of Si-H{sub x} species. • It provided a new way of manufacturing silicon-contained hybrids.

Development of Radiation Hard Radiation Detectors, Differences between Czochralski Silicon and Float Zone Silicon

CERN Document Server

Tuominen, Eija

2012-01-01

The purpose of this work was to develop radiation hard silicon detectors. Radiation detectors made ofsilicon are cost effective and have excellent position resolution. Therefore, they are widely used fortrack finding and particle analysis in large high-energy physics experiments. Silicon detectors willalso be used in the CMS (Compact Muon Solenoid) experiment that is being built at the LHC (LargeHadron Collider) accelerator at CERN (European Organisation for Nuclear Research). This work wasdone in the CMS programme of Helsinki Institute of Physics (HIP).Exposure of the silicon material to particle radiation causes irreversible defects that deteriorate theperformance of the silicon detectors. In HIP CMS Programme, our approach was to improve theradiation hardness of the silicon material with increased oxygen concentration in silicon material. Westudied two different methods: diffusion oxygenation of Float Zone silicon and use of high resistivityCzochralski silicon.We processed, characterised, tested in a parti...

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

Science.gov (United States)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Synthesis and luminescent properties of a novel green-emitting Tb (Ⅲ) complex based on amino-modified fluorine silicone oil and isophorone diisocyanate

Science.gov (United States)

Hao, Haixia; Chu, Yang; Yu, Zhenjiang; Xie, Hongde; Seo, Hyo Jin

2017-10-01

The novel luminescent polymer-rare earth complexes, denoted as (PFSi-IPDI)-Tb(Ⅲ)-Phen, have been successfully synthesized and can be made into flexible films. Amino-modified fluorine silicone oil-isophorone diisocyanate (PFSi-IPDI) was used as the host macromolecular ligand, and 1, 10-Phenanthroline (Phen) as the secondary small-molecular co-ligand. The luminescent lanthanide complexes were characterized by fourier transform infrared (FITR), scanning electron microscope (SEM), thermogravimetric analysis (TGA). The luminescent properties were investigated through photoluminescence excitation (PLE) and emission (PL) spectroscopy. FTIR analysis verifies the successful preparation and integration of PFSi-IPDI to Tb3+. The comparatively uniform morphological structure can be observed in the images of SEM. The polymer-rare earth complexes display the typical luminescence emission peaks under the excitation wavelength of 330 nm. From the decay curve, the short lifetime (about 0.89 ms) is observed for (PFSi-IPDI)-Tb(Ⅲ)-Phen (0.6 mol/L). Moreover, these luminescent polymer-rare earth complexes possess superior thermal stability (T5 > 195 °C). All the interesting results suggest the potential application of the luminescent polymer-rare earth complexes in green-emitting luminescent materials under high temperature.

The Semiconductor Industry and Emerging Technologies: A Study Using a Modified Delphi Method

Science.gov (United States)

Jordan, Edgar A.

2010-01-01

The purpose of this qualitative descriptive study was to determine what leaders in the semiconductor industry thought the future of computing would look like and what emerging materials showed the most promise to overcome the current theoretical limit of 10 nanometers for silicon dioxide. The researcher used a modified Delphi technique in two…

Methods To Determine the Silicone Oil Layer Thickness in Sprayed-On Siliconized Syringes.

Science.gov (United States)

Loosli, Viviane; Germershaus, Oliver; Steinberg, Henrik; Dreher, Sascha; Grauschopf, Ulla; Funke, Stefanie

2018-01-01

The silicone lubricant layer in prefilled syringes has been investigated with regards to siliconization process performance, prefilled syringe functionality, and drug product attributes, such as subvisible particle levels, in several studies in the past. However, adequate methods to characterize the silicone oil layer thickness and distribution are limited, and systematic evaluation is missing. In this study, white light interferometry was evaluated to close this gap in method understanding. White light interferometry demonstrated a good accuracy of 93-99% for MgF 2 coated, curved standards covering a thickness range of 115-473 nm. Thickness measurements for sprayed-on siliconized prefilled syringes with different representative silicone oil distribution patterns (homogeneous, pronounced siliconization at flange or needle side, respectively) showed high instrument (0.5%) and analyst precision (4.1%). Different white light interferometry instrument parameters (autofocus, protective shield, syringe barrel dimensions input, type of non-siliconized syringe used as base reference) had no significant impact on the measured average layer thickness. The obtained values from white light interferometry applying a fully developed method (12 radial lines, 50 mm measurement distance, 50 measurements points) were in agreement with orthogonal results from combined white and laser interferometry and 3D-laser scanning microscopy. The investigated syringe batches (lot A and B) exhibited comparable longitudinal silicone oil layer thicknesses ranging from 170-190 nm to 90-100 nm from flange to tip and homogeneously distributed silicone layers over the syringe barrel circumference (110- 135 nm). Empty break-loose (4-4.5 N) and gliding forces (2-2.5 N) were comparably low for both analyzed syringe lots. A silicone oil layer thickness of 100-200 nm was thus sufficient for adequate functionality in this particular study. Filling the syringe with a surrogate solution including short

Improved Work Function of Poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonic acid) and its Effect on Hybrid Silicon/Organic Heterojunction Solar Cells

Science.gov (United States)

Shen, Xiaojuan; Chen, Ling; Pan, Jianmei; Hu, Yue; Li, Songjun; Zhao, Jie

2016-11-01

Hybrid silicon/organic solar cells have been recently extensively investigated due to their simple structure and low-cost fabrication process. However, the efficiency of the solar cells is greatly limited by the barrier height as well as the carrier recombination at the silicon/organic interface. In this work, hydrochloroplatinic acid (H2PtCl6) is employed into the poly(3,4-ethlenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution, and the work function (WF) of the PEDOT:PSS layer has been successfully improved. Based on the Pt-modified PEDOT:PSS layer, the efficiency of the silicon/PEDOT:PSS cell can be increased to 11.46%, corresponding to 20% enhancement to the one without platinum (Pt) modification. Theoretical and experimental results show that, when increasing the WF of the PEDO:PSS layer, the barrier height between the silicon/PEDOT:PSS interface can be effectively enhanced. Meanwhile, the carrier recombination at the interface is significantly reduced. These results can contribute to better understanding of the interfacial mechanism of silicon/PEDOT:PSS interface, and further improving the device performance of silicon/organic solar cells.

CHARACTERIZATION OF THE ELECTROPHYSICAL PROPERTIES OF SILICON-SILICON DIOXIDE INTERFACE USING PROBE ELECTROMETRY METHODS

Directory of Open Access Journals (Sweden)

V. А. Pilipenko

2017-01-01

Full Text Available Introduction of submicron design standards into microelectronic industry and a decrease of the gate dielectric thickness raise the importance of the analysis of microinhomogeneities in the silicon-silicon dioxide system. However, there is very little to no information on practical implementation of probe electrometry methods, and particularly scanning Kelvin probe method, in the interoperational control of real semiconductor manufacturing process. The purpose of the study was the development of methods for nondestructive testing of semiconductor wafers based on the determination of electrophysical properties of the silicon-silicon dioxide interface and their spatial distribution over wafer’s surface using non-contact probe electrometry methods.Traditional C-V curve analysis and scanning Kelvin probe method were used to characterize silicon- silicon dioxide interface. The samples under testing were silicon wafers of KEF 4.5 and KDB 12 type (orientation <100>, diameter 100 mm.Probe electrometry results revealed uniform spatial distribution of wafer’s surface potential after its preliminary rapid thermal treatment. Silicon-silicon dioxide electric potential values were also higher after treatment than before it. This potential growth correlates with the drop in interface charge density. At the same time local changes in surface potential indicate changes in surface layer structure.Probe electrometry results qualitatively reflect changes of interface charge density in silicon-silicon dioxide structure during its technological treatment. Inhomogeneities of surface potential distribution reflect inhomogeneity of damaged layer thickness and can be used as a means for localization of interface treatment defects.

Silicon microphotonic waveguides

International Nuclear Information System (INIS)

Ta'eed, V.; Steel, M.J.; Grillet, C.; Eggleton, B.; Du, J.; Glasscock, J.; Savvides, N.

2004-01-01

Full text: Silicon microphotonic devices have been drawing increasing attention in the past few years. The high index-difference between silicon and its oxide (Δn = 2) suggests a potential for high-density integration of optical functions on to a photonic chip. Additionally, it has been shown that silicon exhibits strong Raman nonlinearity, a necessary property as light interaction can occur only by means of nonlinearities in the propagation medium. The small dimensions of silicon waveguides require the design of efficient tapers to couple light to them. We have used the beam propagation method (RSoft BeamPROP) to understand the principles and design of an inverse-taper mode-converter as implemented in several recent papers. We report on progress in the design and fabrication of silicon-based waveguides. Preliminary work has been conducted by patterning silicon-on-insulator (SOI) wafers using optical lithography and reactive ion etching. Thus far, only rib waveguides have been designed, as single-mode ridge-waveguides are beyond the capabilities of conventional optical lithography. We have recently moved to electron beam lithography as the higher resolutions permitted will provide the flexibility to begin fabricating sub-micron waveguides

Porous Silicon Structures as Optical Gas Sensors.

Science.gov (United States)

Levitsky, Igor A

2015-08-14

We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers) are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

Temporary surface passivation for characterisation of bulk defects in silicon : a review

OpenAIRE

Grant, Nicholas E.; Murphy, John D.

2017-01-01

Accurate measurements of the bulk minority carrier lifetime in high-quality silicon materials is challenging due to the influence of surface recombination. Conventional surface passivation processes such as thermal oxidation or dielectric deposition often modify the bulk lifetime significantly before measurement. Temporary surface passivation processes at room or very low temperatures enable a more accurate measurement of the true bulk lifetime, as they limit thermal reconfiguration of bulk d...

Multiscale modeling of electroosmotic flow: Effects of discrete ion, enhanced viscosity, and surface friction

Science.gov (United States)

Bhadauria, Ravi; Aluru, N. R.

2017-05-01

We propose an isothermal, one-dimensional, electroosmotic flow model for slit-shaped nanochannels. Nanoscale confinement effects are embedded into the transport model by incorporating the spatially varying solvent and ion concentration profiles that correspond to the electrochemical potential of mean force. The local viscosity is dependent on the solvent local density and is modeled using the local average density method. Excess contributions to the local viscosity are included using the Onsager-Fuoss expression that is dependent on the local ionic strength. A Dirichlet-type boundary condition is provided in the form of the slip velocity that is dependent on the macroscopic interfacial friction. This solvent-surface specific interfacial friction is estimated using a dynamical generalized Langevin equation based framework. The electroosmotic flow of Na+ and Cl- as single counterions and NaCl salt solvated in Extended Simple Point Charge (SPC/E) water confined between graphene and silicon slit-shaped nanochannels are considered as examples. The proposed model yields a good quantitative agreement with the solvent velocity profiles obtained from the non-equilibrium molecular dynamics simulations.

Ceramic silicon-boron-carbon fibers from organic silicon-boron-polymers

Science.gov (United States)

Riccitiello, Salvatore R. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

1993-01-01

Novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers are discussed. The ceramic fibers are thermally stable up to and beyond 1200 C in air. The method of preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymer of the general formula Si(R2)BR(sup 1) includes melt-spinning, crosslinking, and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200 C, from 1200 to 1300 C, and in some cases higher than 1300 C.

Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Pradeepkumar, Aiswarya; Mishra, Neeraj; Kermany, Atieh Ranjbar; Iacopi, Francesca [Queensland Micro and Nanotechnology Centre and Environmental Futures Research Institute, Griffith University, Nathan QLD 4111 (Australia); Boeckl, John J. [Materials and Manufacturing Directorate, Air Force Research Laboratories, Wright-Patterson Air Force Base, Ohio 45433 (United States); Hellerstedt, Jack; Fuhrer, Michael S. [Monash Centre for Atomically Thin Materials, Monash University, Monash, VIC 3800 (Australia)

2016-07-04

Epitaxial cubic silicon carbide on silicon is of high potential technological relevance for the integration of a wide range of applications and materials with silicon technologies, such as micro electro mechanical systems, wide-bandgap electronics, and graphene. The hetero-epitaxial system engenders mechanical stresses at least up to a GPa, pressures making it extremely challenging to maintain the integrity of the silicon carbide/silicon interface. In this work, we investigate the stability of said interface and we find that high temperature annealing leads to a loss of integrity. High–resolution transmission electron microscopy analysis shows a morphologically degraded SiC/Si interface, while mechanical stress measurements indicate considerable relaxation of the interfacial stress. From an electrical point of view, the diode behaviour of the initial p-Si/n-SiC junction is catastrophically lost due to considerable inter-diffusion of atoms and charges across the interface upon annealing. Temperature dependent transport measurements confirm a severe electrical shorting of the epitaxial silicon carbide to the underlying substrate, indicating vast predominance of the silicon carriers in lateral transport above 25 K. This finding has crucial consequences on the integration of epitaxial silicon carbide on silicon and its potential applications.

Memory characteristics of silicon nitride with silicon nanocrystals as a charge trapping layer of nonvolatile memory devices

International Nuclear Information System (INIS)

Choi, Sangmoo; Yang, Hyundeok; Chang, Man; Baek, Sungkweon; Hwang, Hyunsang; Jeon, Sanghun; Kim, Juhyung; Kim, Chungwoo

2005-01-01

Silicon nitride with silicon nanocrystals formed by low-energy silicon plasma immersion ion implantation has been investigated as a charge trapping layer of a polycrystalline silicon-oxide-nitride-oxide-silicon-type nonvolatile memory device. Compared with the control sample without silicon nanocrystals, silicon nitride with silicon nanocrystals provides excellent memory characteristics, such as larger width of capacitance-voltage hysteresis, higher program/erase speed, and lower charge loss rate at elevated temperature. These improved memory characteristics are derived by incorporation of silicon nanocrystals into the charge trapping layer as additional accessible charge traps with a deeper effective trap energy level

Thermally promoted addition of undecylenic acid on thermally hydrocarbonized porous silicon optical reflectors

OpenAIRE

Jalkanen, Tero; Mäkilä, Ermei; Sakka, Tetsuo; Salonen, Jarno; Ogata, Yukio H

2012-01-01

Thermally promoted addition of undecylenic acid is studied as a method for modifying porous silicon optical reflectors that have been pre-treated with thermal hydrocarbonization. Successful derivatization of undecylenic acid is demonstrated and confirmed with Fourier transform infrared and X-ray photoelectron spectroscopies. The results indicate that the hydrocarbonization pre-treatment considerably improves stability against oxidation and chemical dissolution in basic environments. The two-s...

Preparation, Characterization, Thermal, and Flame-Retardant Properties of Green Silicon-Containing Epoxy/Functionalized Graphene Nanosheets Composites

Directory of Open Access Journals (Sweden)

Ming-Yuan Shen

2013-01-01

Full Text Available In this investigation, silane was grafted onto the surface of graphene nanosheets (GNSs through free radical reactions, to form Si-O-Et functional groups that can undergo the sol-gel reaction. To improve the compatibility between the polymer matrix and the fillers, epoxy monomer was modified using a silane coupling agent; then, the functionalized GNSs were added to the modified epoxy to improve the thermal stability and strengthen the flame-retardant character of the composites. High-resolution X-ray photoelectron spectrometry reveals that when the double bonds in VTES are grafted to the surfaces of GNSs. Solid-state 29Si nuclear magnetic resonance presents that the distribution of the signal associated with the T3 structure is wide and significant, indicating that the functionalization reaction of the silicone in the modified epoxy and VTES-GNSs increases the network-like character of the structures. Thermal gravimetric analysis, the integral procedure decomposition temperature, and limiting oxygen index demonstrate that the GNSs composites that contained silicon had a higher thermal stability and stronger flame-retardant character than pure epoxy. The dynamic storage modulus of all of the m-GNSs containing composites was significantly higher than that of the control epoxy, and the modulus of the composites increased with the concentration of m-GNSs.

Use of hydroxypropylmethylcellulose 2% for removing adherent silicone oil from silicone intraocular lenses

OpenAIRE

Wong , S Chien; Ramkissoon , Yashin D; Lopez , Mauricio; Page , Kristopher; Parkin , Ivan P; Sullivan , Paul M

2009-01-01

Abstract Background / aims: To investigate the effect of hydroxypropylmethylcellulose (HPMC) on the physical interaction (contact angle) between silicone oil and a silicone intraocular lens (IOL). Methods: In vitro experiments were performed, to determine the effect of HPMC (0.5%, 1% or 2%), with or without an additional simple mechanical manoeuvre, on the contact angle of silicone oil at the surface of both silicone and acrylic (control) IOLs. A balanced salt solu...

Single-Event Effects in Silicon and Silicon Carbide Power Devices

Science.gov (United States)

Lauenstein, Jean-Marie; Casey, Megan C.; LaBel, Kenneth A.; Topper, Alyson D.; Wilcox, Edward P.; Kim, Hak; Phan, Anthony M.

2014-01-01

NASA Electronics Parts and Packaging program-funded activities over the past year on single-event effects in silicon and silicon carbide power devices are presented, with focus on SiC device failure signatures.

Testing of the effect of the entry beam tube windows of the silicon detectors of the ionisation radiation

International Nuclear Information System (INIS)

Kopestansky, J.; Tykva, R.; Stanek, S.

1995-01-01

This paper deals with testing of the entry beam tube windows of the silicon detectors of the ionisation radiation with surface barrier.The influence of the parameters of basic material and modified technologic preparation on the size and homogeneity of the windows was tested

An improved PIN photodetector with integrated JFET on high-resistivity silicon

International Nuclear Information System (INIS)

Dalla Betta, Gian-Franco; Piemonte, Claudio; Boscardin, Maurizio; Gregori, Paolo; Zorzi, Nicola; Fazzi, Alberto; Pignatel, Giorgio U.

2006-01-01

We report on a PIN photodetector integrated with a Junction Field Effect Transistor (JFET) on a high-resistivity silicon substrate. Owing to a modified fabrication technology, the electrical and noise characteristics of the JFET transistor have been enhanced with respect to the previous versions of the device, allowing the performance to be significantly improved. In this paper, the main design and technological aspects relevant to the proposed structure are addressed and experimental results from the electrical characterization are discussed

Porous Silicon Nanowires

Science.gov (United States)

Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

2011-01-01

In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

Formation of multiple levels of porous silicon for buried insulators and conductors in silicon device technologies

Science.gov (United States)

Blewer, Robert S.; Gullinger, Terry R.; Kelly, Michael J.; Tsao, Sylvia S.

1991-01-01

A method of forming a multiple level porous silicon substrate for semiconductor integrated circuits including anodizing non-porous silicon layers of a multi-layer silicon substrate to form multiple levels of porous silicon. At least one porous silicon layer is then oxidized to form an insulating layer and at least one other layer of porous silicon beneath the insulating layer is metallized to form a buried conductive layer. Preferably the insulating layer and conductive layer are separated by an anodization barrier formed of non-porous silicon. By etching through the anodization barrier and subsequently forming a metallized conductive layer, a fully or partially insulated buried conductor may be fabricated under single crystal silicon.

Oxygen recoil implant from SiO2 layers into single-crystalline silicon

International Nuclear Information System (INIS)

Wang, G.; Chen, Y.; Li, D.; Oak, S.; Srivastav, G.; Banerjee, S.; Tasch, A.; Merrill, P.; Bleiler, R.

2001-01-01

It is important to understand the distribution of recoil-implanted atoms and the impact on device performance when ion implantation is performed at a high dose through surface materials into single crystalline silicon. For example, in ultralarge scale integration impurity ions are often implanted through a thin layer of screen oxide and some of the oxygen atoms are inevitably recoil implanted into single-crystalline silicon. Theoretical and experimental studies have been performed to investigate this phenomenon. We have modified the Monte Carlo ion implant simulator, UT-Marlowe (B. Obradovic, G. Wang, Y. Chen, D. Li, C. Snell, and A. F. Tasch, UT-MARLOWE Manual, 1999), which is based on the binary collision approximation, to follow the full cascade and to dynamically modify the stoichiometry of the Si layer as oxygen atoms are knocked into it. CPU reduction techniques are used to relieve the demand on computational power when such a full cascade simulation is involved. Secondary ion mass spectrometry (SIMS) profiles of oxygen have been carefully obtained for high dose As and BF 2 implants at different energies through oxide layers of various thicknesses, and the simulated oxygen profiles are found to agree very well with the SIMS data. [copyright] 2001 American Institute of Physics

Silicon: electrochemistry and luminescence

NARCIS (Netherlands)

Kooij, Ernst Stefan

1997-01-01

The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

Polycrystalline Silicon Gettered by Porous Silicon and Heavy Phosphorous Diffusion

Institute of Scientific and Technical Information of China (English)

LIU Zuming(刘祖明); Souleymane K Traore; ZHANG Zhongwen(张忠文); LUO Yi(罗毅)

2004-01-01

The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utilization is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the cost, is to increase the minority carrier lifetime by controlling the material defects. The main defects in grain boundaries of polycrystalline silicon gettered by porous silicon and heavy phosphorous diffusion have been studied. The porous silicon was formed on the two surfaces of wafers by chemical etching. Phosphorous was then diffused into the wafers at high temperature (900℃). After the porous silicon and diffusion layers were removed, the minority carrier lifetime was measured by photo-conductor decay. The results show that the lifetime's minority carriers are increased greatly after such treatment.

Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration

Directory of Open Access Journals (Sweden)

Xiaogang Jian

2013-03-01

Full Text Available The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zone I, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zone II about 15 to 20 祄 from the ultrasonic probe/radiator. The bulk of the ingot is in zone III and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 祄 in zone I, 25 to 35 祄 in zone II, and 25 to 55 祄 in zone III. The morphology of the primary ?Al phase is also changed from dendritic (in untreated samples to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.

Understanding and controlling the step bunching instability in aqueous silicon etching

Science.gov (United States)

Bao, Hailing

Chemical etching of silicon has been widely used for more than half a century in the semiconductor industry. It not only forms the basis for current wafer cleaning processes, it also serves as a powerful tool to create a variety of surface morphologies for different applications. Its potential for controlling surface morphology at the atomic scale over micron-size regions is especially appealing. In spite of its wide usage, the chemistry of silicon etching is poorly understood. Many seemingly simple but fundamental questions have not been answered. As a result, the development of new etchants and new etching protocols are based on expensive and tedious trial-and-error experiments. A better understanding of the etching mechanism would direct the rational formulation of new etchants that produce controlled etch morphologies. Particularly, micron-scale step bunches spontaneously develop on the vicinal Si(111) surface etched in KOH or other anisotropic aqueous etchants. The ability to control the size, orientation, density and regularity of these surface features would greatly improve the performance of microelectromechanical devices. This study is directed towards understanding the chemistry and step bunching instability in aqueous anisotropic etching of silicon through a combination of experimental techniques and theoretical simulations. To reveal the cause of step-bunching instability, kinetic Monte Carlo simulations were constructed based on an atomistic model of the silicon lattice and a modified kinematic wave theory. The simulations showed that inhomogeneity was the origin of step-bunching, which was confirmed through STM studies of etch morphologies created under controlled flow conditions. To quantify the size of the inhomogeneities in different etchants and to clarify their effects, a five-parallel-trench pattern was fabricated. This pattern used a nitride mask to protect most regions of the wafer; five evenly spaced etch windows were opened to the Si(110

Thermoelectric characteristics of Pt-silicide/silicon multi-layer structured p-type silicon

International Nuclear Information System (INIS)

Choi, Wonchul; Jun, Dongseok; Kim, Soojung; Shin, Mincheol; Jang, Moongyu

2015-01-01

Electric and thermoelectric properties of silicide/silicon multi-layer structured devices were investigated with the variation of silicide/silicon heterojunction numbers from 3 to 12 layers. For the fabrication of silicide/silicon multi-layered structure, platinum and silicon layers are repeatedly sputtered on the (100) silicon bulk substrate and rapid thermal annealing is carried out for the silicidation. The manufactured devices show ohmic current–voltage (I–V) characteristics. The Seebeck coefficient of bulk Si is evaluated as 195.8 ± 15.3 μV/K at 300 K, whereas the 12 layered silicide/silicon multi-layer structured device is evaluated as 201.8 ± 9.1 μV/K. As the temperature increases to 400 K, the Seebeck coefficient increases to 237.2 ± 4.7 μV/K and 277.0 ± 1.1 μV/K for bulk and 12 layered devices, respectively. The increase of Seebeck coefficient in multi-layered structure is mainly attributed to the electron filtering effect due to the Schottky barrier at Pt-silicide/silicon interface. At 400 K, the thermal conductivity is reduced by about half of magnitude compared to bulk in multi-layered device which shows the efficient suppression of phonon propagation by using Pt-silicide/silicon hetero-junctions. - Highlights: • Silicide/silicon multi-layer structured is proposed for thermoelectric devices. • Electric and thermoelectric properties with the number of layer are investigated. • An increase of Seebeck coefficient is mainly attributed the Schottky barrier. • Phonon propagation is suppressed with the existence of Schottky barrier. • Thermal conductivity is reduced due to the suppression of phonon propagation

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Sahraoui

2015-04-09

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

KAUST Repository

Chaieb, Saharoui; Mughal, Asad Jahangir

2015-01-01

Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

The effect of silicon crystallographic orientation on the formation of silicon nanoclusters during anodic electrochemical etching

International Nuclear Information System (INIS)

Timokhov, D. F.; Timokhov, F. P.

2009-01-01

Possible ways for increasing the photoluminescence quantum yield of porous silicon layers have been investigated. The effect of the anodization parameters on the photoluminescence properties for porous silicon layers formed on silicon substrates with different crystallographic orientations was studied. The average diameters for silicon nanoclusters are calculated from the photoluminescence spectra of porous silicon. The influence of the substrate crystallographic orientation on the photoluminescence quantum yield of porous silicon is revealed. A model explaining the effect of the substrate orientation on the photoluminescence properties for the porous silicon layers formed by anode electrochemical etching is proposed.

Record high efficiency of screen-printed silicon aluminum back surface field solar cell: 20.29%

Science.gov (United States)

Kim, Ki Hyung; Park, Chang Sub; Doo Lee, Jae; Youb Lim, Jong; Yeon, Je Min; Kim, Il Hwan; Lee, Eun Joo; Cho, Young Hyun

2017-08-01

We have achieved a record high cell efficiency of 20.29% for an industrial 6-in. p-type monocrystalline silicon solar cell with a full-area aluminum back surface field (Al-BSF) by simply modifying the cell structure and optimizing the process with the existing cell production line. The cell efficiency was independently confirmed by the Solar Energy Research Institute of Singapore (SERIS). To increase the cell efficiency, for example, in four busbars, double printing, a lightly doped emitter with a sheet resistance of 90 to 100 Ω/□, and front surface passivation by using silicon oxynitride (SiON) on top of a silicon nitride (SiN x ) antireflection layer were adopted. To optimize front side processing, PC1D simulation was carried out prior to cell fabrication. The resulting efficiency gain is 0.64% compared with that in the reference cells with three busbars, a single antireflection coating layer, and a low-sheet-resistance emitter.

Joining elements of silicon carbide

International Nuclear Information System (INIS)

Olson, B.A.

1979-01-01

A method of joining together at least two silicon carbide elements (e.g.in forming a heat exchanger) is described, comprising subjecting to sufficiently non-oxidizing atmosphere and sufficiently high temperature, material placed in space between the elements. The material consists of silicon carbide particles, carbon and/or a precursor of carbon, and silicon, such that it forms a joint joining together at least two silicon carbide elements. At least one of the elements may contain silicon. (author)

Investigation of the quenched surfaces of visibly luminescent macro/nanoporous silicon under the exposure of typical neuron culture media

International Nuclear Information System (INIS)

Unal, B.

2015-01-01

In this research paper, the quenching effects of visible photoluminescence of porous silicon relevant to doping types under an exposure of culture media such as Dulbecco's Modified Eagle's Medium and Phosphate-Buffered Saline have been studied extensively in order to realize the application of a cell culture growth technique for porous silicon, in which biocompatibility is directly based on its size-dependent structures and morphologies. This could restrain the combination of either macro or micro-/nano-dimensional silicon morphologies by stain-etching single crystalline Si surfaces. The dopant-related quenching effect of well-known neuron culture media over visible photoluminescent porous silicon surface is found to be quite obvious for the two culture media mentioned above. Scanning electron microscope images of the cultured neuron cells over porous Si show how they have been linked to, and communicated with, each other, and directed along porous channels, fabricated by a photo lithographic technique. (authors)

Graphitized silicon carbide microbeams: wafer-level, self-aligned graphene on silicon wafers

International Nuclear Information System (INIS)

Cunning, Benjamin V; Ahmed, Mohsin; Mishra, Neeraj; Kermany, Atieh Ranjbar; Iacopi, Francesca; Wood, Barry

2014-01-01

Currently proven methods that are used to obtain devices with high-quality graphene on silicon wafers involve the transfer of graphene flakes from a growth substrate, resulting in fundamental limitations for large-scale device fabrication. Moreover, the complex three-dimensional structures of interest for microelectromechanical and nanoelectromechanical systems are hardly compatible with such transfer processes. Here, we introduce a methodology for obtaining thousands of microbeams, made of graphitized silicon carbide on silicon, through a site-selective and wafer-scale approach. A Ni-Cu alloy catalyst mediates a self-aligned graphitization on prepatterned SiC microstructures at a temperature that is compatible with silicon technologies. The graphene nanocoating leads to a dramatically enhanced electrical conductivity, which elevates this approach to an ideal method for the replacement of conductive metal films in silicon carbide-based MEMS and NEMS devices. (paper)

Fabrication of Silicon nanostructures by UHV-STM lithography in Self-Assembled Monolayers

International Nuclear Information System (INIS)

Sundermann, M.; Brechling, A.; Rott, K.; Meyners, D.; Kleineberg, U.; Heinzmann, U.; Knueller, A.; Eck, W.; Goelzhueuser, A.; Grunze, M.

2002-01-01

Our approach utilizes UHV-STM writing in Self-Assembled Monolayers (SAM). SAMs form highly-ordered ultrathin (∼2-3 nm) monomolecular layers on top of pre-activated Si(100) or Si(111) surfaces. After patterning by UHV-STM writing in constant-current mode at different write parameters (gap voltage, electron dose) the modified Self-Assembled Monolayer serves as an etch mask for an anisotropic wet etch transfer (two-step etch process in aqueous solutions of 5 % HF and 1 M KOH), of the write structure into the silicon substrate. The corresponding silicon nano-structures have been analyzed afterwards by AFM or SEM to characterize the pattern accuracy. We have studied the suitability of three different types of SAMs on silicon single-crystals. Alkyl-chain-type SAMs like Octadecylsilane (ODS) monolayer have been formed by immersion of hydroxylated Si(100) in Octadecyltrichlorosilane (CH 3 (CH 27 SiCl 3 ) while SAMs with aromatic spacer groups such as Hydroxybiphenyl (HBP, (C 6 H 6 ) 2 OH) and Ethoxybiphenyl silane (EBP, (C 6 H 6 ) 2 O(CH 2 ) 3 Si(OCH 3 ) 3 ) are formed on Si(111). (Authors)

A NEW APPROACH TO THE STUDY OF MUCOADHESIVENESS OF POLYMERIC MEMBRANES USING SILICONE DISCS.

Science.gov (United States)

Nowak, Karolina Maria; Szterk, Arkadiusz; Fiedor, Piotr; Bodek, Kazimiera Henryka

2016-01-01

The introduction of new test methods and the modification of existing ones are crucial for obtaining reliable results, which contributes to the development of innovative materials that may have clinical applications. Today, silicone is commonly used in medicine and the diversity of its applications are continually growing. The aim of this study is to evaluate the mucoadhesiveness of polymeric membranes by a method that modifies the existing test methods through the introduction of silicone discs. The matrices were designed for clinical application in the management of diseases within the oral cavity. The use of silicone discs allows reliable and reproducible results to be obtained, which allows us to make various tensometric measurements. In this study, different types of polymeric matrices were examined, as well as their crosslinking and the presence for the active pharmaceutical ingredient were compared to the pure dosage form. The lidocaine hydrochloride (Lid(HCl)) was used as a model active substance, due to its use in dentistry and clinical safety. The results were characterized by a high repeatability (RSD < 10.6%). The advantage of silicone material due to its mechanical strength, chemical and physical resistance, allowed a new test method using a texture analyzer to be proposed.

Use of porous silicon to minimize oxidation induced stacking fault defects in silicon

International Nuclear Information System (INIS)

Shieh, S.Y.; Evans, J.W.

1992-01-01

This paper presents methods for minimizing stacking fault defects, generated during oxidation of silicon, include damaging the back of the wafer or depositing poly-silicon on the back. In either case a highly defective structure is created and this is capable of gettering either self-interstitials or impurities which promote nucleation of stacking fault defects. A novel method of minimizing these defects is to form a patch of porous silicon on the back of the wafer by electrochemical etching. Annealing under inert gas prior to oxidation may then result in the necessary gettering. Experiments were carried out in which wafers were subjected to this treatment. Subsequent to oxidation, the wafers were etched to remove oxide and reveal defects. The regions of the wafer adjacent to the porous silicon patch were defect-free, whereas remote regions had defects. Deep level transient spectroscopy has been used to examine the gettering capability of porous silicon, and the paper discusses the mechanism by which the porous silicon getters

Indentation fatigue in silicon nitride, alumina and silicon carbide ...

Indian Academy of Sciences (India)

Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 m and 25 m, and a sintered silicon carbide (SSiC) are reported. The RIF experiments were conducted using a Vicker's ...

Silicon web process development

Science.gov (United States)

Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.; Skutch, M. E.; Driggers, J. M.; Hopkins, R. H.

1981-01-01

The silicon web process takes advantage of natural crystallographic stabilizing forces to grow long, thin single crystal ribbons directly from liquid silicon. The ribbon, or web, is formed by the solidification of a liquid film supported by surface tension between two silicon filaments, called dendrites, which border the edges of the growing strip. The ribbon can be propagated indefinitely by replenishing the liquid silicon as it is transformed to crystal. The dendritic web process has several advantages for achieving low cost, high efficiency solar cells. These advantages are discussed.

Characterization of silicon oxynitride films prepared by the simultaneous implantation of oxygen and nitrogen ions into silicon

International Nuclear Information System (INIS)

Hezel, R.; Streb, W.

1985-01-01

Silicon oxynitride films about 5 nm in thickness were prepared by simultaneously implanting 5 keV oxygen and nitrogen ions into silicon at room temperature up to saturation. These films with concentrations ranging from pure silicon oxide to silicon nitride were characterized using Auger electron spectroscopy, electron energy loss spectroscopy and depth-concentration profiling. The different behaviour of the silicon oxynitride films compared with those of silicon oxide and silicon nitride with regard to thermal stability and hardness against electron and argon ion irradiation is pointed out. (Auth.)

Porous Silicon Structures as Optical Gas Sensors

Directory of Open Access Journals (Sweden)

Igor A. Levitsky

2015-08-01

Full Text Available We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed

2014-07-29

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed; Rubin, Andrew; Refaat, Mohamed; Sedky, Sherif; Abdo, Mohammad

2014-01-01

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

DEFF Research Database (Denmark)

Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

2015-01-01

An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

Selective formation of porous silicon

Science.gov (United States)

Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

OpenAIRE

K?nig, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

2017-01-01

All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusi...

Optical property of silicon quantum dots embedded in silicon nitride by thermal annealing

Energy Technology Data Exchange (ETDEWEB)

Kim, Baek Hyun, E-mail: bhkim@andrew.cmu.ed [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United Sates (United States); Davis, Robert F. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United Sates (United States); Park, Seong-Ju [Nanophotonic Semiconductors Laboratory, Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, 500-712 (Korea, Republic of)

2010-01-01

We present the effects on the thermal annealing of silicon quantum dots (Si QDs) embedded in silicon nitride. The improved photoluminescence (PL) intensities and the red-shifted PL spectra were obtained with annealing treatment in the range of 700 to 1000 {sup o}C. The shifts of PL spectra were attributed to the increase in the size of Si QDs. The improvement of the PL intensities was also attributed to the reduction of point defects at Si QD/silicon nitride interface and in the silicon nitride due to hydrogen passivation effects.

In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon

Science.gov (United States)

Tokel, Onur; Turnalı, Ahmet; Makey, Ghaith; Elahi, Parviz; ćolakoǧlu, Tahir; Ergeçen, Emre; Yavuz, Ã.-zgün; Hübner, René; Zolfaghari Borra, Mona; Pavlov, Ihor; Bek, Alpan; Turan, Raşit; Kesim, Denizhan Koray; Tozburun, Serhat; Ilday, Serim; Ilday, F. Ã.-mer

2017-10-01

Silicon is an excellent material for microelectronics and integrated photonics1-3, with untapped potential for mid-infrared optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow the fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Embedded optical elements7, electronic devices and better electronic-photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1-µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has an optical index different to that in unmodified parts, enabling the creation of numerous photonic devices. Optionally, these parts can be chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface—that is, `in-chip'—microstructures for microfluidic cooling of chips, vias, micro-electro-mechanical systems, photovoltaic applications and photonic devices that match or surpass corresponding state-of-the-art device performances.

In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon.

Science.gov (United States)

Tokel, Onur; Turnali, Ahmet; Makey, Ghaith; Elahi, Parviz; Çolakoğlu, Tahir; Ergeçen, Emre; Yavuz, Özgün; Hübner, René; Borra, Mona Zolfaghari; Pavlov, Ihor; Bek, Alpan; Turan, Raşit; Kesim, Denizhan Koray; Tozburun, Serhat; Ilday, Serim; Ilday, F Ömer

2017-10-01

Silicon is an excellent material for microelectronics and integrated photonics1-3 with untapped potential for mid-IR optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realised with techniques like reactive ion etching. Embedded optical elements, like in glass7, electronic devices, and better electronic-photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1 µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has a different optical index than unmodified parts, which enables numerous photonic devices. Optionally, these parts are chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface, i.e. , " in-chip" microstructures for microfluidic cooling of chips, vias, MEMS, photovoltaic applications and photonic devices that match or surpass the corresponding state-of-the-art device performances.

Silicon photonics fundamentals and devices

CERN Document Server

Deen, M Jamal

2012-01-01

The creation of affordable high speed optical communications using standard semiconductor manufacturing technology is a principal aim of silicon photonics research. This would involve replacing copper connections with optical fibres or waveguides, and electrons with photons. With applications such as telecommunications and information processing, light detection, spectroscopy, holography and robotics, silicon photonics has the potential to revolutionise electronic-only systems. Providing an overview of the physics, technology and device operation of photonic devices using exclusively silicon and related alloys, the book includes: * Basic Properties of Silicon * Quantum Wells, Wires, Dots and Superlattices * Absorption Processes in Semiconductors * Light Emitters in Silicon * Photodetectors , Photodiodes and Phototransistors * Raman Lasers including Raman Scattering * Guided Lightwaves * Planar Waveguide Devices * Fabrication Techniques and Material Systems Silicon Photonics: Fundamentals and Devices outlines ...

Twenty-fold plasmon-induced enhancement of radiative emission rate in silicon nanocrystals embedded in silicon dioxide

International Nuclear Information System (INIS)

Gardelis, S; Gianneta, V.; Nassiopoulou, A.G

2016-01-01

We report on a 20-fold enhancement of the integrated photoluminescence (PL) emission of silicon nanocrystals, embedded in a matrix of silicon dioxide, induced by excited surface plasmons from silver nanoparticles, which are located in the vicinity of the silicon nanocrystals and separated from them by a silicon dioxide layer of a few nanometers. The electric field enhancement provided by the excited surface plasmons increases the absorption cross section and the emission rate of the nearby silicon nanocrystals, resulting in the observed enhancement of the photoluminescence, mainly attributed to a 20-fold enhancement in the emission rate of the silicon nanocrystals. The observed remarkable improvement of the PL emission makes silicon nanocrystals very useful material for photonic, sensor and solar cell applications.

Shallow boron dopant on silicon An MD study

International Nuclear Information System (INIS)

Perez-Martin, A. Mari Carmen; Jimenez-Rodriguez, Jose J.; Jimenez-Saez, Jose Carlos

2004-01-01

Low energy boron bombardment of silicon has been simulated at room temperature by molecular dynamics (MD). Tersoff potential T3 was used in the simulation smoothly linked up with the universal potential. The boron-silicon (B-Si) interaction was simulated according to Tersoff potential for SiC but modified to account for the B-Si interaction. The algorithm can distinguish a B from a Si neighbour. Si-c, with (2 x 1) surface reconstruction, was bombarded with boron at 200 and 500 eV. These energies were initially chosen as good representative values of the low energy range. Reliable results require of a reasonable good statistic so that 1000-impact points were chosen uniformly distributed over a representative area of a 2 x 1 surface. The distribution of mean projected range for B is given. All kinds of point defect were looked for in a Si damaged target after bombardment. Energetically stable substitutional and interstitial configurations are presented and the relative appearances of the different types of interstitials, for both Si and B, are given. It is also determined the mean length of the distance to the first neighbours of defects

Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

Science.gov (United States)

Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

2015-10-01

Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

Incorporation of the Fe3O4 and SiO2 nanoparticles in epoxy-modified silicone resin as the coating for soft magnetic composites with enhanced performance

Science.gov (United States)

Luo, Dahao; Wu, Chen; Yan, Mi

2018-04-01

Three inorganic-organic hybrids have been designed by incorporating epoxy-modified silicone resin (ESR) with SiO2, Fe3O4 and their mixture in the application as the coating of Fe soft magnetic composites (SMCs). The introduced SiO2 nanoparticles are well dispersed in the ESR, while the Fe3O4 tends to agglomerate or even separate from the ESR. Simultaneous addition of the SiO2 and Fe3O4 gives rise to satisfactory distribution of both nanoparticles and optimized magnetic performance of the SMCs with high permeability (124.6) and low loss (807.8 mW/cm3). On one hand, introduction of the ferromagnetic Fe3O4 reduces the magnetic dilution effect, which is beneficial for improved magnetization and permeability. On the other hand, SiO2 incorporation prevents the agglomeration of the Fe3O4 nanoparticles and gives rise to increased electrical resistivity for reduced core loss as well as enhanced mechanical strength of the SMCs.

Direct Production of Silicones From Sand

Energy Technology Data Exchange (ETDEWEB)

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30

Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

Flexible Thermoelectric Generators on Silicon Fabric

KAUST Repository

Sevilla, Galo T.

2012-11-01

In this work, the development of a Thermoelectric Generator on Flexible Silicon Fabric is explored to extend silicon electronics for flexible platforms. Low cost, easily deployable plastic based flexible electronics are of great interest for smart textile, wearable electronics and many other exciting applications. However, low thermal budget processing and fundamentally limited electron mobility hinders its potential to be competitive with well established and highly developed silicon technology. The use of silicon in flexible electronics involve expensive and abrasive materials and processes. In this work, high performance flexible thermoelectric energy harvesters are demonstrated from low cost bulk silicon (100) wafers. The fabrication of the micro- harvesters was done using existing silicon processes on silicon (100) and then peeled them off from the original substrate leaving it for reuse. Peeled off silicon has 3.6% thickness of bulk silicon reducing the thermal loss significantly and generating nearly 30% more output power than unpeeled harvesters. The demonstrated generic batch processing shows a pragmatic way of peeling off a whole silicon circuitry after conventional fabrication on bulk silicon wafers for extremely deformable high performance integrated electronics. In summary, by using a novel, low cost process, this work has successfully integrated existing and highly developed fabrication techniques to introduce a flexible energy harvester for sustainable applications.

Subwavelength silicon photonics

International Nuclear Information System (INIS)

Cheben, P.; Bock, P.J.; Schmid, J.H.; Lapointe, J.; Janz, S.; Xu, D.-X.; Densmore, A.; Delage, A.; Lamontagne, B.; Florjanczyk, M.; Ma, R.

2011-01-01

With the goal of developing photonic components that are compatible with silicon microelectronic integrated circuits, silicon photonics has been the subject of intense research activity. Silicon is an excellent material for confining and manipulating light at the submicrometer scale. Silicon optoelectronic integrated devices have the potential to be miniaturized and mass-produced at affordable cost for many applications, including telecommunications, optical interconnects, medical screening, and biological and chemical sensing. We review recent advances in silicon photonics research at the National Research Council Canada. A new type of optical waveguide is presented, exploiting subwavelength grating (SWG) effect. We demonstrate subwavelength grating waveguides made of silicon, including practical components operating at telecom wavelengths: input couplers, waveguide crossings and spectrometer chips. SWG technique avoids loss and wavelength resonances due to diffraction effects and allows for single-mode operation with direct control of the mode confinement by changing the refractive index of a waveguide core over a range as broad as 1.6 - 3.5 simply by lithographic patterning. The light can be launched to these waveguides with a coupling loss as small as 0.5 dB and with minimal wavelength dependence, using coupling structures similar to that shown in Fig. 1. The subwavelength grating waveguides can cross each other with minimal loss and negligible crosstalk which allows massive photonic circuit connectivity to overcome the limits of electrical interconnects. These results suggest that the SWG waveguides could become key elements for future integrated photonic circuits. (authors)

Silicon photonic integration in telecommunications

Directory of Open Access Journals (Sweden)

Christopher Richard Doerr

2015-08-01

Full Text Available Silicon photonics is the guiding of light in a planar arrangement of silicon-based materials to perform various functions. We focus here on the use of silicon photonics to create transmitters and receivers for fiber-optic telecommunications. As the need to squeeze more transmission into a given bandwidth, a given footprint, and a given cost increases, silicon photonics makes more and more economic sense.

Silicon microphones - a Danish perspective

DEFF Research Database (Denmark)

Bouwstra, Siebe; Storgaard-Larsen, Torben; Scheeper, Patrick

1998-01-01

Two application areas of microphones are discussed, those for precision measurement and those for hearing instruments. Silicon microphones are under investigation for both areas, and Danish industry plays a key role in both. The opportunities of silicon, as well as the challenges and expectations......, are discussed. For precision measurement the challenge for silicon is large, while for hearing instruments silicon seems to be very promising....

Competitive Protein Adsorption on Polysaccharide and Hyaluronate Modified Surfaces

Science.gov (United States)

Ombelli, Michela; Costello, Lauren; Postle, Corinne; Anantharaman, Vinod; Meng, Qing Cheng; Composto, Russell J.; Eckmann, David M.

2011-01-01

We measured adsorption of bovine serum albumin (BSA) and fibrinogen (Fg) onto six distinct bare and dextran- and hyaluronate-modified silicon surfaces created using two dextran grafting densities and three hyaluronic acid (HA) sodium salts derived from human umbilical cord, rooster comb and streptococcus zooepidemicus. Film thickness and surface morphology depended on HA molecular weight and concentration. BSA coverage was enhanced on surfaces upon competitive adsorption of BSA:Fg mixtures. Dextranization differentially reduced protein adsorption onto surfaces based on oxidation state. Hyaluronization was demonstrated to provide the greatest resistance to protein coverage, equivalent to that of the most resistant dextranized surface. Resistance to protein adsorption was independent of the type of hyaluronic acid utilized. With changing bulk protein concentration from 20 to 40 µg ml−1 for each species, Fg coverage on silicon increased by 4×, whereas both BSA and Fg adsorption on dextran and HA were far less dependent of protein bulk concentration. PMID:21623481

Integrated silicon optoelectronics

CERN Document Server

Zimmermann, Horst

2000-01-01

'Integrated Silicon Optoelectronics'assembles optoelectronics and microelectronics The book concentrates on silicon as the major basis of modern semiconductor devices and circuits Starting from the basics of optical emission and absorption and from the device physics of photodetectors, the aspects of the integration of photodetectors in modern bipolar, CMOS, and BiCMOS technologies are discussed Detailed descriptions of fabrication technologies and applications of optoelectronic integrated circuits are included The book, furthermore, contains a review of the state of research on eagerly expected silicon light emitters In order to cover the topic of the book comprehensively, integrated waveguides, gratings, and optoelectronic power devices are included in addition Numerous elaborate illustrations promote an easy comprehension 'Integrated Silicon Optoelectronics'will be of value to engineers, physicists, and scientists in industry and at universities The book is also recommendable for graduate students speciali...

Process for making silicon

Science.gov (United States)

Levin, Harry (Inventor)

1987-01-01

A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

Silicon etch process

International Nuclear Information System (INIS)

Day, D.J.; White, J.C.

1984-01-01

A silicon etch process wherein an area of silicon crystal surface is passivated by radiation damage and non-planar structure produced by subsequent anisotropic etching. The surface may be passivated by exposure to an energetic particle flux - for example an ion beam from an arsenic, boron, phosphorus, silicon or hydrogen source, or an electron beam. Radiation damage may be used for pattern definition and/or as an etch stop. Ethylenediamine pyrocatechol or aqueous potassium hydroxide anisotropic etchants may be used. The radiation damage may be removed after etching by thermal annealing. (author)

Porous silicon gettering

Energy Technology Data Exchange (ETDEWEB)

Tsuo, Y.S.; Menna, P.; Pitts, J.R. [National Renewable Energy Lab., Golden, CO (United States)] [and others

1996-05-01

The authors have studied a novel extrinsic gettering method that uses the large surface areas produced by a porous-silicon etch as gettering sites. The annealing step of the gettering used a high-flux solar furnace. They found that a high density of photons during annealing enhanced the impurity diffusion to the gettering sites. The authors used metallurgical-grade Si (MG-Si) prepared by directional solidification casing as the starting material. They propose to use porous-silicon-gettered MG-Si as a low-cost epitaxial substrate for polycrystalline silicon thin-film growth.

Investigation of the interface region between a porous silicon layer and a silicon substrate

International Nuclear Information System (INIS)

Lee, Ki-Won; Park, Dae-Kyu; Kim, Young-You; Shin, Hyun-Joon

2005-01-01

Atomic force microscopy (AFM) measurement and X-ray diffraction (XRD) analysis were performed to investigate the physical and structural characteristics of the interface region between a porous silicon layer and a silicon substrate. We discovered that, when anodization time was increased under a constant current density, the Si crystallites in the interface region became larger and formed different lattice parameters than observed in the porous silicon layer. Secondary ion mass spectrometry (SIMS) analysis also revealed that the Si was more concentrated in the interface region than in the porous silicon layer. These results were interpreted by the deficiency of the HF solution in reaching to the interface through the pores during the porous silicon formation

Vapor Pressure and Evaporation Coefficient of Silicon Monoxide over a Mixture of Silicon and Silica

Science.gov (United States)

Ferguson, Frank T.; Nuth, Joseph A., III

2012-01-01

The evaporation coefficient and equilibrium vapor pressure of silicon monoxide over a mixture of silicon and vitreous silica have been studied over the temperature range (1433 to 1608) K. The evaporation coefficient for this temperature range was (0.007 plus or minus 0.002) and is approximately an order of magnitude lower than the evaporation coefficient over amorphous silicon monoxide powder and in general agreement with previous measurements of this quantity. The enthalpy of reaction at 298.15 K for this reaction was calculated via second and third law analyses as (355 plus or minus 25) kJ per mol and (363.6 plus or minus 4.1) kJ per mol respectively. In comparison with previous work with the evaporation of amorphous silicon monoxide powder as well as other experimental measurements of the vapor pressure of silicon monoxide gas over mixtures of silicon and silica, these systems all tend to give similar equilibrium vapor pressures when the evaporation coefficient is correctly taken into account. This provides further evidence that amorphous silicon monoxide is an intimate mixture of small domains of silicon and silica and not strictly a true compound.

Characterization of vertical strain silicon MOSFET incorporating dielectric pocket (SDP-VMOSFET)

Energy Technology Data Exchange (ETDEWEB)

Napiah, Z. A. F. M., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Makhtar, N., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Othman, M. A., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Idris, M. I., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Arith, F., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Yasin, N. Y. M., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com; Taib, S. N., E-mail: zulatfyi@utem.edu.my, E-mail: nazirah6969@gmail.com, E-mail: azlishah@utem.edu.my, E-mail: idzdihar@utem.edu.my, E-mail: faiz.arith@utem.edu.my, E-mail: yashidar@yahoo.com, E-mail: sitinabilahtaib@gmail.com [Centre for Telecommunication Research and Innovation (CeTRI), Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia)

2014-02-24

The vertical Metal-Oxide-Semiconductor Field-Effect-Transistor (MOSFET) leads to a double channel width that can increase the packaging density. The strained silicon MOSFET was introduced to modify the carrier transport properties of silicon in order to enhance transport of both electrons and holes within strained layer. Dielectric pocket was act to control encroachment of the drain doping into the channel and reduce short channel effects (SCE). SDP-VMOSFET which was a combination of those advantages was proposed to overcome the SCE in term of leakage current, threshold voltage roll-off also Drain Induce Barrier Lowering (DIBL). As a result, SDP-VMOSFET produces a better threshold voltage and DIBL compared to related structures. Meanwhile, it gives slightly increased for leakage current compared to Vertical MOSFET Incorporating Dielectric Pocket. The characteristics of the SDP-VMOSFET are analyzed in order to optimize the performance of the device and leading to the next generation of IC technology.

Characterization of vertical strain silicon MOSFET incorporating dielectric pocket (SDP-VMOSFET)

International Nuclear Information System (INIS)

Napiah, Z. A. F. M.; Makhtar, N.; Othman, M. A.; Idris, M. I.; Arith, F.; Yasin, N. Y. M.; Taib, S. N.

2014-01-01

The vertical Metal-Oxide-Semiconductor Field-Effect-Transistor (MOSFET) leads to a double channel width that can increase the packaging density. The strained silicon MOSFET was introduced to modify the carrier transport properties of silicon in order to enhance transport of both electrons and holes within strained layer. Dielectric pocket was act to control encroachment of the drain doping into the channel and reduce short channel effects (SCE). SDP-VMOSFET which was a combination of those advantages was proposed to overcome the SCE in term of leakage current, threshold voltage roll-off also Drain Induce Barrier Lowering (DIBL). As a result, SDP-VMOSFET produces a better threshold voltage and DIBL compared to related structures. Meanwhile, it gives slightly increased for leakage current compared to Vertical MOSFET Incorporating Dielectric Pocket. The characteristics of the SDP-VMOSFET are analyzed in order to optimize the performance of the device and leading to the next generation of IC technology

High temperature corrosion of silicon carbide and silicon nitride in the presence of chloride compound

International Nuclear Information System (INIS)

McNallan, M.

1993-01-01

Silicon carbide and silicon nitride are resistant to oxidation because a protective silicon dioxide films on their surfaces in most oxidizing environments. Chloride compounds can attack the surface in two ways: 1) chlorine can attack the silicon directly to form a volatile silicon chloride compound or 2) alkali compounds combined with the chlorine can be transported to the surface where they flux the silica layer by forming stable alkali silicates. Alkali halides have enough vapor pressure that a sufficient quantity of alkali species to cause accelerated corrosion can be transported to the ceramic surface without the formation of a chloride deposit. When silicon carbide is attacked simultaneously by chlorine and oxygen, the corrosion products include both volatile and condensed spices. Silicon nitride is much more resistance to this type of attack than silicon carbide. Silicon based ceramics are exposed to oxidizing gases in the presence of alkali chloride vapors, the rate of corrosion is controlled primarily by the driving force for the formation of alkali silicate, which can be quantified as the activity of the alkali oxide in equilibrium with the corrosive gas mixture. In a gas mixture containing a fixed partial pressure of KCl, the rate of corrosion is accelerated by increasing the concentration of water vapor and inhibited by increasing the concentration of HCl. Similar results have been obtained for mixtures containing other alkalis and halogens. (Orig./A.B.)

Multifunctional porous silicon nanoparticles for cancer theranostics.

Science.gov (United States)

Wang, Chang-Fang; Sarparanta, Mirkka P; Mäkilä, Ermei M; Hyvönen, Maija L K; Laakkonen, Pirjo M; Salonen, Jarno J; Hirvonen, Jouni T; Airaksinen, Anu J; Santos, Hélder A

2015-04-01

Nanomaterials provide a unique platform for the development of theranostic systems that combine diagnostic imaging modalities with a therapeutic payload in a single probe. In this work, dual-labeled iRGD-modified multifunctional porous silicon nanoparticles (PSi NPs) were prepared from dibenzocyclooctyl (DBCO) modified PSi NPs by strain-promoted azide-alkyne cycloaddition (SPAAC) click chemistry. Hydrophobic antiangiogenic drug, sorafenib, was loaded into the modified PSi NPs to enhance the drug dissolution rate and improve cancer therapy. Radiolabeling of the developed system with (111)In enabled the monitoring of the in vivo biodistribution of the nanocarrier by single photon emission computed tomography (SPECT) in an ectopic PC3-MM2 mouse xenograft model. Fluorescent labeling with Alexa Fluor 488 was used to determine the long-term biodistribution of the nanocarrier by immunofluorescence at the tissue level ex vivo. Modification of the PSi NPs with an iRGD peptide enhanced the tumor uptake of the NPs when administered intravenously. After intratumoral delivery the NPs were retained in the tumor, resulting in efficient tumor growth suppression with particle-loaded sorafenib compared to the free drug. The presented multifunctional PSi NPs highlight the utility of constructing a theranostic nanosystems for simultaneous investigations of the in vivo behavior of the nanocarriers and their drug delivery efficiency, facilitating the selection of the most promising materials for further NP development. Copyright © 2015 Elsevier Ltd. All rights reserved.

RBS/channeling analysis of hydrogen-implanted single crystals of FZ silicon and 6H silicon

International Nuclear Information System (INIS)

Irwin, R.B.

1984-01-01

Single crystals of FZ silicon and 6H silicon carbide were implanted with hydrogen ions (50 and 80 keV, respectively) to fluences from 2 x 10 16 H + /cm 2 to 2 x 10 18 H+/cm 2 . The implantations were carried out at three temperatures: approx.95K, 300 K, and approx.800 K. Swelling of the samples was measured by surface profilometry. RBS/channeling was used to obtain the damage profiles and to determine the amount of hydrogen retained in the lattice. The damage profiles are centered around X/sub m/ for the implants into silicon and around R/sub p/ for silicon carbide. For silicon carbide implanted at 95 K and 300 K and for silicon implanted at 95 K, the peak damage region is amorphous for fluences above 8 x 10 16 H + /cm 2 , 4 x 10 17 H + /cm 2 , and 2 x 10 17 H + /cm 2 , respectively. Silicon implanted at 300 and 800 K and silicon carbide implanted at 800 K remain crystalline up to fluences of 1 x 10 18 H + /cm 2 . The channeling damage results agree with previously reported TEM and electron diffraction data. The predictions of a simple disorder-accumulation model with a linear annealing term explains qualitatively the observed damage profiles in silicon carbide. Quantitatively, however, the model predicts faster development of the damage profiles than is observed at low fluences in both silicon and silicon carbide. For samples implanted at 300 and 800 K, the model also predicts substantially less peak disorder than is observed. The effect of the surface, the retained hydrogen, the shape of S/sub D/(X), and the need for a nonlinear annealing term may be responsible for the discrepancy

Quantum mechanical theory of epitaxial transformation of silicon to silicon carbide

International Nuclear Information System (INIS)

Kukushkin, S A; Osipov, A V

2017-01-01

The paper focuses on the study of transformation of silicon crystal into silicon carbide crystal via substitution reaction with carbon monoxide gas. As an example, the Si(1 0 0) surface is considered. The cross section of the potential energy surface of the first stage of transformation along the reaction pathway is calculated by the method of nudged elastic bands. It is found that in addition to intermediate states associated with adsorption of CO and SiO molecules on the surface, there is also an intermediate state in which all the atoms are strongly bonded to each other. This intermediate state significantly reduces the activation barrier of transformation down to 2.6 eV. The single imaginary frequencies corresponding to the two transition states of this transformation are calculated, one of which is reactant-like, whereas the other is product-like. By methods of quantum chemistry of solids, the second stage of this transformation is described, namely, the transformation of precarbide silicon into silicon carbide. Energy reduction per one cell is calculated for this ‘collapse’ process, and bond breaking energy is also found. Hence, it is concluded that the smallest size of the collapsing islet is 30 nm. It is shown that the chemical bonds of the initial silicon crystal are coordinately replaced by the bonds between Si and C in silicon carbide, which leads to a high quality of epitaxy and a low concentration of misfit dislocations. (paper)

Silicon Nanocrystal Synthesis in Microplasma Reactor

Science.gov (United States)

Nozaki, Tomohiro; Sasaki, Kenji; Ogino, Tomohisa; Asahi, Daisuke; Okazaki, Ken

Nanocrystalline silicon particles with grains smaller than 5 nm are widely recognized as a key material in optoelectronic devices, lithium battery electrodes, and bio-medical labels. Another important characteristic is that silicon is an environmentally safe material that is used in numerous silicon technologies. To date, several synthesis methods such as sputtering, laser ablation, and plasma-enhanced chemical vapor deposition (PECVD) based on low-pressure silane chemistry (SiH4) have been developed for precise control of size and density distributions of silicon nanocrystals. In this study, we explore the possibility of microplasma technologies for efficient production of mono-dispersed nanocrystalline silicon particles on a micrometer-scale, continuous-flow plasma reactor operated at atmospheric pressure. Mixtures of argon, hydrogen, and silicon tetrachloride were activated using a very-high-frequency (144 MHz) power source in a capillary glass tube with volume of less than 1 μl. Fundamental plasma parameters of the microplasma were characterized using optical emission spectroscopy, which respectively indicated electron density of 1015 cm-3, argon excitation temperature of 5000 K, and rotational temperature of 1500 K. Such high-density non-thermal reactive plasma can decompose silicon tetrachloride into atomic silicon to produce supersaturated silicon vapor, followed by gas-phase nucleation via three-body collision: particle synthesis in high-density plasma media is beneficial for promoting nucleation processes. In addition, further growth of silicon nuclei can be terminated in a short-residence-time reactor. Micro-Raman scattering spectra showed that as-deposited particles are mostly amorphous silicon with a small fraction of silicon nanocrystals. Transmission electron micrography confirmed individual 3-15 nm silicon nanocrystals. Although particles were not mono-dispersed, they were well separated and not coagulated.

Nanostructured silicon for thermoelectric

Science.gov (United States)

Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

2011-06-01

Thermoelectric modules convert thermal energy into electrical energy and vice versa. At present bismuth telluride is the most widely commercial used material for thermoelectric energy conversion. There are many applications where bismuth telluride modules are installed, mainly for refrigeration. However, bismuth telluride as material for energy generation in large scale has some disadvantages. Its availability is limited, it is hot stable at higher temperatures (>250°C) and manufacturing cost is relatively high. An alternative material for energy conversion in the future could be silicon. The technological processing of silicon is well advanced due to the rapid development of microelectronics in recent years. Silicon is largely available and environmentally friendly. The operating temperature of silicon thermoelectric generators can be much higher than of bismuth telluride. Today silicon is rarely used as a thermoelectric material because of its high thermal conductivity. In order to use silicon as an efficient thermoelectric material, it is necessary to reduce its thermal conductivity, while maintaining high electrical conductivity and high Seebeck coefficient. This can be done by nanostructuring into arrays of pillars. Fabrication of silicon pillars using ICP-cryogenic dry etching (Inductive Coupled Plasma) will be described. Their uniform height of the pillars allows simultaneous connecting of all pillars of an array. The pillars have diameters down to 180 nm and their height was selected between 1 micron and 10 microns. Measurement of electrical resistance of single silicon pillars will be presented which is done in a scanning electron microscope (SEM) equipped with nanomanipulators. Furthermore, measurement of thermal conductivity of single pillars with different diameters using the 3ω method will be shown.

Studies on the reactive melt infiltration of silicon and silicon-molybdenum alloys in porous carbon

Science.gov (United States)

Singh, M.; Behrendt, D. R.

1992-01-01

Investigations on the reactive melt infiltration of silicon and silicon-1.7 and 3.2 at percent molybdenum alloys into porous carbon preforms have been carried out by process modeling, differential thermal analysis (DTA) and melt infiltration experiments. These results indicate that the initial pore volume fraction of the porous carbon preform is a critical parameter in determining the final composition of the raction-formed silicon carbide and other residual phases. The pore size of the carbon preform is very detrimental to the exotherm temperatures due to liquid silicon-carbon reactions encountered during the reactive melt infiltration process. A possible mechanism for the liquid silicon-porous (glassy) carbon reaction has been proposed. The composition and microstructure of the reaction-formed silicon carbide has been discussed in terms of carbon preform microstructures, infiltration materials, and temperatures.

1366 Project Silicon: Reclaiming US Silicon PV Leadership

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Adam [1366 Technologies, Bedford, MA (United States)

2016-02-16

1366 Technologies’ Project Silicon addresses two of the major goals of the DOE’s PV Manufacturing Initiative Part 2 program: 1) How to reclaim a strong silicon PV manufacturing presence and; 2) How to lower the levelized cost of electricity (“LCOE”) for solar to $0.05-$0.07/kWh, enabling wide-scale U.S. market adoption. To achieve these two goals, US companies must commercialize disruptive, high-value technologies that are capable of rapid scaling, defensible from foreign competition, and suited for US manufacturing. These are the aims of 1366 Technologies Direct Wafer ™ process. The research conducted during Project Silicon led to the first industrial scaling of 1366’s Direct Wafer™ process – an innovative, US-friendly (efficient, low-labor content) manufacturing process that destroys the main cost barrier limiting silicon PV cost-reductions: the 35-year-old grand challenge of making quality wafers (40% of the cost of modules) without the cost and waste of sawing. The SunPath program made it possible for 1366 Technologies to build its demonstration factory, a key and critical step in the Company’s evolution. The demonstration factory allowed 1366 to build every step of the process flow at production size, eliminating potential risk and ensuring the success of the Company’s subsequent scaling for a 1 GW factory to be constructed in Western New York in 2016 and 2017. Moreover, the commercial viability of the Direct Wafer process and its resulting wafers were established as 1366 formed key strategic partnerships, gained entry into the $8B/year multi-Si wafer market, and installed modules featuring Direct Wafer products – the veritable proving grounds for the technology. The program also contributed to the development of three Generation 3 Direct Wafer furnaces. These furnaces are the platform for copying intelligently and preparing our supply chain – large-scale expansion will not require a bigger machine but more machines. SunPath filled the

In Situ X-ray Diffraction Studies of (De)lithiation Mechanism in Silicon Nanowire Anodes

KAUST Repository

Misra, Sumohan

2012-06-26

Figure Persented: Silicon is a promising anode material for Li-ion batteries due to its high theoretical specific capacity. From previous work, silicon nanowires (SiNWs) are known to undergo amorphorization during lithiation, and no crystalline Li-Si product has been observed. In this work, we use an X-ray transparent battery cell to perform in situ synchrotron X-ray diffraction on SiNWs in real time during electrochemical cycling. At deep lithiation voltages the known metastable Li 15Si 4 phase forms, and we show that avoiding the formation of this phase, by modifying the SiNW growth temperature, improves the cycling performance of SiNW anodes. Our results provide insight on the (de)lithiation mechanism and a correlation between phase evolution and electrochemical performance for SiNW anodes. © 2012 American Chemical Society.

High-aspect-ratio, silicon oxide-enclosed pillar structures in microfluidic liquid chromatography.

Science.gov (United States)

Taylor, Lisa C; Lavrik, Nickolay V; Sepaniak, Michael J

2010-11-15

The present paper discusses the ability to separate chemical species using high-aspect-ratio, silicon oxide-enclosed pillar arrays. These miniaturized chromatographic systems require smaller sample volumes, experience less flow resistance, and generate superior separation efficiency over traditional packed bed liquid chromatographic columns, improvements controlled by the increased order and decreased pore size of the systems. In our distinctive fabrication sequence, plasma-enhanced chemical vapor deposition (PECVD) of silicon oxide is used to alter the surface and structural properties of the pillars for facile surface modification while improving the pillar mechanical stability and increasing surface area. The separation behavior of model compounds within our pillar systems indicated an unexpected hydrophobic-like separation mechanism. The effects of organic modifier, ionic concentration, and pressure-driven flow rate were studied. A decrease in the organic content of the mobile phase increased peak resolution while detrimentally effecting peak shape. A resolution of 4.7 (RSD = 3.7%) was obtained for nearly perfect Gaussian shaped peaks, exhibiting plate heights as low as 1.1 and 1.8 μm for fluorescein and sulforhodamine B, respectively. Contact angle measurements and DART mass spectrometry analysis indicate that our employed elastomeric soft bonding technique modifies pillar properties, creating a fortuitous stationary phase. This discovery provides evidence supporting the ability to easily functionalize PECVD oxide surfaces by gas-phase reactions.

Silicon-micromachined microchannel plates

CERN Document Server

Beetz, C P; Steinbeck, J; Lemieux, B; Winn, D R

2000-01-01

Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of approx 0.5 to approx 25 mu m, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposite...

Porous silicon carbide (SIC) semiconductor device

Science.gov (United States)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1996-01-01

Porous silicon carbide is fabricated according to techniques which result in a significant portion of nanocrystallites within the material in a sub 10 nanometer regime. There is described techniques for passivating porous silicon carbide which result in the fabrication of optoelectronic devices which exhibit brighter blue luminescence and exhibit improved qualities. Based on certain of the techniques described porous silicon carbide is used as a sacrificial layer for the patterning of silicon carbide. Porous silicon carbide is then removed from the bulk substrate by oxidation and other methods. The techniques described employ a two-step process which is used to pattern bulk silicon carbide where selected areas of the wafer are then made porous and then the porous layer is subsequently removed. The process to form porous silicon carbide exhibits dopant selectivity and a two-step etching procedure is implemented for silicon carbide multilayers.

Silicon Photonics Cloud (SiCloud)

DEFF Research Database (Denmark)

DeVore, P. T. S.; Jiang, Y.; Lynch, M.

2015-01-01

Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

Si-modified BHA bioceramics as a drug delivery system: Effect of modification method on structure and Rifampicin release

Directory of Open Access Journals (Sweden)

Olena Sych

2015-09-01

Full Text Available The work is devoted to the investigation of two different methods for introduction of silicon into ceramics, based on biogenic hydroxyapatite (BHA, on the structure and properties. Thus, porous samples of Si-modified BHA-based ceramics containing 2 or 5 wt.% Si were prepared by using two different precursors, i.e. polymethylsiloxane polyhydrate and fine silica (Aerosil® 200 powder. After the modification with silicon a marked change in the structure of material was observed. The use of Aerosil® 200 permits preparation of a more uniform structure as compared to that obtained by using polymethylsiloxane polyhydrate. However, the latter promotes an increase in both the porosity of samples (from 43 to 62.3% and their solubility in saline (from 0.18 to 1.20 wt.%/day as compared to the results obtained after the modification with Aerosil® 200, where maximal porosity and solubility were 48.5% and 0.23 wt.%/day, respectively. At the same time, the modification of hydroxyapatite ceramics with silicon using silica makes it possible to prolong release of a drug (e.g. Rifampicin out of sample pores for the first 24 h as compared to the ceramics modified with polymethylsiloxane polyhydrate.

The silicon-silicon oxide multilayers utilization as intrinsic layer on pin solar cells

International Nuclear Information System (INIS)

Colder, H.; Marie, P.; Gourbilleau, F.

2008-01-01

Silicon nanostructures are promising candidate for the intrinsic layer on pin solar cells. In this work we report on new material: silicon-rich silicon oxide (SRSO) deposited by reactive magnetron sputtering of a pure silica target and an interesting structure: multilayers consisting of a stack of SRSO and pure silicon oxide layers. Two thicknesses of the SRSO sublayer, t SRSO , are studied 3 nm and 5 nm whereas the thickness of silica sublayer is maintaining at 3 nm. The presence of nanocrystallites of silicon, evidenced by X-Ray diffraction (XRD), leads to photoluminescence (PL) emission at room temperature due to the quantum confinement of the carriers. The PL peak shifts from 1.3 eV to 1.5 eV is correlated to the decreasing of t SRSO from 5 nm down to 3 nm. In the purpose of their potential utilization for i-layer, the optical properties are studied by absorption spectroscopy. The achievement a such structures at promising absorption properties. Moreover by favouring the carriers injection by the tunnel effect between silicon nanograins and silica sublayers, the multilayers seem to be interesting for solar cells

Method of forming buried oxide layers in silicon

Science.gov (United States)

Sadana, Devendra Kumar; Holland, Orin Wayne

2000-01-01

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Effects of ion implantation on charges in the silicon--silicon dioxide system

International Nuclear Information System (INIS)

Learn, A.J.; Hess, D.W.

1977-01-01

Structures consisting of thermally grown oxide on silicon were implanted with boron, arsenic, or argon ions. For argon implantation through oxides, an increased fixed oxide charge (Q/sub ss/) was observed with the increase being greater for than for silicon. This effect is attributed to oxygen recoil which produces additional excess ionized silicon in the oxide of a type similar to that arising in thermal oxidation. Fast surface state (N/sub st/) generation was also noted which in most cases obscured the Q/sub ss/ increase. Of various heat treatments tested, only a 900 degreeC anneal in hydrogen annihilated N/sub st/ and allowed Q/sub ss/ measurement. Such N/sub st/ apparently arises as a consequence of implantation damage at the silicon--silicon dioxide interface. With the exception of boron implantations into thick oxides or through aluminum electrodes, reduction of the mobile ionic charge (Q/sub o/) was achieved by implantation. The reduction again is presumably damage related and is not negated by high-temperature annealing but may be counterbalanced by aluminum incorporation in the oxide

Silicon-micromachined microchannel plates

International Nuclear Information System (INIS)

Beetz, Charles P.; Boerstler, Robert; Steinbeck, John; Lemieux, Bryan; Winn, David R.

2000-01-01

Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of ∼0.5 to ∼25 μm, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposited or nucleated in the channels or the first strike surface. Results on resistivity, secondary emission and gain are presented

Removal of inclusions from silicon

Science.gov (United States)

Ciftja, Arjan; Engh, Thorvald Abel; Tangstad, Merete; Kvithyld, Anne; Øvrelid, Eivind Johannes

2009-11-01

The removal of inclusions from molten silicon is necessary to satisfy the purity requirements for solar grade silicon. This paper summarizes two methods that are investigated: (i) settling of the inclusions followed by subsequent directional solidification and (infiltration by ceramic foam filters. Settling of inclusions followed by directional solidification is of industrial importance for production of low-cost solar grade silicon. Filtration is reported as the most efficient method for removal of inclusions from the top-cut silicon scrap.

Silicon Tracking Upgrade at CDF

International Nuclear Information System (INIS)

Kruse, M.C.

1998-04-01

The Collider Detector at Fermilab (CDF) is scheduled to begin recording data from Run II of the Fermilab Tevatron in early 2000. The silicon tracking upgrade constitutes both the upgrade to the CDF silicon vertex detector (SVX II) and the new Intermediate Silicon Layers (ISL) located at radii just beyond the SVX II. Here we review the design and prototyping of all aspects of these detectors including mechanical design, data acquisition, and a trigger based on silicon tracking

Radiation Hardening of Silicon Detectors

CERN Multimedia

Leroy, C; Glaser, M

2002-01-01

%RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

Silicon Alloying On Aluminium Based Alloy Surface

International Nuclear Information System (INIS)

Suryanto

2002-01-01

Silicon alloying on surface of aluminium based alloy was carried out using electron beam. This is performed in order to enhance tribological properties of the alloy. Silicon is considered most important alloying element in aluminium alloy, particularly for tribological components. Prior to silicon alloying. aluminium substrate were painted with binder and silicon powder and dried in a furnace. Silicon alloying were carried out in a vacuum chamber. The Silicon alloyed materials were assessed using some techniques. The results show that silicon alloying formed a composite metal-non metal system in which silicon particles are dispersed in the alloyed layer. Silicon content in the alloyed layer is about 40% while in other place is only 10.5 %. The hardness of layer changes significantly. The wear properties of the alloying alloys increase. Silicon surface alloying also reduced the coefficient of friction for sliding against a hardened steel counter face, which could otherwise be higher because of the strong adhesion of aluminium to steel. The hardness of the silicon surface alloyed material dropped when it underwent a heating cycle similar to the ion coating process. Hence, silicon alloying is not a suitable choice for use as an intermediate layer for duplex treatment

Silicon microfabricated beam expander

Science.gov (United States)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Silicon germanium as a novel mask for silicon deep reactive ion etching

KAUST Repository

Serry, Mohamed Y.

2013-10-01

This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0silicon, silicon oxide, and photoresist was determined at different etching temperatures, ICP and RF powers, and SF6 to O2 ratios. The study demonstrates that the etching selectivity of the SiGe mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.

Reduction in Recombination Current Density in Boron Doped Silicon Using Atomic Hydrogen

Science.gov (United States)

Young, Matthew Garett

The solar industry has grown immensely in recent years and has reached a point where solar energy has now become inexpensive enough that it is starting to emerge as a mainstream electrical generation source. However, recent economic analysis has suggested that for solar to become a truly wide spread source of electricity, the costs still need to plummet by a factor of 8x. This demands new and innovative concepts to help lower such cost. In pursuit of this goal, this dissertation examines the use of atomic hydrogen to lessen the recombination current density in the boron doped region of n-type silicon solar cells. This required the development of a boron diffusion process that maintained the bulk lifetime of n-type silicon such that the recombination current density could be extracted by photoconductance spectroscopy. It is demonstrated that by hydrogenating boron diffusions, the majority carrier concentration can be controlled. By using symmetrically diffused test structures with quinhydrone-methanol surface passivation the recombination current density of a hydrogenated boron profile is shown to be less than that of a standard boron profile, by as much as 30%. This is then applied to a modified industrial silicon solar cell process to demonstrate an efficiency enhancement of 0.4%.

Structural modification of silicon during the formation process of porous silicon

International Nuclear Information System (INIS)

Martin-Palma, R.J.; Pascual, L.; Landa-Canovas, A.R.; Herrero, P.; Martinez-Duart, J.M.

2005-01-01

Direct examination of porous silicon (PS) by the use of high resolution transmission electron microscopy (HRTEM) allowed us to perform a deep insight into the formation mechanisms of this material. In particular, the structure of the PS/Si interface and that of the silicon nanocrystals that compose porous silicon were analyzed in detail. Furthermore, image processing was used to study in detail the structure of PS. The mechanism of PS formation and lattice matching between the PS layer and the Si substrate is analyzed and discussed. Finally, a formation mechanism for PS based on the experimental observations is proposed

Development of low cost silicon solar cells by reusing the silicon saw dust collected during wafering process

International Nuclear Information System (INIS)

Zaidi, Z.I.; Raza, B.; Ahmed, M.; Sheikh, H.; Qazi, I.A.

2002-01-01

Silicon material due to its abundance in nature and maximum conversion efficiency has been successfully being used for the fabrication of electronic and photovoltaic devices such as ICs, diodes, transistors and solar cells. The 80% of the semiconductor industry is ruled by silicon material. Single crystal silicon solar cells are in use for both space and terrestrial application, due to the well developed technology and better efficiency than polycrystalline and amorphous silicon solar cells. The current research work is an attempt to reduce the cost of single crystal silicon solar cells by reusing the silicon saw dust obtained during the watering process. During the watering process about 45% Si material is wasted in the form of Si powder dust. Various waste powder silicon samples were analyzed using inductively Coupled Plasma (ICP) technique, for metallic impurities critical for solar grade silicon material. The results were evaluated from impurity and cost point of view. (author)

Thin film silicon on silicon nitride for radiation hardened dielectrically isolated MISFET's

International Nuclear Information System (INIS)

Neamen, D.; Shedd, W.; Buchanan, B.

1975-01-01

The permanent ionizing radiation effects resulting from charge trapping in a silicon nitride isolation dielectric have been determined for a total ionizing dose up to 10 7 rads (Si). Junction FET's, whose active channel region is directly adjacent to the silicon-silicon nitride interface, were used to measure the effects of the radiation induced charge trapping in the Si 3 N 4 isolation dielectric. The JFET saturation current and channel conductance versus junction gate voltage and substrate voltage were characterized as a function of the total ionizing radiation dose. The experimental results on the Si 3 N 4 are compared to results on similar devices with SiO 2 dielectric isolation. The ramifications of using the silicon nitride for fabricating radiation hardened dielectrically isolated MIS devices are discussed

The silicon vertex tracker for star and future applications of silicon drift detectors

International Nuclear Information System (INIS)

Bellwied, Rene

2001-01-01

The Silicon Vertex Tracker (SVT) for the STAR experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory has recently been completed and installed. First data were taken in July 2001. The SVT is based on a novel semi-conductor technology called Silicon Drift Detectors. 216 large area (6 by 6 cm) Silicon wafers were employed to build a three barrel device capable of vertexing and tracking in a high occupancy environment. Its intrinsic radiation hardness, its operation at room temperature and its excellent position resolution (better than 20 micron) in two dimensions with a one dimensional detector readout, make this technology very robust and inexpensive and thus a viable alternative to CCD, Silicon pixel and Silicon strip detectors in a variety of applications from fundamental research in high-energy and nuclear physics to astrophysics to medical imaging. I will describe the development that led to the STAR-SVT, its performance and possible applications for the near future

Optoelectronic enhancement of monocrystalline silicon solar cells by porous silicon-assisted mechanical grooving

Energy Technology Data Exchange (ETDEWEB)

Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-03-15

One of the most important factors influencing silicon solar cells performances is the front side reflectivity. Consequently, new methods for efficient reduction of this reflectivity are searched. This has always been done by creating a rough surface that enables incident light of being absorbed within the solar cell. Combination of texturization-porous silicon surface treatment was found to be an attractive technical solution for lowering the reflectivity of monocrystalline silicon (c-Si). The texturization of the monocrystalline silicon wafer was carried out by means of mechanical grooving. A specific etching procedure was then applied to form a thin porous silicon layer enabling to remove mechanical damages. This simple and low cost method reduces the total reflectivity from 29% to 7% in the 300 - 950 nm wavelength range and enhances the diffusion length of the minority carriers from 100 {mu}m to 790 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The dark side of silicon energy efficient computing in the dark silicon era

CERN Document Server

Liljeberg, Pasi; Hemani, Ahmed; Jantsch, Axel; Tenhunen, Hannu

2017-01-01

This book presents the state-of-the art of one of the main concerns with microprocessors today, a phenomenon known as "dark silicon". Readers will learn how power constraints (both leakage and dynamic power) limit the extent to which large portions of a chip can be powered up at a given time, i.e. how much actual performance and functionality the microprocessor can provide. The authors describe their research toward the future of microprocessor development in the dark silicon era, covering a variety of important aspects of dark silicon-aware architectures including design, management, reliability, and test. Readers will benefit from specific recommendations for mitigating the dark silicon phenomenon, including energy-efficient, dedicated solutions and technologies to maximize the utilization and reliability of microprocessors. Enables readers to understand the dark silicon phenomenon and why it has emerged, including detailed analysis of its impacts; Presents state-of-the-art research, as well as tools for mi...

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa

2013-05-30

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Mechanically flexible optically transparent silicon fabric with high thermal budget devices from bulk silicon (100)

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto; Sevilla, Galo T.

2013-01-01

Today’s information age is driven by silicon based electronics. For nearly four decades semiconductor industry has perfected the fabrication process of continuingly scaled transistor – heart of modern day electronics. In future, silicon industry will be more pervasive, whose application will range from ultra-mobile computation to bio-integrated medical electronics. Emergence of flexible electronics opens up interesting opportunities to expand the horizon of electronics industry. However, silicon – industry’s darling material is rigid and brittle. Therefore, we report a generic batch fabrication process to convert nearly any silicon electronics into a flexible one without compromising its (i) performance; (ii) ultra-large-scale-integration complexity to integrate billions of transistors within small areas; (iii) state-of-the-art process compatibility, (iv) advanced materials used in modern semiconductor technology; (v) the most widely used and well-studied low-cost substrate mono-crystalline bulk silicon (100). In our process, we make trenches using anisotropic reactive ion etching (RIE) in the inactive areas (in between the devices) of a silicon substrate (after the devices have been fabricated following the regular CMOS process), followed by a dielectric based spacer formation to protect the sidewall of the trench and then performing an isotropic etch to create caves in silicon. When these caves meet with each other the top portion of the silicon with the devices is ready to be peeled off from the bottom silicon substrate. Release process does not need to use any external support. Released silicon fabric (25 μm thick) is mechanically flexible (5 mm bending radius) and the trenches make it semi-transparent (transparency of 7%). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Silicon-to-silicon wafer bonding using evaporated glass

DEFF Research Database (Denmark)

Weichel, Steen; Reus, Roger De; Lindahl, M.

1998-01-01

Anodic bending of silicon to silicon 4-in. wafers using an electron-beam evaporated glass (Schott 8329) was performed successfully in air at temperatures ranging from 200 degrees C to 450 degrees C. The composition of the deposited glass is enriched in sodium as compared to the target material....... The roughness of the as-deposited films was below 5 nm and was found to be unchanged by annealing at 500 degrees C for 1 h in air. No change in the macroscopic edge profiles of the glass film was found as a function of annealing; however, small extrusions appear when annealing above 450 degrees C. Annealing...... of silicon/glass structures in air around 340 degrees C for 15 min leads to stress-free structures. Bonded wafer pairs, however, show no reduction in stress and always exhibit compressive stress. The bond yield is larger than 95% for bonding temperatures around 350 degrees C and is above 80% for bonding...

Elite silicon and solar power

International Nuclear Information System (INIS)

Yasamanov, N.A.

2000-01-01

The article is of popular character, the following issues being considered: conversion of solar energy into electric one, solar batteries in space and on the Earth, growing of silicon large-size crystals, source material problems relating to silicon monocrystals production, outlooks of solar silicon batteries production [ru

Porous silicon: X-rays sensitivity

International Nuclear Information System (INIS)

Gerstenmayer, J.L.; Vibert, Patrick; Mercier, Patrick; Rayer, Claude; Hyvernage, Michel; Herino, Roland; Bsiesy, Ahmad

1994-01-01

We demonstrate that high porosity anodically porous silicon is radioluminescent. Interests of this study are double. Firstly: is the construction of porous silicon X-rays detectors (imagers) possible? Secondly: is it necessary to protect silicon porous based optoelectronic systems from ionising radiations effects (spatial environment)? ((orig.))

High-density oxidized porous silicon

International Nuclear Information System (INIS)

Gharbi, Ahmed; Souifi, Abdelkader; Remaki, Boudjemaa; Halimaoui, Aomar; Bensahel, Daniel

2012-01-01

We have studied oxidized porous silicon (OPS) properties using Fourier transform infraRed (FTIR) spectroscopy and capacitance–voltage C–V measurements. We report the first experimental determination of the optimum porosity allowing the elaboration of high-density OPS insulators. This is an important contribution to the research of thick integrated electrical insulators on porous silicon based on an optimized process ensuring dielectric quality (complete oxidation) and mechanical and chemical reliability (no residual pores or silicon crystallites). Through the measurement of the refractive indexes of the porous silicon (PS) layer before and after oxidation, one can determine the structural composition of the OPS material in silicon, air and silica. We have experimentally demonstrated that a porosity approaching 56% of the as-prepared PS layer is required to ensure a complete oxidation of PS without residual silicon crystallites and with minimum porosity. The effective dielectric constant values of OPS materials determined from capacitance–voltage C–V measurements are discussed and compared to FTIR results predictions. (paper)

Silicon spintronics with ferromagnetic tunnel devices

International Nuclear Information System (INIS)

Jansen, R; Sharma, S; Dash, S P; Min, B C

2012-01-01

In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

Study of double porous silicon surfaces for enhancement of silicon solar cell performance

Science.gov (United States)

Razali, N. S. M.; Rahim, A. F. A.; Radzali, R.; Mahmood, A.

2017-09-01

In this work, design and simulation of double porous silicon surfaces for enhancement of silicon solar cell is carried out. Both single and double porous structures are constructed by using TCAD ATHENA and TCAD DEVEDIT tools of the SILVACO software respectively. After the structures were created, I-V characteristics and spectral response of the solar cell were extracted using ATLAS device simulator. Finally, the performance of the simulated double porous solar cell is compared with the performance of both single porous and bulk-Si solar cell. The results showed that double porous silicon solar cell exhibited 1.8% efficiency compared to 1.3% and 1.2% for single porous silicon and bulk-Si solar cell.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

Energy Technology Data Exchange (ETDEWEB)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca, E-mail: f.iacopi@griffith.edu.au [Environmental Futures Research Institute, Griffith University, Nathan 4111 (Australia); Wood, Barry [Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia 4072 (Australia)

2016-05-02

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm{sup −2} with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

All-solid-state supercapacitors on silicon using graphene from silicon carbide

International Nuclear Information System (INIS)

Wang, Bei; Ahmed, Mohsin; Iacopi, Francesca; Wood, Barry

2016-01-01

Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm"−"2 with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

Enhanced Raman scattering in porous silicon grating.