Crystal Structure and Substrate Specificity of PTPN12

Directory of Open Access Journals (Sweden)

Hui Li

2016-05-01

Full Text Available PTPN12 is an important tumor suppressor that plays critical roles in various physiological processes. However, the molecular basis underlying the substrate specificity of PTPN12 remains uncertain. Here, enzymological and crystallographic studies have enabled us to identify two distinct structural features that are crucial determinants of PTPN12 substrate specificity: the pY+1 site binding pocket and specific basic charged residues along its surface loops. Key structurally plastic regions and specific residues in PTPN12 enabled recognition of different HER2 phosphorylation sites and regulated specific PTPN12 functions. In addition, the structure of PTPN12 revealed a CDK2 phosphorylation site in a specific PTPN12 loop. Taken together, our results not only provide the working mechanisms of PTPN12 for desphosphorylation of its substrates but will also help in designing specific inhibitors of PTPN12.

Physical masking process for integrating micro metallic structures on polymer substrate

DEFF Research Database (Denmark)

Islam, Mohammad Aminul; Hansen, Hans Nørgaard

2009-01-01

plasmon devices need micro metallic structures on a polymer substrate with an uniform metal layer thickness in the nanometer range. A well known fabrication process to achieve such metallic surface pattern on polymer substrate is photolithography which involves an expensive mask and toxic chemicals......Integration of micro metallic structures in polymer devices is a broad multi-disciplinary research field, consisting of various combinations of mechanical, chemical and physical fabrication methods. Each of the methods has its specific advantages and disadvantages. Some applications like surface....... The current study shows a novel approach for fabricating thin micro metallic structures on polymer substrates using a simple physical mask and a PVD equipment. The new process involves fewer process steps, it is cost effective and suitable for high volume industrial production. Current study suggests...

Highly reproducible surface-enhanced Raman scattering-active Au nanostructures prepared by simple electrodeposition: origin of surface-enhanced Raman scattering activity and applications as electrochemical substrates.

Science.gov (United States)

Choi, Suhee; Ahn, Miri; Kim, Jongwon

2013-05-24

The fabrication of effective surface-enhanced Raman scattering (SERS) substrates has been the subject of intensive research because of their useful applications. In this paper, dendritic gold (Au) rod (DAR) structures prepared by simple one-step electrodeposition in a short time were examined as an effective SERS-active substrate. The SERS activity of the DAR surfaces was compared to that of other nanostructured Au surfaces with different morphologies, and its dependence on the structural variation of DAR structures was examined. These comparisonal investigations revealed that highly faceted sharp edge sites present on the DAR surfaces play a critical role in inducing a high SERS activity. The SERS enhancement factor was estimated to be greater than 10(5), and the detection limit of rhodamine 6G at DAR surfaces was 10(-8)M. The DAR surfaces exhibit excellent spot-to-spot and substrate-to-substrate SERS enhancement reproducibility, and their long-term stability is very good. It was also demonstrated that the DAR surfaces can be effectively utilized in electrochemical SERS systems, wherein a reversible SERS behavior was obtained during the cycling to cathodic potential regions. Considering the straightforward preparation of DAR substrates and the clean nature of SERS-active Au surfaces prepared in the absence of additives, we expect that DAR surfaces can be used as cost-effective SERS substrates in analytical and electrochemical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Novel transparent high-performance AgNWs/ZnO electrodes prepared on unconventional substrates with 3D structured surfaces

Science.gov (United States)

Lan, Wei; Yang, Zhiwei; Zhang, Yue; Wei, Yupeng; Wang, Pengxiang; Abas, Asim; Tang, Guomei; Zhang, Xuetao; Wang, Junya; Xie, Erqing

2018-03-01

With the development of optoelectronic devices with three-dimensional (3D) structured surfaces, transparent electrodes that can be deposited on non-plane substrates have become increasingly important. In this paper, novel transparent silver nanowire (AgNWs)/ZnO film electrodes were uniformly prepared on treated 3D glass and PET substrates with a combination of spin-coating and heat-welding. The AgNWs/ZnO films show a transmittance of ∼88% and a sheet resistance of ∼10 Ω/sq. They are comparable with commercial ITO films. Furthermore, only a small in-plane resistance variation of ∼1 Ω/sq was measured using four-point probe mapping in films with a 10 cm × 10 cm area. These results confirm that these novel film electrodes are very uniform. Both electrical resistance and optical transmittance of the films remain mostly intact after 1000 bending cycles and tape peeling-tests with 10 cycles. The films show high thermal stability for more than one month at 80 °C. The strategy provides a new route for the design and fabrication of optoelectronic devices with 3D structured surfaces.

Surface treatment of glass substrates for the preparation of long-lived carbon stripper foils

International Nuclear Information System (INIS)

Takeuchi, Suehiro; Takekoshi, Eiko

1981-02-01

Glass substrates having uniformly distributed microscopic grains on the surfaces are useful to make long-lived carbon stripper foils for heavy ions. A method of surface treatment of glass substrates to form the surface structure is described. This method consists of precipitation of glass components, such as soda, onto the surfaces in a hot and humid atmosphere and a fogging treatment of forming microscopic grains of the precipitated substances. Some results of studies on the treatment conditions are also presented. (author)

Catalyst free growth of CNTs by CVD on nanoscale rough surfaces of silicon substrates

Science.gov (United States)

Damodar, D.; Sahoo, R. K.; Jacob, C.

2013-06-01

Catalyst free growth of carbon nanotubes (CNT) has been achieved using atmospheric pressure chemical vapor deposition (APCVD) on surface modified Si(111) substrates. The effect of the substrate surface has been observed by partially etching with KOH (potassium hydroxide) solution which is an anisotropic etchant. Scanning electron microscopy (SEM) confirmed the formation of CNTs over most of the area of the substrate where substrates were anisotropically etched. Transmission electron microscopy (TEM) was used to observe the internal structure of the CNTs. Raman spectroscopy further confirmed the formation of the carbon nanostructures and also their graphitic crystallinity.

Competitive concurrence of surface wrinkling and dewetting of liquid crystalline polymer films on non-wettable substrates.

Science.gov (United States)

Song, Sung E; Choi, Gwan H; Yi, Gi-Ra; Yoo, Pil J

2017-11-01

Polymeric thin films coated on non-wettable substrates undergo film-instabilities, which are usually manifested as surface deformation in the form of dewetting or wrinkling. The former takes place in fluidic films, whereas the latter occurs in solid films. Therefore, there have rarely been reports of systems involving simultaneous deformations of dewetting and wrinkling. In this study, we propose polymeric thin films of liquid crystalline (LC) mesogens prepared on a non-wettable Si substrate and apply a treatment of plasma irradiation to form a thin polymerized layer at the surface. The resulting compressive stress generated in the surface region drives the formation of wrinkles, while at the same time, dipolar attraction between LC molecules induces competitive cohesive dewetting. Intriguing surface structures were obtained whereby dewetting-like hole arrays are nested inside the randomly propagated wrinkles. The structural features are readily controlled by the degree of surface cross-linking, hydrophilicity of the substrates, and the LC film thickness. In particular, dewetting of LC mesogens is observed to be restricted to occur at the trough regions of wrinkles, exhibiting the typical behavior of geometrically confined dewetting. Finally, wrinkling-dewetting mixed structures are separated from the substrate in the form of free standing films to demonstrate the potential applicability as membranes.

Surface characterization and chemical analysis of bamboo substrates pretreated by alkali hydrogen peroxide.

Science.gov (United States)

Song, Xueping; Jiang, Yan; Rong, Xianjian; Wei, Wei; Wang, Shuangfei; Nie, Shuangxi

2016-09-01

The surface characterization and chemical analysis of bamboo substrates by alkali hydrogen peroxide pretreatment (AHPP) were investigated in this study. The results tended to manifest that AHPP prior to enzymatic and chemical treatment was potential for improving accessibility and reactivity of bamboo substrates. The inorganic components, organic solvent extractives and acid-soluble lignin were effectively removed by AHPP. X-ray photoelectron spectroscopy (XPS) analysis indicated that the surface of bamboo chips had less lignin but more carbohydrate after pre-treatment. Fiber surfaces became etched and collapsed, and more pores and debris on the substrate surface were observed with Scanning Electron Microscopy (SEM). Brenauer-Emmett-Teller (BET) results showed that both of pore volume and surface area were increased after AHPP. Although XRD analysis showed that AHPP led to relatively higher crystallinity, pre-extraction could overall enhance the accessibility of enzymes and chemicals into the bamboo structure. Copyright © 2016. Published by Elsevier Ltd.

Paper based Flexible and Conformal SERS Substrate for Rapid Trace Detection on Real-world Surfaces

Science.gov (United States)

Singamaneni, Srikanth; Lee, Chang; Tian, Limei

2011-03-01

One of the important but often overlooked considerations in the design of surface enhanced Raman scattering (SERS) substrates for trace detection is the efficiency of sample collection. Conventional designs based on rigid substrates such as silicon, alumina, and glass resist conformal contact with the surface under investigation, making the sample collection inefficient. We demonstrate a novel SERS substrate based on common filter paper adsorbed with gold nanorods, which allows conformal contact with real-world surfaces, thus dramatically enhancing the sample collection efficiency compared to conventional rigid substrates. We demonstrate the detection of trace amounts of analyte (140 pg spread over 4 cm2) by simply swabbing the surface under investigation with the novel SERS substrate. The hierarchical fibrous structure of paper serves as a 3D vasculature for easy uptake and transport of the analytes to the electromagnetic hot spots in the paper. Simple yet highly efficient and cost effective SERS substrate demonstrated here brings SERS based trace detection closer to real-world applications. We acknowledge the financial support from Center for Materials Innovation at Washington University.

Construction of extracellular microenvironment to improve surface endothelialization of NiTi alloy substrate

Energy Technology Data Exchange (ETDEWEB)

Liu, Peng, E-mail: liupeng79@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Zhao, Yongchun; Yan, Ying; Hu, Yan; Yang, Weihu [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Cai, Kaiyong, E-mail: kaiyong_cai@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China)

2015-10-01

To mimic extracellular microenvironment of endothelial cell, a bioactive multilayered structure of gelatin/chitosan pair, embedding with vascular endothelial growth factor (VEGF), was constructed onto NiTi alloy substrate surface via a layer-by-layer assembly technique. The successful fabrication of the multilayered structure was demonstrated by scanning electron microscopy, atomic force microscopy, contact angle measurement, attenuated total reflection-fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The growth behaviors of endothelial cells on various NiTi alloy substrates were investigated in vitro. Cytoskeleton observation, MTT assay, and wound healing assay proved that the VEGF-embedded multilayer structure positively stimulated adhesion, proliferation and motogenic responses of endothelial cells. More importantly, the present system promoted the nitric oxide production of endothelial cells. The approach affords an alternative to construct extracellular microenvironment for improving surface endothelialization of a cardiovascular implant. - Highlights: • Biofunctional multilayer films mimicking extracellular microenvironment were successfully fabricated. • Multilayered structure stimulated the biological responses of endothelial cells. • The approach affords an efficient approach for surface endothelialization of stent implant.

Enhanced printability of thermoplastic polyurethane substrates by silica particles surface interactions

Energy Technology Data Exchange (ETDEWEB)

Cruz, S., E-mail: s.cruz@dep.uminho.pt [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal); Rocha, L.A. [CMEMS, University of Minho, 4804-533 Guimarães (Portugal); Viana, J.C. [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal)

2016-01-01

Graphical abstract: - Highlights: • A new method development for surface treatment of thermoplastic polyurethane (TPU) substrates. • The proposed method increases TPU surface energy (by 45%) and consequently the TPU wettability. • Great increase of the TPU surface roughness (by 621%). • Inkjet printed conductive ink was applied to the surface treated TPU substrate and significant improvements on the printability were obtained. - Abstract: A new method developed for the surface treatment of thermoplastic polymer substrates that increases their surface energies is introduced in this paper. The method is environmental friendly and low cost. In the proposed surface treatment method, nanoparticles are spread over the thermoplastic polyurethane (TPU) flexible substrate surface and then thermally fixed. This latter step allows the nanoparticles sinking-in on the polymer surface, resulting in a higher polymer–particle interaction at their interfacial region. The addition of nanoparticles onto the polymer surface increases surface roughness. The extent of the nanoparticles dispersion and sink-in in the substrate was evaluated through microscopy analysis (SEM). The roughness of the surface treated polymeric substrate was evaluated by AFM analysis. Substrate critical surface tension (ST) was measured by contact angle. In general, a homogeneous roughness form is achieved to a certain level. Great increase of the TPU surface roughness (by 621%) was induced by the propose method. The proposed surface treatment method increased significantly the substrate ST (by 45%) and consequently the TPU wettability. This novel surface treatment of thermoplastic polymers was applied to the inkjet printing of TPU substrates with conductive inks, and significant improvements on the printability were obtained.

Electrospinning onto Insulating Substrates by Controlling Surface Wettability and Humidity

Science.gov (United States)

Choi, WooSeok; Kim, Geon Hwee; Shin, Jung Hwal; Lim, Geunbae; An, Taechang

2017-11-01

We report a simple method for electrospinning polymers onto flexible, insulating substrates by controlling the wettability of the substrate surface. Water molecules were adsorbed onto the surface of a hydrophilic polymer substrate by increasing the local humidity around the substrate. The adsorbed water was used as the ground electrode for electrospinning. The electrospun fibers were deposited only onto hydrophilic areas of the substrate, allowing for patterning through wettability control. Direct writing of polymer fiber was also possible through near-field electrospinning onto a hydrophilic surface.

Self-assembly nanoparticle based tripetaloid structure arrays as surface-enhanced Raman scattering substrates

International Nuclear Information System (INIS)

Sun Mingrui; Qian Chuang; Wu Wengang; Yu Wenxuan; Wang Yifei; Mao Haiyang

2012-01-01

This paper reports a novel highly ordered tripetaloid structure array (TPSA) which performs very well as an active surface-enhanced Raman scattering (SERS) substrate. The TPSA is easily fabricated by anisotropic etching of a self-assembly silica-nanoparticle bilayer and a subsequent metal deposition step, with notable uniformity and reproducibility. Electromagnetic simulation indicates that the narrow inter-gaps and edge protrusions in the TPSA act as hot spots. In addition, the peak electromagnetic field intensity in the inter-gaps changes slightly and periodically as the polarization of the incident light varies from 0° to 360°. SERS experiments show that the SERS enhancement factor (EF) of a Au-film-covered TPSA is 12 times higher than that of regular Au-film-over-nanoparticles, and not sensitive to the polarization of the incident light. The spatially averaged EF of the TPSA is as high as 5.7 × 10 6 , and the local EF of its hot spots is much higher. (paper)

Preparation and Wetting Behavior of Lyophobic Surface on Zinc Substrate

Directory of Open Access Journals (Sweden)

HAN Xiang-xiang

2018-03-01

Full Text Available Micro-nano structure on zinc substrate was fabricated through the combination of chemical etching with hydrochloric acid aqueous solution and hydrothermal reaction. After modification with perfluorooctanoic solution, the lyophobic surface was prepared. The phase composition, microstructure, chemical composition, and wettability of the as-obtained surface were investigated by X-ray diffractometer, scanning electron microscope, Fourier transform infrared spectrometer, and contact angle tester. The results show that a layer of ZnO nano-rods grows on the surface of the submicrometer structure, and exhibits good resistance to water impact and stability under the combined action of low surface energy material. When hydrochloric acid concentration is 1.0mol/L and hydrothermal reaction temperature is 95℃, the lyophobic surface possesses the best morphology of ZnO nano-rods. The maximum contact angles of distilled water and peanut oil are 154.65° and 144.65°, respectively, and the sliding angle is less than 10°.

Surface control alloy substrates and methods of manufacture therefor

Energy Technology Data Exchange (ETDEWEB)

Fritzemeier, Leslie G. (Mendon, MA); Li, Qi (Marlborough, MA); Rupich, Martin W. (Framingham, MA); Thompson, Elliott D. (Coventry, RI); Siegal, Edward J. (Malden, MA); Thieme, Cornelis Leo Hans (Westborough, MA); Annavarapu, Suresh (Brookline, MA); Arendt, Paul N. (Los Alamos, NM); Foltyn, Stephen R. (Los Alamos, NM)

2004-05-04

Methods and articles for controlling the surface of an alloy substrate for deposition of an epitaxial layer. The invention includes the use of an intermediate layer to stabilize the substrate surface against oxidation for subsequent deposition of an epitaxial layer.

Light extraction from GaN-based LED structures on silicon-on-insulator substrates

Energy Technology Data Exchange (ETDEWEB)

Tripathy, S.; Teo, S.L.; Lin, V.K.X.; Chen, M.F. [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology, and Research), 117602 (Singapore); Dadgar, A.; Krost, A. [Institut fuer Exerimentelle Physik, Otto-von Guericke Universitaet Magdeburg, Universitaetsplatz 1, 39016 Magdeburg (Germany); AZZURRO Semiconductors AG, Universitaetsplatz 1, 39016 Magdeburg (Germany); Christen, J. [Institut fuer Exerimentelle Physik, Otto-von Guericke Universitaet Magdeburg, Universitaetsplatz 1, 39016 Magdeburg (Germany)

2010-01-15

Nano-patterning of GaN-based devices is a promising technology in the development of high output power devices. Recent researches have been focused on the realization of two-dimensional (2D) photonic crystal (PhC) structure to improve light extraction efficiency and to control the direction of emission. In this study, we have demonstrated improved light extraction from green light emitting diode (LED) structures on thin silicon-on-insulator (SOI) substrates using surface nanopatterning. Scanning electron microscopy (SEM) is used to probe the size, shape, and etch depth of nano-patterns on the LED surfaces. Different types of nanopatterns were created by e-beam lithography and inductively coupled plasma etching. The LED structures after post processing are studied by photoluminescence (PL) measurements. The GaN nanophotonic structures formed by ICP etching led to more than five-fold increase in the intensity of the green emission. The improved light extraction is due to the combination of SOI substrate reflectivity and photonic structures on top GaN LED surfaces. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Polarized luminescence of nc-Si-SiO x nanostructures on silicon substrates with patterned surface

Science.gov (United States)

Michailovska, Katerina; Mynko, Viktor; Indutnyi, Ivan; Shepeliavyi, Petro

2018-05-01

Polarization characteristics and spectra of photoluminescence (PL) of nc-Si-SiO x structures formed on the patterned and plane c-Si substrates are studied. The interference lithography with vacuum chalcogenide photoresist and anisotropic wet etching are used to form a periodic relief (diffraction grating) on the surface of the substrates. The studied nc-Si-SiO x structures were produced by oblique-angle deposition of Si monoxide in vacuum and the subsequent high-temperature annealing. The linear polarization memory (PM) effect in PL of studied structure on plane substrate is manifested only after the treatment of the structures in HF and is explained by the presence of elongated Si nanoparticles in the SiO x nanocolumns. But the PL output from the nc-Si-SiO x structure on the patterned substrate depends on how this radiation is polarized with respect to the grating grooves and is much less dependent on the polarization of the exciting light. The measured reflection spectra of nc-Si-SiO x structure on the patterned c-Si substrate confirmed the influence of pattern on the extraction of polarized PL.

A substrate independent approach for generation of surface gradients

Energy Technology Data Exchange (ETDEWEB)

Goreham, Renee V. [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); Mierczynska, Agnieszka; Pierce, Madelene [Ian Wark Research Institute, University of South Australia, Mawson Lakes 5095 (Australia); Short, Robert D.; Taheri, Shima; Bachhuka, Akash; Cavallaro, Alex; Smith, Louise E. [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); Vasilev, Krasimir, E-mail: krasimir.vasilev@unisa.edu.au [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia)

2013-01-01

Recently, surface gradients have attracted significant interest for various research and technological applications. In this paper, we report a facile and versatile method for generating surface gradients of immobilized nanoparticles, nanotopography and ligands that is independent from the substrate material. The method consists of first depositing a functional polymer layer on a substrate and subsequent time controlled immersion of this functionalized substrate in solution gold nanoparticles (AuNPs), silver nanoparticles (AgNPs) or poly (styrenesulfonate) (PSS). Chemical characterization by X-ray Photoelectron Spectroscopy (XPS) and morphological analysis by Atomic Force Microscopy (AFM) show that the density of nanoparticles and the concentration of PSS across the surface increases in a gradient manner. As expected, time of immersion determines the concentration of surface bound species. We also demonstrate the generation of surface gradients of pure nanotopography. This is achieved by depositing a 5 nm thick plasma polymer layer on top of the number density gradient of nanoparticles to achieve a homogeneous surface chemistry. The surface independent approach for generation of surface gradients presented in this paper may open opportunities for a wider use of surface gradient in research and in various technologies. - Highlights: ► We present a substrate independent approach for generation of surface gradients. ► We demonstrate well-defined density gradients of gold and silver nanoparticles. ► We provide an example of pure surface nanotopography gradients. ► We demonstrate concentration gradients of bound ligands.

A substrate independent approach for generation of surface gradients

International Nuclear Information System (INIS)

Goreham, Renee V.; Mierczynska, Agnieszka; Pierce, Madelene; Short, Robert D.; Taheri, Shima; Bachhuka, Akash; Cavallaro, Alex; Smith, Louise E.; Vasilev, Krasimir

2013-01-01

Recently, surface gradients have attracted significant interest for various research and technological applications. In this paper, we report a facile and versatile method for generating surface gradients of immobilized nanoparticles, nanotopography and ligands that is independent from the substrate material. The method consists of first depositing a functional polymer layer on a substrate and subsequent time controlled immersion of this functionalized substrate in solution gold nanoparticles (AuNPs), silver nanoparticles (AgNPs) or poly (styrenesulfonate) (PSS). Chemical characterization by X-ray Photoelectron Spectroscopy (XPS) and morphological analysis by Atomic Force Microscopy (AFM) show that the density of nanoparticles and the concentration of PSS across the surface increases in a gradient manner. As expected, time of immersion determines the concentration of surface bound species. We also demonstrate the generation of surface gradients of pure nanotopography. This is achieved by depositing a 5 nm thick plasma polymer layer on top of the number density gradient of nanoparticles to achieve a homogeneous surface chemistry. The surface independent approach for generation of surface gradients presented in this paper may open opportunities for a wider use of surface gradient in research and in various technologies. - Highlights: ► We present a substrate independent approach for generation of surface gradients. ► We demonstrate well-defined density gradients of gold and silver nanoparticles. ► We provide an example of pure surface nanotopography gradients. ► We demonstrate concentration gradients of bound ligands

[Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

Science.gov (United States)

Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

2014-02-01

The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process

Science.gov (United States)

McKee, Rodney A.; Walker, Frederick J.

1993-01-01

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

Anti-reflection textured structures by wet etching and island lithography for surface-enhanced Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Chao, Bo-Kai [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Cheng, Hsin-Hung [Department of Marine Engineering, Taipei College of Maritime Technology, Taipei 11174, Taiwan (China); Nien, Li-Wei; Chen, Miin-Jang [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Nagao, Tadaaki [Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Hsueh, Chun-Hway, E-mail: hsuehc@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2015-12-01

Graphical abstract: - Highlights: • We fabricated textured SERS substrate with a high surface area and low reflectance. • Large surface area of substrate contains more gold nanodroplets to absorb analytes. • Low reflectance of textured SERS substrate enabled multiple reflections of incident laser light. • We obtained strong SERS enhancement from nanopillar-on-pyramid SERS substrate. - Abstract: A high surface area and low reflection textured surface-enhanced Raman scattering (SERS) substrate with plasmonic gold nanodroplets fabricated by wet etching and island lithography was reported in the present study. Specifically, four textured substrates, planar, pyramid, nanopillar, and nanopillar-on-pyramid, were fabricated. The fabricated structures were simulated using the finite-difference time-domain method and the results agreed with the reflection and dark-field scattering measurements. Although the SERS signals varied in different measured regions because of the random nanostructure, the SERS substrates with nanopillar-on-pyramid structure always have the stronger enhancement factor than the SERS substrates with only pyramids or nanopillars. Based on the atomic force microscope and reflection measurements, the nanopillar-on-pyramid structure provided a large surface area and multiple reflections for SERS enhancement, which was about 3 orders of magnitude larger than that of the planar substrate. Our results can be applied to fabricate the inexpensive, large surface area, and high SERS enhancement substrates.

Improvement of organic solar cells by flexible substrate and ITO surface treatments

International Nuclear Information System (INIS)

Cheng, Yuang-Tung; Ho, Jyh-Jier; Wang, Chien-Kun; Lee, William; Lu, Chih-Chiang; Yau, Bao-Shun; Nain, Jhen-Liang; Chang, Shun-Hsyung; Chang, Chiu-Cheng; Wang, Kang L.

2010-01-01

In this paper, surface treatments on polyethylene terephthalate with polymeric hard coating (PET-HC) substrates are described. The effect of the contact angle on the treatment is first investigated. It has been observed that detergent is quite effective in removing organic contamination on the flexible PET-HC substrates. Next, using a DC-reactive magnetron sputter, indium tin oxide (ITO) thin films of 90 nm are grown on a substrate treated by detergent. Then, various ITO surface treatments are made for improving the performance of the finally developed organic solar cells with structure Al/P3HT:PCBM/PEDOT:PSS/ITO/PET. It is found that the parameters of the ITO including resistivity, carrier concentration, transmittance, surface morphology, and work function depended on the surface treatments and significantly influence the solar cell performance. With the optimal conditions for detergent treatment on flexible PET substrates, the ITO film with a resistivity of 5.6 x 10 -4 Ω cm and average optical transmittance of 84.1% in the visible region are obtained. The optimal ITO surface treated by detergent for 5 min and then by UV ozone for 20 min exhibits the best WF value of 5.22 eV. This improves about 8.30% in the WF compared with that of the untreated ITO film. In the case of optimal treatment with the organic photovoltaic device, meanwhile, 36.6% enhancement in short circuit current density (J sc ) and 92.7% enhancement in conversion efficiency (η) over the untreated solar cell are obtained.

Thiolated poly(ɛ-caprolactone) macroligand with vacant coordination sites on gold substrate: Synthesis and surface characterization

Science.gov (United States)

Farah, Abdiaziz A.; Zheng, Susan H.; Morin, Sylvie; Bensebaa, Farid; Pietro, William J.

2007-04-01

Surface-confined telechelic poly(ɛ-caprolactone) macroligand with two distinct functional groups per polymeric chain has been synthesized and characterized. The molecular microstructure of the macroligand with regard to the properties of the end-capped functionalities and with those on surface substrate has been studied by solution and surface analytical methods (i.e., X-ray photoelectron spectroscopy (XPS), grazing angle reflectance-Fourier transform IR spectroscopy (GA-FTIR), water contact angle measurements, and atomic force microscopy (AFM)) to elucidate the structure and properties of such multifunctional polymer on gold (1 1 1) substrate.

Micro- and nano-surface structures based on vapor-deposited polymers

Directory of Open Access Journals (Sweden)

Hsien-Yeh Chen

2017-07-01

Full Text Available Vapor-deposition processes and the resulting thin polymer films provide consistent coatings that decouple the underlying substrate surface properties and can be applied for surface modification regardless of the substrate material and geometry. Here, various ways to structure these vapor-deposited polymer thin films are described. Well-established and available photolithography and soft lithography techniques are widely performed for the creation of surface patterns and microstructures on coated substrates. However, because of the requirements for applying a photomask or an elastomeric stamp, these techniques are mostly limited to flat substrates. Attempts are also conducted to produce patterned structures on non-flat surfaces with various maskless methods such as light-directed patterning and direct-writing approaches. The limitations for patterning on non-flat surfaces are resolution and cost. With the requirement of chemical control and/or precise accessibility to the linkage with functional molecules, chemically and topographically defined interfaces have recently attracted considerable attention. The multifunctional, gradient, and/or synergistic activities of using such interfaces are also discussed. Finally, an emerging discovery of selective deposition of polymer coatings and the bottom-up patterning approach by using the selective deposition technology is demonstrated.

Growth and domain structure of YBa2Cu3Ox films on neodymium gallate substrates with deviation of surface normal from [110] NdGaO3

International Nuclear Information System (INIS)

Bdikin, I.K.; Mozhaev, P.B.; Ovsyannikov, G.A.; Komissinskij, F.V.; Kotelyanskij, I.M.; Raksha, E.I.

2001-01-01

One investigated into growth, crystalline structure and electrophysical properties of YBa 2 Cu 3 O x (YBCO) epitaxial films grown on NdGaO 3 (NGO) substrates with substrate surface normal deviation from [110] by 5-26.6 deg angle around [001] with CeO 2 epitaxial sublayer or without it. Orientation of YBCO epitaxial films grown at these substrates is shown to be governed by occurrence of symmetrically equipment directions in substrates and in CeO 2 layer, as well as, by film precipitation rate. At precipitation high rate YBCO films on CeO 2 sublayer grow in [001] orientation independently of orientation of substrate and sublayer. One determined that at increase of substrate plane deviation angle from (110) NGO twinning of one or of both twin complexes in YBCO might be suppressed [ru

Durable superhydrophobic surfaces made by intensely connecting a bipolar top layer to the substrate with a middle connecting layer.

Science.gov (United States)

Zhi, Jinghui; Zhang, Li-Zhi

2017-08-30

This study reported a simple fabrication method for a durable superhydrophobic surface. The superhydrophobic top layer of the durable superhydrophobic surface was connected intensely to the substrate through a middle connecting layer. Glycidoxypropyltrimethoxysilane (KH-560) after hydrolysis was used to obtain a hydrophilic middle connecting layer. It could be adhered to the hydrophilic substrate by covalent bonds. Ring-open reaction with octadecylamine let the KH-560 middle layer form a net-like structure. The net-like sturcture would then encompass and station the silica particles that were used to form the coarse micro structures, intensely to increase the durability. The top hydrophobic layer with nano-structures was formed on the KH-560 middle layer. It was obtained by a bipolar nano-silica solution modified by hexamethyldisilazane (HMDS). This layer was connected to the middle layer intensely by the polar Si hydroxy groups, while the non-polar methyl groups on the surface, accompanied by the micro and nano structures, made the surface rather hydrophobic. The covalently interfacial interactions between the substrate and the middle layer, and between the middle layer and the top layer, strengthened the durability of the superhydrophobic surface. The abrasion test results showed that the superhydrophobic surface could bear 180 abrasion cycles on 1200 CW sandpaper under 2 kPa applied pressure.

The influence of the surface atomic structure on surface diffusion

International Nuclear Information System (INIS)

Ghaleb, Dominique

1984-03-01

This work represents the first quantitative study of the influence of the surface atomic structure on surface diffusion (in the range: 0.2 Tf up 0.5 Tf; Tf: melting temperature of the substrate). The analysis of our results on a microscopic scale shows low formation and migration energies for adatoms; we can describe the diffusion on surfaces with a very simple model. On (110) surfaces at low temperature the diffusion is controlled by the exchange mechanism; at higher temperature direct jumps of adatoms along the channels contribute also to the diffusion process. (author) [fr

Investigation the effects of metallic substrate surfaces due to ion-plasma treatment

International Nuclear Information System (INIS)

Shulaev, V.M.; Taran, V.S.; Timoshenko, A.I.; Gasilin, V.V.

2011-01-01

It has been found correlation between modification effects and duration of ion-plasma cleaning the substrate surface with titanium ions. Experiments were carried out using serial vacuum-arc equipment ''Bulat-6'' at the stationary mode in non-filtered titanium plasma, which contained considerable quantity of evaporated material droplets. The polished cylinder substrates (diameter and height 9,14,20 mm) have been treated. The substrates were manufactured of stainless steel 12X18H10T and non-oxygen copper M00b. The substrates surface roughness after ion-plasma treatment has been investigated with electron microscope JEOL JSM-840 and optic interference non-contact profilograph- profilometer ''Micron-alpha''. According obtained results the surface of copper and stainless steel substrates has been treated to intensive modification, i.e. substrate surface after treatment significantly differs from initial one. During final ion-plasma treatment a number of effects occur: purification from surface oxides is accompanied with metallic surface ''contamination'' by the cathode material macrodroplets, surface micromelting accompanied by roughness increase, the surface layer annealing with noticeable decrease of hardness.

ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer.

Science.gov (United States)

Costa, Saionara V; Gonçalves, Agnaldo S; Zaguete, Maria A; Mazon, Talita; Nogueira, Ana F

2013-09-21

In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.

Surface-enhanced raman spectroscopy substrate for arsenic sensing in groundwater

Science.gov (United States)

Yang, Peidong; Mulvihill, Martin; Tao, Andrea R.; Sinsermsuksakul, Prasert; Arnold, John

2015-06-16

A surface-enhanced Raman spectroscopy (SERS) substrate formed from a plurality of monolayers of polyhedral silver nanocrystals, wherein at least one of the monolayers has polyvinypyrrolidone (PVP) on its surface, and thereby configured for sensing arsenic is described. Highly active SERS substrates are formed by assembling high density monolayers of differently shaped silver nanocrystals onto a solid support. SERS detection is performed directly on this substrate by placing a droplet of the analyte solution onto the nanocrystal monolayer. Adsorbed polymer, polyvinypyrrolidone (PVP), on the surface of the nanoparticles facilitates the binding of both arsenate and arsenite near the silver surface, allowing for highly accurate and sensitive detection capabilities.

Structural basis for substrate placement by an archaeal box C/D ribonucleoprotein particle.

Science.gov (United States)

Xue, Song; Wang, Ruiying; Yang, Fangping; Terns, Rebecca M; Terns, Michael P; Zhang, Xinxin; Maxwell, E Stuart; Li, Hong

2010-09-24

Box C/D small nucleolar and Cajal body ribonucleoprotein particles (sno/scaRNPs) direct site-specific 2'-O-methylation of ribosomal and spliceosomal RNAs and are critical for gene expression. Here we report crystal structures of an archaeal box C/D RNP containing three core proteins (fibrillarin, Nop56/58, and L7Ae) and a half-mer box C/D guide RNA paired with a substrate RNA. The structure reveals a guide-substrate RNA duplex orientation imposed by a composite protein surface and the conserved GAEK motif of Nop56/58. Molecular modeling supports a dual C/D RNP structure that closely mimics that recently visualized by electron microscopy. The substrate-bound dual RNP model predicts an asymmetric protein distribution between the RNP that binds and methylates the substrate RNA. The predicted asymmetric nature of the holoenzyme is consistent with previous biochemical data on RNP assembly and provides a simple solution for accommodating base-pairing between the C/D guide RNA and large ribosomal and spliceosomal substrate RNAs. Copyright © 2010 Elsevier Inc. All rights reserved.

MOVPE and characterization of GaN-based structures on alternative substrates

Energy Technology Data Exchange (ETDEWEB)

Dikme, Y.

2006-06-20

This study involves growth experiments of GaN-based layer structures on silicon (Si), lithium aluminate (LiAlO{sub 2}) and the composite substrate SiCOI. Substrate specific preparation and growth procedures were developed. Because of the different lattice constants and thermal expansion coefficients between GaN and the substrate materials and because of the high depositions temperatures (>1000 C) complex interlayers are required to create a crossover from the substrate to the GaN layer and to prevent substrate/layer bowing and cracks developing in the epitaxial layers. Crystallographic, thermal and electronic properties of these materials were investigated and the developed layers were used as buffer layers for electronic and opto electronic devices. On Si AlN/GaN distributed Bragg reflectors (DBR), InGaN/GaN multiple quantum well (MQW) and AlGaN/GaN HEMT (high electron mobility transistor) were demonstrated. The transistor structures showed high power densities, which were comparable to industrially fabricated devices. As well as the reflection of a certain wavelength region, the DBR layers additionally showed positive influence on succeeding GaN top layer optical properties. For the first time laser emission of an optically pumped InGaN/GaN MQW on Si was demonstrated with low excitation density and a high operating temperature. GaN-based structures were deposited on LiAlO2 in the m-plane crystal orientation; that do not exhibit polarization mechanisms in growth direction. For the deposition of coalesced GaN films a seal-coating of the LiAlO{sub 2} surface was developed and finally LED structures were grown on these substrates. For the first time electroluminescence of LED structures on LiAlO{sub 2} was achieved. The growth on the composite substrate SiCOI was initiated with an HT AlN layer and it was demonstrated that SiCOI is comparable to a bulk SiC substrate for the GaN-based epitaxy. The developed and investigated layer structure served as buffer for the

Tailored topography control of biopolymer surfaces by ultrafast lasers for cell–substrate studies

International Nuclear Information System (INIS)

Rusen, L.; Cazan, M.; Mustaciosu, C.; Filipescu, M.; Sandel, S.; Zamfirescu, M.; Dinca, V.; Dinescu, M.

2014-01-01

Nowadays, the culture surfaces used for in vitro testing must be capable of possessing an improved interface for cell interactions and adhesion. For this reason, the materials used need to have an appropriate chemistry and architecture of its surface, resembling to the extracellular matrix. Within this context, in this work we combined the advantages of natural biopolymer characteristics (chitosan) with the flexibility in surface texturing by ultrafast laser for creating functional microstructured surfaces for cell–substrate in vitro studies. A Ti:Sapphire femtosecond laser irradiation (λ = 775 nm and 387 nm) was used for tailoring surface morphological characteristics of chitosan based films (i.e. polymer “bubbles”, “fingertips” and “sponge-like” structures). These structures were investigated by scanning electron microscopy and atomic force microscopy. The morphology of the structures obtained was correlated with the response of oligodendrocytes cells line. In vitro tests on the patterned surface showed that early cell growth was conditioned by the microtopography and indicate possible uses of the structures in biomedical applications.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Dewani, Aliya A., E-mail: a.ashraf@griffith.edu.au; O’Keefe, Steven G.; Thiel, David V.; Galehdar, Amir [School Of Electrical Engineering, Griffith University, Brisbane, 4111 (Australia)

2015-02-15

A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Directory of Open Access Journals (Sweden)

Aliya A. Dewani

2015-02-01

Full Text Available A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm, flexible transparent plastic substrate (relative permittivity 3.2. It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Optically transparent frequency selective surfaces on flexible thin plastic substrates

Science.gov (United States)

Dewani, Aliya A.; O'Keefe, Steven G.; Thiel, David V.; Galehdar, Amir

2015-02-01

A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

Influence of substrate preparation on the shaping of the topography of the surface of nanoceramic oxide layers

Science.gov (United States)

Bara, Marek; Kubica, Marek

2014-02-01

The paper discusses the shaping mechanism and changes occurring in the structure and topography of the surface of nanoceramic oxide layers during their formation. The paper presents the influence of substrate preparation on the surface topography of oxide layers. The layers were produced via hard anodizing on the EN AW-5251 aluminum alloy. The layers obtained were subjected to microscope examinations, image and chemical composition analyses, and stereometric examinations. Heredity of substrate properties in the topography of the surface of nanoceramic oxide layers formed as a result of electrochemical oxidation has been shown.

A high-coverage nanoparticle monolayer for the fabrication of a subwavelength structure on InP substrates.

Science.gov (United States)

Kim, Dae-Seon; Park, Min-Su; Jang, Jae-Hyung

2011-08-01

Subwavelength structures (SWSs) were fabricated on the Indium Phosphide (InP) substrate by utilizing the confined convective self-assembly (CCSA) method followed by reactive ion etching (RIE). The surface condition of the InP substrate was changed by depositing a 30-nm-thick SiO2 layer and subsequently treating the surface with O2 plasma to achieve better surface coverage. The surface coverage of nanoparticle monolayer reached 90% by using O2 plasma-treated SiO2/InP substrate among three kinds of starting substrates such as the bare InP, SiO2/InP and O2 plasma-treated SiO2/InP substrate. A nanoparticle monolayer consisting of polystyrene spheres with diameter of 300 nm was used as an etch mask for transferring a two-dimensional periodic pattern onto the InP substrate. The fabricated conical SWS with an aspect ratio of 1.25 on the O2 plasma-treated SiO2/InP substrate exhibited the lowest reflectance. The average reflectance of the conical SWS was 5.84% in a spectral range between 200 and 900 nm under the normal incident angle.

Influence of Surface Geometry of Grating Substrate on Director in Nematic Liquid Crystal Cell

International Nuclear Information System (INIS)

Ye Wenjiang; Xing Hongyu; Yang Guochen; Zhang Zhidong; Sun Yubao; Chen Guoying; Xuan Li

2011-01-01

The director in nematic liquid crystal cell with a weak anchoring grating substrate and a strong anchoring planar substrate is relative to the coordinates x and z. The influence of the surface geometry of the grating substrate in the cell on the director profile is numerically simulated using the two-dimensional finite-difference iterative method under the condition of one elastic constant approximation and zero driven voltage. The deepness of groove and the cell gap affect the distribution of director. For the relatively shallow groove and the relatively thick cell gap, the director is only dependent on the coordinate z. For the relatively deep groove and the relatively thin cell gap, the director must be dependent on the two coordinates x and z because of the increased elastic strain energy induced by the grating surface. (condensed matter: structural, mechanical, and thermal properties)

Substrate structures for InP-based devices

International Nuclear Information System (INIS)

Wanlass, M.W.; Sheldon, P.

1990-01-01

A substrate structure for an InP-based semiconductor device having an InP based film is described. The substrate structure includes a substrate region having a lightweight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice-matched at the opposite end to the InP=based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region, and the InP-based device

Structure and photoluminescence properties of ZnS films grown on porous Si substrates

Science.gov (United States)

Wang, Cai-feng; Hu, Bo; Yi, Hou-hui; Li, Wei-bing

2011-11-01

ZnS films were deposited on porous silicon (PS) substrates with different porosities. With the increase of PS substrate porosity, the XRD diffraction peak intensity decreases and the surface morphology of the ZnS films becomes rougher. Voids appear in the films, due to the increased roughness of PS structure. The photoluminescence (PL) spectra of the samples before and after deposition of ZnS were measured to study the effect of substrate porosity on the luminescence properties of ZnS/PS composites. As-prepared PS substrates emit strong red light. The red PL peak of PS after deposition of ZnS shows an obvious blueshift. As PS substrate porosity increases, the trend of blueshift increases. A green emission at about 550 nm was also observed when the porosity of PS increased, which is ascribed to the defect-center luminescence of ZnS. The effect of annealing time on the structural and luminescence properties of ZnS/PS composites were also studied. With the increase of annealing time, the XRD diffraction peak intensity and the self-activated luminescence intensity of ZnS increase, and, the surface morphology of the ZnS films becomes smooth and compact. However, the red emission intensity of PS decreases, which was associated with a redshift. White light emission was obtained by combining the luminescence of ZnS with the luminescence of PS.

Silver inkjet printing with control of surface energy and substrate temperature

International Nuclear Information System (INIS)

Lee, S-H; Shin, K-Y; Hwang, J Y; Kang, K T; Kang, H S

2008-01-01

The characteristics of silver inkjet printing were intensively investigated with control of surface energy and substrate temperature. A fluorocarbon (FC) film was spincoated on a silicon (Si) substrate to obtain a hydrophobic surface, and an ultraviolet (UV)/ozone (O 3 ) treatment was performed to control the surface wettability of the FC film surface. To characterize the surface changes, we performed measurements of the static and dynamic contact angles and calculated the surface energy by Wu's harmonic mean model. The surface energy of the FC film increased with the UV/O 3 treatment time, while the contact angles decreased. In silver inkjet printing, the hydrophobic FC film could reduce the diameter of the printed droplets. Merging of deposited droplets was observed when the substrate was kept at room temperature. Substrate heating was effective in preventing the merging phenomenon among the deposited droplets, and in reducing the width of printed lines. The merging phenomenon of deposited droplets was also prevented by increasing the UV/O 3 treatment time. Continuous silver lines in the width range of 48.04–139.21 µm were successfully achieved by inkjet printing on the UV/O 3 -treated hydrophobic FC films at substrate temperatures below 90 °C

Electronic, structural, and substrate effect properties of single-layer covalent organic frameworks

International Nuclear Information System (INIS)

Liang, Liangbo; Zhu, Pan; Meunier, Vincent

2015-01-01

Recently synthesized two-dimensional covalent organic frameworks (COFs) exhibit high surface area, large pore size, and unique structural architectures, making them promising materials for various energy applications. Here, a total of nine COFs structures, including two deposited on a hexagonal boron nitride substrate, are investigated using density functional theory, quasi-particle many-body theory within the GW approximation, and an image charge model. The structures considered belong to two major families (thiophene-based COF-n (T-COF-n) and tetrakis (4-aminophenyl) porphyrin-x (TAPP-x)) differing from the presence of B—O or C=N linkers. While T-COF-n structures are shown to constitute planar networks, TAPP-x systems can display non-negligible corrugation due to the out-of-plane rotation of phenyl rings. We find that the electronic properties do not differ significantly when altering the chain molecules within each family. Many-body effects are shown to lead to large band-gap increase while the presence of the substrate yields appreciable reductions of the gaps, due to substrate polarization effects

Metal oxide nanorod arrays on monolithic substrates

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

2018-01-02

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

Influence of the substrate texture on the structural and electrochemical properties of sputtered LiCoO2 thin films

International Nuclear Information System (INIS)

Jung, Ki-Taek; Cho, Gyu-Bong; Kim, Ki-Won; Nam, Tae-Hyun; Jeong, Hyo-Min; Huh, Sun-Chul; Chung, Han-Shik; Noh, Jung-Pil

2013-01-01

LiCoO 2 thin films were fabricated on textured and annealed STS304 substrates by direct current magnetron sputtering method. The effects of the substrate texture on the structural and electrochemical properties of the LiCoO 2 thin film deposited on both the substrates have been investigated. The crystal structures and surface morphologies of the deposited films were analyzed by X-ray diffractometry (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM). Based on the XRD analysis, the LiCoO 2 thin film deposited on the textured substrate was found to exhibit (003) preferred orientation, while the film deposited on annealed substrate exhibited (104) preferred orientation. In addition, SEM analysis revealed that the film deposited on the textured substrate showed a smooth morphology. On the other hand, the film deposited on the annealed substrate exhibited a very rough surface morphology, which resulted in a higher surface area. Consequently, the initial discharge capacity of the film deposited on the annealed substrate was higher than that of the film deposited on the textured substrate. The film deposited on the textured substrate exhibited a good cyclic performance compared to the film deposited on the annealed substrate. - Highlights: • The sputtered LiCoO 2 thin films were influenced by the substrate texture. • The film deposited on the annealed substrate exhibited (104) preferred orientation. • The film deposited on the textured substrate exhibited a good cyclic performance

The Nanofabrication and Application of Substrates for Surface-Enhanced Raman Scattering

Directory of Open Access Journals (Sweden)

Xian Zhang

2012-01-01

Full Text Available Surface-enhanced Raman scattering (SERS was discovered in 1974 and impacted Raman spectroscopy and surface science. Although SERS has not been developed to be an applicable detection tool so far, nanotechnology has promoted its development in recent decades. The traditional SERS substrates, such as silver electrode, metal island film, and silver colloid, cannot be applied because of their enhancement factor or stability, but newly developed substrates, such as electrochemical deposition surface, Ag porous film, and surface-confined colloids, have better sensitivity and stability. Surface enhanced Raman scattering is applied in other fields such as detection of chemical pollutant, biomolecules, DNA, bacteria, and so forth. In this paper, the development of nanofabrication and application of surface-enhanced Ramans scattering substrate are discussed.

Periodic array-based substrates for surface-enhanced infrared spectroscopy

Science.gov (United States)

Mayerhöfer, Thomas G.; Popp, Jürgen

2018-01-01

At the beginning of the 1980s, the first reports of surface-enhanced infrared spectroscopy (SEIRS) surfaced. Probably due to signal-enhancement factors of only 101 to 103, which are modest compared to those of surface-enhanced Raman spectroscopy (SERS), SEIRS did not reach the same significance up to date. However, taking the compared to Raman scattering much larger cross-sections of infrared absorptions and the enhancement factors together, SEIRS reaches about the same sensitivity for molecular species on a surface in terms of the cross-sections as SERS and, due to the complementary nature of both techniques, can valuably augment information gained by SERS. For the first 20 years since its discovery, SEIRS relied completely on metal island films, fabricated by either vapor or electrochemical deposition. The resulting films showed a strong variance concerning their structure, which was essentially random. Therefore, the increase in the corresponding signal-enhancement factors of these structures stagnated in the last years. In the very same years, however, the development of periodic array-based substrates helped SEIRS to gather momentum. This development was supported by technological progress concerning electromagnetic field solvers, which help to understand plasmonic properties and allow targeted design. In addition, the strong progress concerning modern fabrication methods allowed to implement these designs into practice. The aim of this contribution is to critically review the development of these engineered surfaces for SEIRS, to compare the different approaches with regard to their performance where possible, and report further gain of knowledge around and in relation to these structures.

Fabrication of a Au–polystyrene sphere substrate with three-dimensional nanofeatures for surface-enhanced Raman spectroscopy

International Nuclear Information System (INIS)

Hu, Xiaotang; Xu, Zongwei; Li, Kang; Fang, Fengzhou; Wang, Liyang

2015-01-01

Graphical abstract: Methods for fabricating three-dimensional nanofeature arrays for surface-enhanced Raman spectroscopy (SERS) substrates were explored by combining the self-assembly of nanoscale polystyrene (PS) spheres with subsequent Au film ion sputter coating modulation. The substrate's nanoscale hot-spot features were controlled using the Au coating film thickness regulation and focused ion beam (FIB) nano-patterning regulation methods. Scanning electron microscopy and Raman spectroscopy were employed to analyze the substrate morphology and the enhancement mechanism of the three-dimensional SERS substrate. PS microspheres with diameters of 151 nm and 360 nm were coated with Au layers of different thicknesses ranging from 10 nm to 270 nm. The configuration of the Au–PS spheres can be regulated to hexagonal close packing with nanoscale V-shaped slits with a 10 to 20 nm gap pattern. Nanoscale Au particles and clusters with a clear outline covered the surface of the PS spheres, in which the multiple-scale structures increase the specific surface area of the SERS-active substrate. Nanoscale cracks formed on the smaller Au–PS spheres with a diameter of 151 nm, which also exhibited strong SERS activity. The substrate surface temperature regularly increased after Au coating, and the thermal expansion coefficient difference and PS glass transition properties were studied to explain the Au–PS spheres nanofeature configuration development. The fabricated Au–PS spheres SERS feature is a type of three-dimensional and highly ordered array, which can show Raman scattering characteristics by providing a SERS enhancement factor of greater than 107. - Highlights: • Au film coating over PS nanospheres was studied to develop 3D SERS substrate. • The Au–PS sphere can be hexagonal close packing with 10–20 nm nanoscale gaps. • PS glass transition property results in Au–PS sphere nano configuration evolution. • The nanoscale Au clusters with clear outline were

Fabrication of a Au–polystyrene sphere substrate with three-dimensional nanofeatures for surface-enhanced Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hu, Xiaotang; Xu, Zongwei, E-mail: zongweixu@163.com; Li, Kang; Fang, Fengzhou, E-mail: fzfang@tju.edu.cn; Wang, Liyang

2015-11-15

Graphical abstract: Methods for fabricating three-dimensional nanofeature arrays for surface-enhanced Raman spectroscopy (SERS) substrates were explored by combining the self-assembly of nanoscale polystyrene (PS) spheres with subsequent Au film ion sputter coating modulation. The substrate's nanoscale hot-spot features were controlled using the Au coating film thickness regulation and focused ion beam (FIB) nano-patterning regulation methods. Scanning electron microscopy and Raman spectroscopy were employed to analyze the substrate morphology and the enhancement mechanism of the three-dimensional SERS substrate. PS microspheres with diameters of 151 nm and 360 nm were coated with Au layers of different thicknesses ranging from 10 nm to 270 nm. The configuration of the Au–PS spheres can be regulated to hexagonal close packing with nanoscale V-shaped slits with a 10 to 20 nm gap pattern. Nanoscale Au particles and clusters with a clear outline covered the surface of the PS spheres, in which the multiple-scale structures increase the specific surface area of the SERS-active substrate. Nanoscale cracks formed on the smaller Au–PS spheres with a diameter of 151 nm, which also exhibited strong SERS activity. The substrate surface temperature regularly increased after Au coating, and the thermal expansion coefficient difference and PS glass transition properties were studied to explain the Au–PS spheres nanofeature configuration development. The fabricated Au–PS spheres SERS feature is a type of three-dimensional and highly ordered array, which can show Raman scattering characteristics by providing a SERS enhancement factor of greater than 107. - Highlights: • Au film coating over PS nanospheres was studied to develop 3D SERS substrate. • The Au–PS sphere can be hexagonal close packing with 10–20 nm nanoscale gaps. • PS glass transition property results in Au–PS sphere nano configuration evolution. • The nanoscale Au clusters with clear outline

Micro/nano engineering on stainless steel substrates to produce superhydrophobic surfaces

Energy Technology Data Exchange (ETDEWEB)

Beckford, Samuel; Zou Min, E-mail: mzou@uark.edu

2011-12-30

Creating micro-/nano-scale topography on material surfaces to change their wetting properties has been a subject of much interest in recent years. Wenzel in 1936 and Cassie and Baxter in 1944 proposed that by microscopically increasing the surface roughness of a substrate, it is possible to increase its hydrophobicity. This paper reports the fabrication of micro-textured surfaces and nano-textured surfaces, and the combination of both on stainless steel substrates by sandblasting, thermal evaporation of aluminum, and aluminum-induced crystallization (AIC) of amorphous silicon (a-Si). Meanwhile, fluorinated carbon films were used to change the chemical composition of the surfaces to render the surfaces more hydrophobic. These surface modifications were investigated to create superhydrophobic surfaces on stainless steel substrates. The topography resulting from these surface modifications was analyzed by scanning electron microscopy and surface profilometry. The wetting properties of these surfaces were characterized by water contact angle measurement. The results of this study show that superhydrophobic surfaces can be produced by either micro-scale surface texturing or nano-scale surface texturing, or the combination of both, after fluorinated carbon film deposition.

Effects of substrate temperature, substrate orientation, and energetic atomic collisions on the structure of GaN films grown by reactive sputtering

Energy Technology Data Exchange (ETDEWEB)

Schiaber, Ziani S.; Lisboa-Filho, Paulo N.; Silva, José H. D. da [Universidade Estadual Paulista, UNESP, Bauru, São Paulo 17033-360 (Brazil); Leite, Douglas M. G. [Universidade Federal de Itajubá, UNIFEI, Itajubá, Minas Gerais 37500-903 (Brazil); Bortoleto, José R. R. [Universidade Estadual Paulista, UNESP, Sorocaba, São Paulo 18087-180 (Brazil)

2013-11-14

The combined effects of substrate temperature, substrate orientation, and energetic particle impingement on the structure of GaN films grown by reactive radio-frequency magnetron sputtering are investigated. Monte-Carlo based simulations are employed to analyze the energies of the species generated in the plasma and colliding with the growing surface. Polycrystalline films grown at temperatures ranging from 500 to 1000 °C clearly showed a dependence of orientation texture and surface morphology on substrate orientation (c- and a-plane sapphire) in which the (0001) GaN planes were parallel to the substrate surface. A large increase in interplanar spacing associated with the increase in both a- and c-parameters of the hexagonal lattice and a redshift of the optical bandgap were observed at substrate temperatures higher than 600 °C. The results showed that the tensile stresses produced during the film's growth in high-temperature deposition ranges were much larger than the expected compressive stresses caused by the difference in the thermal expansion coefficients of the film and substrate in the cool-down process after the film growth. The best films were deposited at 500 °C, 30 W and 600 °C, 45 W, which corresponds to conditions where the out diffusion from the film is low. Under these conditions the benefits of the temperature increase because of the decrease in defect density are greater than the problems caused by the strongly strained lattice that occurr at higher temperatures. The results are useful to the analysis of the growth conditions of GaN films by reactive sputtering.

Improved surface bioactivity of stainless steel substrates using osteocalcin mimetic peptide

International Nuclear Information System (INIS)

Hosseini, Samaneh; Naderi-Manesh, Hossein; Vali, Hojatollah; Faghihi, Shahab

2014-01-01

Although stainless steel has a good biocompatibility for most clinical cases, the higher tissue response (bone bonding property) is required in orthopedic field. In this study, to improve bone-bonding ability of stainless steel substrates, a specific sequence of osteocalcin mimetic peptide is used as bioactive coating material to biochemically modify the surface of metallic samples. This sequence consists of thirteen amino acids present in the first helix of osteocalcin is synthesized in amidic form and physically adsorbed on the surface of 316LS (316 low carbon surgical grade) stainless steel substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to characterize the surface of peptide coated and uncoated substrates. The bioactivity and bone bonding ability of coated and uncoated substrates are assessed by level of hydroxyapatite formation, using transmission electron microscopy (TEM), energy-dispersive x-ray (EDS), and scanning electron microscopy (SEM). The pre-osteoblast cell attachment and proliferation are also evaluated by MTT assay. The results show that the surface of coated sample is homogenously covered by the peptide and display a rougher surface relative to uncoated sample. TEM images reveal the formation of plate-like hydroxyapatite crystals in the presence of the peptide and an amorphous calcium phosphate phase without the peptide. Pre-osteoblast cells proliferation is significantly higher on the surface of peptide coated substrate, while cell attachment remains unaffected by the peptide coatings. Pre-osteoblast cells also demonstrate a higher degree of spreading on the surface of coated sample. It is believed that osteocalcin mimetic peptide improve surface bioactivity and promote hydroxyapatite crystal formation may lead to increased mineralization and bone formation on the surface of metallic biomedical devices. - Graphical abstract: A peptide sequence located in the first helix of OC is selected based on its

Improved surface bioactivity of stainless steel substrates using osteocalcin mimetic peptide

Energy Technology Data Exchange (ETDEWEB)

Hosseini, Samaneh [Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology, Tehran 14965/161 (Iran, Islamic Republic of); Naderi-Manesh, Hossein, E-mail: naderman@modares.ac.ir [Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Vali, Hojatollah [Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7 (Canada); Faghihi, Shahab, E-mail: sfaghihi@nigeb.ac.ir [Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology, Tehran 14965/161 (Iran, Islamic Republic of)

2014-02-14

Although stainless steel has a good biocompatibility for most clinical cases, the higher tissue response (bone bonding property) is required in orthopedic field. In this study, to improve bone-bonding ability of stainless steel substrates, a specific sequence of osteocalcin mimetic peptide is used as bioactive coating material to biochemically modify the surface of metallic samples. This sequence consists of thirteen amino acids present in the first helix of osteocalcin is synthesized in amidic form and physically adsorbed on the surface of 316LS (316 low carbon surgical grade) stainless steel substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to characterize the surface of peptide coated and uncoated substrates. The bioactivity and bone bonding ability of coated and uncoated substrates are assessed by level of hydroxyapatite formation, using transmission electron microscopy (TEM), energy-dispersive x-ray (EDS), and scanning electron microscopy (SEM). The pre-osteoblast cell attachment and proliferation are also evaluated by MTT assay. The results show that the surface of coated sample is homogenously covered by the peptide and display a rougher surface relative to uncoated sample. TEM images reveal the formation of plate-like hydroxyapatite crystals in the presence of the peptide and an amorphous calcium phosphate phase without the peptide. Pre-osteoblast cells proliferation is significantly higher on the surface of peptide coated substrate, while cell attachment remains unaffected by the peptide coatings. Pre-osteoblast cells also demonstrate a higher degree of spreading on the surface of coated sample. It is believed that osteocalcin mimetic peptide improve surface bioactivity and promote hydroxyapatite crystal formation may lead to increased mineralization and bone formation on the surface of metallic biomedical devices. - Graphical abstract: A peptide sequence located in the first helix of OC is selected based on its

A lattice Boltzmann model for substrates with regularly structured surface roughness

Science.gov (United States)

Yagub, A.; Farhat, H.; Kondaraju, S.; Singh, T.

2015-11-01

Superhydrophobic surface characteristics are important in many industrial applications, ranging from the textile to the military. It was observed that surfaces fabricated with nano/micro roughness can manipulate the droplet contact angle, thus providing an opportunity to control the droplet wetting characteristics. The Shan and Chen (SC) lattice Boltzmann model (LBM) is a good numerical tool, which holds strong potentials to qualify for simulating droplets wettability. This is due to its realistic nature of droplet contact angle (CA) prediction on flat smooth surfaces. But SC-LBM was not able to replicate the CA on rough surfaces because it lacks a real representation of the physics at work under these conditions. By using a correction factor to influence the interfacial tension within the asperities, the physical forces acting on the droplet at its contact lines were mimicked. This approach allowed the model to replicate some experimentally confirmed Wenzel and Cassie wetting cases. Regular roughness structures with different spacing were used to validate the study using the classical Wenzel and Cassie equations. The present work highlights the strength and weakness of the SC model and attempts to qualitatively conform it to the fundamental physics, which causes a change in the droplet apparent contact angle, when placed on nano/micro structured surfaces.

AlGaN/GaN HEMT structures on ammono bulk GaN substrate

International Nuclear Information System (INIS)

Kruszewski, P; Prystawko, P; Krysko, M; Smalc-Koziorowska, J; Leszczynski, M; Kasalynas, I; Nowakowska-Siwinska, A; Plesiewicz, J; Dwilinski, R; Zajac, M; Kucharski, R

2014-01-01

The work shows a successful fabrication of AlGaN/GaN high electron mobility transistor (HEMT) structures on the bulk GaN substrate grown by ammonothermal method providing an ultralow dislocation density of 10 4  cm −2  and wafers of size up to 2 inches in diameter. The AlGaN layers grown by metalorganic chemical vapor phase epitaxy method demonstrate atomically smooth surface, flat interfaces with reproduced low dislocation density as in the substrate. The test electronic devices—Schottky diodes and transistors—were designed without surface passivation and were successfully fabricated using mask-less laser-based photolithography procedures. The Schottky barrier devices demonstrate exceptionally low reverse currents smaller by a few orders of magnitude in comparison to the Schottky diodes made of AlGaN/GaN HEMT on sapphire substrate. (paper)

Influence of substrate temperature on structural, morphological and electrical properties of PbSe film deposited by radio frequency sputtering

Energy Technology Data Exchange (ETDEWEB)

Feng, Wenran, E-mail: fengwenran@bipt.edu.cn [College of Materials Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Beijing Key Lab of Special Elastomer Composite Materials, Beijing 102617 (China); Wang, Xiaoyang [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Fei [College of Materials Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Beijing Key Lab of Special Elastomer Composite Materials, Beijing 102617 (China); Liu, Wan [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhou, Hai; Wang, Shuo; Li, Haoran [College of Materials Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Beijing Key Lab of Special Elastomer Composite Materials, Beijing 102617 (China)

2015-03-02

PbSe films were prepared by radio frequency magnetron sputtering from PbSe slices target under different substrate temperatures (from room temperature to 300 °C). The effect of substrate temperature on structural properties of PbSe thin film was investigated. The surface morphology and the crystal structure of film were determined using field emission scanning electron microscopy and X-ray diffractometry, respectively. It was found that the grain shape changed with substrate temperature. When the substrate temperature was below 250 °C, most of the crystal grains were spherical in shape. For temperatures above 250 °C, the grains transformed to triangle or prismatic ones. Meanwhile, with increasing substrate temperature, the preferential orientation of the film changed from (200) to (220). To figure out the intrinsic mechanisms for this behavior, the texture coefficient, as well as the comparison between surface energy and elastic strain energy was performed. At lower temperature, the film growth was determined by surface energy, which was replaced by strain energy at higher temperature. Therefore, the diversity of crystal structure and morphology of the films at different substrate temperatures occurred. Moreover, the electrical properties of the p-type PbSe films are also quite dependent on substrate temperature. With substrate temperature increased, the electrical resistivity decreased from 1.88 to 0.14 Ω cm, while the carrier concentration increased from 1.74 × 10{sup 18} to 4.08 × 10{sup 19} cm{sup −3} as the mobility was enhanced from 0.54 to 2.21 cm{sup 2}/Vs. - Highlights: • PbSe thin films were deposited by radio frequency magnetron sputtering. • Substrate temperature determines crystal structure of PbSe films. • Transformation behaviors of PbSe films were explained by energy calculations.

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates

Energy Technology Data Exchange (ETDEWEB)

Xiao, J; Huang, Y [Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208 (United States); Ryu, S Y; Paik, U [Division of Materials Science and Engineering, Hanyang University, 17 Hangdang-dong, Sungdong-gu, Seoul 133-791 (Korea, Republic of); Hwang, K-C [Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Rogers, J A, E-mail: y-huang@northwestern.edu, E-mail: jrogers@uiuc.edu [Department of Materials Science and Engineering, Frederick-Seitz Materials Research Laboratory and Beckman Institute, University of Illinois at Urbana-Champaign, Illinois 61801 (United States)

2010-02-26

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

Mechanics of nanowire/nanotube in-surface buckling on elastomeric substrates

International Nuclear Information System (INIS)

Xiao, J; Huang, Y; Ryu, S Y; Paik, U; Hwang, K-C; Rogers, J A

2010-01-01

A continuum mechanics theory is established for the in-surface buckling of one-dimensional nanomaterials on compliant substrates, such as silicon nanowires on elastomeric substrates observed in experiments. Simple analytical expressions are obtained for the buckling wavelength, amplitude and critical buckling strain in terms of the bending and tension stiffness of the nanomaterial and the substrate elastic properties. The analysis is applied to silicon nanowires, single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanotube bundles. For silicon nanowires, the measured buckling wavelength gives Young's modulus to be 140 GPa, which agrees well with the prior experimental studies. It is shown that the energy for in-surface buckling is lower than that for normal (out-of-surface) buckling, and is therefore energetically favorable.

Understanding surface structure and chemistry of single crystal lanthanum aluminate

KAUST Repository

Pramana, Stevin S.

2017-03-02

The surface crystallography and chemistry of a LaAlO3 single crystal, a material mainly used as a substrate to deposit technologically important thin films (e.g. for superconducting and magnetic devices), was analysed using surface X-ray diffraction and low energy ion scattering spectroscopy. The surface was determined to be terminated by Al-O species, and was significantly different from the idealised bulk structure. Termination reversal was not observed at higher temperature (600 °C) and chamber pressure of 10−10 Torr, but rather an increased Al-O occupancy occurred, which was accompanied by a larger outwards relaxation of Al from the bulk positions. Changing the oxygen pressure to 10−6 Torr enriched the Al site occupancy fraction at the outermost surface from 0.245(10) to 0.325(9). In contrast the LaO, which is located at the next sub-surface atomic layer, showed no chemical enrichment and the structural relaxation was lower than for the top AlO2 layer. Knowledge of the surface structure will aid the understanding of how and which type of interface will be formed when LaAlO3 is used as a substrate as a function of temperature and pressure, and so lead to improved design of device structures.

Nanostructured surface enhanced Raman scattering substrates for explosives detection

DEFF Research Database (Denmark)

Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja

2010-01-01

Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives...

Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

DEFF Research Database (Denmark)

Rodrigo, K.; Czuba, P.; Toftmann, B.

2006-01-01

The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements...

Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

Energy Technology Data Exchange (ETDEWEB)

Sedao, Xxx, E-mail: sedao.xxx@gmail.com [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Maurice, Claire [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Quey, Romain; Blanc, Gilles [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Pigeon, Florent [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France)

2014-05-01

Graphical abstract: -- Highlight: •Lattice rotation and its distribution in laser-induced periodic surface structures (LIPSS) and the subsurface region on a nickel substrate are revealed using electron backscatter diffraction (EBSD). -- Abstract: We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1–3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

Substrate Vibrations as Promoters of Chemical Reactivity on Metal Surfaces.

Science.gov (United States)

Campbell, Victoria L; Chen, Nan; Guo, Han; Jackson, Bret; Utz, Arthur L

2015-12-17

Studies exploring how vibrational energy (Evib) promotes chemical reactivity most often focus on molecular reagents, leaving the role of substrate atom motion in heterogeneous interfacial chemistry underexplored. This combined theoretical and experimental study of methane dissociation on Ni(111) shows that lattice atom motion modulates the reaction barrier height during each surface atom's vibrational period, which leads to a strong variation in the reaction probability (S0) with surface temperature (Tsurf). State-resolved beam-surface scattering studies at Tsurf = 90 K show a sharp threshold in S0 at translational energy (Etrans) = 42 kJ/mol. When Etrans decreases from 42 kJ/mol to 34 kJ/mol, S0 decreases 1000-fold at Tsurf = 90 K, but only 2-fold at Tsurf = 475 K. Results highlight the mechanism for this effect, provide benchmarks for DFT calculations, and suggest the potential importance of surface atom induced barrier height modulation in heterogeneously catalyzed reactions, particularly on structurally labile nanoscale particles and defect sites.

Electron beam irradiating process for rendering rough or topographically irregular surface substrates smooth; and coated substrates produced thereby

International Nuclear Information System (INIS)

Nablo, S.V.

1979-01-01

This disclosure involves a novel process for instantaneous electron-beam curing of very thin low viscosity, solventless coating upon rough, irregular or textured surfaces of a substrate such as paper or the like. Through rather critical timing and energy adjustment procedures, the coating firmly adheres to the surface before the coating can conform to the roughness or texture contour or substantially penetrate into the surface. By this method a solidified very smooth outer surface is provided for the substrate that is particularly used for metalization and other finished layerings. (author)

A liquid aluminum corrosion resistance surface on steel substrate

International Nuclear Information System (INIS)

Wang Deqing; Shi Ziyuan; Zou Longjiang

2003-01-01

The process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt. The thickness of the pure aluminum layer on the steel substrate is reduced with the increase in temperature and time in initial aluminizing, and the thickness of the aluminum layer does not increase with time at given temperature when identical temperature and complete wetting occur between liquid aluminum and the substrate surface. The thickness of the Fe-Al intermetallic layer on the steel base is increased with increasing bath temperature and time. Based on the experimental data and the mathematics model developed by the study, a maximum exists in the thickness of the Fe-Al intermetallic at certain dipping temperature. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis reveals that the top portion of the steel substrate is composed of a thin layer of α-Al 2 O 3 , followed by a thinner layer of FeAl 3 , and then a much thicker one of Fe 2 Al 5 on the steel base side. In addition, there is a carbon enrichment zone in diffusion front. The aluminum oxide surface formed on the steel substrate is in perfect condition after corrosion test in liquid aluminum at 750 deg. C for 240 h, showing extremely good resistance to aluminum melt corrosion

Electromagnetic Modelling of Raman Enhancement from Nanoscale Structures as a Means to Predict the Efficacy of SERS Substrates

Directory of Open Access Journals (Sweden)

Richard J. C. Brown

2007-01-01

Full Text Available The requirement to optimise the balance between signal enhancement and reproducibility in surface enhanced Raman spectroscopy (SERS is stimulating the development of novel substrates for enhancing Raman signals. This paper describes the application of finite element electromagnetic modelling to predict the Raman enhancement produced from a variety of SERS substrates with differently sized, spaced and shaped morphologies with nanometre dimensions. For the first time, a theoretical comparison between four major generic types of SERS substrate (including metal nanoparticles, structured surfaces, and sharp tips has been performed and the results are presented and discussed. The results of the modelling are consistent with published experimental data from similar substrates.

Effect of substrate surface on electromigration-induced sliding at hetero-interfaces

International Nuclear Information System (INIS)

Kumar, Praveen; Dutta, Indranath

2013-01-01

Electromigration (EM)-induced interfacial sliding between a metal film and Si substrate occurs when (i) only few grains exist across the width of the film and (ii) diffusivity through the interfacial region is significantly greater than diffusivity through the film. Here, the effect of the substrate surface layer on the kinetics of EM-induced interfacial sliding is assessed using Si substrates coated with various thin film interlayers. The kinetics of interfacial sliding, and therefore the EM-driven mass flow rate, strongly depends on the type of the interlayer (and hence the substrate surface composition), such that strongly bonded interfaces with slower interfacial diffusivity produce slower sliding. (paper)

Modification of Bi:YIG film properties by substrate surface ion pre-treatment

International Nuclear Information System (INIS)

Shaposhnikov, A.N.; Prokopov, A.R.; Karavainikov, A.V.; Berzhansky, V.N.; Mikhailova, T.V.; Kotov, V.A.; Balabanov, D.E.; Sharay, I.V.; Salyuk, O.Y.; Vasiliev, M.; Golub, V.O.

2014-01-01

Highlights: • Effects of substrates ion beam treatment on magnetoptical properties Bi:YIG films. • Substrate surface damage results in sign inversion of the magneto-optical effects. • Atomically smooth films growth takes place on low energy ions treated substrates. • High energy ions treatment results in selective nucleation mechanism of the growth. - Abstract: The effect of a controlled ion beam pre-treatment of (1 1 1)-oriented Gd 3 Ga 5 O 12 substrates on the magneto-optical properties and surface morphology of the ultrathin bismuth-substituted yttrium–iron garnet films with a composition Bi 2.8 Y 0.2 Fe 5 O 12 was studied. It has been shown that the observed sign inversion of magneto-optical effects (Faraday rotation and magnetic circular dichroism) observed in films that were deposited on the GGG substrate pre-treated by 1 keV and 4 keV Ar + ion beams is a result of the substrate surface amorphization caused by the ion bombardment

Substrate structure dependence of the growth modes of p-quaterphenyl thin films on gold

International Nuclear Information System (INIS)

Muellegger, S.; Mitsche, S.; Poelt, P.; Haenel, K.; Birkner, A.; Woell, C.; Winkler, A.

2005-01-01

The variably oriented crystallite surfaces of a recrystallized polycrystalline gold sample served as substrates for the investigation of the structure dependence of p-quaterphenyl (4P) thin film growth. The films were prepared in ultrahigh vacuum by organic molecular beam evaporation. Optical microscopy, scanning electron microscopy, combined with laterally resolved electron backscatter diffraction and scanning tunnelling microscopy have been applied to determine the correlation between the substrate surface structure and 4P film morphology. Crystallite surfaces consisting of (110) terraces favour highly anisotropic needle-like 4P growth with the needle orientation normal to the Au directions. Atomic steps on vicinal planes with narrow terraces (< 2 nm) can also induce anisotropy in the 4P thin film growth, in particular elongated 4P islands normal to the step direction. In contrast to that, a nearly isotropic distribution of the needle orientations is observed on Au grains terminated by highly symmetric (111) or (100) crystal planes. Additionally, patches of continuous 4P layers can be found on these surfaces. There is strong evidence that the 4P molecules within the needle-like crystallites are oriented parallel to the Au surface, whereas for the continuous layers the 4P molecules are oriented nearly upright on the surface

Surface Modification of Polymer Substrates for Biomedical Applications

Directory of Open Access Journals (Sweden)

Oldřich Neděla

2017-09-01

Full Text Available While polymers are widely utilized materials in the biomedical industry, they are rarely used in an unmodified state. Some kind of a surface treatment is often necessary to achieve properties suitable for specific applications. There are multiple methods of surface treatment, each with their own pros and cons, such as plasma and laser treatment, UV lamp modification, etching, grafting, metallization, ion sputtering and others. An appropriate treatment can change the physico-chemical properties of the surface of a polymer in a way that makes it attractive for a variety of biological compounds, or, on the contrary, makes the polymer exhibit antibacterial or cytotoxic properties, thus making the polymer usable in a variety of biomedical applications. This review examines four popular methods of polymer surface modification: laser treatment, ion implantation, plasma treatment and nanoparticle grafting. Surface treatment-induced changes of the physico-chemical properties, morphology, chemical composition and biocompatibility of a variety of polymer substrates are studied. Relevant biological methods are used to determine the influence of various surface treatments and grafting processes on the biocompatibility of the new surfaces—mammalian cell adhesion and proliferation is studied as well as other potential applications of the surface-treated polymer substrates in the biomedical industry.

Atomic structure of the SbCu surface alloy: A surface X-ray diffraction study

DEFF Research Database (Denmark)

Meunier, I.; Gay, J.M.; Lapena, L.

1999-01-01

The dissolution at 400 degrees C of an antimony layer deposited at room temperature on a Cu(111) substrate leads to a surface alloy with a p(root 3x root 3)R 30 degrees x 30 degrees superstructure and a Sb composition of 1/3.We present here a structural study of this Sb-Cu compound by surface X...

Grafted membranes and substrates having surfaces with switchable superoleophilicity and superoleophobicity and applications thereof

KAUST Repository

Zhang, Lianbin

2013-10-10

Disclosed herein are surface-modified membranes and other surface-modified substrates exhibiting switchable oleophobicity and oleophilicity in aqueous media. These membranes and substrates may be used for variety of applications, including controllable oil/water separation processes, oil spill cleanup, and oil/water purification. Also provided are the making and processing of such surface-modified membranes and other surface-modified substrates.

Grafted membranes and substrates having surfaces with switchable superoleophilicity and superoleophobicity and applications thereof

KAUST Repository

Zhang, Lianbin; Wang, Peng

2013-01-01

Disclosed herein are surface-modified membranes and other surface-modified substrates exhibiting switchable oleophobicity and oleophilicity in aqueous media. These membranes and substrates may be used for variety of applications, including controllable oil/water separation processes, oil spill cleanup, and oil/water purification. Also provided are the making and processing of such surface-modified membranes and other surface-modified substrates.

Graphene-on-semiconductor substrates for analog electronics

Science.gov (United States)

Lagally, Max G.; Cavallo, Francesca; Rojas-Delgado, Richard

2016-04-26

Electrically conductive material structures, analog electronic devices incorporating the structures and methods for making the structures are provided. The structures include a layer of graphene on a semiconductor substrate. The graphene layer and the substrate are separated by an interfacial region that promotes transfer of charge carriers from the surface of the substrate to the graphene.

Thin Bioactive Zn Substituted Hydroxyapatite Coating Deposited on Ultrafine Grained Titanium Substrate: Structure Analysis

Science.gov (United States)

Prosolov, Konstantin A.; Belyavskaya, Olga A.; Muehle, Uwe; Sharkeev, Yurii P.

2018-02-01

Nanocrystalline Zn substituted hydroxyapatite coatings were deposited by radiofrequency magnetron sputtering on the surface of ultrafine-grained titanium substrates. Cross section transmission electron microscopy provided information about the morphology and texture of the thin film while in-column energy dispersive X-ray analysis confirmed the presence of Zn in the coating. The Zn substituted hydroxyapatite coating was formed by an equiaxed polycrystalline grain structure. Effect of substrate crystallinity on the structure of deposited coating is discussed. An amorphous TiO2 sublayer of 8 nm thickness was detected in the interface between the polycrystalline coating and the Ti substrate. Its appearance in the amorphous state is attributed to prior to deposition etching of the substrate and subsequent condensation of oxygen-containing species sputtered from the target. This layer contributes to the high coating-to-substrate adhesion. The major P-O vibrational modes of high intensity were detected by Raman spectroscopy. The Zn substituted hydroxyapatite could be a material of choice when antibacterial osteoconductive coating with a possibility of withstanding mechanical stress during implantation and service is needed.

Thin Bioactive Zn Substituted Hydroxyapatite Coating Deposited on Ultrafine-Grained Titanium Substrate: Structure Analysis

Directory of Open Access Journals (Sweden)

Konstantin A. Prosolov

2018-02-01

Full Text Available Nanocrystalline Zn-substituted hydroxyapatite coatings were deposited by radiofrequency magnetron sputtering on the surface of ultrafine-grained titanium substrates. Cross-section transmission electron microscopy provided information about the morphology and texture of the thin film while in-column energy dispersive X-ray analysis confirmed the presence of Zn in the coating. The Zn-substituted hydroxyapatite coating was formed by an equiaxed polycrystalline grain structure. Effect of substrate crystallinity on the structure of deposited coating is discussed. An amorphous TiO2 sublayer of 8-nm thickness was detected in the interface between the polycrystalline coating and the Ti substrate. Its appearance in the amorphous state is attributed to prior to deposition etching of the substrate and subsequent condensation of oxygen-containing species sputtered from the target. This layer contributes to the high coating-to-substrate adhesion. The major P–O vibrational modes of high intensity were detected by Raman spectroscopy. The Zn-substituted hydroxyapatite could be a material of choice when antibacterial osteoconductive coating with a possibility of withstanding mechanical stress during implantation and service is needed.

Preparation and surface characterization of plasma-treated and biomolecular-micropatterned polymer substrates

Science.gov (United States)

Langowski, Bryan Alfred

A micropatterning process creates distinct microscale domains on substrate surfaces that differ from the surfaces' original chemical/physical properties. Numerous micropatterning methods exist, each having relative advantages and disadvantages in terms of cost, ease, reproducibility, and versatility. Polymeric surfaces micropatterned with biomolecules have many applications, but are specifically utilized in tissue engineering as cell scaffolds that attempt to controlled tissue generation in vivo and ex vivo. As the physical and chemical cues presented by micropatterned substrates control resulting cellular behavior, characterization of these cues via surface-sensitive analytical techniques is essential in developing cell scaffolds that mimic complex in vivo physicochemical environments. The initial focus of this thesis is the chemical and physical characterization of plasma-treated, microcontact-printed (muCP) polymeric substrates used to direct nerve cell behavior. Unmodified and oxygen plasma-treated poly(methyl methacrylate) (PMMA) substrates were analyzed by surface sensitive techniques to monitor plasma-induced chemical and physical modifications. Additionally, protein-micropattern homogeneity and size were microscopically evaluated. Lastly, poly(dimethylsiloxane) (PDMS) stamps and contaminated PMMA substrates were characterized by spectroscopic and microscopic methods to identify a contamination source during microcontact printing. The final focus of this thesis is the development of microscale plasma-initiated patterning (muPIP) as a versatile, reproducible micropatterning method. Using muPIP, polymeric substrates were micropatterned with several biologically relevant inks. Polymeric substrates were characterized following muPIP by surface-sensitive techniques to identify the technique's underlying physical and chemical bases. In addition, neural stem cell response to muPIP-generated laminin micropatterns was microscopically and biologically evaluated

Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

Science.gov (United States)

Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

2016-09-30

Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface.

Influence of viscoelastic property on laser-generated surface acoustic waves in coating-substrate systems

International Nuclear Information System (INIS)

Sun Hongxiang; Zhang Shuyi; Xu Baiqiang

2011-01-01

Taking account of the viscoelasticity of materials, the pulsed laser generation of surface acoustic waves in coating-substrate systems has been investigated quantitatively by using the finite element method. The displacement spectra of the surface acoustic waves have been calculated in frequency domain for different coating-substrate systems, in which the viscoelastic properties of the coatings and substrates are considered separately. Meanwhile, the temporal displacement waveforms have been obtained by applying inverse fast Fourier transforms. The numerical results of the normal surface displacements are presented for different configurations: a single plate, a slow coating on a fast substrate, and a fast coating on a slow substrate. The influences of the viscoelastic properties of the coating and the substrate on the attenuation of the surface acoustic waves have been studied. In addition, the influence of the coating thickness on the attenuation of the surface acoustic waves has been also investigated in detail.

Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

Energy Technology Data Exchange (ETDEWEB)

Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

2000-05-01

The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

Characteristics of surface acoustic waves in (11\\bar 2 0)ZnO film/ R-sapphire substrate structures

Science.gov (United States)

Wang, Yan; Zhang, ShuYi; Xu, Jing; Xie, YingCai; Lan, XiaoDong

2018-02-01

(11\\bar 2 0)ZnO film/ R-sapphire substrate structure is promising for high frequency acoustic wave devices. The propagation characteristics of SAWs, including the Rayleigh waves along [0001] direction and Love waves along [1ī00] direction, are investigated by using 3 dimensional finite element method (3D-FEM). The phase velocity ( v p), electromechanical coupling coefficient ( k 2), temperature coefficient of frequency ( TCF) and reflection coefficient ( r) of Rayleigh wave and Love wave devices are theoretically analyzed. Furthermore, the influences of ZnO films with different crystal orientation on SAW properties are also investigated. The results show that the 1st Rayleigh wave has an exceedingly large k 2 of 4.95% in (90°, 90°, 0°) (11\\bar 2 0)ZnO film/ R-sapphire substrate associated with a phase velocity of 5300 m/s; and the 0th Love wave in (0°, 90°, 0°) (11\\bar 2 0)ZnO film/ R-sapphire substrate has a maximum k 2 of 3.86% associated with a phase velocity of 3400 m/s. And (11\\bar 2 0)ZnO film/ R-sapphire substrate structures can be used to design temperature-compensated and wide-band SAW devices. All of the results indicate that the performances of SAW devices can be optimized by suitably selecting ZnO films with different thickness and crystal orientations deposited on R-sapphire substrates.

Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

Science.gov (United States)

Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

2015-11-01

The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

Modification of Bi:YIG film properties by substrate surface ion pre-treatment

Energy Technology Data Exchange (ETDEWEB)

Shaposhnikov, A.N.; Prokopov, A.R.; Karavainikov, A.V.; Berzhansky, V.N.; Mikhailova, T.V. [Taurida National V.I. Vernadsky University, Vernadsky Avenue, 4, Simferopol, 95007 (Ukraine); Kotov, V.A. [V.A. Kotelnikov Institute of Radio Engineering and Electronics, RAS, 11 Mohovaya Street, Moscow, 125009 (Russian Federation); Balabanov, D.E. [Moscow Institute of Physics and Technology, Dolgoprudny, 141700 (Russian Federation); Sharay, I.V.; Salyuk, O.Y. [Institute of Magnetism, NAS of Ukraine, 03142, Kiev (Ukraine); Vasiliev, M. [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup 6027 (Australia); Golub, V.O., E-mail: v_o_golub@yahoo.com [Institute of Magnetism, NAS of Ukraine, 03142, Kiev (Ukraine)

2014-07-01

Highlights: • Effects of substrates ion beam treatment on magnetoptical properties Bi:YIG films. • Substrate surface damage results in sign inversion of the magneto-optical effects. • Atomically smooth films growth takes place on low energy ions treated substrates. • High energy ions treatment results in selective nucleation mechanism of the growth. - Abstract: The effect of a controlled ion beam pre-treatment of (1 1 1)-oriented Gd{sub 3}Ga{sub 5}O{sub 12} substrates on the magneto-optical properties and surface morphology of the ultrathin bismuth-substituted yttrium–iron garnet films with a composition Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} was studied. It has been shown that the observed sign inversion of magneto-optical effects (Faraday rotation and magnetic circular dichroism) observed in films that were deposited on the GGG substrate pre-treated by 1 keV and 4 keV Ar{sup +} ion beams is a result of the substrate surface amorphization caused by the ion bombardment.

Electrostatic cloaking of surface structure for dynamic wetting

Science.gov (United States)

Shiomi, Junichiro; Nita, Satoshi; Do-Quang, Minh; Wang, Jiayu; Chen, Yu-Chung; Suzuki, Yuji; Amberg, Gustav

2017-11-01

Dynamic wetting problems are fundamental to the understanding of the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, as surfaces may often be naturally charged, or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena. Here we investigate the interplay between electric forces and surface structures in dynamic wetting. While surface microstructures can significantly hinder the spreading, we find that the electrostatics can ``cloak'' the microstructures, i.e. deactivate the hindering. We identify the physics in terms of reduction in contact-line friction, which makes the dynamic wetting inertial force dominant and insensitive to the substrate properties. This work was financially supported in part by, the Japan Society for the Promotion of Science, Swedish Governmental Agency for Innovation Systems, and the Japan Science and Technology Agency.

Effect of substrate temperature on the morphological, structural, and optical properties of RF sputtered Ge1−x Snx films on Si substrate

International Nuclear Information System (INIS)

Mahmodi, H; Hashim, M R

2017-01-01

In this study, Ge 1−x Sn x alloy films are co-sputtered on Si(100) substrates using RF magnetron sputtering at different substrate temperatures. Scanning electron micrographs, atomic force microscopy (AFM), Raman spectroscopy, and x-ray photoemission spectroscopy (XPS) are conducted to investigate the effect of substrate temperature on the structural and optical properties of grown GeSn alloy films. AFM results show that RMS surface roughness of the films increases from 1.02 to 2.30 nm when raising the substrate temperature. This increase could be due to Sn surface segregation that occurs when raising the substrate temperature. Raman spectra exhibits the lowest FWHM value and highest phonon intensity for a film sputtered at 140 °C. The spectra show that decreasing the deposition temperature to 140 °C improves the crystalline quality of the alloy films and increases nanocrystalline phase formation. The results of Raman spectra and XPS confirm Ge–Sn bond formation. The optoelectronic characteristics of fabricated metal-semiconductor-metal photodetectors on sputtered samples at room temperature (RT) and 140 °C are studied in the dark and under illumination. The sample sputtered at 140 °C performs better than the RT sputtered sample. (paper)

Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

KAUST Repository

Yue, Weisheng

2017-03-28

Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

Biofunctionalization on alkylated silicon substrate surfaces via "click" chemistry.

Science.gov (United States)

Qin, Guoting; Santos, Catherine; Zhang, Wen; Li, Yan; Kumar, Amit; Erasquin, Uriel J; Liu, Kai; Muradov, Pavel; Trautner, Barbara Wells; Cai, Chengzhi

2010-11-24

Biofunctionalization of silicon substrates is important to the development of silicon-based biosensors and devices. Compared to conventional organosiloxane films on silicon oxide intermediate layers, organic monolayers directly bound to the nonoxidized silicon substrates via Si-C bonds enhance the sensitivity of detection and the stability against hydrolytic cleavage. Such monolayers presenting a high density of terminal alkynyl groups for bioconjugation via copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC, a "click" reaction) were reported. However, yields of the CuAAC reactions on these monolayer platforms were low. Also, the nonspecific adsorption of proteins on the resultant surfaces remained a major obstacle for many potential biological applications. Herein, we report a new type of "clickable" monolayers grown by selective, photoactivated surface hydrosilylation of α,ω-alkenynes, where the alkynyl terminal is protected with a trimethylgermanyl (TMG) group, on hydrogen-terminated silicon substrates. The TMG groups on the film are readily removed in aqueous solutions in the presence of Cu(I). Significantly, the degermanylation and the subsequent CuAAC reaction with various azides could be combined into a single step in good yields. Thus, oligo(ethylene glycol) (OEG) with an azido tag was attached to the TMG-alkyne surfaces, leading to OEG-terminated surfaces that reduced the nonspecific adsorption of protein (fibrinogen) by >98%. The CuAAC reaction could be performed in microarray format to generate arrays of mannose and biotin with varied densities on the protein-resistant OEG background. We also demonstrated that the monolayer platform could be functionalized with mannose for highly specific capturing of living targets (Escherichia coli expressing fimbriae) onto the silicon substrates.

Atomic Scale Structure-Chemistry Relationships at Oxide Catalyst Surfaces and Interfaces

Science.gov (United States)

McBriarty, Martin E.

Oxide catalysts are integral to chemical production, fuel refining, and the removal of environmental pollutants. However, the atomic-scale phenomena which lead to the useful reactive properties of catalyst materials are not sufficiently understood. In this work, the tools of surface and interface science and electronic structure theory are applied to investigate the structure and chemical properties of catalytically active particles and ultrathin films supported on oxide single crystals. These studies focus on structure-property relationships in vanadium oxide, tungsten oxide, and mixed V-W oxides on the surfaces of alpha-Al2O3 and alpha-Fe2O 3 (0001)-oriented single crystal substrates, two materials with nearly identical crystal structures but drastically different chemical properties. In situ synchrotron X-ray standing wave (XSW) measurements are sensitive to changes in the atomic-scale geometry of single crystal model catalyst surfaces through chemical reaction cycles, while X-ray photoelectron spectroscopy (XPS) reveals corresponding chemical changes. Experimental results agree with theoretical calculations of surface structures, allowing for detailed electronic structure investigations and predictions of surface chemical phenomena. The surface configurations and oxidation states of V and W are found to depend on the coverage of each, and reversible structural shifts accompany chemical state changes through reduction-oxidation cycles. Substrate-dependent effects suggest how the choice of oxide support material may affect catalytic behavior. Additionally, the structure and chemistry of W deposited on alpha-Fe 2O3 nanopowders is studied using X-ray absorption fine structure (XAFS) measurements in an attempt to bridge single crystal surface studies with real catalysts. These investigations of catalytically active material surfaces can inform the rational design of new catalysts for more efficient and sustainable chemistry.

Leaky surface acoustic waves in Z-LiNbO3 substrates with epitaxial AIN overlays

International Nuclear Information System (INIS)

Bu, G.; Ciplys, D.; Shur, M.S.; Namkoong, G.; Doolittle, W.A.; Hunt, W.D.

2004-01-01

The properties of leaky surface acoustic waves (LSAW) in MBE grown AIN layer on Z-cut LiNbO 3 structures have been studied by numerical simulation and experimental measurements and compared with those of Rayleigh waves in the same structure. In the range of AIN layer thicknesses studied (0 3 substrate was essentially constant at around 4400 m/s. The measured electromechanical coupling coefficients (K 2 ) for the LSAW are roughly 1/4 of the predicted values, which might be due to the strong attenuation of the leaky wave unaccounted for during the parameter extraction. The thin AIN film slightly improved the measured temperature coefficient of frequency for the LSAW over that attained for the Z-cut, X-propagating LiNbO 3 substrate alone

PbSe quantum well mid-infrared vertical external cavity surface emitting laser on Si-substrates

Science.gov (United States)

Fill, M.; Khiar, A.; Rahim, M.; Felder, F.; Zogg, H.

2011-05-01

Mid-infrared vertical external cavity surface emitting lasers based on PbSe/PbSrSe multi-quantum-well structures on Si-substrates are realized. A modular design allows growing the active region and the bottom Bragg mirror on two different Si-substrates, thus facilitating comparison between different structures. Lasing is observed from 3.3 to 5.1 μm wavelength and up to 52 °C heat sink temperature with 1.55 μm optical pumping. Simulations show that threshold powers are limited by Shockley-Read recombination with lifetimes as short as 0.1 ns. At higher temperatures, an additional threshold power increase occurs probably due to limited carrier diffusion length and carrier leakage, caused by an unfavorable band alignment.

Electric field stimulation through a substrate influences Schwann cell and extracellular matrix structure

Science.gov (United States)

Nguyen, Hieu T.; Wei, Claudia; Chow, Jacqueline K.; Nguy, Lindsey; Nguyen, Hieu K.; Schmidt, Christine E.

2013-08-01

Objective. Electric field (EF) stimulation has been used to cue cell growth for tissue engineering applications. In this study, we explore the electrical parameters and extracellular mechanisms that elicit changes in cell behavior when stimulated through the substrate. Approach. Rat Schwann cell morphology was compared when exposed to EF through the media or a conductive indium tin oxide substrate. Ionic and structural effects were then analyzed on Matrigel and collagen I, respectively. Main results. When stimulating through media, cells had greater alignment perpendicular to the EF with higher current densities (106 mA cm-2 at 245 mV mm-1), and reached maximum alignment within 8 h. Stimulation through the substrate with EF (up to 110 mV mm-1) did not affect Schwann cell orientation, however the EF caused extracellular matrix (ECM) coatings on substrates to peel away, suggesting EF can physically change the ECM. Applying alternating current (ac) 2-1000 Hz signals through the media or substrate both caused cells to flatten and protrude many processes, without preferential alignment. Matrigel exposed to a substrate EF of 10 mV mm-1 for 2 h had a greater calcium concentration near the cathode, but quickly dissipated when the EF was removed. Schwann cells seeded 7 d after gels were exposed to substrate EF still aligned perpendicular to the EF direction. Microscopy of collagen I exposed to substrate EF shows alignment and bundling of fibrils. Significance. These findings demonstrate EF exposure can control Schwann cell alignment and morphology, change ECM bulk/surface architecture, and align ECM structures.

Wet-chemical passivation of atomically flat and structured silicon substrates for solar cell application

Science.gov (United States)

Angermann, H.; Rappich, J.; Korte, L.; Sieber, I.; Conrad, E.; Schmidt, M.; Hübener, K.; Polte, J.; Hauschild, J.

2008-04-01

Special sequences of wet-chemical oxidation and etching steps were optimised with respect to the etching behaviour of differently oriented silicon to prepare very smooth silicon interfaces with excellent electronic properties on mono- and poly-crystalline substrates. Surface photovoltage (SPV) and photoluminescence (PL) measurements, atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations were utilised to develop wet-chemical smoothing procedures for atomically flat and structured surfaces, respectively. Hydrogen-termination as well as passivation by wet-chemical oxides were used to inhibit surface contamination and native oxidation during the technological processing. Compared to conventional pre-treatments, significantly lower micro-roughness and densities of surface states were achieved on mono-crystalline Si(100), on evenly distributed atomic steps, such as on vicinal Si(111), on silicon wafers with randomly distributed upside pyramids, and on poly-crystalline EFG ( Edge-defined Film-fed- Growth) silicon substrates. The recombination loss at a-Si:H/c-Si interfaces prepared on c-Si substrates with randomly distributed upside pyramids was markedly reduced by an optimised wet-chemical smoothing procedure, as determined by PL measurements. For amorphous-crystalline hetero-junction solar cells (ZnO/a-Si:H(n)/c-Si(p)/Al) with textured c-Si substrates the smoothening procedure results in a significant increase of short circuit current Isc, fill factor and efficiency η. The scatter in the cell parameters for measurements on different cells is much narrower, as compared to conventional pre-treatments, indicating more well-defined and reproducible surface conditions prior to a-Si:H emitter deposition and/or a higher stability of the c-Si surface against variations in the a-Si:H deposition conditions.

Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

KAUST Repository

Yue, Weisheng; Wang, Zhihong; Whittaker, John; Lopez-royo, Francisco; Yang, Yang; Zayats, Anatoly

2017-01-01

that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold

Methods to introduce sub-micrometer, symmetry-breaking surface corrugation to silicon substrates to increase light trapping

Energy Technology Data Exchange (ETDEWEB)

Han, Sang Eon; Hoard, Brittany R.; Han, Sang M.; Ghosh, Swapnadip

2018-04-10

Provided is a method for fabricating a nanopatterned surface. The method includes forming a mask on a substrate, patterning the substrate to include a plurality of symmetry-breaking surface corrugations, and removing the mask. The mask includes a pattern defined by mask material portions that cover first surface portions of the substrate and a plurality of mask space portions that expose second surface portions of the substrate, wherein the plurality of mask space portions are arranged in a lattice arrangement having a row and column, and the row is not oriented parallel to a [110] direction of the substrate. The patterning the substrate includes anisotropically removing portions of the substrate exposed by the plurality of spaces.

Fabrication and characterization of surface barrier detector from commercial silicon substrate

International Nuclear Information System (INIS)

Costa, Fabio Eduardo da; Silva, Julio Batista Rodrigues da

2015-01-01

This work used 5 silicon substrates, n-type with resistivity between 500-20,000 Ω.cm, with 12 mm diameter and 1 mm thickness, from Wacker - Chemitronic, Germany. To produce the surface barrier detectors, the substrates were first cleaned, then, they were etched with HNO 3 solution. After this, a deposition of suitable materials on the crystal was made, to produce the desired population inversion of the crystal characteristics. The substrates received a 10 mm diameter gold contact in one of the surfaces and a 5 mm diameter aluminum in the other. The curves I x V and the energy spectra for 28 keV and 59 keV, for each of the produced detectors, were measured. From the 5 substrates, 4 of them resulted in detectors and one did not present even diode characteristics. The results showed that the procedures used are suitable to produce detectors with this type of silicon substrates. (author)

Influence of substrate orientation on the structural properties of GaAs nanowires in MOCVD

Energy Technology Data Exchange (ETDEWEB)

Muhammad, R., E-mail: rosnita@utm.my; Othaman, Z., E-mail: zulothaman@gmail.com; Ibrahim, Z., E-mail: zuhairi@utm.my; Sakrani, S., E-mail: samsudi3@yahoo.com [Faculty of Science, UniversitiTeknologi Malaysia, 81310 UTM, Johor (Malaysia); Wahab, Y., E-mail: wyussof@gmail.com [Razak School, UniversitiTeknologi Malaysia, 54100 Kuala Lumpur (Malaysia)

2016-04-19

In this study, the effect of substrate orientation on the structural properties of GaAs nanowires grown by a metal organic chemical vapor deposition has been investigated. Gold colloids were used as catalyst to initiate the growth of nanowiresby the vapour-liquid-solid (VLS) mechanism. From the field-emission scanning electron microscopy (FE-SEM), the growth of the nanowires were at an elevation angle of 90°, 60°, 65° and 35° with respect to the GaAs substrate for (111)B, (311)B, (110) and (100) orientations respectively. The preferential NW growth direction is always <111>B. High-resolution transmission electron microscope (HRTEM) micrograph showed the NWs that grew on the GaAs(111)B has more structural defects when compared to others. Energy dispersive X-ray analysis (EDX) indicated the presence of Au, Ga and As. The bigger diameter NWs dominates the (111)B substrate surface.

Surface-enhanced Raman spectroscopy based on conical holed enhancing substrates

International Nuclear Information System (INIS)

Chen, Yao; Chen, Zeng-Ping; Zuo, Qi; Shi, Cai-Xia; Yu, Ru-Qin

2015-01-01

In this contribution, surface-enhanced Raman spectroscopy (SERS) based on conical holed glass substrates deposited with silver colloids was reported for the first time. It combines the advantages of both dry SERS assays based on plane films deposited with silver colloids and wet SERS assays utilizing cuvettes or capillary tubes. Compared with plane glass substrates deposited with silver colloids, the conical holed glass substrates deposited with silver colloids exhibited five-to ten-folds of increase in the rate of signal enhancement, due to the internal multiple reflections of both the excitation laser beam and the Raman scattering photons within conical holes. The application of conical holed glass substrates could also yield significantly stronger and more reproducible SERS signals than SERS assays utilizing capillary tubes to sample the mixture of silver colloids and the solution of the analyte of interest. The conical holed glass substrates in combination with the multiplicative effects model for surface-enhanced Raman spectroscopy (MEM SERS ) achieved quite sensitive and precise quantification of 6-mercaptopurine in complex plasma samples with an average relative prediction error of about 4% and a limit of detection of about 0.02 μM using a portable i-Raman 785H spectrometer. It is reasonable to expect that SERS technique based on conical holed enhancing substrates in combination with MEM SERS model can be developed and extended to other application areas such as drug detection, environmental monitoring, and clinic analysis, etc. - Highlights: • A novel conical holed SERS enhancing substrate was designed and manufactured. • The optimal conical holed glass substrates can produce stronger SERS signal. • The novel substrates can overcome the shortcomings of both dry and wet methods. • The novel substrates coupled with MEM SERS can realize quantitative SERS assays

Surface morphology of homoepitaxial GaN grown on non- and semipolar GaN substrates

Energy Technology Data Exchange (ETDEWEB)

Wernicke, Tim; Hoffmann, Veit; Netzel, Carsten; Knauer, Arne; Weyers, Markus [FBH, Berlin (Germany); Ploch, Simon; Rass, Jens [Institute of Solid State Physics, TU Berlin (Germany); Schade, Lukas; Schwarz, Ulrich [IAF, Freiburg (Germany); Kneissl, Michael [FBH, Berlin (Germany); Institute of Solid State Physics, TU Berlin (Germany)

2010-07-01

Recently a number of groups have reported laser diodes in the green spectral range on semi- and nonpolar GaN. Nevertheless the growth process on semipolar surfaces is not well understood. In this study 3.5 {mu} m thick MOVPE grown GaN layers on bulk m-plane, (11 anti 22), (10 anti 12), and (10 anti 11) GaN substrates were investigated. XRD rocking curves exhibit a FWHM of less than 150{sup ''}, indicating excellent crystalline quality. But the surface morphology exhibits hillocks with a height of 1 {mu}m and lateral extension of 150 {mu}m in many cases. Depending on the substrate orientation and the growth temperature different hillock shapes were observed. Morphology and luminescence data point to threading dislocations as formation sources. In QWs the hillock structure is reproduced in the emission intensity and wavelength distribution on (10 anti 11) but not on the m-plane surfaces. The hillocks could be eliminated for the semipolar planes (not for the m-plane) by increasing the reactor pressure and lowering the growth temperature. Hillock free separate confinement laser structures emitting at 405 nm feature a very homogeneous luminescence in micro-PL and show amplified spontaneous emission under high power stripe excitation. Furthermore the In incorporation was found to be highest in QWs on (10 anti 11).

Laser writing of single-crystalline gold substrates for surface enhanced Raman spectroscopy

Science.gov (United States)

Singh, Astha; Sharma, Geeta; Ranjan, Neeraj; Mittholiya, Kshitij; Bhatnagar, Anuj; Singh, B. P.; Mathur, Deepak; Vasa, Parinda

2017-07-01

Surface enhanced Raman scattering (SERS) spectroscopy, a powerful contemporary tool for studying low-concentration analytes via surface plasmon induced enhancement of local electric field, is of utility in biochemistry, material science, threat detection, and environmental studies. We have developed a simple, fast, scalable, and relatively low-cost optical method of fabricating and characterizing large-area, reusable and broadband SERS substrates with long storage lifetime. We use tightly focused, intense infra-red laser pulses to write gratings on single-crystalline, Au (1 1 1) gold films on mica which act as SERS substrates. Our single-crystalline SERS substrates compare favourably, in terms of surface quality and roughness, to those fabricated in poly-crystalline Au films. Tests show that our SERS substrates have the potential of detecting urea and 1,10-phenantroline adulterants in milk and water, respectively, at 0.01 ppm (or lower) concentrations.

Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates

DEFF Research Database (Denmark)

Yuan, Scott Wu; Ho, Ho Pui; Lee, Rebecca K.Y.

2009-01-01

We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree of repro......We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree...

On the structure and surface chemical composition of indium-tin oxide films prepared by long-throw magnetron sputtering

International Nuclear Information System (INIS)

Chuang, M.J.; Huang, H.F.; Wen, C.H.; Chu, A.K.

2010-01-01

Structures and surface chemical composition of indium tin oxide (ITO) thin films prepared by long-throw radio-frequency magnetron sputtering technique have been investigated. The ITO films were deposited on glass substrates using a 20 cm target-to-substrate distance in a pure argon sputtering environment. X-ray diffraction results showed that an increase in substrate temperature resulted in ITO structure evolution from amorphous to polycrystalline. Field-emission scanning electron microscopy micrographs suggested that the ITO films were free of bombardment of energetic particles since the microstructures of the films exhibited a smaller grain size and no sub-grain boundary could be observed. The surface composition of the ITO films was characterized by X-ray photoelectron spectroscopy (XPS). Oxygen atoms in both amorphous and crystalline ITO structures were observed from O 1 s XPS spectra. However, the peak of the oxygen atoms in amorphous ITO phase could only be found in samples prepared at low substrate temperatures. Its relative peak area decreased drastically when substrate temperatures were larger than 200 o C. In addition, a composition analysis from the XPS results revealed that the films deposited at low substrate temperatures contained high concentration of oxygen at the film surfaces. The oxygen-rich surfaces can be attributed to hydrolysis reactions of indium oxides, especially when large amount of the amorphous ITO were developed near the film surfaces.

Well-ordered structure of methylene blue monolayers on Au(111) surface: electrochemical scanning tunneling microscopy studies.

Science.gov (United States)

Song, Yonghai; Wang, Li

2009-02-01

Well-ordered structure of methylene blue (MB) monolayers on Au(111) surface has been successfully obtained by controlling the substrate potential. Electrochemical scanning tunneling microscopy (ECSTM) examined the monolayers of MB on Au(111) in 0.1 M HClO(4) and showed long-range ordered, interweaved arrays of MB with quadratic symmetry on the substrate in the potential range of double-layer charging. High-resolution ECSTM image further revealed the details of the MB monolayers structure of c(5 x 5 radical 3)rect and the flat-lying orientation of ad-molecules. The dependence of molecular organization on the substrate potential and the formation mechanism of well-ordered structure on Au(111) surface were investigated in detail. The obtained well-ordered structure at the interface between a metal and an aqueous electrolyte might possibly be used as high-density device for signal memory and templates for the advanced nanopatterning of surfaces. (c) 2008 Wiley-Liss, Inc.

Two-dimensional Si nanosheets with local hexagonal structure on a MoS(2) surface.

Science.gov (United States)

Chiappe, Daniele; Scalise, Emilio; Cinquanta, Eugenio; Grazianetti, Carlo; van den Broek, Bas; Fanciulli, Marco; Houssa, Michel; Molle, Alessandro

2014-04-02

The structural and electronic properties of a Si nanosheet (NS) grown onto a MoS2 substrate by means of molecular beam epitaxy are assessed. Epitaxially grown Si is shown to adapt to the trigonal prismatic surface lattice of MoS2 by forming two-dimensional nanodomains. The Si layer structure is distinguished from the underlying MoS2 surface structure. The local electronic properties of the Si nanosheet are dictated by the atomistic arrangement of the layer and unlike the MoS2 hosting substrate they are qualified by a gap-less density of states. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ag/SiO2 surface-enhanced Raman scattering substrate for plasticizer detection

Science.gov (United States)

Wu, Ming-Chung; Lin, Ming-Pin; Lin, Ting-Han; Su, Wei-Fang

2018-04-01

In this study, we demonstrated a simple method of fabricating a high-performance surface-enhanced Raman scattering (SERS) substrate. Monodispersive SiO2 colloidal spheres were self-assembled on a silicon wafer, and then a silver layer was coated on it to obtain a Ag/SiO2 SERS substrate. The Ag/SiO2 SERS substrates were used to detect three kinds of plasticizer with different concentrations, namely, including bis(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate (BBP), and dibutyl phthalate (DBP). The enhancement of Raman scattering intensity caused by surface plasmon resonance can be observed using the Ag/SiO2 SERS substrates. The Ag/SiO2 SERS substrate with a 150-nm-thick silver layer can detect plasticizers, and it satisfies the detection limit of plasticizers at 100 ppm. The developed highly sensitive Ag/SiO2 SERS substrates show a potential for the design and fabrication of functional sensors to identify the harmful plasticizers that plastic products release in daily life.

Theoretical Investigation on Structural and Electronic Properties of InN Growth on Ce-Stabilized Zirconia (111 Substrates

Directory of Open Access Journals (Sweden)

Yao Guo

2016-01-01

Full Text Available The structural and electronic properties of InN on Ce-stabilized zirconia (CeSZ (111 substrates are investigated using first-principles calculations based on density functional theory with GGA + U method. Surface energy calculations indicate that the structure of Ce-segregated surface is more energetically stable than that of Ce-segregation-free surface. Adsorption energies of indium and nitrogen atoms on both Ce-segregated and Ce-segregation-free CeSZ (111 surfaces at the initial growth stage have been studied. The results suggest that the first layer of InN films consists of a nitrogen layer, which leads to epitaxial relationships between InN (0001 // CeSZ (111 and InN [112¯0] // CeSZ [11¯0]. In addition, density of states (DOS analysis revealed that the hybridization effect plays a crucial role in determining the interface structure for the growth of InN on CeSZ (111 surfaces. Furthermore, adsorption energies of indium atoms on the nitrogen layer have also been evaluated in order to investigate the lattice polarity determination for InN films. It was found that an indium atom preferentially adsorbs at the center of three nitrogen atoms stacked on the CeSZ substrate, which results in the formation of In-polarity InN.

UV Direct Laser Interference Patterning of polyurethane substrates as tool for tuning its surface wettability

Energy Technology Data Exchange (ETDEWEB)

Estevam-Alves, Regina [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Günther, Denise; Dani, Sophie; Eckhardt, Sebastian; Roch, Teja [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany); Mendonca, Cleber R., E-mail: crmendon@ifsc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Cestari, Ismar N. [Heart Institute (InCOr), University of São Paulo Medical School, São Paulo 05403-000 (Brazil); Lasagni, Andrés F., E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany)

2016-06-30

Highlights: • First reported experiments on Direct Laser Interference Patterning of polyurethane. • First reported sub-micrometer structures (feature size ∼250 nm) fabricated in polyurethane materials using laser processing technologies. • Anisotropic wetting behavior of structured surfaces and possibility to tune the contact angle as function of surface structure parameters. - Abstract: Direct Laser Interference Patterning (DLIP) is a versatile tool for the fabrication of micro and sub-micropatterns on different materials. In this work, DLIP was used to produce periodic surface structures on polyurethane (PU) substrates with spatial periods ranging from 0.5 to 5.0 μm. The influence of the laser energy density on the quality and topographical characteristics of the produced micropatterns was investigated. To characterize the surface topography of the produced structures, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Confocal Microscopy (CFM) were utilized. It was found that high quality and defect free periodic line-like patterns with spatial periods down to 500 nm could be fabricated, with structure depths between 0.88 up to 1.25 μm for spatial periods larger than 2.0 μm and up to 270 nm for spatial periods between 500 nm and 1.0 μm. Measurements of the contact angle of water on the treated surface allowed to identify an anisotropic wetting behavior depending mainly on the spatial period and filling factor of the structured surfaces.

Facile method for preparing superoleophobic surfaces with hierarchical microcubic/nanowire structures

Science.gov (United States)

Kwak, Wonshik; Hwang, Woonbong

2016-02-01

To facilitate the fabrication of superoleophobic surfaces having hierarchical microcubic/nanowire structures (HMNS), even for low surface tension liquids including octane (surface tension = 21.1 mN m-1), and to understand the influences of surface structures on the oleophobicity, we developed a convenient method to achieve superoleophobic surfaces on aluminum substrates using chemical acid etching, anodization and fluorination treatment. The liquid repellency of the structured surface was validated through observable experimental results the contact and sliding angle measurements. The etching condition required to ensure high surface roughness was established, and an optimal anodizing condition was determined, as a critical parameter in building the superoleophobicity. The microcubic structures formed by acid etching are essential for achieving the formation of the hierarchical structure, and therefore, the nanowire structures formed by anodization lead to an enhancement of the superoleophobicity for low surface tension liquids. Under optimized morphology by microcubic/nanowire structures with fluorination treatment, the contact angle over 150° and the sliding angle less than 10° are achieved even for octane.

Enhanced osteointegration of medical titanium implant with surface modifications in micro/nanoscale structures

Directory of Open Access Journals (Sweden)

Liwen Lin

2014-01-01

Full Text Available Biomimetic design and substrate-based surface modification of medical implants will help to improve the integration of tissue to its material interfaces. Surface energy, composition, roughness, and topography all influence the biological responses of the implants, such as protein adsorption and cell adhesion, proliferation and differentiation. In the current study, different surface structures of Ti implants were constructed using facile surface techniques to create various micro-, nano-, and nano/micro composite scale topography. We have fabricated three types of hierarchical structures of TiO2 coating on Ti implants, including nanotube structure, nano sponge-like structure, and nano/micro nest-like structure. The osteointegration and biomechanical performance of the coated Ti screws were evaluated by histology and removal of torque force test in vivo. We found that the nano/micro nest-like and nanotube structured surface possessed better osteointegration ability. It indicated that the alkaline hydrothermally treated Ti substrate was the best for bone-implant integration in terms of all in vitro and in vivo testing parameters. The alkaline hydrothermally treated surface displayed a hydrophilic (contact angle value 5.92 ± 1.2, higher roughness (Ra value 911.3 ± 33.8 nm, higher specific surface area (8.26 ± 1.051 m2/g, and greater apatite inductivity. The electrochemical surface modification may become a powerful approach to enhance metal implant to bone integration in orthopaedic applications.

Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

Science.gov (United States)

Balpande, Suresh S.; Pande, Rajesh S.

2016-04-01

Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of harvester and

Etching of GaAs substrates to create As-rich surface

Indian Academy of Sciences (India)

WINTEC

during the manipulations of the substrate after the chemi- cal etching process. ... using the four techniques described in table 1 and for an. *Author for ... Etching of GaAs substrates to create As-rich surface. 563. Table 1. Treatment procedures used. Treatment. Techniques. 1st stage. 2nd stage. 3rd stage. 4th stage. 1. Treated ...

Silver endotaxy in silicon under various ambient conditions and their use as surface enhanced Raman spectroscopy substrates

International Nuclear Information System (INIS)

Juluri, R.R.; Ghosh, A.; Bhukta, A.; Sathyavathi, R.; Satyam, P.V.

2015-01-01

Search for reliable, robust and efficient substrates for surface enhanced Raman spectroscopy (SERS) leads to the growth of various shapes and nanostructures of noble metals, and in particular, Ag nanostructures for this purpose. Coherently embedded (also known as endotaxial) Ag nanostructures in silicon substrates can be made robust and reusable SERS substrates. In this paper, we show the possibility of the growth of Ag endotaxial structures in Si crystal during Ar and low-vacuum annealing conditions while this is absent in O 2 and ultra high vacuum (UHV) annealing conditions and along with their respective use as SERS substrates. Systems annealed under air-annealing and low-vacuum conditions were found to show larger enhancement factors (typically ≈ 5 × 10 5 in SERS measurement for 0.5 nM Crystal Violet (CV) molecule) while the systems prepared under UHV-annealing conditions (where no endotaxial Ag structures were formed) were found to be not effective as SERS substrates. Extensive electron microscopy, synchrotron X-ray diffraction and Rutherford backscattering spectrometry techniques were used to understand the structural aspects. - Highlights: • Various aspects on the growth of endotaxial Ag nanostructures are presented. • Optimum amount of oxygen is necessary for the growth of endotaxial structures. • Reaction of oxygen with GeOx and SiOx plays a crucial role. • Ag nanostructures prepared under UHV conditions show low SERS activity • SERS enhancement is better for low-vacuum and argon annealing conditions

Surface structure of ultrathin metal films deposited on copper single crystals

International Nuclear Information System (INIS)

Butterfield, M.T.

2000-04-01

Ultrathin films of Cobalt, Iron and Manganese have been thermally evaporated onto an fcc Copper (111) single crystal substrate and investigated using a variety of surface structural techniques. The small lattice mismatch between these metals and the Cu (111) substrate make them an ideal candidate for the study of the phenomena of pseudomorphic film growth. This is important for the understanding of the close relationship between film structure and magnetic properties. Growing films with the structure of their substrate rather than their bulk phase may provide an opportunity to grow materials with novel physical and magnetic properties, and hence new technological applications. Both Cobalt and Iron have been found to initially maintain a registry with the fcc Cu (111) surface in a manner consistent with pseudomorphic growth. This growth is complicated by island rather than layer by layer growth in the initials stages of the film. In both cases a change in the structure of the film seems to occur at a point where the coalescence of islands in the film may be expected to occur. When the film does change structure they do not form a perfect overlayer with the structure of their bulk counterpart. The films do contain a number of features representative of the bulk phase but also contain considerable disorder and possibly remnants of fcc (111) structure. The order present in these films can be greatly improved by annealing. Manganese appears to grow with an fcc Mn (111) lattice spacing and there is no sign of a change in structure in films of up to 4.61 ML thick. The gradual deposition and annealing of a film to 300 deg. C, with a total deposition time the same as that for a 1 ML thick film, causes a surface reconstruction to occur that is apparent in a R30 deg. (√3 x √3) LEED pattern. This is attributed to the formation of a surface alloy, which is also supported by the local expansion of the Cu lattice in the (111) direction. (author)

Synthesis of Graphene Based Membranes: Effect of Substrate Surface Properties on Monolayer Graphene Transfer.

Science.gov (United States)

Kafiah, Feras; Khan, Zafarullah; Ibrahim, Ahmed; Atieh, Muataz; Laoui, Tahar

2017-01-21

In this work, we report the transfer of graphene onto eight commercial microfiltration substrates having different pore sizes and surface characteristics. Monolayer graphene grown on copper by the chemical vapor deposition (CVD) process was transferred by the pressing method over the target substrates, followed by wet etching of copper to obtain monolayer graphene/polymer membranes. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) measurements were carried out to explore the graphene layer transferability. Three factors, namely, the substrate roughness, its pore size, and its surface wetting (degree of hydrophobicity) are found to affect the conformality and coverage of the transferred graphene monolayer on the substrate surface. A good quality graphene transfer is achieved on the substrate with the following characteristics; being hydrophobic (CA > 90°), having small pore size, and low surface roughness, with a CA to RMS (root mean square) ratio higher than 2.7°/nm.

Method of electrode printing on one or more surfaces of a dielectric substrate

KAUST Repository

Neophytou, Marios

2017-09-14

Described herein is a method for printing electrodes surfaces of a dielectric substrate. Provided herein is a new method of depositing electrically conductive electrodes of any shape on flexible and/or rigid dielectric substrates/surfaces and devices so produced. In various embodiments, the devices can generate ionic wind, for example to remove dust or other debris or contaminants or to remove ice or humidity from a surface.

Method of electrode printing on one or more surfaces of a dielectric substrate

KAUST Repository

Neophytou, Marios; Kirkus, Mindaugas; Lacoste, Deanna A.

2017-01-01

Described herein is a method for printing electrodes surfaces of a dielectric substrate. Provided herein is a new method of depositing electrically conductive electrodes of any shape on flexible and/or rigid dielectric substrates/surfaces and devices so produced. In various embodiments, the devices can generate ionic wind, for example to remove dust or other debris or contaminants or to remove ice or humidity from a surface.

Palladium clusters deposited on the heterogeneous substrates

Energy Technology Data Exchange (ETDEWEB)

Wang, Kun, E-mail: cqdxwk@126.com [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China); Liu, Juanfang, E-mail: juanfang@cqu.edu.cn [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China); Chen, Qinghua, E-mail: qhchen@cqu.edu.cn [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China)

2016-07-15

Graphical abstract: The site-exchange between the substrate and cluster atoms can result in the formation of the surface alloys and the reconstruction of the cluster structure before the collision system approaching the thermal equilibrium. The deposited cluster adjusted the atom arrangement as possibly as to match the substrate lattice arrangement from bottom to up. The structural reconstruction is accompanied by the system potential energy minimization. - Highlights: • The deposition process can divide explicitly into three stages: adsorption, collision, relaxation. • The local melt does not emerge inside the substrate during the deposition process. • Surface alloys are formed by the site-exchange between the cluster and substrate atoms. • The cluster reconstructs the atom arrangement following as the substrate lattice arrangement from bottom to up. • The structural reconstruction ability and scope depend on the cluster size and incident energy. - Abstract: To improve the performance of the Pd composite membrane prepared by the cold spraying technology, it is extremely essential to give insights into the deposition process of the cluster and the heterogeneous deposition of the big Pd cluster at the different incident velocities on the atomic level. The deposition behavior, morphologies, energetic and interfacial configuration were examined by the molecular dynamic simulation and characterized by the cluster flattening ratio, the substrate maximum local temperature, the atom-embedded layer number and the surface-alloy formation. According to the morphology evolution, three deposition stages and the corresponding structural and energy evolution were clearly identified. The cluster deformation and penetrating depth increased with the enhancement of the incident velocity, but the increase degree also depended on the substrate hardness. The interfacial interaction between the cluster and the substrate can be improved by the higher substrate local temperature

Direct writing of large-area micro/nano-structural arrays on single crystalline germanium substrates using femtosecond lasers

Science.gov (United States)

Li, Lin; Wang, Jun

2017-06-01

A direct writing technique for fabricating micro/nano-structural arrays without using a multi-scanning process, multi-beam interference, or any assisted microlens arrays is reported. Various sub-wavelength micro/nano-structural arrays have been directly written on single crystalline germanium substrate surfaces using femtosecond laser pulses. The evolution of the multiscale surface morphology from periodic micro/nano-structures to V-shaped microgrooves has been achieved, and the relationship between array characteristics and laser polarization directions has been discussed. The self-organization model agrees well with the experimental results in this study.

Modification and structuring of conducting polymer films on insulating substrates by ion beam treatment

International Nuclear Information System (INIS)

Asmus, T.; Wolf, Gerhard K.

2000-01-01

Besides the commonly used procedures of UV-, X-ray and electron beam lithography, surface structuring by ion beam processes represents an alternative route to receive patterns in the nanometre-micrometre scale. In this work we focused on changes of surface properties of the polymer materials induced by ion irradiation and on reproducing hexagonal and square patterns in the micrometre scale. To achieve a better understanding of modification and structuring of insulating and conducting polymers by ion beam treatment we investigated effects of 14 keV Ar + bombardment on thin films of doped conducting polyethoxithiophene (PEOT) and polyethylenedioxithiophene (PEDT) on polyethersulfone (PES) as insulating substrate within the fluence range from 10 14 to 10 17 ions/cm 2 . Changes of surface properties like wettability, solubility, topology and electrochemical behaviour have been studied by contact angle technique, AFM/LFM, cyclovoltammetry and electrochemical microelectrode. By irradiation through copper masks structured patterns were achieved. These patterns can be converted by galvanic or electroless copper deposition in structured metal layers

Effect of surface area of substrates aiming the optimization of carbon nanotube production from ferrocene

International Nuclear Information System (INIS)

Osorio, A.G.; Bergmann, C.P.

2013-01-01

Highlights: ► An optimized synthesis of CNTs by ferrocene is proposed. ► The surface area of substrates influences the nucleation of CNTs. ► The higher the surface area of substrates the lower the temperature of synthesis. ► Chemical composition of substrates has no influence on the growth of CNTs. - Abstract: Ferrocene is widely used for the synthesis of carbon nanotubes due to its ability to act as catalyst and precursor of the synthesis. This paper proposes an optimization of the synthesis of carbon nanotubes from ferrocene, using a substrate with high surface area for their nucleation. Four different surface areas of silica powder were tested: 0.5, 50, 200 and 300 m 2 /g. Raman spectroscopy and microscopy were used to characterize the product obtained and X-ray diffraction and thermal analysis were also performed to evaluate the phases of the material. It was observed that the silica powder with the highest surface area allowed the synthesis of carbon nanotubes to occur at a lower temperature (600 °C), whereas substrates with a surface area lower than 50 m 2 /g will only form carbon nanotubes at temperatures higher than 750 °C. In order to evaluate the influence of chemical composition of the substrate, three different ceramic powders were analyzed: alumina, silica and zirconia. carbon black and previously synthesized carbon nanotubes were also used as substrate for the synthesis and the results showed that the chemical composition of the substrate does not play a relevant role in the synthesis of carbon nanotubes, only the surface area showed an influence.

Three-dimensional noble-metal nanostructure: A new kind of substrate for sensitive, uniform, and reproducible surface-enhanced Raman scattering

International Nuclear Information System (INIS)

Tian Cui-Feng; You Hong-Jun; Fang Ji-Xiang

2014-01-01

Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique for highly sensitive structural detection of low concentration analyte. The SERS activities largely depend on the topography of the substrate. In this review, we summarize the recent progress in SERS substrate, especially focusing on the three-dimensional (3D) noble-metal substrate with hierarchical nanostructure. Firstly, we introduce the background and general mechanism of 3D hierarchical SERS nanostructures. Then, a systematic overview on the fabrication, growth mechanism, and SERS property of various noble-metal substrates with 3D hierarchical nanostructures is presented. Finally, the applications of 3D hierarchical nanostructures as SERS substrates in many fields are discussed. (invited review — international conference on nanoscience and technology, china 2013)

Surface-enhanced Raman scattering (SERS)-based volatile organic compounds (VOCs) detection using plasmonic bimetallic nanogap substrate

DEFF Research Database (Denmark)

Wong, Chi Lok; Dinish, U. S.; Buddharaju, Kavitha Devi

2014-01-01

In this paper, we present surface-enhanced Raman scattering (SERS)-based volatile organic compounds (VOCs) detection with bimetallic nanogap structure substrate. Deep UV photolithography at the wavelength of 250 nm is used to pattern circular shape nanostructures. The nanogap between adjacent cir......-based VOCs detection platform for point-of-care breath analysis, homeland security, chemical sensing and environmental monitoring....

Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

International Nuclear Information System (INIS)

Mallick, Sougata; Mallik, Srijani; Bedanta, Subhankar

2015-01-01

Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field

Enhanced photocatalytic properties of hierarchical three-dimensional TiO{sub 2} grown on femtosecond laser structured titanium substrate

Energy Technology Data Exchange (ETDEWEB)

Huang, Ting, E-mail: huangting@bjut.edu.cn; Lu, Jinlong; Xiao, Rongshi; Wu, Qiang; Yang, Wuxiong

2017-05-01

Highlights: • The hierarchical 3D-TiO{sub 2} is fabricated on femtosecond laser structured Ti substrate. • The formation mechanism of hierarchical 3D-TiO{sub 2} is proposed. • The structure-induced improvement of photocatalytic activity is reported. - Abstract: Three-dimensional micro-/nanostructured TiO{sub 2} (3D-TiO{sub 2}) fabricated on titanium substrate effectively improves its performance in photocatalysis, dye-sensitized solar cell and lithium-ion battery applications. In this study, the hierarchical 3D-TiO{sub 2} with anatase phase directly grown on femtosecond laser structured titanium substrate is reported. First, the primary columnar arrays were fabricated on the surface of titanium substrate by femtosecond laser structuring. Next, the secondary nano-sheet substructures were grown on the primary columnar arrays by NaOH hydrothermal treatment. Followed by ion-exchange process in HCl and annealing in the air, the hierarchical anatase 3D-TiO{sub 2} was achieved. The hierarchical anatase 3D-TiO{sub 2} exhibited enhanced performances in light harvesting and absorption ability compared to that of nano-sheet TiO{sub 2} grown on flat titanium surface without femtosecond laser structuring. The photocatalytic degradation of methyl orange reveals that photocatalytic efficiency of the hierarchical anatase 3D-TiO{sub 2} was improved by a maximum of 57% compared to that of nano-sheet TiO{sub 2} (55% vs 35%). Meanwhile, the hierarchical anatase 3D-TiO{sub 2} remained mechanically stable and constant in consecutive degradation cycles, which promises significance in practical application.

Surface Enhanced Raman Scattering Substrates Made by Oblique Angle Deposition: Methods and Applications

Directory of Open Access Journals (Sweden)

Hin On Chu

2017-02-01

Full Text Available Surface Enhanced Raman Spectroscopy presents a rapid, non-destructive method to identify chemical and biological samples with up to single molecule sensitivity. Since its discovery in 1974, the technique has become an intense field of interdisciplinary research, typically generating >2000 publications per year since 2011. The technique relies on the localised surface plasmon resonance phenomenon, where incident light can couple with plasmons at the interface that result in the generation of an intense electric field. This field can propagate from the surface from the metal-dielectric interface, so molecules within proximity will experience more intense Raman scattering. Localised surface plasmon resonance wavelength is determined by a number of factors, such as size, geometry and material. Due to the requirements of the surface optical response, Ag and Au are typical metals used for surface enhanced Raman applications. These metals then need to have nano features that improve the localised surface plasmon resonance, several variants of these substrates exist; surfaces can range from nanoparticles in a suspension, electrochemically roughened electrodes to metal nanostructures on a substrate. The latter will be the focus of this review, particularly reviewing substrates made by oblique angle deposition. Oblique angle deposition is the technique of growing thin films so that the material flux is not normal to the surface. Films grown in this fashion will possess nanostructures, due to the atomic self-shadowing effect, that are dependent mainly on the deposition angle. Recent developments, applications and highlights of surface enhanced Raman scattering substrates made by oblique angle deposition will be reviewed.

Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse

Science.gov (United States)

Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

2018-05-01

Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10‑9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

Optimizing The Organic/Inorganic Barrier Structure For Flexible Plastic Substrate Encapsulation

Directory of Open Access Journals (Sweden)

Yi-Chiuan Lin

2012-07-01

Full Text Available A multilayered barrier structure stacked with organosilicon and silicon oxide (SiOx films consecutively prepared using plasma-enhanced chemical vapor deposition (PECVD was developed to encapsulate flexible plastic substrate. The evolution on the residual internal stress, structural quality of the organosilicon/SiOx multilayered structure as well as its adhesion to the substrate were found to correlate closely with the thickness of the inset organosilicon layer. Due to the significant discrepancy in the thermal expansion coefficient between the substrate and SiOx film, the thickness of the organosilicon layer deposited onto the substrate and SiOx film thus was crucial to optimize the barrier property of the organosilicon/SiOx structure. The organosilicon/SiOx barrier structure possessed a lowest residual compressive stress and quality adhesion to the substrate was achieved from engineering the organosilicon layer thickness in the multilayered structure. The relaxation of the residual internal stress in the barrier structure led to a dense SiOx film as a consequence of the enhancement in the Si-O-Si networks and thereby resulted in the reduction of the water vapor permeation. Accordingly, a water vapor transmission rate (WVTR below 1 × 10-2 g/m2 /day being potential for the application on the flexible optoelectronic device packaging was achievable from the 3-pairs organosilicon/SiOx multilayered structure deposited onto the polyethylene terephthalate (PET substrate.

Mechanical Q-factor measurements on a test mass with a structured surface

Energy Technology Data Exchange (ETDEWEB)

Nawrodt, R [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Zimmer, A [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Koettig, T [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Clausnitzer, T [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Bunkowski, A [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Kley, E B [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Schnabel, R [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Danzmann, K [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Nietzsche, S [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Vodel, W [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Tuennermann, A [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Seidel, P [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany)

2007-07-15

We present mechanical Q-factors (quality factors) of a crystalline quartz test mass with a nano-structured surface, measured in the temperature regime from 5 to 300 K. The nano-structure was a grating with a period of 2 {mu}m and a depth of about 0.1 {mu}m. Comparative measurements were performed on the plain substrate and on the structured test mass with different numbers of SiO{sub 2}/Ta{sub 2}O{sub 5} coating layers. The measurements at different stages of the test mass fabrication process show that the surface distortion induced by the nanostructure does not severely lower the mechanical Q-factor of the substrate. Damping due to a multi-layer coating stack was found to be orders of magnitude higher. The results provide vital information concerning the potential usage of low-thermal noise nano-structured test masses in future generations of high-precision laser interferometers and in current attempts to measure quantum effects of macroscopic mirror oscillators.

Structure of Ge(100) surfaces for high-efficiency photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Olson, J.M.; McMahon, W.E. [National Renewable Energy Lab., Golden, CO (United States)

1998-09-01

While much is known about the Ge(100) surface in a UHV/MBE environment, little has been published about this surface in an MOCVD environment. The main objective of this study is to determine the structure of the surface of Ge substrates in the typical MOCVD reactor immediately prior to and following the heteronucleation of GaAs and other lattice-matched III-V alloys, and to determine the conditions necessary for the growth of device-quality epilayers. In this paper the authors present the first STM images of the MOCVD-prepared Ge surfaces. Although many of the observed features are very similar to UHV- or MBE-prepared surfaces, there are distinct and important differences. For example, while the As-terminated surfaces for MBE-Ge and MOCVD-Ge are virtually identical, the AsH{sub 3}-treated surfaces in an MOCVD reactor are quite different. The terrace reconstruction is rotated by {pi}/2, and significant step bunching or faceting is also observed. Time-dependent RD kinetic studies also reveal, for the first time, several interesting features: the transition rate from an As-terminated (1 x 2) terrace reconstruction to a stable AsH{sub 3}-annealed surface is a function of the substrate temperature, substrate miscut from (100) and AsH{sub 3} partial pressure, and, for typical prenucleation conditions, is relatively slow. These results explain many of the empirically derived nucleation conditions that have been devised by numerous groups.

Effects O2 plasma surface treatment on the electrical properties of the ITO substrate

International Nuclear Information System (INIS)

Hong, Jin-Woong; Oh, Dong-Hoon; Shim, Sang-Min; Lee, Young-Sang; Kang, Yong-Gil; Shin, Jong-Yeol

2012-01-01

The indium-tin-oxide (ITO) substrate is used as a transparent electrode in organic light-emitting diodes (OLEDs) and organic photovoltaic cells. The effect of an O 2 plasma surface treatment on the electrical properties of the ITO substrate was examined. The four-point probe method, an atomic force microscope (AFM), a LCR meter, a Cole-Cole plot, and a conductive mechanism analysis were used to assess the properties of the treated ITO substrates. The four-point probe method and the AFM study revealed a lower ITO surface resistance of 17.6 Ω/sq and an average roughness of 2 nm, respectively, for a substrate treated by a plasma at 250 W for 40 s. The lower surface resistance of the ITO substrate treated at 250 W for 40 s was confirmed by using a LCR meter. An amorphous fluoropolymer (AF) was deposited on an ITO substrate treated under the optimal conditions and on a non-plasma treated ITO substrate as well. The potential barriers for charge injection in these devices were 0.25 eV and 0.15 eV, respectively, indicating a 0.1-eV decrease due to the plasma treatment.

The construction of hierarchical structure on Ti substrate with superior osteogenic activity and intrinsic antibacterial capability

Science.gov (United States)

Huang, Ying; Zha, Guangyu; Luo, Qiaojie; Zhang, Jianxiang; Zhang, Feng; Li, Xiaohui; Zhao, Shifang; Zhu, Weipu; Li, Xiaodong

2014-01-01

The deficient osseointegration and implant-associated infections are pivotal issues for the long-term clinical success of endosteal Ti implants, while development of functional surfaces that can simultaneously overcome these problems remains highly challenging. This study aimed to fabricate sophisticated Ti implant surface with both osteogenic inducing activity and inherent antibacterial ability simply via tailoring surface topographical features. Micro/submciro/nano-scale structure was constructed on Ti by three cumulative subtractive methods, including sequentially conducted sandblasting as well as primary and secondary acid etching treatment. Topographical features of this hierarchical structure can be well tuned by the time of the secondary acid treatment. Ti substrate with mere micro/submicro-scale structure (MS0-Ti) served as a control to examine the influence of hierarchical structures on surface properties and biological activities. Surface analysis indicated that all hierarchically structured surfaces possessed exactly the same surface chemistry as that of MS0-Ti, and all of them showed super-amphiphilicity, high surface free energy, and high protein adsorption capability. Biological evaluations revealed surprisingly antibacterial ability and excellent osteogenic activity for samples with optimized hierarchical structure (MS30-Ti) when compared with MS0-Ti. Consequently, for the first time, a hierarchically structured Ti surface with topography-induced inherent antibacterial capability and excellent osteogenic activity was constructed. PMID:25146099

Controllable wettability and morphology of electrodeposited surfaces on zinc substrates

Energy Technology Data Exchange (ETDEWEB)

Zhang, Binyan; Lu, Shixiang, E-mail: shixianglu@bit.edu.cn; Xu, Wenguo, E-mail: wenguoxu60@bit.edu.cn; Cheng, Yuanyuan

2016-01-01

Graphical abstract: Superhydrophobic surfaces combining hierarchical micro/nanostructures were fabricated on zinc substrates by etching, electrodeposition of ZnO coatings and annealing. Such superhydrophobic surfaces offer possibilities for chemical, biological, electronic and microfluidic applications. - Highlights: • Superhydrophobic surface was fabricated via electrodeposition of ZnO and annealing. • The ZnO hierarchical micro/nanostructures contribute to the surface superhydrophobicity. • Surface wettability and morphology can be controlled by varying process conditions. • The anti-icing properties and reversible wetting behaviors of the ZnO coatings were studied. - Abstract: Superhydrophobic surfaces combining hierarchical micro/nanostructures were fabricated on zinc substrates by etching in hydrochloric acid solution, electrodeposition of ZnO coatings and subsequent thermal annealing. The optimal coatings were electrodeposited at −1.25 V for 900 s on the etched zinc substrates and then annealed at 200 °C for 60 min, which could achieve a maximum water contact angle of 170 ± 2° and an ultra-low sliding angle of approximately 0°. By conducting SEM and water CA analysis, we found that the morphology and wettability of prepared samples were controllable by the fabrication process. Interestingly, even without any additional modification, the samples prepared under different electrodeposition conditions (including Zn(CH{sub 3}COO){sub 2} concentration from 5 mM to 40 mM and deposition time from 300 s to 1500 s) exhibited superhydrophobic character. The influences of the Zn(CH{sub 3}COO){sub 2} concentration, deposition time, annealing temperature and annealing time on the wetting behaviors were also discussed in detail. Such superhydrophobic surfaces possess long-term stability, and good corrosion resistance as well as self-cleaning ability. In addition, the anti-icing properties of the ZnO films were investigated. These surfaces could be rapidly and

Controllable wettability and morphology of electrodeposited surfaces on zinc substrates

International Nuclear Information System (INIS)

Zhang, Binyan; Lu, Shixiang; Xu, Wenguo; Cheng, Yuanyuan

2016-01-01

Graphical abstract: Superhydrophobic surfaces combining hierarchical micro/nanostructures were fabricated on zinc substrates by etching, electrodeposition of ZnO coatings and annealing. Such superhydrophobic surfaces offer possibilities for chemical, biological, electronic and microfluidic applications. - Highlights: • Superhydrophobic surface was fabricated via electrodeposition of ZnO and annealing. • The ZnO hierarchical micro/nanostructures contribute to the surface superhydrophobicity. • Surface wettability and morphology can be controlled by varying process conditions. • The anti-icing properties and reversible wetting behaviors of the ZnO coatings were studied. - Abstract: Superhydrophobic surfaces combining hierarchical micro/nanostructures were fabricated on zinc substrates by etching in hydrochloric acid solution, electrodeposition of ZnO coatings and subsequent thermal annealing. The optimal coatings were electrodeposited at −1.25 V for 900 s on the etched zinc substrates and then annealed at 200 °C for 60 min, which could achieve a maximum water contact angle of 170 ± 2° and an ultra-low sliding angle of approximately 0°. By conducting SEM and water CA analysis, we found that the morphology and wettability of prepared samples were controllable by the fabrication process. Interestingly, even without any additional modification, the samples prepared under different electrodeposition conditions (including Zn(CH_3COO)_2 concentration from 5 mM to 40 mM and deposition time from 300 s to 1500 s) exhibited superhydrophobic character. The influences of the Zn(CH_3COO)_2 concentration, deposition time, annealing temperature and annealing time on the wetting behaviors were also discussed in detail. Such superhydrophobic surfaces possess long-term stability, and good corrosion resistance as well as self-cleaning ability. In addition, the anti-icing properties of the ZnO films were investigated. These surfaces could be rapidly and reversibly switched

Fabrication of complex nanoscale structures on various substrates

Science.gov (United States)

Han, Kang-Soo; Hong, Sung-Hoon; Lee, Heon

2007-09-01

Polymer based complex nanoscale structures were fabricated and transferred to various substrates using reverse nanoimprint lithography. To facilitate the fabrication and transference of the large area of the nanostructured layer to the substrates, a water-soluble polyvinyl alcohol mold was used. After generation and transference of the nanostructured layer, the polyvinyl alcohol mold was removed by dissolving in water. A residue-free, UV-curable, glue layer was formulated and used to bond the nanostructured layer onto the substrates. As a result, nanometer scale patterned polymer layers were bonded to various substrates and three-dimensional nanostructures were also fabricated by stacking of the layers.

Physico-chemical properties of PDMS surfaces suitable as substrates for cell cultures

Energy Technology Data Exchange (ETDEWEB)

Raczkowska, Joanna, E-mail: joanna.raczkowska@uj.edu.pl [The Marian Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-428 Kraków (Poland); Prauzner-Bechcicki, Szymon [Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Lukes, Jaroslav; Sepitka, Josef [Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, 16607 Prague (Czech Republic); Bernasik, Andrzej [Faculty of Physics and Applied Computer Science, AGH - University of Science and Technology, Reymonta 19, 30-049 Kraków (Poland); Awsiuk, Kamil [The Marian Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-428 Kraków (Poland); Paluszkiewicz, Czesława; Pabijan, Joanna; Lekka, Małgorzata [Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Budkowski, Andrzej [The Marian Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-428 Kraków (Poland)

2016-12-15

Highlights: • Series of PDMS substrates with monotonically tuned elasticity were produced. • Method to estimate PDMS stiffness based on AFM force-distance curves was shown. • No change in surface properties of PDMS other than elasticity was demonstrated. • MTT performed for cancer cells showed impact of PDMS elasticity on cells behavior. - Abstract: Elastic properties of the substrate have profound effect on adhesion and proliferation of cells. Here, we introduce a method to produce polydimethylsiloxane (PDMS) substrates with stiffness tuned monotonically from 1.67 to 0.24 MPa, by the time of UV irradiation adjusted up to 5 h. The Young’s modulus (determined by using nanoindenter) scales linearly with stiffness calculated using AFM-based force spectroscopy data. Such a relation enables the determination of the Young modulus from AFM force – distance curves also when the Herz model is not applicable. Our findings demonstrate that surface properties of PDMS substrates are not affected by the applied methodology of tuning substrate elasticity. Finally, the colorimetric proliferation assay (MTT) carried out for non-malignant (HCV29) and cancerous (T24) bladder cancer cells depicted a significant contribution of PDMS substrate elasticity to the behavior of cells. The softer PDMS substrate demonstrated excellent cytocompatibility whereas the stiff one is more cell-repellent.

Friction of hydrogels with controlled surface roughness on solid flat substrates.

Science.gov (United States)

Yashima, Shintaro; Takase, Natsuko; Kurokawa, Takayuki; Gong, Jian Ping

2014-05-14

This study investigated the effect of hydrogel surface roughness on its sliding friction against a solid substrate having modestly adhesive interaction with hydrogels under small normal pressure in water. The friction test was performed between bulk polyacrylamide hydrogels of varied surface roughness and a smooth glass substrate by using a strain-controlled rheometer with parallel-plates geometry. At small pressure (normal strain 1.4-3.6%), the flat surface gel showed a poor reproducibility in friction. In contrast, the gels with a surface roughness of 1-10 μm order showed well reproducible friction behaviors and their frictional stress was larger than that of the flat surface hydrogel. Furthermore, the flat gel showed an elasto-hydrodynamic transition while the rough gels showed a monotonous decrease of friction with velocity. The difference between the flat surface and the rough surface diminished with the increase of the normal pressure. These phenomena are associated with the different contact behaviors of these soft hydrogels in liquid, as revealed by the observation of the interface using a confocal laser microscope.

Cold Gas-Sprayed Deposition of Metallic Coatings onto Ceramic Substrates Using Laser Surface Texturing Pre-treatment

Science.gov (United States)

Kromer, R.; Danlos, Y.; Costil, S.

2018-04-01

Cold spraying enables a variety of metals dense coatings onto metal surfaces. Supersonic gas jet accelerates particles which undergo with the substrate plastic deformation. Different bonding mechanisms can be created depending on the materials. The particle-substrate contact time, contact temperature and contact area upon impact are the parameters influencing physicochemical and mechanical bonds. The resultant bonding arose from plastic deformation of the particle and substrate and temperature increasing at the interface. The objective was to create specific topography to enable metallic particle adhesion onto ceramic substrates. Ceramic did not demonstrate deformation during the impact which minimized the intimate bonds. Laser surface texturing was hence used as prior surface treatment to create specific topography and to enable mechanical anchoring. Particle compressive states were necessary to build up coating. The coating deposition efficiency and adhesion strength were evaluated. Textured surface is required to obtain strong adhesion of metallic coatings onto ceramic substrates. Consequently, cold spray coating parameters depend on the target material and a methodology was established with particle parameters (diameters, velocities, temperatures) and particle/substrate properties to adapt the surface topography. Laser surface texturing is a promising tool to increase the cold spraying applications.

Power electronics substrate for direct substrate cooling

Science.gov (United States)

Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

2012-05-01

Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

Orthogonal functionalization of nanoporous substrates: control of 3D surface functionality.

Science.gov (United States)

Lazzara, Thomas D; Kliesch, Torben-Tobias; Janshoff, Andreas; Steinem, Claudia

2011-04-01

Anodic aluminum oxide (AAO) membranes with aligned, cylindrical, nonintersecting pores were selectively functionalized in order to create dual-functionality substrates with different pore-rim and pore-interior surface functionalities, using silane chemistry. We used a two-step process involving an evaporated thin gold film to protect the underlying surface functionality of the pore rims. Subsequent treatment with oxygen plasma of the modified AAO membrane removed the unprotected organic functional groups, i.e., the pore-interior surface. After gold removal, the substrate became optically transparent, and displayed two distinct surface functionalities, one at the pore-rim surface and another at the pore-interior surface. We achieved a selective hydrophobic functionalization with dodecyl-trichlorosilane of either the pore rims or the pore interiors. The deposition of planar lipid membranes on the functionalized areas by addition of small unilamellar vesicles occurred in a predetermined fashion. Small unilamellar vesicles only ruptured upon contact with the hydrophobic substrate regions forming solid supported hybrid bilayers. In addition, pore-rim functionalization with dodecyl-trichlorosilane allowed the formation of pore-spanning hybrid lipid membranes as a result of giant unilamellar vesicle rupture. Confocal laser scanning microscopy was employed to identify the selective spatial localization of the adsorbed fluorescently labeled lipids. The corresponding increase in the AAO refractive index due to lipid adsorption on the hydrophobic regions was monitored by optical waveguide spectroscopy. This simple orthogonal functionalization route is a promising method to control the three-dimensional surface functionality of nanoporous films. © 2011 American Chemical Society

Adhesion and friction in polymer films on solid substrates: conformal sites analysis and corresponding surface measurements.

Science.gov (United States)

An, Rong; Huang, Liangliang; Mineart, Kenneth P; Dong, Yihui; Spontak, Richard J; Gubbins, Keith E

2017-05-21

In this work, we present a statistical mechanical analysis to elucidate the molecular-level factors responsible for the static and dynamic properties of polymer films. This analysis, which we term conformal sites theory, establishes that three dimensionless parameters play important roles in determining differences from bulk behavior for thin polymer films near to surfaces: a microscopic wetting parameter, α wx , defined as the ratio of polymer-substrate interaction to polymer-polymer interaction; a dimensionless film thickness, H*; and dimensionless temperature, T*. The parameter α wx introduced here provides a more fundamental measure of wetting than previous metrics, since it is defined in terms of intermolecular forces and the atomic structure of the substrate, and so is valid at the nanoscale for gas, liquid or solid films. To test this theoretical analysis, we also report atomic force microscopy measurements of the friction coefficient (μ), adhesion force (F A ) and glass transition temperature (T g ) for thin films of two polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on two planar substrates, graphite and silica. Both the friction coefficient and the glass transition temperature are found to increase as the film thickness decreases, and this increase is more pronounced for the graphite than for the silica surface. The adhesion force is also greater for the graphite surface. The larger effects encountered for the graphite surface are attributed to the fact that the microscopic wetting parameter, α wx , is larger for graphite than for silica, indicating stronger attraction of polymer chains to the graphite surface.

Influence of substrate quality on structural properties of AlGaN/GaN superlattices grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Schubert, F. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); Merkel, U.; Schmult, S. [TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany); Mikolajick, T. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany)

2014-02-28

Short-period AlGaN/GaN superlattices were established as versatile test structures to investigate the structural properties of molecular beam epitaxy (MBE)-grown GaN and AlGaN layers and their dependence on the GaN substrate quality. X-ray diffractometry data of the investigated superlattices allow access to relevant structural parameters such as aluminum mole fraction and layer thicknesses. The occurrence of theoretically predicted intense high-order satellite peaks and pronounced interface fringes in the diffraction pattern reflects abrupt interfaces and perfect 2-dimensional growth resulting in smooth surfaces. The data unambiguously demonstrate that the structural quality of the MBE grown layers is limited by the structural properties of the GaN substrate.

Topography evolution of rough-surface metallic substrates by solution deposition planarization method

Science.gov (United States)

Chu, Jingyuan; Zhao, Yue; Liu, Linfei; Wu, Wei; Zhang, Zhiwei; Hong, Zhiyong; Li, Yijie; Jin, Zhijian

2018-01-01

As an emerging technique for surface smoothing, solution deposition planarization (SDP) has recently drawn more attention on the fabrication of the second generation high temperature superconducting (2G-HTS) tapes. In our work, a number of amorphous oxide layers were deposited on electro-polished or mirror-rolled metallic substrates by chemical solution route. Topography evolution of surface defects on these two types of metallic substrates was thoroughly investigated by atomic force microscopy (AFM). It was showed that root mean square roughness values (at 50 × 50 μm2 scanning scale) on both rough substrates reduced to ∼5 nm after coating with SDP-layer. The smoothing effect was mainly attributed to decrease of the depth at grain boundary grooving on the electro-polished metallic substrate. On the mirror-rolled metallic substrates, the amplitude and frequency of the height fluctuation perpendicular to the rolling direction were gradually reduced as depositing more numbers of SDP-layer. A high Jc value of 4.17 MA cm-2 (at 77 K, s.f.) was achieved on a full stack of YBCO/CeO2/IBAD-MgO/SDP-layer/C276 sample. This study enhanced understanding of the topography evolution on the surface defects covered by the SDP-layer, and demonstrated a low-cost route for fabricating IBAD-MgO based YBCO templates with a simplified architecture.

Control of Alq3 wetting layer thickness via substrate surface functionalization.

Science.gov (United States)

Tsoi, Shufen; Szeto, Bryan; Fleischauer, Michael D; Veinot, Jonathan G C; Brett, Michael J

2007-06-05

The effects of substrate surface energy and vapor deposition rate on the initial growth of porous columnar tris(8-hydroxyquinoline)aluminum (Alq3) nanostructures were investigated. Alq3 nanostructures thermally evaporated onto as-supplied Si substrates bearing an oxide were observed to form a solid wetting layer, likely caused by an interfacial energy mismatch between the substrate and Alq3. Wetting layer thickness control is important for potential optoelectronic applications. A dramatic decrease in wetting layer thickness was achieved by depositing Alq3 onto alkyltrichlorosilane-derivatized Si/oxide substrates. Similar effects were noted with increasing deposition rates. These two effects enable tailoring of the wetting layer thickness.

Morphology, structure, and electrical properties of YBa2Cu3Ox thin films on tilted NdGaO3 substrates, deposited by DC-sputtering

International Nuclear Information System (INIS)

Mozhaev, Peter B.; Kotelyanskii, Iosif M.; Luzanov, Valery A.; Mozhaeva, Julia E.; Donchev, Todor; Mateev, Emil; Nurgaliev, Timur; Bdikin, Igor K.; Narymbetov, Bakhyt Zh.

2005-01-01

Thin YBa 2 Cu 3 O x (YBCO) films were deposited using DC-sputtering technique on NdGaO 3 substrates, tilted from (1 1 0) orientation by 0-26 deg . The structure and surface quality of the substrates were carefully characterized to obtain reliable results of thin films deposition. Structural, morphological and electrical properties of the YBCO thin films show three different ranges of inclination angle: vicinal, intermediate and high. In the vicinal range the properties of the film are generally the same as of the standard films deposited on (1 1 0) NdGaO 3 substrate. An increase of the inclination angle to the intermediate range results in a significant improvement of morphology and structural quality of the film. Best electrical parameters are measured for the films of the intermediate range also. Probable reason for such behavior is simultaneous and regular seeding of the film in the joints of facets on the substrate surface. Further increase of inclination angle leads to step bunching and oxygen out-diffusion, destroying both structural and electrical perfection of the tilted-axes YBCO film

Superhydrophobic and superoleophobic surface by electrodeposition on magnesium alloy substrate: Wettability and corrosion inhibition.

Science.gov (United States)

Liu, Yan; Li, Shuyi; Wang, Yaming; Wang, Huiyuan; Gao, Ke; Han, Zhiwu; Ren, Luquan

2016-09-15

Superamphiphobic (both superhydrophobic and superoleophobic) surfaces have attracted great interests in the fundamental research and practical application. This research successfully fabricated the superamphiphobic surfaces by combining the nickel plating process and modification with perfluorocaprylic acid. The cooperation of hierarchical micro-nano structures and perfluorocaprylic acid with low surface energy plays an important role in the formation of superamphiphobic surfaces. The contact angles of water/oil have reached up to 160.2±1°/152.4±1°, respectively. Contrast with bare substrate, the electrochemical measurements of superamphiphobic surfaces, not only the EIS measurement, but also potentiodynamic polarization curves, all revealed that, the surface corrosion inhibition was improved significantly. Moreover, superamphiphobic surfaces exhibited superior stability in the solutions with a large pH range, also could maintain excellent performance after storing for a long time in the air. This method is easy, feasible and effective, and could be used to fabricate large-area mutli-functional surface. Such a technique will develop a new approach to fabricate superamphiphobic surfaces on different engineering materials. Copyright © 2016 Elsevier Inc. All rights reserved.

Structural colors of the SiO2/polyethyleneimine thin films on poly(ethylene terephthalate) substrates

International Nuclear Information System (INIS)

Jia, Yanrong; Zhang, Yun; Zhou, Qiubao; Fan, Qinguo; Shao, Jianzhong

2014-01-01

The SiO 2 /polyethyleneimine (PEI) films with structural colors on poly(ethylene terephthalate) (PET) substrates were fabricated by an electrostatic self-assembly method. The morphology of the films was characterized by Scanning Electron Microscopy. The results showed that there was no distinguishable multilayered structure found of SiO 2 /PEI films. The optical behaviors of the films were investigated through the color photos captured by a digital camera and the color measurement by a multi-angle spectrophotometer. Different hue and brightness were observed at various viewing angles. The structural colors were dependent on the SiO 2 particle size and the number of assembly cycles. The mechanism of the structural colors generated from the assembled films was elucidated. The morphological structures and the optical properties proved that the SiO 2 /PEI film fabricated on PET substrate formed a homogeneous inorganic/organic SiO 2 /PEI composite layer, and the structural colors were originated from single thin film interference. - Highlights: • SiO 2 /PEI thin films were electrostatic self-assembled on PET substrates. • The surface morphology and optical behavior of the film were investigated. • The structural colors varied with various SiO 2 particle sizes and assembly cycles. • Different hue and lightness of SiO 2 /PEI film were observed at various viewing angles. • Structural color of the SiO 2 /PEI film originated from single thin film interference

Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

Energy Technology Data Exchange (ETDEWEB)

Balpande, Suresh S., E-mail: balpandes@rknec.edu [Ph.D.. Scholar, Department of Electronics Engineering Shri Ramdeobaba College of Engineering & Management, Nagpur-13, (M.S.) (India); Pande, Rajesh S. [Professor, Department of Electronics Engineering Shri Ramdeobaba College of Engineering & Management, Nagpur-13, (M.S.) (India)

2016-04-13

Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of

Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

International Nuclear Information System (INIS)

Balpande, Suresh S.; Pande, Rajesh S.

2016-01-01

Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of

Studying substrate effects on localized surface plasmons in an individual silver nanoparticle using electron energy-loss spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fujiyoshi, Yoshifumi; Nemoto, Takashi; Kurata, Hiroki, E-mail: kurata@eels.kuicr.kyoto-u.ac.jp

2017-04-15

In this study, electron energy-loss spectroscopy (EELS) in conjunction with scanning transmission electron microscopy (STEM) was used to investigate surface plasmons in a single silver nanoparticle (NP) on a magnesium oxide substrate, employing an incident electron trajectory parallel to the substrate surface. This parallel irradiation allowed a direct exploration of the substrate effects on localized surface plasmon (LSP) excitations as a function of the distance from the substrate. The presence of the substrate was found to lower the symmetry of the system, such that the resonance energies of LSPs were dependent on the polarization direction relative to the substrate surface. The resulting mode splitting could be detected by applying different electron trajectories, providing results similar to those previously obtained from optical studies using polarized light. However, the LSP maps obtained by STEM-EELS analysis show an asymmetric intensity distribution with the highest intensity at the top surface of the NP (that is, far from the substrate), a result that is not predicted by optical simulations. We show that modifications of the applied electric field by the substrate cause this asymmetric intensity distribution in the LSP maps.

Experimental and Numerical Study of the Influence of Substrate Surface Preparation on Adhesion Mechanisms of Aluminum Cold Spray Coatings on 300M Steel Substrates

Science.gov (United States)

Nastic, A.; Vijay, M.; Tieu, A.; Rahmati, S.; Jodoin, B.

2017-10-01

The effect of substrate surface topography on the creation of metallurgical bonds and mechanical anchoring points has been studied for the cold spray deposition of pure aluminum on 300M steel substrate material. The coatings adhesion strength showed a significant decrease from 31.0 ± 5.7 MPa on polished substrates to 6.9 ± 2.0 MPa for substrates with roughness of 2.2 ± 0.5 μm. Strengths in the vicinity of 45 MPa were reached for coatings deposited onto forced pulsed waterjet treated surfaces with roughnesses larger than 33.8 μm. Finite element analysis has confirmed the sole presence of mechanical anchoring in coating adhesion strength for all surface treatment except polished surfaces. Grit embedment has been shown to be non-detrimental to coating adhesion for the current deposited material combination. The particle deformation process during impacts has been studied through finite element analysis using the Preston-Tonks-Wallace (PTW) constitutive model. The obtained equivalent plastic strain (PEEQ), temperature, contact pressure and velocity vector were correlated to the particle ability to form metallurgical bonds. Favorable conditions for metallurgical bonding were found to be highest for particles deposited on polished substrates, as confirmed by fracture surface analysis.

Tailoring Si(100) substrate surfaces for GaP growth by Ga deposition: A low-energy electron microscopy study

Energy Technology Data Exchange (ETDEWEB)

Rienäcker, Michael; Borkenhagen, Benjamin, E-mail: b.borkenhagen@pe.tu-clausthal.de; Lilienkamp, Gerhard; Daum, Winfried [TU Clausthal, Institut für Energieforschung und Physikalische Technologien, Leibnizstraße 4, D-38678 Clausthal-Zellerfeld (Germany)

2015-08-07

For GaP-on-Si(100) heteroepitaxy, currently considered as a model system for monolithic integration of III–V semiconductors on Si(100), the surface steps of Si(100) have a major impact on the quality of the GaP film. Monoatomic steps cause antiphase domains in GaP with detrimental electronic properties. A viable route is to grow the III–V epilayer on single-domain Si(100) with biatomic steps, but preferably not at the expense of reduced terrace widths introduced by miscut substrates. We have performed in situ investigations of the influence of Ga deposition on the kinetics of surface steps and terraces of Si(100) at substrate temperatures above 600 °C by low-energy electron microscopy. Starting from nearly equally distributed T{sub A} and T{sub B} terraces of a two-domain Si(100) surface, submonolayer deposition of Ga results in a transformation into a surface dominated by T{sub A} terraces and biatomic D{sub A} steps. This transformation is reversible, and Si(100) with monoatomic steps is recovered upon termination of the Ga flux. Under conditions of higher coverages (but still below 0.25 monolayer), we observe restructuring into a surface with T{sub B} dominance, similar to the findings of Hara et al. [J. Appl. Phys. 98, 083515 (2005)]. The occurrence and mutual transformations of surface structures with different terrace and step structures in a narrow range of temperatures and Ga deposition rates is discussed.

Review of Recent Progress of Plasmonic Materials and Nano-Structures for Surface-Enhanced Raman Scattering

Directory of Open Access Journals (Sweden)

Alan X. Wang

2015-05-01

Full Text Available Surface-enhanced Raman scattering (SERS has demonstrated single-molecule sensitivity and is becoming intensively investigated due to its significant potential in chemical and biomedical applications. SERS sensing is highly dependent on the substrate, where excitation of the localized surface plasmons (LSPs enhances the Raman scattering signals of proximate analyte molecules. This paper reviews research progress of SERS substrates based on both plasmonic materials and nano-photonic structures. We first discuss basic plasmonic materials, such as metallic nanoparticles and nano-rods prepared by conventional bottom-up chemical synthesis processes. Then, we review rationally-designed plasmonic nano-structures created by top-down approaches or fine-controlled synthesis with high-density hot-spots to provide large SERS enhancement factors (EFs. Finally, we discuss the research progress of hybrid SERS substrates through the integration of plasmonic nano-structures with other nano-photonic devices, such as photonic crystals, bio-enabled nanomaterials, guided-wave systems, micro-fluidics and graphene.

Electrochemical construction of micro–nano spongelike structure on titanium substrate for enhancing corrosion resistance and bioactivity

International Nuclear Information System (INIS)

Jiang, Pinliang; Lin, Longxiang; Zhang, Fan; Dong, Xiang; Ren, Lei; Lin, Changjian

2013-01-01

Highlights: • A hierarchical micro–nano spongelike TiO 2 layer was constructed on Ti substrate. • The micro–nano TiO 2 surface presented good corrosion resistance. • Excellent biomineration ability was observed on such micro–nano TiO 2 layer. • Superior MG63 cell viability was discerned on the micro–nano structured surface. -- Abstract: Surface structures of medical implants generally play a crucial role in tissue growth and healing while implanted into a living body. The surface design and modification of implants can effectively promote its biocompatibility and integration ability. In this study, a hierarchically superhydrophilic structure on titanium surface with a nano-spongelike titania layer on the micro-roughened titanium surface was constructed through dual acid etching and electrochemical treatments. It is shown that the structure of micro/nano-spongelike TiO 2 provides not only better corrosion resistance and less oxygen vacancies, but also much higher ability of biomineralization after immersion in simulated body fluid (SBF) for 14 days. It is evident, by the cell culture for the different samples, that the micro–nano spongelike structured surface on Ti significantly promotes human osteoblast-like MG63 cell attachment and proliferation. All evaluations of electrochemical behavior and biological responses in this study indicate that the micro/nano-spongelike structure on Ti surface is of excellent chemical stability, bioactivity as well as biocompatibility for biomedical implant applications

Fabrication of chitosan-silver nanoparticle hybrid 3D porous structure as a SERS substrate for biomedical applications

Science.gov (United States)

Jung, Gyeong-Bok; Kim, Ji-Hye; Burm, Jin Sik; Park, Hun-Kuk

2013-05-01

We propose a simple, low-cost, large-area, and functional surface enhanced Raman scattering (SERS) substrate for biomedical applications. The SERS substrate with chitosan-silver nanoparticles (chitosan-Ag NPs) hybrid 3D porous structure was fabricated simply by a one-step method. The chitosan was used as a template for the Ag NPs deposition. SERS enhancement by the chitosan-Ag NPs substrate was experimentally verified using rhodamine B as an analyte. Thiolated single stranded DNA was also measured for atopic dermatitis genetic markers (chemokines CCL17) at a low concentration of 5 pM. We successfully designed a novel SERS substrate with silver nanoparticle hybridized 3D porous chitosan that has the potential to become a highly sensitive and selective tool for biomedical applications.

Crystal Structure and Substrate Specificity of D-Galactose-6-Phosphate Isomerase Complexed with Substrates

Science.gov (United States)

Lee, Jung-Kul; Pan, Cheol-Ho

2013-01-01

D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26), which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD), catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi). Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays. PMID:24015281

Crystal structure and substrate specificity of D-galactose-6-phosphate isomerase complexed with substrates.

Directory of Open Access Journals (Sweden)

Woo-Suk Jung

Full Text Available D-Galactose-6-phosphate isomerase from Lactobacillus rhamnosus (LacAB; EC 5.3.1.26, which is encoded by the tagatose-6-phosphate pathway gene cluster (lacABCD, catalyzes the isomerization of D-galactose-6-phosphate to D-tagatose-6-phosphate during lactose catabolism and is used to produce rare sugars as low-calorie natural sweeteners. The crystal structures of LacAB and its complex with D-tagatose-6-phosphate revealed that LacAB is a homotetramer of LacA and LacB subunits, with a structure similar to that of ribose-5-phosphate isomerase (Rpi. Structurally, LacAB belongs to the RpiB/LacAB superfamily, having a Rossmann-like αβα sandwich fold as has been identified in pentose phosphate isomerase and hexose phosphate isomerase. In contrast to other family members, the LacB subunit also has a unique α7 helix in its C-terminus. One active site is distinctly located at the interface between LacA and LacB, whereas two active sites are present in RpiB. In the structure of the product complex, the phosphate group of D-tagatose-6-phosphate is bound to three arginine residues, including Arg-39, producing a different substrate orientation than that in RpiB, where the substrate binds at Asp-43. Due to the proximity of the Arg-134 residue and backbone Cα of the α6 helix in LacA to the last Asp-172 residue of LacB with a hydrogen bond, a six-carbon sugar-phosphate can bind in the larger pocket of LacAB, compared with RpiB. His-96 in the active site is important for ring opening and substrate orientation, and Cys-65 is essential for the isomerization activity of the enzyme. Two rare sugar substrates, D-psicose and D-ribulose, show optimal binding in the LacAB-substrate complex. These findings were supported by the results of LacA activity assays.

Highly efficient construction of oriented sandwich structures for surface-enhanced Raman scattering

International Nuclear Information System (INIS)

Guo Hongyun; Xu Weiqing; Xu Shuping; Zhou Ji; Lombardi, John R

2013-01-01

The purpose of this study is to solve the problem of low achievement in fabricating sandwich surface-enhanced Raman scattering (SERS) substrates. We demonstrated a highly efficient sandwich structure by the oriented assembly of metal nanoparticles (NPs) on a periodic hexagonal array of metal nanoprisms with 1,4-benzenedithiol (1,4-BDT) as linkers. The metal nanoprism array was prepared by vacuum deposition of metal on a close-packed polystyrene nanosphere pre-patterned substrate. The metal nanoprism array presents different surface properties from the pits left from the removal of polystyrene nanospheres, which causes linkers to selectively adsorb on the metal nanoprism array and sequentially leads to the oriented immobilization of the second-layer metal NPs, avoiding mismatched orientation. These sandwich SERS substrates were characterized by extinction spectroscopy and atomic force microscopy and their enhancement activity was evaluated under different excitation wavelengths. The sandwich structure greatly increases the achievement of ‘hot spots’ to almost 100% of all the metal nanoprisms and enables a large amplification of SERS signals by a factor of ten. This method has the advantages of simplicity, high efficiency, high throughput, controllability and high reproducibility. It has significance in both the study of SERS substrates and the development of plasmonic devices. (paper)

Deconvoluting the effects of surface chemistry and nanoscale topography: Pseudomonas aeruginosa biofilm nucleation on Si-based substrates.

Science.gov (United States)

Zhang, Jing; Huang, Jinglin; Say, Carmen; Dorit, Robert L; Queeney, K T

2018-06-01

The nucleation of biofilms is known to be affected by both the chemistry and topography of the underlying substrate, particularly when topography includes nanoscale (topography vs. chemistry is complicated by concomitant variation in both as a result of typical surface modification techniques. Analyzing the behavior of biofilm-forming bacteria exposed to surfaces with systematic, independent variation of both topography and surface chemistry should allow differentiation of the two effects. Silicon surfaces with reproducible nanotopography were created by anisotropic etching in deoxygenated water. Surface chemistry was varied independently to create hydrophilic (OH-terminated) and hydrophobic (alkyl-terminated) surfaces. The attachment and proliferation of Psuedomonas aeruginosa to these surfaces was characterized over a period of 12 h using fluorescence and confocal microscopy. The number of attached bacteria as well as the structural characteristics of the nucleating biofilm were influenced by both surface nanotopography and surface chemistry. In general terms, the presence of both nanoscale features and hydrophobic surface chemistry enhance bacterial attachment and colonization. However, the structural details of the resulting biofilms suggest that surface chemistry and topography interact differently on each of the four surface types we studied. Copyright © 2018 Elsevier Inc. All rights reserved.

Structural basis for substrate specificities of cellular deoxyribonucleoside kinases

DEFF Research Database (Denmark)

Johansson, K.; Ramaswamy, S.; Ljungcrantz, C.

2001-01-01

Deoxyribonucleoside kinases phosphorylate deoxyribonucleosides and activate a number of medically important nucleoside analogs. Here we report the structure of the Drosophila deoxyribonucleoside kinase with deoxycytidine bound at the nucleoside binding site and that of the human deoxyguanosine ki......; this is apparently due to the presence of Arg 118, which provides favorable hydrogen bonding interactions with the substrate. The two new structures provide an explanation for the substrate specificity of cellular deoxyribonucleoside kinases....

Enhanced osteointegration of medical titanium implant with surface modifications in micro/nanoscale structures

OpenAIRE

Lin, Liwen; Wang, Hui; Ni, Ming; Rui, Yunfeng; Cheng, Tian-Yuan; Cheng, Cheng-Kung; Pan, Xiaohua; Li, Gang; Lin, Changjian

2014-01-01

Biomimetic design and substrate-based surface modification of medical implants will help to improve the integration of tissue to its material interfaces. Surface energy, composition, roughness, and topography all influence the biological responses of the implants, such as protein adsorption and cell adhesion, proliferation and differentiation. In the current study, different surface structures of Ti implants were constructed using facile surface techniques to create various micro-, nano-, and...

Patterning of gold substrates by surface-initiated polymerization

Energy Technology Data Exchange (ETDEWEB)

Dyer, D.J. [Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901-4409 (United States)

2003-09-01

The design and synthesis of durable and functional organic coatings is an important topic in contemporary polymer science. The well-defined patterning of inorganic substrates is highlighted with an emphasis on planar gold. New advances in contact printing and surface initiated polymerization promise unprecedented control of the polymer architecture in the micrometer and nanometer range. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Nanowire surface fastener fabrication on flexible substrate

Science.gov (United States)

Toku, Yuhki; Uchida, Keita; Morita, Yasuyuki; Ju, Yang

2018-07-01

The market for wearable devices has increased considerably in recent years. In response to this demand, flexible electronic circuit technology has become more important. The conventional bonding technology in electronic assembly depends on high-temperature processes such as reflow soldering, which result in undesired thermal damages and residual stress at a bonding interface. In addition, it exhibits poor compatibility with bendable or stretchable device applications. Therefore, there is an urgent requirement to attach electronic parts on printed circuit boards with good mechanical and electrical properties at room temperature. Nanowire surface fasteners (NSFs) are candidates for resolving these problems. This paper describes the fabrication of an NSF on a flexible substrate, which can be used for room temperature conductive bonding. The template method is used for preparing high-density nanowire arrays. A Cu thin film is layered on the template as the flexible substrate. After etching the template, a Cu NSF is obtained on the Cu film substrate. In addition, the electrical and mechanical properties of the Cu NSF are studied under various fabrication conditions. The Cu NSF exhibits high shear adhesion strength (∼234 N cm‑2) and low contact resistivity (2.2 × 10‑4 Ω cm2).

Layer Dependence and Light Tuning Surface Potential of 2D MoS2 on Various Substrates.

Science.gov (United States)

Li, Feng; Qi, Junjie; Xu, Minxuan; Xiao, Jiankun; Xu, Yuliang; Zhang, Xiankun; Liu, Shuo; Zhang, Yue

2017-04-01

Here surface potential of chemical vapor deposition (CVD) grown 2D MoS 2 with various layers is reported, and the effect of adherent substrate and light illumination on surface potential of monolayer MoS 2 are investigated. The surface potential of MoS 2 on Si/SiO 2 substrate decreases from 4.93 to 4.84 eV with the increase in the number of layer from 1 to 4 or more. Especially, the surface potentials of monolayer MoS 2 are strongly dependent on its adherent substrate, which are determined to be 4.55, 4.88, 4.93, 5.10, and 5.50 eV on Ag, graphene, Si/SiO 2 , Au, and Pt substrates, respectively. Light irradiation is introduced to tuning the surface potential of monolayer MoS 2 , with the increase in light intensity, the surface potential of MoS 2 on Si/SiO 2 substrate decreases from 4.93 to 4.74 eV, while increases from 5.50 to 5.56 eV on Pt substrate. The I-V curves on vertical of monolayer MoS 2 /Pt heterojunction show the decrease in current with the increase of light intensity, and Schottky barrier height at MoS 2 /Pt junctions increases from 0.302 to 0.342 eV. The changed surface potential can be explained by trapped charges on surface, photoinduced carriers, charge transfer, and local electric field. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Replication fidelity assessment of large area sub-μm structured polymer surfaces using scatterometry

International Nuclear Information System (INIS)

Calaon, M; Hansen, H N; Tosello, G; Madsen, M H; Weirich, J; Hansen, P E; Garnaes, J; Tang, P T

2015-01-01

The present study addresses one of the key challenges in the product quality control of transparent structured polymer substrates, the replication fidelity of sub-μm structures over a large area. Additionally the work contributes to the development of new techniques focused on in-line characterization of large nanostructured surfaces using scatterometry. In particular an approach to quantify the replication fidelity of high volume manufacturing processes such as polymer injection moulding is presented. Both periodic channels and semi-spherical structures were fabricated on nickel shims used for later injection moulding of Cyclic-olefin-copolymer (COC) substrate were the sub-μm features where ultimately transferred. The scatterometry system was validated using calibrated atomic force microscopy measurements and a model based on scalar diffraction theory employed to calculate the expected angular distribution of the reflected and the transmitted intensity for the nickel surfaces and structured COC and, respectively. (paper)

Surface crystallographic structures of cellulose nanofiber films and overlayers of pentacene

Science.gov (United States)

Nakayama, Yasuo; Mori, Toshiaki; Tsuruta, Ryohei; Yamanaka, Soichiro; Yoshida, Koki; Imai, Kento; Koganezawa, Tomoyuki; Hosokai, Takuya

2018-03-01

Cellulose nanofibers or nanocellulose is a promising recently developed biomass and biodegradable material used for various applications. In order to utilize this material as a substrate in organic electronic devices, thorough understanding of the crystallographic structures of the surfaces of the nanocellulose composites and of their interfaces with organic semiconductor molecules is essential. In this work, surface crystallographic structures of nanocellulose films (NCFs) and overlayers of pentacene were investigated by two-dimensional grazing-incidence X-ray diffraction. The NCFs are found to crystallize on solid surfaces with the crystal lattice preserving the same structure of the known bulk phase, whereas distortion of interchain packing toward the surface normal direction is suggested. The pentacene overlayers on the NCFs are found to form the thin-film phase with an in-plane mean crystallite size of over 10 nm.

Silver-coated Si nanograss as highly sensitive surface-enhanced Raman spectroscopy substrates

Energy Technology Data Exchange (ETDEWEB)

Tang, Jing; Kuo, Huei Pei; Hu, Min; Li, Zhiyong; Williams, R.S. [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Ou, Fung Suong [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Rice University, Department of Applied Physics, Houston, TX (United States); Stickle, William F. [Hewlett-Packard Company, Advanced Diagnostic Lab, Corvallis, OR (United States)

2009-09-15

We created novel surface-enhanced Raman spectroscopy (SERS) substrates by metalization (Ag) of Si nanograss prepared by a Bosch process which involves deep reactive ion etching of single crystalline silicon. No template or lithography was needed for making the Si nanograss, thus providing a simple and inexpensive method to achieve highly sensitive large-area SERS substrates. The dependence of the SERS effect on the thickness of the metal deposition and on the surface morphology and topology of the substrate prior to metal deposition was studied in order to optimize the SERS signals. We observed that the Ag-coated Si nanograss can achieve uniform SERS enhancement over large area ({proportional_to}1 cm x 1 cm) with an average EF (enhancement factor) of 4.2 x 10{sup 8} for 4-mercaptophenol probe molecules. (orig.)

Zinc oxide nanotubes decorated with silver nanoparticles as an ultrasensitive substrate for surface-enhanced Raman scattering

International Nuclear Information System (INIS)

Gao, M.; Feng, B.; Sun, Y.; Xing, G.; Li, S.; Yang, J.; Yang, L.; Zhang, Y.; Liu, H.; Fan, H.; Sui, Y.; Zhang, Z.; Liu, S.; Song, H.

2012-01-01

We report on the fabrication of a highly aligned silver-decorated array of zinc oxide nanotubes for use in surface-enhanced Raman spectroscopy (SERS). The ZnO nanotube array was first prepared by chemical etching, and the silver nanoparticles (AgNPs) were then deposited on their surface by magnetron sputtering. Such ZnO/Ag hybrid structures are shown to act as SERS-active substrates with remarkable sensitivity. The enhancement factor can be as high as 10 5 when using 4-mercaptopyridine in solution as a SERS probe. The synergistic combination between SERS 'hot spots' and the formation of an interfacial electric field between the zinc oxide nanotubes and the AgNPs in our opinion contribute to the high sensitivity. The relative standard deviations of signal intensities for the major SERS peaks are <7 %. This demonstrates that the optimized ZnO/Ag hybrid represents an excellent SERS substrate that may be used in trace analysis and ultrasensitive molecular sensing. (author)

Structural rearrangements in the C/W(001) surface system

International Nuclear Information System (INIS)

Lyman, P.F.; Mullins, D.R.

1995-01-01

We have investigated the surface structure of the C/W(001) surface system at submonolayer C coverages using Auger-electron spectroscopy and high-resolution core-level photoelectron spectroscopy. Core-level spectroscopy is a sensitive probe of an atom's local electronic environment; by examining the core levels of the W atoms in the selvedge region, we monitored the response of the substrate to C adsorption. The average shift of the 4f core-level binding energy provided evidence for a heretofore unknown surface reconstruction that occurs upon submonolayer C adsorption. We also performed line-shape analysis on these core-level spectra, and have thereby elucidated the mechanism by which the low-coverage (√2 x √2 )R45 degree structure evolves to a c(3 √2 x √2 )R45 degree arrangement upon further C adsorption. The line-shape analysis also provides corroborating evidence for a proposed model of the saturated C/W(001)-(5x1) surface structure, and suggests that the first two or three atomic W layers are perturbed by the C adsorption and attendant reconstruction

Utilizing wideband AMC structures for high-gain inkjet-printed antennas on lossy paper substrate

KAUST Repository

Cook, Benjamin Stassen

2013-01-01

Significant gain and bandwidth improvement of inkjet-printed antennas with integrated artificial magnetic conductor (AMC) is achieved by utilizing wideband ground-backed frequency selective surfaces (FSSs) to overcome the high losses of organic substrates such as paper. A microstrip-fed monopole mounted on an artificial magnetic conductor is demonstrated to improve the gain by 5 dB over previous works and exhibit much wider impedance bandwidth while maintaining a thin antenna profile and a 20% electrical size reduction. The effect of AMC bandwidth on substrate losses and the gain reduction caused by finite AMC array effects are investigated in an effort to produce high-gain, miniaturized, low-cost wearable and structure mount antennas. © 2013 IEEE.

Facile fabrication of superhydrophobic surfaces with low roughness on Ti–6Al–4V substrates via anodization

Energy Technology Data Exchange (ETDEWEB)

Gao, Yuze; Sun, Yuwen, E-mail: ywsun@dlut.edu.cn; Guo, Dongming

2014-09-30

Highlights: • A facile and efficient method for fabricating low-roughness superhydrophobic titanium alloy surfaces is successfully developed. • Formation mechanism of micro-scale pore structures built by a novel anodic oxidation is carefully analyzed. • The prepared superhydrophobic surface possesses good durability and abrasion resistance. - Abstract: The combination of suitable micro-scale structures and low surface energy modification plays a vital role in fabricating superhydrophobic surfaces on hydrophilic metal substrates. This work proposes a simple, facile and efficient method of fabricating superhydrophobic titanium alloy surfaces with low surface roughness. Complex micro-pore structures are generated on titanium alloy surfaces by anodic oxidation in the NaOH and H{sub 2}O{sub 2} mixed solution. Fluoroalkylsilane (FAS) is used to reduce the surface energy of the electrochemically oxidized surface. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Zygogpi-xp6 (ZYGO) and contact angle measurements are performed to determine the morphological features, chemical composition, surface roughness and wettability. The formation mechanism of micro-scale rough structures, wettability of the superhydrophobic surfaces and the relationship between reaction time with wettability and roughness of the superhydrophobic surfaces are also analyzed in detail. The as-prepared titanium alloy surfaces not only show low roughness Ra = 0.669 μm and good superhydrophobicity with a water contact angle of 158.5° ± 1.9° as well as a water tilting angle of 5.3° ± 1.1°, but also possess good long-term stability and abrasion resistance.

Electrohydrodynamic Direct-Write Orderly Micro/Nanofibrous Structure on Flexible Insulating Substrate

Directory of Open Access Journals (Sweden)

Jiang-Yi Zheng

2014-01-01

Full Text Available AC pulse-modulated electrohydrodynamic direct-writing (EDW was utilized to direct-write orderly micro/nanofibrous structure on the flexible insulating polyethylene terephthalate (PET substrate. During the EDW process, AC electrical field induced charges to reciprocate along the jet and decreased the charge repulsive force that applied on charged jet. Thanks to the smaller charge repulsive force, stable straight jet can be built up to direct-write orderly micro/nanofibrous structures on the insulating substrate. The minimum motion velocity required to direct-write straight line fibrous structure on insulating PET substrate was 700 mm/s. Moreover, the influences of AC voltage amplitude, frequency, and duty cycle ratio on the line width of fibrous structures were investigated. This work proposes a novel solution to overcome the inherent charge repulsion emerging on the insulating substrate, and promotes the application of EDW technology on the flexible electronics.

Precise micropatterning of silver nanoparticles on plastic substrates

International Nuclear Information System (INIS)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2017-01-01

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV–vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Precise micropatterning of silver nanoparticles on plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A., E-mail: tapani.pakkanen@uef.fi

2017-04-15

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV–vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Ultrasmooth, Polydopamine Modified Surfaces for Block Copolymer Nanopatterning on Inert and Flexible Substrates

Science.gov (United States)

Katsumata, Reika; Cho, Joon Hee; Zhou, Sunshine; Kim, Chae Bin; Dulaney, Austin; Janes, Dustin; Ellison, Christopher

Nature has engineered universal, catechol-containing adhesives that can be synthetically mimicked in the form of polydopamine (PDA). We exploited PDA to enable block copolymer (BCP) nanopatterning on a variety of soft material surfaces in a way that can potentially be applied to flexible electrical devices. Applying BCP nanopatterning to soft substrates is challenging because soft substrates are often chemically inert and possess incompatible low surface energies. In this study, we exploited PDA to enable the formation of BCP nanopatterns on a variety of surfaces such as Teflon, poly(ethylene terephthalate) (PET), and Kapton. While previous studies produced a PDA coating layer too rough for BCP nanopatterning, we succeeded in fabricating conformal and ultra-smooth surfaces of PDA by engineering the PDA coating process and post-sonication procedure. This chemically functionalized, biomimetic thin film (3 nm thick) served as a reactive platform for subsequently grafting a surface treatment to perpendicularly orient a lamellae-forming BCP layer. Furthermore, we demonstrated that a perfectly nanopatterned PDA-PET substrate can be bent without distorting or damaging the nanopattern in conditions that far exceeds typical bending curvatures in roll-to-roll manufacturing.

Surface enhanced Raman spectroscopy detection of biomolecules using EBL fabricated nanostructured substrates.

Science.gov (United States)

Peters, Robert F; Gutierrez-Rivera, Luis; Dew, Steven K; Stepanova, Maria

2015-03-20

Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules is reported. The entire sequence of relevant experimental steps is described, involving the fabrication of nanostructured substrates using electron beam lithography, immobilization of biomolecules on the substrates, and their characterization utilizing surface-enhanced Raman spectroscopy (SERS). Three different designs of nano-biological systems are employed, including protein A, glucose binding protein, and a dopamine binding DNA aptamer. In the latter two cases, the binding of respective ligands, D-glucose and dopamine, is also included. The three kinds of biomolecules are immobilized on nanostructured substrates by different methods, and the results of SERS imaging are reported. The capabilities of SERS to detect vibrational modes from surface-immobilized proteins, as well as to capture the protein-ligand and aptamer-ligand binding are demonstrated. The results also illustrate the influence of the surface nanostructure geometry, biomolecules immobilization strategy, Raman activity of the molecules and presence or absence of the ligand binding on the SERS spectra acquired.

Influence of indium-tin oxide surface structure on the ordering and coverage of carboxylic acid and thiol monolayers

International Nuclear Information System (INIS)

Cerruti, Marta; Rhodes, Crissy; Losego, Mark; Efremenko, Alina; Maria, Jon-Paul; Fischer, Daniel; Franzen, Stefan; Genzer, Jan

2007-01-01

This paper analyses the variability of self-assembled monolayers (SAMs) formation on ITO depending on the substrate surface features. In particular, we report on the formation of carboxylic acid- and thiol-based SAMs on two lots of commercially prepared indium-tin oxide (ITO) thin films. Contact angle measurements, electrochemical experiments, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy showed that the quality of monolayers formed differed substantially between the two ITO batches. Only one of the two ITO substrates was capable of forming well-organized thiol- and carboxylic acid-based SAMs. In order to rationalize these observations, atomic force microscopy and x-ray diffraction analyses were carried out, and SAMs were prepared on ITO substrates fabricated by sputtering in our laboratories. An attempt was made to influence the film microstructure and surface morphology by varying substrate temperatures during ITO deposition. Good-quality thiol and carboxylic acid SAMs were obtained on one of the ITO substrates prepared in-house. While our characterization could not single out conclusively one specific parameter in ITO surface structure that could be responsible for good SAMs formation, we could point out homogeneous surface morphology as a relevant factor for the quality of the SAMs. Evidence was also found for ITO crystallographic orientation to be a parameter influencing SAMs organization

Surface modification of ceramic and metallic alloy substrates by laser raster-scanning

Science.gov (United States)

Ramos Grez, Jorge Andres

This work describes the feasibility of continuous wave laser-raster scan-processing under controlled atmospheric conditions as employed in three distinct surface modification processes: (a) surface roughness reduction of indirect-Selective Laser Sintered 420 martensitic stainless steel-40 wt. % bronze infiltrated surfaces; (b) Si-Cr-Hf-C coating consolidation over 3D carbon-carbon composites cylinders; (c) dendritic solidification structures of Mar-M 247 confined powder precursor grown from polycrystalline Alloy 718 substrates. A heat transfer model was developed to illustrate that the aspect ratio of the laser scanned pattern and the density of scanning lines play a significant role in determining peak surface temperature, heating and cooling rates and melt resident times. Comprehensive characterization of the surface of the processed specimens was performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical metallography, X-ray diffraction (XRD), and, in certain cases, tactile profilometry. In Process (a), it was observed that a 24% to 37% roughness Ra reduction could be accomplished from the as-received value of 2.50+/-0.10 microns for laser energy densities ranging from 350 to 500 J/cm2. In Process (b), complete reactive wetting of carbon-carbon composite cylinders surface was achieved by laser melting a Si-Cr-Hf-C slurry. Coatings showed good thermal stability at 1000°C in argon, and, when tested in air, a percent weight reduction rate of -6.5 wt.%/hr was achieved. A soda-glass overcoat applied over the coated specimens by conventional means revealed a percent weight reduction rate between -1.4 to -2.2 wt.%/hr. Finally, in Process (c), microstructure of the Mar-M 247 single layer deposits, 1 mm in height, grown on Alloy 718 polycrystalline sheets, resulted in a sound metallurgical bond, low porosity, and uniform thickness. Polycrystalline dendrites grew preferentially along the [001] direction from the substrate up to 400

Structure formation in bis(terpyridine) derivative adlayers: molecule-substrate versus molecule-molecule interactions.

Science.gov (United States)

Hoster, Harry E; Roos, Matthias; Breitruck, Achim; Meier, Christoph; Tonigold, Katrin; Waldmann, Thomas; Ziener, Ulrich; Landfester, Katharina; Behm, R Jürgen

2007-11-06

The influence of the substrate and the deposition conditions-vapor deposition versus deposition from solution-on the structures formed upon self-assembly of deposited bis(terpyridine) derivative (2,4'-BTP) monolayers on different hexagonal substrates, including highly oriented pyrolytic graphite (HOPG), Au(111), and (111)-oriented Ag thin films, was investigated by high-resolution scanning tunneling microscopy and by model calculations of the intermolecular energies and the lateral corrugation of the substrate-adsorbate interaction. Similar quasi-quadratic network structures with almost the same lattice constants obtained on all substrates are essentially identical to the optimum configuration expected from an optimization of the adlayer structure with C-H...N-type bridging bonds as a structure-determining factor, which underlines a key role of the intermolecular interactions in adlayer order. Slight distortions from the optimum values to form commensurate adlayer structures on the metal substrates and the preferential orientation of the adlayer with respect to the substrate are attributed to the substrate-adsorbate interactions, specifically, the lateral corrugation in the substrate-adsorbate interaction upon lateral displacement and rotation of the adsorbed BTP molecules. The fact that similar adlayer structures are obtained on HOPG under ultrahigh vacuum conditions (solid|gas interface) and on HOPG in trichlorobenzene (solid|liquid interface) indicates that the intermolecular interactions are not severely affected by the solvent.

Correlation between substrate bias, growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon films

International Nuclear Information System (INIS)

Liu Aiping; Zhu Jiaqi; Han Jiecai; Wu Huaping; Jia Zechun

2007-01-01

We investigate the growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon (ta-C:P) films which are deposited at different substrate biases by filtered cathodic vacuum arc technique with PH 3 as the dopant source. The films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, Raman spectroscopy, residual stress measurement, UV/VIS/NIR absorption spectroscopy and temperature-dependent conductivity measurement. The atomic fraction of phosphorus in the films as a function of substrate bias is obtained by XPS analysis. The optimum bias for phosphorus incorporation is about -80 V. Raman spectra show that the amorphous structures of all samples with atomic-scaled smooth surface are not remarkably changed when PH 3 is implanted, but some small graphitic crystallites are formed. Moreover, phosphorus impurities and higher-energetic impinging ions are favorable for the clustering of sp 2 sites dispersed in sp 3 skeleton and increase the level of structural ordering for ta-C:P films, which further releases the compressive stress and enhances the conductivity of the films. Our analysis establishes an interrelationship between microstructure, stress state, electrical properties, and substrate bias, which helps to understand the deposition mechanism of ta-C:P films

Iridium Coating Deposited by Double Glow Plasma Technique — Effect of Glow Plasma on Structure of Coating at Single Substrate Edge

International Nuclear Information System (INIS)

Wu Wangping; Chen Zhaofeng; Liu Yong

2012-01-01

Double glow plasma technique has a high deposition rate for preparing iridium coating. However, the glow plasma can influence the structure of the coating at the single substrate edge. In this study, the iridium coating was prepared by double glow plasma on the surface of single niobium substrate. The microstructure of iridium coating at the substrate edge was observed by scanning electron microscopy. The composition of the coating was confirmed by energy dispersive spectroscopy and X-ray diffraction. There was a boundary between the coating and the substrate edge. The covered area for the iridium coating at the substrate edge became fewer and fewer from the inner area to the outer flange-area. The bamboo sprout-like particles on the surface of the substrate edge were composed of elemental niobium. The substrate edge was composed of the Nb coating and there was a transition zone between the Ir coating and the Nb coating. The interesting phenomenon of the substrate edge could be attributed to the effects of the bias voltages and the plasma cloud in the deposition chamber. The substrate edge effect could be mitigated or eliminated by adding lots of small niobium plates around the substrate in a deposition process. (plasma technology)

Structural and magnetic properties of (NdBa)MnO₃ films on lattice-matched substrates

DEFF Research Database (Denmark)

Khoryushin, Alexey V.; Mozhaeva, Julia E.; Mozhaev, Peter B.

2013-01-01

Structural and magnetic properties of (NdBa)MnO3 thin films grown on several perovskite substrates by pulsed laser deposition are presented. A high crystal quality epitaxial film with smooth surface and low level of internal strain may be grown up to thicknesses of 70 nm. The in-plane distortion ...

Interplay between grain structure and protein adsorption on functional response of osteoblasts: ultrafine-grained versus coarse-grained substrates.

Science.gov (United States)

Misra, R D K; Nune, C; Pesacreta, T C; Somani, M C; Karjalainen, L P

2013-01-01

The rapid adsorption of proteins is the starting and primary biological response that occurs when a biomedical device is implanted in the physiological system. The biological response, however, depends on the surface characteristics of the device. Considering the significant interest in nano-/ultrafine surfaces and nanostructured coatings, we describe here, the interplay between grain structure and protein adsorption (bovine serum albumin: BSA) on osteoblasts functions by comparing nanograined/ultrafine-grained (NG/UFG) and coarse-grained (CG: grain size in the micrometer range) substrates by investigating cell-substrate interactions. The protein adsorption on NG/UFG surface was beneficial in favorably modulating biological functions including cell attachment, proliferation, and viability, whereas the effect was less pronounced on protein adsorbed CG surface. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on protein adsorbed NG/UFG surface. The functional response followed the sequence: NG/UFG(BSA) > NG/UFG > CG(BSA) > CG. The differences in the cellular response on bare and protein adsorbed NG/UFG and CG surfaces are attributed to cumulative contribution of grain structure and degree of hydrophilicity. The study underscores the potential advantages of protein adsorption on artificial biomedical devices to enhance the bioactivity and regulate biological functions. Copyright © 2012 Wiley Periodicals, Inc.

Superhydrophobic surface based on a coral-like hierarchical structure of ZnO.

Directory of Open Access Journals (Sweden)

Jun Wu

2010-12-01

Full Text Available Fabrication of superhydrophobic surfaces has attracted much interest in the past decade. The fabrication methods that have been studied are chemical vapour deposition, the sol-gel method, etching technique, electrochemical deposition, the layer-by-layer deposition, and so on. Simple and inexpensive methods for manufacturing environmentally stable superhydrophobic surfaces have also been proposed lately. However, work referring to the influence of special structures on the wettability, such as hierarchical ZnO nanostructures, is rare.This study presents a simple and reproducible method to fabricate a superhydrophobic surface with micro-scale roughness based on zinc oxide (ZnO hierarchical structure, which is grown by the hydrothermal method with an alkaline aqueous solution. Coral-like structures of ZnO were fabricated on a glass substrate with a micro-scale roughness, while the antennas of the coral formed the nano-scale roughness. The fresh ZnO films exhibited excellent superhydrophilicity (the apparent contact angle for water droplet was about 0°, while the ability to be wet could be changed to superhydrophobicity after spin-coating Teflon (the apparent contact angle greater than 168°. The procedure reported here can be applied to substrates consisting of other materials and having various shapes.The new process is convenient and environmentally friendly compared to conventional methods. Furthermore, the hierarchical structure generates the extraordinary solid/gas/liquid three-phase contact interface, which is the essential characteristic for a superhydrophobic surface.

One-step synthesis and patterning of aligned polymer nanowires on a substrate

Science.gov (United States)

Wang, Zhong L [Marietta, GA; Wang, Xudong [Atlanta, GA; Morber, Jenny R [Atlanta, GA; Liu, Jin [Danbury, CT

2011-11-08

In a method of making a polymer structure on a substrate a layer of a first polymer, having a horizontal top surface, is applied to a surface of the substrate. An area of the top surface of the polymer is manipulated to create an uneven feature that is plasma etched to remove a first portion from the layer of the first polymer thereby leaving the polymer structure extending therefrom. A light emitting structure includes a conductive substrate from which an elongated nanostructure of a first polymer extends. A second polymer coating is disposed about the nanostructure and includes a second polymer, which includes a material such that a band gap exists between the second polymer coating and the elongated nanostructure. A conductive material coats the second polymer coating. The light emitting structure emits light when a voltage is applied between the conductive substrate and the conductive coating.

Unique structural modulation of a non-native substrate by cochaperone DnaJ.

Science.gov (United States)

Tiwari, Satyam; Kumar, Vignesh; Jayaraj, Gopal Gunanathan; Maiti, Souvik; Mapa, Koyeli

2013-02-12

The role of bacterial DnaJ protein as a cochaperone of DnaK is strongly appreciated. Although DnaJ unaccompanied by DnaK can bind unfolded as well as native substrate proteins, its role as an individual chaperone remains elusive. In this study, we demonstrate that DnaJ binds a model non-native substrate with a low nanomolar dissociation constant and, more importantly, modulates the structure of its non-native state. The structural modulation achieved by DnaJ is different compared to that achieved by the DnaK-DnaJ complex. The nature of structural modulation exerted by DnaJ is suggestive of a unique unfolding activity on the non-native substrate by the chaperone. Furthermore, we demonstrate that the zinc binding motif along with the C-terminal substrate binding domain of DnaJ is necessary and sufficient for binding and the subsequent binding-induced structural alterations of the non-native substrate. We hypothesize that this hitherto unknown structural alteration of non-native states by DnaJ might be important for its chaperoning activity by removing kinetic traps of the folding intermediates.

Explosive Contamination from Substrate Surfaces: Differences and Similarities in Contamination Techniques Using RDX and C-4

Science.gov (United States)

Miller, C. J.; Yoder, T. S.

2010-06-01

found on canvas or denim, suede leather such as might be found on jackets, purses, or shoes, and painted metal obtained from a car hood at a junk yard. The samples were not pre-cleaned prior to testing and contained sizing agents, and in the case of the metal, oil and dirt. The substrates were photographed using a Zeiss Discover V12 stereoscope with Axiocam ICc1 3 megapixel digital camera to determine the difference in the crystalline structure and surface contamination in an attempt to determine differences and similarities associated with current contamination deposition techniques. Some samples were analyzed using scanning electron microscopy (SEM) and some were extracted and analyzed with high performance liquid chromatography (HPLC) or gas chromatography with an electron capture detector (GC-ECD) to quantify the data.

Use of low energy alkali ion scattering as a probe of surface structure

International Nuclear Information System (INIS)

Overbury, S.H.

1986-01-01

An overview is given of the use of low energy ion scattering as a probe of surface structure with emphasis on work done using alkali ions. Various schemes for extracting structural information from the ion energy and angle distributions are discussed in terms of advantages and disadvantages of each. The scattering potential which is the primary non-structural parameter needed for analysis, is discussed in terms of recent experimental results. The structure of clean and reconstructed surfaces are discussed, with examples of measurements of layer relaxations on the Mo(111) surface and missing row reconstructions on the Au(110) and Pt(110) surfaces. Studies of adsorbate covered surfaces are presented with respect to location of the adsorbate and its effect on the structure of the underlying substrate. Finally, examples are given which demonstrate the sensitivity of ion scattering to surface defects and disordering on reconstructed Au(110) and Pt(110) surfaces and unreconstructed Mo(111) surfaces, and to ordering of adsorbates on Mo(001). 47 refs., 12 figs

The interplay between surface charging and microscale roughness during plasma etching of polymeric substrates

Science.gov (United States)

Memos, George; Lidorikis, Elefterios; Kokkoris, George

2018-02-01

The surface roughness developed during plasma etching of polymeric substrates is critical for a variety of applications related to the wetting behavior and the interaction of surfaces with cells. Toward the understanding and, ultimately, the manipulation of plasma induced surface roughness, the interplay between surface charging and microscale roughness of polymeric substrates is investigated by a modeling framework consisting of a surface charging module, a surface etching model, and a profile evolution module. The evolution of initially rough profiles during plasma etching is calculated by taking into account as well as by neglecting charging. It is revealed, on the one hand, that the surface charging contributes to the suppression of root mean square roughness and, on the other hand, that the decrease of the surface roughness induces a decrease of the charging potential. The effect of charging on roughness is intense when the etching yield depends solely on the ion energy, and it is mitigated when the etching yield additionally depends on the angle of ion incidence. The charging time, i.e., the time required for reaching a steady state charging potential, is found to depend on the thickness of the polymeric substrate, and it is calculated in the order of milliseconds.

Surface treatment effect on Si (111) substrate for carbon deposition using DC unbalanced magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Aji, A. S., E-mail: aji.ravazes70@gmail.com; Sahdan, M. F.; Hendra, I. B.; Dinari, P.; Darma, Y. [Quantum Semiconductor and Devices Lab., Physics of Material Electronics Research Division, Department of Physics, Institut Teknologi Bandung (Indonesia)

2015-04-16

In this work, we studied the effect of HF treatment in silicon (111) substrate surface for depositing thin layer carbon. We performed the deposition of carbon by using DC Unbalanced Magnetron Sputtering with carbon pallet (5% Fe) as target. From SEM characterization results it can be concluded that the carbon layer on HF treated substrate is more uniform than on substrate without treated. Carbon deposition rate is higher as confirmed by AFM results if the silicon substrate is treated by HF solution. EDAX characterization results tell that silicon (111) substrate with HF treatment have more carbon fraction than substrate without treatment. These results confirmed that HF treatment on silicon Si (111) substrates could enhance the carbon deposition by using DC sputtering. Afterward, the carbon atomic arrangement on silicon (111) surface is studied by performing thermal annealing process to 900 °C. From Raman spectroscopy results, thin film carbon is not changing until 600 °C thermal budged. But, when temperature increase to 900 °C, thin film carbon is starting to diffuse to silicon (111) substrates.

Surface-engineered substrates for improved human pluripotent stem cell culture under fully defined conditions.

Science.gov (United States)

Saha, Krishanu; Mei, Ying; Reisterer, Colin M; Pyzocha, Neena Kenton; Yang, Jing; Muffat, Julien; Davies, Martyn C; Alexander, Morgan R; Langer, Robert; Anderson, Daniel G; Jaenisch, Rudolf

2011-11-15

The current gold standard for the culture of human pluripotent stem cells requires the use of a feeder layer of cells. Here, we develop a spatially defined culture system based on UV/ozone radiation modification of typical cell culture plastics to define a favorable surface environment for human pluripotent stem cell culture. Chemical and geometrical optimization of the surfaces enables control of early cell aggregation from fully dissociated cells, as predicted from a numerical model of cell migration, and results in significant increases in cell growth of undifferentiated cells. These chemically defined xeno-free substrates generate more than three times the number of cells than feeder-containing substrates per surface area. Further, reprogramming and typical gene-targeting protocols can be readily performed on these engineered surfaces. These substrates provide an attractive cell culture platform for the production of clinically relevant factor-free reprogrammed cells from patient tissue samples and facilitate the definition of standardized scale-up friendly methods for disease modeling and cell therapeutic applications.

Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

KAUST Repository

Chen, Ping-Hei

2011-01-01

This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Enhanced columnar structure in CsI layer by substrate patterning

Energy Technology Data Exchange (ETDEWEB)

Jing, T.; Cho, G.; Drewery, J.; Kaplan, S.N.; Mireshghi, A.; Perez-Mendez, V.; Wildermuth, D. [Lawrence Berkeley Lab., CA (United States); Fujieda, I. [Xerox Palo Alto Research Center, CA (United States)

1991-10-01

Columnar structure in evaporated CsI layers can be controlled by patterning substrates as well as varying evaporation conditions. Mesh-patterned substrates with various dimensions were created by spin-coating polyimide on glass or amorphous silicon substrates and defining patterns with standard photolithography technique. CsI(Tl) layers 200--1000 {mu}m were evaporated. Scintillation properties of these evaporated layers, such as light yield and speed, were equivalent to those of the source materials. Spatial resolution of X-ray detectors consisting of these layers and a linear array of X-ray detectors consisting of these layers and a linear array of Si photodiodes was evaluated by exposing them to a 25{mu}m narrow beam of X-ray. The results obtained with 200{mu}m thick CsI layers coupled to a linear photodiode array with 20 dots/mm resolution showed that the spatial resolution of CsI(Tl) evaporated on patterned substrates was about 75 {mu}m FWHM, whereas that on CsI(Tl) on flat substrates was about 230 {mu}m FWHM. Micrographs taken by SEM revealed that these layers retained the well-defined columnar structure originating from substrate patterns. Adhesion and light transmission of CsI(Tl) were also improved by patterning the substrate.

Superhydrophilic nanopillar-structured quartz surfaces for the prevention of biofilm formation in optical devices

Science.gov (United States)

Han, Soo; Ji, Seungmuk; Abdullah, Abdullah; Kim, Duckil; Lim, Hyuneui; Lee, Donghyun

2018-01-01

Bacterial biofilm formation on optical devices such as contact lenses, optical glasses, endoscopic devices, and microscopic slides and lenses are major concerns in the field of medicine and biomedical engineering. To solve these problems, here we present the first report of superhydrophilic transparent nanopillar-structured surfaces with bactericidal properties. To construct bactericidal surfaces, we imitated a topological mechanism found in nature in which nanopillar-structured surfaces cause a mechanical disruption of the outer cell membranes of bacteria, resulting in bacterial cell death. We used nanosphere lithography to fabricate nanopillars with various sharpnesses and heights on a quartz substrate. Water contact angle and light reflectance measurements revealed superhydrophilic, antifogging and antireflective properties, which are important for use in optical devices. To determine bactericidal efficiency, the fabricated surfaces were incubated and tested against two Gram-negative bacteria associated with biofilm formation and various diseases in humans, Pseudomonas aeruginosa and Escherichia coli. The highest bactericidal activity was achieved with nanopillars that measured 300 nm in height and 10 nm in apex diameter. Quartz substrates patterned with such nanopillars killed ∼38,000 P. aeruginosa and ∼27,000 E. coli cells cm-2 min-1, respectively. Thus, the newly designed nanopillar-structured bactericidal surfaces are suitable for use in the development of superhydrophilic and transparent optical devices.

Sensitive Detection of Biomolecules by Surface Enhanced Raman Scattering using Plant Leaves as Natural Substrates

Directory of Open Access Journals (Sweden)

Sharma Vipul

2017-01-01

Full Text Available Detection of biomolecules is highly important for biomedical and other biological applications. Although several methods exist for the detection of biomolecules, surface enhanced Raman scattering (SERS has a unique role in greatly enhancing the sensitivity. In this work, we have demonstrated the use of natural plant leaves as facile, low cost and eco-friendly SERS substrates for the sensitive detection of biomolecules. Specifically, we have investigated the influence of surface topography of five different plant leaf based substrates, deposited with Au, on the SERS performance by using L-cysteine as a model biomolecule. In addition, we have also compared the effect of sputter deposition of Au thin film with dropcast deposition of Au nanoparticles on the leaf substrates. Our results indicate that L-cysteine could be detected with high sensitivity using these plant leaf based substrates and the leaf possessing hierarchical micro/nanostructures on its surface shows higher SERS enhancement compared to a leaf having a nearplanar surface. Furthermore, leaves with drop-casted Au nanoparticle clusters performed better than the leaves sputter deposited with a thin Au film.

AFM imaging and fractal analysis of surface roughness of AlN epilayers on sapphire substrates

Energy Technology Data Exchange (ETDEWEB)

Dallaeva, Dinara, E-mail: dinara.dallaeva@yandex.ru [Brno University of Technology, Faculty of Electrical Engineering and Communication, Physics Department, Technická 8, 616 00 Brno (Czech Republic); Ţălu, Ştefan [Technical University of Cluj-Napoca, Faculty of Mechanical Engineering, Department of AET, Discipline of Descriptive Geometry and Engineering Graphics, 103-105 B-dul Muncii Street, Cluj-Napoca 400641, Cluj (Romania); Stach, Sebastian [University of Silesia, Faculty of Computer Science and Materials Science, Institute of Informatics, Department of Biomedical Computer Systems, ul. Będzińska 39, 41-205 Sosnowiec (Poland); Škarvada, Pavel; Tománek, Pavel; Grmela, Lubomír [Brno University of Technology, Faculty of Electrical Engineering and Communication, Physics Department, Technická 8, 616 00 Brno (Czech Republic)

2014-09-01

Graphical abstract: - Highlights: • We determined the complexity of 3D surface roughness of aluminum nitride layers. • We used atomic force microscopy and analyzed their fractal geometry. • We determined the fractal dimension of surface roughness of aluminum nitride layers. • We determined the dependence of layer morphology on substrate temperature. - Abstract: The paper deals with AFM imaging and characterization of 3D surface morphology of aluminum nitride (AlN) epilayers on sapphire substrates prepared by magnetron sputtering. Due to the effect of temperature changes on epilayer's surface during the fabrication, a surface morphology is studied by combination of atomic force microscopy (AFM) and fractal analysis methods. Both methods are useful tools that may assist manufacturers in developing and fabricating AlN thin films with optimal surface characteristics. Furthermore, they provide different yet complementary information to that offered by traditional surface statistical parameters. This combination is used for the first time for measurement on AlN epilayers on sapphire substrates, and provides the overall 3D morphology of the sample surfaces (by AFM imaging), and reveals fractal characteristics in the surface morphology (fractal analysis)

Localized surface plasmon resonance properties of Ag nanorod arrays on graphene-coated Au substrate

Science.gov (United States)

Mu, Haiwei; Lv, Jingwei; Liu, Chao; Sun, Tao; Chu, Paul K.; Zhang, Jingping

2017-11-01

Localized surface plasmon resonance (LSPR) on silver nanorod (SNR) arrays deposited on a graphene-coated Au substrate is investigated by the discrete dipole approximation (DDA) method. The resonance peaks in the extinction spectra of the SNR/graphene/Au structure show significantly different profiles as SNR height, and refractive index of the surrounding medium are varied gradually. Numerical simulation reveals that the shifts in the resonance peaks arise from hybridization of multiple plasmon modes as a result of coupling between the SNR arrays and graphene-coated Au substrate. Moreover, the LSPR modes blue-shifts from 800 nm to 700 nm when the thickness of the graphene layer in the metal nanoparticle (NP) - graphene hybrid nanostructure increases from 1 nm to 5 nm, which attribute to charge transfer between the graphene layer and SNR arrays. The results provide insights into metal NP-graphene hybrid nanostructures which have potential applications in plasmonics.

Thermocapillary droplet actuation on structured solid surfaces

Science.gov (United States)

Karapetsas, George; Chamakos, Nikolaos T.; Papathanasiou, Athanasios G.

2017-11-01

The present work investigates, through 2D and 3D finite element simulations, the thermocapillary-driven flow inside a droplet which resides on a non-uniformly heated patterned surface. We employ a recently proposed sharp-interface scheme capable of efficiently modelling the flow over complicate surfaces and consider a wide range of substrate wettabilities, i.e. from hydrophilic to super-hydrophobic surfaces. Our simulations indicate that due to the presence of the solid structures and the induced effect of contact angle hysteresis, inherently predicted by our model, a critical thermal gradient arises beyond which droplet migration is possible, in line with previous experimental observations. The migration velocity as well as the direction of motion depends on the combined action of the net mechanical force along the contact line and the thermocapillary induced flow at the liquid-air interface. We also show that through a proper control and design of the substrate wettability, the contact angle hysteresis and the induced flow field it is possible to manipulate the droplet dynamics, e.g. controlling its motion along a predefined track or entrapping by a wetting defect a droplet based on its size as well as providing appropriate conditions for enhanced mixing inside the droplet. Funding from the European Research Council under the Europeans Community's Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no. [240710] is acknowledged.

X-ray Multilayers and Thin-Shell Substrate Surface-Figure Correction

Science.gov (United States)

Windt, David

We propose a comprehensive experimental research program whose two main goals are (a) to improve the performance of hard X-ray multilayer coatings and (b) to develop a high-throughput method to correct mid-frequency surface errors in thin-shell mirror substrates. Achieving these goals will enable the cost-effective construction of light- weight, highly-nested X-ray telescopes having greater observational sensitivity, wider energy coverage, and higher angular resolution than can be achieved at present. The realization of this technology will thus benefit the development of a variety of Explorer- class NASA X-ray astronomy missions now being formulated for both the soft and hard X-ray bands, and will enable the construction of future facility-class X-ray missions that will require both high sensitivity and high resolution. Building on the success of our previous APRA-funded research, we plan to investigate new thin-film growth techniques, new materials, and new aperiodic coating designs in order to develop new hard X-ray multilayers that have higher X-ray reflectance, wider energy response, lower film stress, and good stability, and that can be produced more quickly, at reduced cost. Additionally, we propose to build upon our extensive experience in sub-nm film-thickness control using velocity modulation and masked deposition techniques, and in the recent development of low-roughness, low-stress films grown by reactive sputtering, in order to develop new methods for correcting mid-frequency surface errors in thin-shell mirror substrates using both differential deposition and ion-beam figuring, either alone or in combination. These two surface-correction techniques already being used for sub-nm figuring of precision optics in a variety of disciplines, including diffraction-limited EUV lithography and synchrotron applications requiring sub-micron focusing are ideally suited for controlling mm-scale surface errors in the thin-shell substrates used for astronomical X

Preparation of Stable Superhydrophobic Coatings on Wood Substrate Surfaces via Mussel-Inspired Polydopamine and Electroless Deposition Methods

Directory of Open Access Journals (Sweden)

Kaili Wang

2017-06-01

Full Text Available Mussel-inspired polydopamine (PDA chemistry and electroless deposition approaches were used to prepare stable superhydrophobic coatings on wood surfaces. The as-formed PDA coating on a wood surface exhibited a hierarchical micro/nano roughness structure, and functioned as an “adhesive layer” between the substrate and a metallic film by the metal chelating ability of the catechol moieties on PDA, allowing for the formation of a well-developed micro/nanostructure hierarchical roughness. Additionally, the coating acted as a stable bridge between the substrate and hydrophobic groups. The morphology and chemical components of the prepared superhydrophobic wood surfaces were characterized by scanning electron microscopy (SEM, Fourier transform infrared (FT-IR spectroscopy, and X-ray photoelectron spectroscopy (XPS. The PDA and octadecylamine (OA modified surface showed excellent superhydrophobicity with a water contact angle (CA of about 153° and a rolling angle (RA of about 9°. The CA further increased to about 157° and RA reduced to about 5° with the Cu metallization. The superhydrophobic material exhibited outstanding stability in harsh conditions including ultraviolet aging, ultrasonic washing, strong acid-base and organic solvent immersion, and high-temperature water boiling. The results suggested that the PDA/OA layers were good enough to confer robust, degradation-resistant superhydrophobicity on wood substrates. The Cu metallization was likely unnecessary to provide significant improvements in superhydrophobic property. However, due to the amazing adhesive capacity of PDA, the electroless deposition technique may allow for a wide range of potential applications in biomimetic materials.

Enhanced lateral heat dissipation packaging structure for GaN HEMTs on Si substrate

International Nuclear Information System (INIS)

Cheng, Stone; Chou, Po-Chien; Chieng, Wei-Hua; Chang, E.Y.

2013-01-01

This work presents a technology for packaging AlGaN/GaN high electron mobility transistors (HEMTs) on a Si substrate. The GaN HEMTs are attached to a V-groove copper base and mounted on a TO-3P leadframe. The various thermal paths from the GaN gate junction to the case are carried out for heat dissipation by spreading to protective coating; transferring through the bond wires; spreading in the lateral device structure through the adhesive layer, and vertical heat spreading of silicon chip bottom. Thermal characterization showed a thermal resistance of 13.72 °C/W from the device to the TO-3P package. Experimental tests of a 30 mm gate-periphery single chip packaged in a 5 × 3 mm V-groove Cu base with a 100 V drain bias showed power dissipation of 22 W. -- Highlights: ► An enhanced packaging structure designed for AlGaN/GaN HEMTs on an Si substrate. ► The V-groove copper base is designed on the device periphery surface heat conduction for enhancing Si substrate thermal dissipation. ► The proposed device shows a lower thermal resistance and upgrade in thermal conductivity capability. ► This work provides useful thermal IR imagery information to aid in designing high efficiency package for GaN HEMTs on Si

Ultra-high sensitive substrates for surface enhanced Raman scattering, made of 3 nm gold nanoparticles embedded on SiO2 nanospheres

Science.gov (United States)

Phatangare, A. B.; Dhole, S. D.; Dahiwale, S. S.; Bhoraskar, V. N.

2018-05-01

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10-18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10-6 M to 10-18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10-18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

Influence of Surface Roughness and Agitation on the Morphology of Magnetite Films Electrodeposited on Carbon Steel Substrates

Directory of Open Access Journals (Sweden)

Soon-Hyeok Jeon

2016-11-01

Full Text Available In this work, we investigated the effects of surface roughness and agitation on the morphology of magnetite films electrodeposited from alkaline Fe(III-triethanolamine (TEA solutions on carbon steel substrates. The surface roughness of the carbon steel substrates was maintained in the range of 1.64–0.06 μm by using mechanical grinding and polishing methods. The agitation speed was set at 0 and 900 rpm during the electrodeposition process. The particle size and surface roughness value of the magnetite films gradually decreased with decreasing substrate roughness. However, the influence of the substrate roughness on the thickness of the magnetite film was negligible. The morphology of the magnetite film fabricated at 900 rpm appeared to be highly faceted compared to that of the magnetite film produced at 0 rpm. The thickness and surface roughness of the magnetite film significantly increased with the agitation speed, which also significantly affected the electrodeposition efficiency. The effects of substrate surface roughness and agitation on the morphology of magnetite films electrodeposited on carbon steel substrates were also discussed. The obtained results provide critical information for the simulation of magnetite deposits on carbon steel pipes in the secondary systems of nuclear power plants.

Self-Assembled Nanocube-Based Plasmene Nanosheets as Soft Surface-Enhanced Raman Scattering Substrates toward Direct Quantitative Drug Identification on Surfaces.

Science.gov (United States)

Si, Kae Jye; Guo, Pengzhen; Shi, Qianqian; Cheng, Wenlong

2015-05-19

We report on self-assembled nanocube-based plasmene nanosheets as new surface-enhanced Raman scattering (SERS) substrates toward direct identification of a trace amount of drugs sitting on topologically complex real-world surfaces. The uniform nanocube arrays (superlattices) led to low spatial SERS signal variances (∼2%). Unlike conventional SERS substrates which are based on rigid nanostructured metals, our plasmene nanosheets are mechanically soft and optically semitransparent, enabling conformal attachment to real-world solid surfaces such as banknotes for direct SERS identification of drugs. Our plasmene nanosheets were able to detect benzocaine overdose down to a parts-per-billion (ppb) level with an excellent linear relationship (R(2) > 0.99) between characteristic peak intensity and concentration. On banknote surfaces, a detection limit of ∼0.9 × 10(-6) g/cm(2) benzocaine could be achieved. Furthermore, a few other drugs could also be identified, even in their binary mixtures with our plasmene nanosheets. Our experimental results clearly show that our plasmene sheets represent a new class of unique SERS substrates, potentially serving as a versatile platform for real-world forensic drug identification.

Process for depositing epitaxial alkaline earth oxide onto a substrate and structures prepared with the process

Science.gov (United States)

McKee, Rodney A.; Walker, Frederick J.

1996-01-01

A process and structure involving a silicon substrate utilize molecular beam epitaxy (MBE) and/or electron beam evaporation methods and an ultra-high vacuum facility to grow a layup of epitaxial alkaline earth oxide films upon the substrate surface. By selecting metal constituents for the oxides and in the appropriate proportions so that the lattice parameter of each oxide grown closely approximates that of the substrate or base layer upon which oxide is grown, lattice strain at the film/film or film/substrate interface of adjacent films is appreciably reduced or relieved. Moreover, by selecting constituents for the oxides so that the lattice parameters of the materials of adjacent oxide films either increase or decrease in size from one parameter to another parameter, a graded layup of films can be grown (with reduced strain levels therebetween) so that the outer film has a lattice parameter which closely approximates that of, and thus accomodates the epitaxial growth of, a pervoskite chosen to be grown upon the outer film.

Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

International Nuclear Information System (INIS)

Rychlewski, T.V.

1984-01-01

Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof

Design, fabrication and characterisation of advanced substrate crosstalk suppression structures in silicon on insulator substrates with buried ground planes (GPSOI)

International Nuclear Information System (INIS)

Stefanou, Stefanos

2002-07-01

Substrate crosstalk or coupling has been acknowledged to be a limiting factor in mixed signal RF integration. Although high levels of integration and high frequencies of operation are desirable for mixed mode RF and microwave circuits, they make substrate crosstalk more pronounced and may lead to circuit performance degradation. High signal isolation is dictated by requirements for low power dissipation, reduced number of components and lower integration costs for feasible system-on-chip (SoC) solutions. Substrate crosstalk suppression in ground plane silicon-on-insulator (GPSOI) substrates is investigated in this thesis. Test structures are designed and fabricated on SOI substrates with a buried WSi 2 plane that is connected to ground; hence it is called a ground plane. A Faraday cage structure that exhibits very high degrees of signal isolation is presented and compared to other SOI isolation schemes. The Faraday cage structure is shown to achieve 20 dB increased isolation in the frequency range of 0.5-50 GHz compared to published data for high resistivity (200 Ωcm) thin film SOI substrates with no ground planes, but where capacitive guard rings were used. The measurement results are analysed with the aid of planar electromagnetic simulators and compact lumped element models of all the fabricated test structures are developed. The accuracy of the lumped models is validated against experimental measurements. (author)

Catalytic Efficiency of Basidiomycete Laccases: Redox Potential versus Substrate-Binding Pocket Structure

Directory of Open Access Journals (Sweden)

Olga A. Glazunova

2018-04-01

Full Text Available Laccases are copper-containing oxidases that catalyze a one-electron abstraction from various phenolic and non-phenolic compounds with concomitant reduction of molecular oxygen to water. It is well-known that laccases from various sources have different substrate specificities, but it is not completely clear what exactly provides these differences. The purpose of this work was to study the features of the substrate specificity of four laccases from basidiomycete fungi Trametes hirsuta, Coriolopsis caperata, Antrodiella faginea, and Steccherinum murashkinskyi, which have different redox potentials of the T1 copper center and a different structure of substrate-binding pockets. Enzyme activity toward 20 monophenolic substances and 4 phenolic dyes was measured spectrophotometrically. The kinetic parameters of oxidation of four lignans and lignan-like substrates were determined by monitoring of the oxygen consumption. For the oxidation of the high redox potential (>700 mV monophenolic substrates and almost all large substrates, such as phenolic dyes and lignans, the redox potential difference between the enzyme and the substrate (ΔE played the defining role. For the low redox potential monophenolic substrates, ΔE did not directly influence the laccase activity. Also, in the special cases, the structure of the large substrates, such as dyes and lignans, as well as some structural features of the laccases (flexibility of the substrate-binding pocket loops and some amino acid residues in the key positions affected the resulting catalytic efficiency.

Fabrication of hydrophobic surface with hierarchical structure on Mg alloy and its corrosion resistance

International Nuclear Information System (INIS)

Wang Jun; Li Dandan; Liu Qi; Yin Xi; Zhang Ying; Jing Xiaoyan; Zhang Milin

2010-01-01

A hydrotalcite/hydromagnesite conversion coating with hierarchical structure has been fabricated on a Mg alloy substrate by in situ hydrothermal crystallization method. A MgO layer existing between the hydrotalcite/hydromagnesite film and the substrate was formed prior to the hydrotalcite/hydromagnesite film during the crystallization process. After surface treatment with silane coupling agent, the surface of conversion coating changes from hydrophilic to hydrophobic. Scanning electron microscopy (SEM) revealed that the silylated conversion coating with hierarchical structure maintains the original rough surface of which was composed of numerous micro-scale flakes and beautiful flower-like protrusions. Polarization measurements have shown that the hydrophobic conversion coating exhibited a low corrosion current density value of 0.432 μA/cm 2 , which means that the hydrophobic conversion coating can effectively protect Mg alloy from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the hydrophobic conversion coating was 9000 Ω. It means that the coating served as a passive layer with high charge transfer resistance.

Non-leaky modes and bandgaps of surface acoustic waves in wrinkled stiff-film/compliant-substrate bilayers

Science.gov (United States)

Li, Guo-Yang; Xu, Guoqiang; Zheng, Yang; Cao, Yanping

2018-03-01

Surface acoustic wave (SAW) devices have found a wide variety of technical applications, including SAW filters, SAW resonators, microfluidic actuators, biosensors, flow measurement devices, and seismic wave shields. Stretchable/flexible electronic devices, such as sensory skins for robotics, structural health monitors, and wearable communication devices, have received considerable attention across different disciplines. Flexible SAW devices are essential building blocks for these applications, wherein piezoelectric films may need to be integrated with the compliant substrates. When piezoelectric films are much stiffer than soft substrates, SAWs are usually leaky and the devices incorporating them suffer from acoustic losses. In this study, the propagation of SAWs in a wrinkled bilayer system is investigated, and our analysis shows that non-leaky modes can be achieved by engineering stress patterns through surface wrinkles in the system. Our analysis also uncovers intriguing bandgaps (BGs) related to the SAWs in a wrinkled bilayer system; these are caused by periodic deformation patterns, which indicate that diverse wrinkling patterns could be used as metasurfaces for controlling the propagation of SAWs.

Cell wall structure suitable for surface display of proteins in Saccharomyces cerevisiae.

Science.gov (United States)

Matsuoka, Hiroyuki; Hashimoto, Kazuya; Saijo, Aki; Takada, Yuki; Kondo, Akihiko; Ueda, Mitsuyoshi; Ooshima, Hiroshi; Tachibana, Taro; Azuma, Masayuki

2014-02-01

A display system for adding new protein functions to the cell surfaces of microorganisms has been developed, and applications of the system to various fields have been proposed. With the aim of constructing a cell surface environment suitable for protein display in Saccharomyces cerevisiae, the cell surface structures of cell wall mutants were investigated. Four cell wall mutant strains were selected by analyses using a GFP display system via a GPI anchor. β-Glucosidase and endoglucanase II were displayed on the cell surface in the four mutants, and their activities were evaluated. mnn2 deletion strain exhibited the highest activity for both the enzymes. In particular, endoglucanase II activity using carboxymethylcellulose as a substrate in the mutant strain was 1.9-fold higher than that of the wild-type strain. In addition, the activity of endoglucanase II released from the mnn2 deletion strain by Zymolyase 20T treatment was higher than that from the wild-type strain. The results of green fluorescent protein (GFP) and endoglucanase displays suggest that the amounts of enzyme displayed on the cell surface were increased by the mnn2 deletion. The enzyme activity of the mnn2 deletion strain was compared with that of the wild-type strain. The relative value (mnn2 deletion mutant/wild-type strain) of endoglucanase II activity using carboxymethylcellulose as a substrate was higher than that of β-glucosidase activity using p-nitrophenyl-β-glucopyranoside as a substrate, suggesting that the cell surface environment of the mnn2 deletion strain facilitates the binding of high-molecular-weight substrates to the active sites of the displayed enzymes. Copyright © 2014 John Wiley & Sons, Ltd.

Facile fabrication of superhydrophobic surface with nanowire structures on nickel foil

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xia, E-mail: zx@henu.edu.cn [Laboratory of Special Functional Materials, Henan University, Kaifeng 475001 (China); Guo, Yonggang [School of Mechanical and Electrical Engineering, Henan University of Technology, Zhengzhou 450007 (China); Liu, Yue; Yang, Xue; Pan, Jieqiong; Zhang, Pingyu [Laboratory of Special Functional Materials, Henan University, Kaifeng 475001 (China)

2013-12-15

A simple solution immersion method was developed for the preparation of superhydrophobic surface with nanowire structures on magnetic nickel substrate. The morphology feature, chemical composition and superhydrophobicity of the resultant surface were analyzed by means of scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectrum and water contact angle measurements, respectively. The surface wettability could be easily changed from superhydrophilic to superhydrophobic by a simple chemical modification with stearic acid. It is confirmed that the synergic effect of the surface microstructure and surface free energy contribute to the unique water repellence. Interestingly, the superhydrophobic nickel foil can be used to fabricate a miniature magnetic boat with a controlled movement on water surface.

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

Energy Technology Data Exchange (ETDEWEB)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun [Inje University, Gimhae (Korea, Republic of); Lee, Won Jae [Dong-Eui University, Busan (Korea, Republic of); Chang, Ji Ho [Korea Maritime University, Busan (Korea, Republic of); Son, Chang Sik [Silla University, Busan (Korea, Republic of); Choi, Hee Lack [Pukyong National University, Busan (Korea, Republic of)

2012-06-15

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

International Nuclear Information System (INIS)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun; Lee, Won Jae; Chang, Ji Ho; Son, Chang Sik; Choi, Hee Lack

2012-01-01

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Fabrication and characterization of surface barrier detector from commercial silicon substrate

International Nuclear Information System (INIS)

Silva, Julio Batista Rodrigues

2016-01-01

In this work it was developed radiation detectors silicon surface barrier that were capable of detecting the presence of gamma radiation from a low energy of iodine-125 seeds used in brachytherapy treatments. >From commercial silicon substrates detectors were developed, one sequence left of chemical treatments to the surfaces of these substrates with the intention of minimizing the possible noise generated, validation of the samples obtained as diodes, ensuring detector characteristics and effective use as detector for Iodine-125 radioactive sources with energy of about 25 keV and Americium-251 with energy on the order of 59 keV. Finished performing the analysis of the obtained energy spectra and so it was possible to observe the ability of these detectors to measure the energy from these seeds. (author)

Interface structure and mechanics between graphene and metal substrates: a first-principles study

Science.gov (United States)

Xu, Zhiping; Buehler, Markus J.

2010-12-01

Graphene is a fascinating material not only for technological applications, but also as a test bed for fundamental insights into condensed matter physics due to its unique two-dimensional structure. One of the most intriguing issues is the understanding of the properties of graphene and various substrate materials. In particular, the interfaces between graphene and metal substrates are of critical importance in applications of graphene in integrated electronics, as thermal materials, and in electromechanical devices. Here we investigate the structure and mechanical interactions at a graphene-metal interface through density functional theory (DFT)-based calculations. We focus on copper (111) and nickel (111) surfaces adhered to a monolayer of graphene, and find that their cohesive energy, strength and electronic structure correlate directly with their atomic geometry. Due to the strong coupling between open d-orbitals, the nickel-graphene interface has a much stronger cohesive energy with graphene than copper. We also find that the interface cohesive energy profile features a well-and-shoulder shape that cannot be captured by simple pair-wise models such as the Lennard-Jones potential. Our results provide a detailed understanding of the interfacial properties of graphene-metal systems, and help to predict the performance of graphene-based nanoelectronics and nanocomposites. The availability of structural and energetic data of graphene-metal interfaces could also be useful for the development of empirical force fields for molecular dynamics simulations.

Patterned Electroplating of Micrometer Scale Magnetic Structures on Glass Substrates

NARCIS (Netherlands)

de Vries, A.H.B.; Kanger, Johannes S.; Krenn, Bea E.; van Driel, Roel

2004-01-01

This paper has developed a new method of micro patterned electroplating that enables the fabrication of micrometer scale magnetic structures on glass substrates. In contrast to other methods, the process as developed here leaves the surrounding substrate area untouched: that is there is no seed

Patterned electroplating of micrometer scale magnetic structures on glass substrates.

NARCIS (Netherlands)

de Vries, A.H.B.; Kanger, S.J.; Krenn, G.E.; van Driel, R.

2004-01-01

This paper has developed a new method of micro patterned electroplating that enables the fabrication of micrometer scale magnetic structures on glass substrates. In contrast to other methods, the process as developed here leaves the surrounding substrate area untouched: that is there is no seed

Performance Characteristics of Bio-Inspired Metal Nanostructures as Surface-Enhanced Raman Scattered (SERS) Substrates.

Science.gov (United States)

Areizaga-Martinez, Hector I; Kravchenko, Ivan; Lavrik, Nickolay V; Sepaniak, Michael J; Hernández-Rivera, Samuel P; De Jesús, Marco A

2016-09-01

The fabrication of high-performance plasmonic nanomaterials for bio-sensing and trace chemical detection is a field of intense theoretical and experimental research. The use of metal-silicon nanopillar arrays as analytical sensors has been reported with reasonable results in recent years. The use of bio-inspired nanocomposite structures that follow the Fibonacci numerical architecture offers the opportunity to develop nanostructures with theoretically higher and more reproducible plasmonic fields over extended areas. The work presented here describes the nanofabrication process for a series of 40 µm × 40 µm bio-inspired arrays classified as asymmetric fractals (sunflower seeds and romanesco broccoli), bilaterally symmetric (acacia leaves and honeycombs), and radially symmetric (such as orchids and lily flowers) using electron beam lithography. In addition, analytical capabilities were evaluated using surface-enhanced Raman scattering (SERS). The substrate characterization and SERS performance of the developed substrates as the strategies to assess the design performance are presented and discussed. © The Author(s) 2016.

Structure and scintillation properties of CsI(Tl) films on Si single crystal substrates

Energy Technology Data Exchange (ETDEWEB)

Guo, Lina [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Liu, Shuang, E-mail: shuangliu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Chen, Dejun; Zhang, Shangjian; Liu, Yong; Zhong, Zhiyong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Falco, Charles M. [University of Arizona, College of Optical Sciences, AZ 85721 (United States)

2016-10-30

Highlights: • We obtained the desired micro-columnar structure of CsI(Tl) films on the orienting Si substrates. • We improved the micro-columnar structure of CsI(Tl) films under the relatively large deposition rate through using the substrate with a pre-deposited CsI nanolayer. • We modeled the interface structures between the CsI(Tl) films with (200) and (310) orientation and Si(111) substrates to explain the preferred orientation of film under the influence of the orienting substrate significantly. • We gained a new spectrum of the CsI(Tl) films peaked at 740 nm wavelength. - Abstract: CsI(Tl) scintillation films fabricated on glass substrates are widely applied for X-ray imaging because their ability to grow in micro-columnar structure and proper emission wavelength matching CCD cameras. But the coupling process between the CsI(Tl) films and Si-based photo detector would cause coupling loss. In this work, CsI(Tl) films were deposited on the orienting Si substrates and the Si substrates covered by the pre-deposited CsI nanolayers. Structure and scintillation properties of films were examined by using scanning electron microscopy, X-ray diffraction, photoluminescence and radioluminescent spectrum. The films deposited on the orienting Si substrates show the micro-columnar morphology with perfect single crystalline structure and the photoluminescence spectra with bimodal distribution. The performances of the films prepared on the pre-deposited CsI nanolayer, containing micro-columns structure and the light yield are improved.

Structure and scintillation properties of CsI(Tl) films on Si single crystal substrates

International Nuclear Information System (INIS)

Guo, Lina; Liu, Shuang; Chen, Dejun; Zhang, Shangjian; Liu, Yong; Zhong, Zhiyong; Falco, Charles M.

2016-01-01

Highlights: • We obtained the desired micro-columnar structure of CsI(Tl) films on the orienting Si substrates. • We improved the micro-columnar structure of CsI(Tl) films under the relatively large deposition rate through using the substrate with a pre-deposited CsI nanolayer. • We modeled the interface structures between the CsI(Tl) films with (200) and (310) orientation and Si(111) substrates to explain the preferred orientation of film under the influence of the orienting substrate significantly. • We gained a new spectrum of the CsI(Tl) films peaked at 740 nm wavelength. - Abstract: CsI(Tl) scintillation films fabricated on glass substrates are widely applied for X-ray imaging because their ability to grow in micro-columnar structure and proper emission wavelength matching CCD cameras. But the coupling process between the CsI(Tl) films and Si-based photo detector would cause coupling loss. In this work, CsI(Tl) films were deposited on the orienting Si substrates and the Si substrates covered by the pre-deposited CsI nanolayers. Structure and scintillation properties of films were examined by using scanning electron microscopy, X-ray diffraction, photoluminescence and radioluminescent spectrum. The films deposited on the orienting Si substrates show the micro-columnar morphology with perfect single crystalline structure and the photoluminescence spectra with bimodal distribution. The performances of the films prepared on the pre-deposited CsI nanolayer, containing micro-columns structure and the light yield are improved.

Transmission X-ray scattering as a probe for complex liquid-surface structures

Energy Technology Data Exchange (ETDEWEB)

Fukuto, Masafumi; Yang, Lin; Nykypanchuk, Dmytro; Kuzmenko, Ivan

2016-01-28

The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray scattering to simultaneously probe local intermolecular structures and heterogeneous domain morphologies on liquid surfaces. To test the feasibility of this approach, transmission small- and wide-angle X-ray scattering (TSAXS/TWAXS) studies of Langmuir films formed on water meniscus against a vertically immersed hydrophilic Si substrate were recently carried out. First-order diffraction rings were observed in TSAXS patterns from a monolayer of hexagonally packed gold nanoparticles and in TWAXS patterns from a monolayer of fluorinated fatty acids, both as a Langmuir monolayer on water meniscus and as a Langmuir–Blodgett monolayer on the substrate. The patterns taken at multiple spots have been analyzed to extract the shape of the meniscus surface and the ordered-monolayer coverage as a function of spot position. These results, together with continual improvement in the brightness and spot size of X-ray beams available at synchrotron facilities, support the possibility of using scanning-probe TSAXS/TWAXS to characterize heterogeneous structures at liquid surfaces.

Influence of the surface free energy of silane-coupled mica substrate on the fixing and straightening of DNA

International Nuclear Information System (INIS)

Sasou, Megumi; Sugiyama, Shigeru; Ishida, Takao; Ohtani, Toshio; Miyake, Koji

2009-01-01

Methyltrimethoxysilane (MTMS)-coupled mica substrate is reportedly suitable for fixing and straightening of DNA, but 3-aminopropyltriethoxysilane (APTES)-coupled mica substrate has been found less suitable. On MTMS-coupled mica substrate, the straightness of fixed DNA was sufficient, and the adsorption of contaminants was not observed using fluorescence microscopy and atomic force microscopy. For the APTES-coupled mica substrate, however, aggregated or curved DNA and adsorption of contaminants were observed. To clarify the surface factors that are responsible for this suitability, we analyzed the surface free energies of these substrates using the extended Fowkes theory. In each of the surface free energy components, the dispersion force component in the MTMS-coupled mica substrate was lower than that in the APTES-coupled mica substrate. The ratio of the polar force component on the MTMS-coupled mica substrate was about one order of magnitude on the APTES-coupled mica substrate. In addition, the ratio of the hydrogen-bonding force component for the MTMS-coupled mica substrate was about two times larger than that of the APTES-coupled mica substrate. These results suggest that the polar force and hydrogen-bonding force components are important factors for the fixation and straightening of DNA and that the dispersion force components influence the production and adsorption of contaminants.

Flexible Near-Field Nanopatterning with Ultrathin, Conformal Phase Masks on Nonplanar Substrates for Biomimetic Hierarchical Photonic Structures.

Science.gov (United States)

Kwon, Young Woo; Park, Junyong; Kim, Taehoon; Kang, Seok Hee; Kim, Hyowook; Shin, Jonghwa; Jeon, Seokwoo; Hong, Suck Won

2016-04-26

Multilevel hierarchical platforms that combine nano- and microstructures have been intensively explored to mimic superior properties found in nature. However, unless directly replicated from biological samples, desirable multiscale structures have been challenging to efficiently produce to date. Departing from conventional wafer-based technology, new and efficient techniques suitable for fabricating bioinspired structures are highly desired to produce three-dimensional architectures even on nonplanar substrates. Here, we report a facile approach to realize functional nanostructures on uneven microstructured platforms via scalable optical fabrication techniques. The ultrathin form (∼3 μm) of a phase grating composed of poly(vinyl alcohol) makes the material physically flexible and enables full-conformal contact with rough surfaces. The near-field optical effect can be identically generated on highly curved surfaces as a result of superior conformality. Densely packed nanodots with submicron periodicity are uniformly formed on microlens arrays with a radius of curvature that is as low as ∼28 μm. Increasing the size of the gratings causes the production area to be successfully expanded by up to 16 in(2). The "nano-on-micro" structures mimicking real compound eyes are transferred to flexible and stretchable substrates by sequential imprinting, facilitating multifunctional optical films applicable to antireflective diffusers for large-area sheet-illumination displays.

Surface biofunctionalization and production of miniaturized sensor structures using aerosol printing technologies

International Nuclear Information System (INIS)

Grunwald, Ingo; Groth, Esther; Wirth, Ingo; Schumacher, Julian; Maiwald, Marcus; Zoellmer, Volker; Busse, Matthias

2010-01-01

The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics.

Surface biofunctionalization and production of miniaturized sensor structures using aerosol printing technologies.

Science.gov (United States)

Grunwald, Ingo; Groth, Esther; Wirth, Ingo; Schumacher, Julian; Maiwald, Marcus; Zoellmer, Volker; Busse, Matthias

2010-03-01

The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics.

Surface biofunctionalization and production of miniaturized sensor structures using aerosol printing technologies

Energy Technology Data Exchange (ETDEWEB)

Grunwald, Ingo; Groth, Esther; Wirth, Ingo; Schumacher, Julian; Maiwald, Marcus; Zoellmer, Volker; Busse, Matthias, E-mail: ingo.wirth@ifam.frauhofer.d [Fraunhofer Institute for Manufacturing Technology and Applied Materials Research (IFAM), Wiener Strasse 12, 28359 Bremen (Germany)

2010-03-15

The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics.

Properties of nickel films growth by radio frequency magnetron sputtering at elevated substrate temperatures

Energy Technology Data Exchange (ETDEWEB)

Muslim, Noormariah, E-mail: 14h8702@ubd.edu.bn [Centre for Advanced Material and Energy Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410 (Brunei Darussalam); Soon, Ying Woan [Centre for Advanced Material and Energy Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410 (Brunei Darussalam); Physical and Geological Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410 (Brunei Darussalam); Lim, Chee Ming; Voo, Nyuk Yoong [Centre for Advanced Material and Energy Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410 (Brunei Darussalam)

2016-08-01

Pure nickel (Ni) thin films of thicknesses of 100 nm were deposited on glass substrates by radio frequency magnetron sputtering at a power of 100 W and at various substrate temperatures i.e., room temperature, 100, 200, and 300 °C. The crystalline structure, surface topography, surface morphology, electrical resistivity, and optical properties of the deposited films were studied. The properties of the Ni films could be controlled by altering the substrate temperature. Specifically, the films featured a face-centered cubic crystalline structure with predominant (111) crystallite orientation at all the substrate temperatures employed, as observed from the X-ray diffraction analysis. Films deposited at substrate temperatures greater than 200 °C additionally displayed crystalline (200) and (220) diffraction peaks. The surface morphology analysis revealed that the grain size of the Ni thin films increased with increasing substrate temperatures employed. This increase was accompanied with a decrease in the resistivity of the Ni films. The surface roughness of the films increased with increasing substrate temperatures employed, as observed from the atomic force microscopy analysis. - Highlights: • RF magnetron sputtering is a good alternative method to deposit Ni films. • Properties of Ni films could be controlled simply by tuning substrate temperatures. • Crystallite size and surface roughness increased with substrate temperatures. • Electrical resistivity reduced with increasing substrate temperatures. • Optical properties also changed with substrate temperatures.

CW substrate-free metal-cavity surface microemitters at 300 K

International Nuclear Information System (INIS)

Lu, Chien-Yao; Chang, Shu-Wei; Chuang, Shun Lien; Germann, Tim D; Pohl, Udo W; Bimberg, Dieter

2011-01-01

In this paper substrate-free metal-cavity surface microemitters are demonstrated. The optical cavity is formed by a metal reflector, metal-surrounded sidewall and n-doped distributed-Bragg reflector, which provides optical feedback and carrier injection. We describe a simple design principle with the modal properties modified by geometry and metal-insulator cladding. Both resonant cavity light-emitting diodes (1.85 µm diameter and 0.6 µm height) and lasers (2.0 µm diameter and 2.5 µm height) are successfully fabricated and characterized. These two types of devices operate at room temperature under continuous-wave (CW) operation. Since the devices are substrate-free, they can be bonded to any substrates. From the threshold currents of the lasers, we obtain a high characteristic temperature of 425 K in the range of 10–27 °C. We also discuss a general approach to improve the diffraction from small-aperture devices

Surface adsorption of lattice HP proteins: Thermodynamics and structural transitions using Wang-Landau sampling

International Nuclear Information System (INIS)

Li Yingwai; Landau, David P; Wüst, Thomas

2012-01-01

Wang-Landau sampling has been applied to investigate the thermodynamics and structural properties of a lattice hydrophobic-polar heteropolymer (the HP protein model) interacting with an attractive substrate. For simplicity, we consider a short HP sequence consisting of only 36 monomers interacting with a substrate which attracts all monomers in the sequence. The conformational “phase transitions” have been identified by a canonical analysis of the specific heat and suitable structural observables. Three major “transitions”, namely, adsorption, hydrophobic core formation and “flattening” of adsorbed structures, are observed. Depending on the surface attractive strength relative to the intra-protein attraction among the H monomers, these processes take place in different sequences upon cooling.

Comparative of fibroblast and osteoblast cells adhesion on surface modified nanofibrous substrates based on polycaprolactone.

Science.gov (United States)

Sharifi, Fereshteh; Irani, Shiva; Zandi, Mojgan; Soleimani, Masoud; Atyabi, Seyed Mohammad

2016-12-01

One of the determinant factors for successful bioengineering is to achieve appropriate nano-topography and three-dimensional substrate. In this research, polycaprolactone (PCL) nano-fibrous mat with different roughness modified with O 2 plasma was fabricated via electrospinning. The purpose of this study was to evaluate the effect of plasma modification along with surface nano-topography of mats on the quality of human fibroblast (HDFs) and osteoblast cells (OSTs)-substrate interaction. Surface properties were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, Fourier-transformation infrared spectroscopy. We evaluated mechanical properties of fabricated mats by tensile test. The viability and proliferation of HDFs and OSTs on the substrates were followed by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT). Mineralization of the substrate was determined by alizarin red staining method and calcium content of OSTs was determined by calcium content kit. Cells morphology was studied by SEM analysis. The results revealed that the plasma-treated electrospun nano-fibrous substrate with higher roughness was an excellent designed substrate. A bioactive topography for stimulating proliferation of HDFs and OSTs is to accelerate the latter's differentiation time. Therefore, the PCL substrate with high density and major nano-topography were considered as a bio-functional and elegant bio-substrate for tissue regeneration applications.

High-performance flexible surface-enhanced Raman scattering substrates fabricated by depositing Ag nanoislands on the dragonfly wing

Science.gov (United States)

Wang, Yuhong; Wang, Mingli; Shen, Lin; Sun, Xin; Shi, Guochao; Ma, Wanli; Yan, Xiaoya

2018-04-01

Natural dragonfly wing (DW), as a template, was deposited on noble metal sliver (Ag) nanoislands by magnetron sputtering to fabricate a flexible, low-cost, large-scale and environment-friendly surface-enhanced Raman scattering (SERS) substrate (Ag/DW substrate). Generally, materials with regular surface nanostructures are chosen for the templates, the selection of our new material with irregular surface nanostructures for substrates provides a new idea for the preparation of high-performance SERS-active substrates and many biomimetic materials. The optimum sputtering time of metal Ag was also investigated at which the prepared SERS-active substrates revealed remarkable SERS activities to 4-aminothiophenol (4-ATP) and crystal violet (CV). Even more surprisingly, the Ag/DW substrate with such an irregular template had reached the enhancement factor (EF) of ∼1.05 × 105 and the detection limit of 10-10 M to 4-ATP. The 3D finite-different time-domain (3D-FDTD) simulation illustrated that the "hot spots" between neighbouring Ag nanoislands at the top of pillars played a most important role in generating electromagnetic (EM) enhancement and strengthening Raman signals.

Preparation of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using a coupling method of liquid plasma and electrochemical machining

Science.gov (United States)

Meng, Jianbing; Dong, Xiaojuan; Wei, Xiuting; Yin, Zhanmin

2014-03-01

Hard anti-adhesion surfaces, with low roughness and wear resistance, on aluminium substrates of rubber plastic moulds were fabricated via a new coupling method of liquid plasma and electrochemical machining. With the aid of liquid plasma thermal polishing and electrochemical anodic dissolution, micro/nano-scale binary structures were prepared as the base of the anti-adhesion surfaces. The anti-adhesion behaviours of the resulting aluminium surfaces were analysed by a surface roughness measuring instrument, a scanning electron microscope (SEM), a Fourier-transform infrared spectrophotometer (FTIR), an X-ray diffractometer (XRD), an optical contact angle meter, a digital Vickers micro-hardness (Hv) tester, and electronic universal testing. The results show that, after the liquid plasma and electrochemical machining, micro/nano-scale binary structures composed of micro-scale pits and nano-scale elongated boss structures were present on the sample surfaces. As a result, the anti-adhesion surfaces fabricated by the above coupling method have good anti-adhesion properties, better wear resistance and lower roughness.

Preparation of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using a coupling method of liquid plasma and electrochemical machining

Directory of Open Access Journals (Sweden)

Jianbing Meng

2014-02-01

Full Text Available Hard anti-adhesion surfaces, with low roughness and wear resistance, on aluminium substrates of rubber plastic moulds were fabricated via a new coupling method of liquid plasma and electrochemical machining. With the aid of liquid plasma thermal polishing and electrochemical anodic dissolution, micro/nano-scale binary structures were prepared as the base of the anti-adhesion surfaces. The anti-adhesion behaviours of the resulting aluminium surfaces were analysed by a surface roughness measuring instrument, a scanning electron microscope (SEM, a Fourier-transform infrared spectrophotometer (FTIR, an X-ray diffractometer (XRD, an optical contact angle meter, a digital Vickers micro-hardness (Hv tester, and electronic universal testing. The results show that, after the liquid plasma and electrochemical machining, micro/nano-scale binary structures composed of micro-scale pits and nano-scale elongated boss structures were present on the sample surfaces. As a result, the anti-adhesion surfaces fabricated by the above coupling method have good anti-adhesion properties, better wear resistance and lower roughness.

Preparation of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using a coupling method of liquid plasma and electrochemical machining

Energy Technology Data Exchange (ETDEWEB)

Meng, Jianbing, E-mail: jianbingmeng@126.com; Dong, Xiaojuan; Wei, Xiuting; Yin, Zhanmin [School of Mechanical Engineering, Shandong University of Technology, Zibo, 255049 (China)

2014-03-15

Hard anti-adhesion surfaces, with low roughness and wear resistance, on aluminium substrates of rubber plastic moulds were fabricated via a new coupling method of liquid plasma and electrochemical machining. With the aid of liquid plasma thermal polishing and electrochemical anodic dissolution, micro/nano-scale binary structures were prepared as the base of the anti-adhesion surfaces. The anti-adhesion behaviours of the resulting aluminium surfaces were analysed by a surface roughness measuring instrument, a scanning electron microscope (SEM), a Fourier-transform infrared spectrophotometer (FTIR), an X-ray diffractometer (XRD), an optical contact angle meter, a digital Vickers micro-hardness (Hv) tester, and electronic universal testing. The results show that, after the liquid plasma and electrochemical machining, micro/nano-scale binary structures composed of micro-scale pits and nano-scale elongated boss structures were present on the sample surfaces. As a result, the anti-adhesion surfaces fabricated by the above coupling method have good anti-adhesion properties, better wear resistance and lower roughness.

Crystal Nucleation Using Surface-Energy-Modified Glass Substrates.

Science.gov (United States)

Nordquist, Kyle A; Schaab, Kevin M; Sha, Jierui; Bond, Andrew H

2017-08-02

Systematic surface energy modifications to glass substrates can induce nucleation and improve crystallization outcomes for small molecule active pharmaceutical ingredients (APIs) and proteins. A comparatively broad probe for function is presented in which various APIs, proteins, organic solvents, aqueous media, surface energy motifs, crystallization methods, form factors, and flat and convex surface energy modifications were examined. Replicate studies ( n ≥ 6) have demonstrated an average reduction in crystallization onset times of 52(4)% (alternatively 52 ± 4%) for acetylsalicylic acid from 91% isopropyl alcohol using two very different techniques: bulk cooling to 0 °C using flat surface energy modifications or microdomain cooling to 4 °C from the interior of a glass capillary having convex surface energy modifications that were immersed in the solution. For thaumatin and bovine pancreatic trypsin, a 32(2)% reduction in crystallization onset times was demonstrated in vapor diffusion experiments ( n ≥ 15). Nucleation site arrays have been engineered onto form factors frequently used in crystallization screening, including microscope slides, vials, and 96- and 384-well high-throughput screening plates. Nucleation using surface energy modifications on the vessels that contain the solutes to be crystallized adds a layer of useful variables to crystallization studies without requiring significant changes to workflows or instrumentation.

Nonlinear surface waves at ferrite-metamaterial waveguide structure

Science.gov (United States)

Hissi, Nour El Houda; Mokhtari, Bouchra; Eddeqaqi, Noureddine Cherkaoui; Shabat, Mohammed Musa; Atangana, Jacques

2016-09-01

A new ferrite slab made of a metamaterial (MTM), surrounded by a nonlinear cover cladding and a ferrite substrate, was shown to support unusual types of electromagnetic surface waves. We impose the boundary conditions to derive the dispersion relation and others necessary to formulate the proposed structure. We analyse the dispersion properties of the nonlinear surface waves and we calculate the associated propagation index and the film-cover interface nonlinearity. In the calculation, several sets of the permeability of the MTM are considered. Results show that the waves behaviour depends on the values of the permeability of the MTM, the thickness of the waveguide and the film-cover interface nonlinearity. It is also shown that the use of the singular solutions to the electric field equation allows to identify several new properties of surface waves which do not exist in conventional waveguide.

Electrical isolation of dislocations in Ge layers on Si(001 substrates through CMOS-compatible suspended structures

Directory of Open Access Journals (Sweden)

Vishal Ajit Shah, Maksym Myronov, Chalermwat Wongwanitwatana, Lewis Bawden, Martin J Prest, James S Richardson-Bullock, Stephen Rhead, Evan H C Parker, Terrance E Whall and David R Leadley

2012-01-01

Full Text Available Suspended crystalline Ge semiconductor structures are created on a Si(001 substrate by a combination of epitaxial growth and simple patterning from the front surface using anisotropic underetching. Geometric definition of the surface Ge layer gives access to a range of crystalline planes that have different etch resistance. The structures are aligned to avoid etch-resistive planes in making the suspended regions and to take advantage of these planes to retain the underlying Si to support the structures. The technique is demonstrated by forming suspended microwires, spiderwebs and van der Pauw cross structures. We finally report on the low-temperature electrical isolation of the undoped Ge layers. This novel isolation method increases the Ge resistivity to 280 Ω cm at 10 K, over two orders of magnitude above that of a bulk Ge on Si(001 layer, by removing material containing the underlying misfit dislocation network that otherwise provides the main source of electrical conduction.

Micropatterned Azopolymer Surfaces Modulate Cell Mechanics and Cytoskeleton Structure.

Science.gov (United States)

Rianna, Carmela; Ventre, Maurizio; Cavalli, Silvia; Radmacher, Manfred; Netti, Paolo A

2015-09-30

Physical and chemical characteristics of materials are important regulators of cell behavior. In particular, cell elasticity is a fundamental parameter that reflects the state of a cell. Surface topography finely modulates cell fate and function via adhesion mediated signaling and cytoskeleton generated forces. However, how topographies alter cell mechanics is still unclear. In this work we have analyzed the mechanical properties of peripheral and nuclear regions of NIH-3T3 cells on azopolymer substrates with different topographic patterns. Micrometer scale patterns in the form of parallel ridges or square lattices of surface elevations were encoded on light responsive azopolymer films by means of contactless optical methods. Cell mechanics was investigated by atomic force microscopy (AFM). Cells and consequently the cell cytoskeleton were oriented along the linear patterns affecting cytoskeletal structures, e.g., formation of actin stress fibers. Our data demonstrate that topographic substrate patterns are recognized by cells and mechanical information is transferred by the cytoskeleton. Furthermore, cytoskeleton generated forces deform the nucleus, changing its morphology that appears to be related to different mechanical properties in the nuclear region.

Structure determination by photoelectron diffraction of small molecules on surfaces

International Nuclear Information System (INIS)

Booth, N.A.

1998-05-01

The synchrotron radiation based technique of Photoelectron Diffraction (PhD) has been applied to three adsorption systems. Structure determinations, are presented for each system which involve the adsorption of small molecules on the low index {110} plane of single crystal Cu and Ni substrates. For the NH 3 -Cu(110) system PhD was successful in determining a N-Cu bondlength of 2.05 ± 0.03 A as well as values for the anisotropic vibrational amplitudes of the N and an expansion of the 1st to 2nd Cu substrate layer spacing from the bulk value of 0.08 ± 0.08 A. The most significant and surprising structural parameter determined for this system was that the N atom occupies an asymmetric adsorption site. Rather than being situated in the expected high symmetry atop site the N atom was found to be offset parallel to the surface by 0.37 ± 0.12 A in the [001] azimuth. In studying the glycine-Cu(110) system the adsorption structure of an amino-acid has been quantified. The local adsorption geometries of all the atoms involved in the molecule to surface bond have been determined. The glycine molecule is found to be bonded to the surface via both its amino and carboxylate functional groups. The molecule straddles two [11-bar0] rows of the Cu substrate. The two O atoms are found to be in identical sites both approximately atop Cu atoms on the [11-bar0] rows offset parallel to the surface by 0.80 ± 0.05 A in the [001] azimuth, the O-Cu bondlength was found to be 2.03 ± 0.05 A. The N atom was also found to adsorb in an approximately atop geometry but offset parallel to the surface by 0.24 ± 0.10A in the [11-bar0] direction, the N-Cu bondlength was found to be 2.05± 0.05 A. PhD was unsuccessful in determining the positions of the two C atoms that form a bridge between the two functional groups bonded to the surface due to difficulties in separating the two inequivalent contributions to the final intensity modulation function. For the CN-Ni(110) system both PhD and Near Edge

Biomimetic hydrophobic surface fabricated by chemical etching method from hierarchically structured magnesium alloy substrate

Energy Technology Data Exchange (ETDEWEB)

Liu, Yan; Yin, Xiaoming; Zhang, Jijia [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Wang, Yaming [Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001 (China); Han, Zhiwu, E-mail: zwhan@jlu.edu.cn [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Ren, Luquan [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China)

2013-09-01

As one of the lightest metal materials, magnesium alloy plays an important role in industry such as automobile, airplane and electronic product. However, magnesium alloy is hindered due to its high chemical activity and easily corroded. Here, inspired by typical plant surfaces such as lotus leaves and petals of red rose with super-hydrophobic character, the new hydrophobic surface is fabricated on magnesium alloy to improve anti-corrosion by two-step methodology. The procedure is that the samples are processed by laser first and then immersed and etched in the aqueous AgNO{sub 3} solution concentrations of 0.1 mol/L, 0.3 mol/L and 0.5 mol/L for different times of 15 s, 40 s and 60 s, respectively, finally modified by DTS (CH{sub 3}(CH{sub 2}){sub 11}Si(OCH{sub 3}){sub 3}). The microstructure, chemical composition, wettability and anti-corrosion are characterized by means of SEM, XPS, water contact angle measurement and electrochemical method. The hydrophobic surfaces with microscale crater-like and nanoscale flower-like binary structure are obtained. The low-energy material is contained in surface after DTS treatment. The contact angles could reach up to 138.4 ± 2°, which hydrophobic property is both related to the micro–nano binary structure and chemical composition. The results of electrochemical measurements show that anti-corrosion property of magnesium alloy is improved. Furthermore, our research is expected to create some ideas from natural enlightenment to improve anti-corrosion property of magnesium alloy while this method can be easily extended to other metal materials.

Comparative of fibroblast and osteoblast cells adhesion on surface modified nanofibrous substrates based on polycaprolactone

OpenAIRE

Sharifi, Fereshteh; Irani, Shiva; Zandi, Mojgan; Soleimani, Masoud; Atyabi, Seyed Mohammad

2016-01-01

One of the determinant factors for successful bioengineering is to achieve appropriate nano-topography and three-dimensional substrate. In this research, polycaprolactone (PCL) nano-fibrous mat with different roughness modified with O2 plasma was fabricated via electrospinning. The purpose of this study was to evaluate the effect of plasma modification along with surface nano-topography of mats on the quality of human fibroblast (HDFs) and osteoblast cells (OSTs)-substrate interaction. Surfac...

Fabrication of biomimetic resorption lacunae-like structure on titanium surface and its osteoblast responses

Science.gov (United States)

Huo, Fangjun; Guo, Weihua; Wu, Hao; Wang, Yueting; He, Gang; Xie, Li; Tian, Weidong

2018-04-01

Biomimetic specific surface structure could improve biological behaviors of specific cells and eventual tissue integration. Featuring titanium surface with structures resembling bone resorption lacunae (RL) can be a promising approach to improve the osteoblast responses and osseointegration of implants. As a most common used dental implant surface, sandblasting and acid etching (SLA) surface has micro-sized structures with dimensions similar to RL, but great differences exist when it comes to shape and contour. In this work, by anodizing titanium substrate in a novel HCOONa/CH3COONa electrolyte, RL-like crater structures were fabricated with highly similar size, shape and contour. Compared with SLA, it was much more similar to RL structure in shape and contour. Furthermore, through subsequent alkali-heat treatment, nano-sized structures that overlaid the whole surface were obtained, which further mimic undercuts features inside the RL. The as-prepared surface was consisted of crystalline titania and exhibited super-hydrophilicity with good stability. In vitro evaluation results showed that the surface could significantly improve adhesion, proliferation and differentiation of MG63 cells in comparison with SLA. This new method may be a promising candidate for biomimetic modification of titanium implant to promote osseointegration.

Gold split-ring resonators (SRRs) as substrates for surface-enhanced raman scattering

KAUST Repository

Yue, Weisheng

2013-10-24

We used gold split ring resonators (SRRs) as substrates for surface-enhanced Raman scattering (SERS). The arrays of SRRs were fabricated by electron-beam lithography in combination with plasma etching. In the detection of rhodamine 6G (R6G) molecules, SERS enhancement factors of the order of 105 was achieved. This SERS enhancement increased as the size of the split gap decrease as a consequence of the matching between the resonance wavelength of the SRRs and the excitation wavelength of SERS. As the size of the split gap decreased, the localized surface plasmon resonance shifted to near the excitation wavelength and, thus, resulted in the increase in the electric field on the nanostructures. We used finite integration method (FIT) to simulate numerically the electromagnetic properties of the SRRs. The results of the simulation agreed well with our experimental observations. We anticipate this work will provide an approach to manipulate the SERS enhancement by modulating the size of split gap with SRRs without affecting the area and structural arrangement. © 2013 American Chemical Society.

Gold split-ring resonators (SRRs) as substrates for surface-enhanced raman scattering

KAUST Repository

Yue, Weisheng; Yang, Yang; Wang, Zhihong; Chen, Longqing; Wang, Xianbin

2013-01-01

We used gold split ring resonators (SRRs) as substrates for surface-enhanced Raman scattering (SERS). The arrays of SRRs were fabricated by electron-beam lithography in combination with plasma etching. In the detection of rhodamine 6G (R6G) molecules, SERS enhancement factors of the order of 105 was achieved. This SERS enhancement increased as the size of the split gap decrease as a consequence of the matching between the resonance wavelength of the SRRs and the excitation wavelength of SERS. As the size of the split gap decreased, the localized surface plasmon resonance shifted to near the excitation wavelength and, thus, resulted in the increase in the electric field on the nanostructures. We used finite integration method (FIT) to simulate numerically the electromagnetic properties of the SRRs. The results of the simulation agreed well with our experimental observations. We anticipate this work will provide an approach to manipulate the SERS enhancement by modulating the size of split gap with SRRs without affecting the area and structural arrangement. © 2013 American Chemical Society.

Mechanical behavior of Ti-Ta-based surface alloy fabricated on TiNi SMA by pulsed electron-beam melting of film/substrate system

Science.gov (United States)

Meisner, S. N.; Yakovlev, E. V.; Semin, V. O.; Meisner, L. L.; Rotshtein, V. P.; Neiman, A. A.; D'yachenko, F.

2018-04-01

The physical-mechanical properties of the Ti-Ta based surface alloy with thickness up to ∼2 μm fabricated through the multiple (up to 20 cycles) alternation of magnetron deposition of Ti70Ta30 (at.%) thin (50 nm) films and their liquid-phase mixing with the NiTi substrate by microsecond low-energy, high current pulsed electron beam (LEHCPEB: ≤15 keV, ∼2 J/cm2) are presented. Two types of NiTi substrates (differing in the methods of melting alloys) were pretreated with LEHCPEB to improve the adhesion of thin-film coating and to protect it from local delimitation because of the surface cratering under pulsed melting. The methods used in the research include nanoindentation, transmission electron microscopy, and depth profile analysis of nanohardness, Vickers hardness, elastic modulus, depth recovery ratio, and plasticity characteristic as a function of indentation depth. For comparison, similar measurements were carried out with NiTi substrates in the initial state and after LEHCPEB pretreatment, as well as on "Ti70Ta30(1 μm) coating/NiTi substrate" system. It was shown that the upper surface layer in both NiTi substrates is the same in properties after LEHCPEB pretreatment. Our data suggest that the type of multilayer surface structure correlates with its physical-mechanical properties. For NiTi with the Ti-Ta based surface alloy ∼1 μm thick, the highest elasticity falls on the upper submicrocrystalline layer measuring ∼0.2 μm and consisting of two Ti-Ta based phases: α‧‧ martensite (a = 0.475 nm, b = 0.323 nm, c = 0.464 nm) and β austenite (a = 0.327 nm). Beneath the upper layer there is an amorphous sublayer followed by underlayers with coarse (>20 nm) and fine (<20 nm) average grain sizes which provide a gradual transition of the mechanical parameters to the values of the NiTi substrate.

Scalable Inkjet-Based Structural Color Printing by Molding Transparent Gratings on Multilayer Nanostructured Surfaces.

Science.gov (United States)

Jiang, Hao; Kaminska, Bozena

2018-04-24

To enable customized manufacturing of structural colors for commercial applications, up-scalable, low-cost, rapid, and versatile printing techniques are highly demanded. In this paper, we introduce a viable strategy for scaling up production of custom-input images by patterning individual structural colors on separate layers, which are then vertically stacked and recombined into full-color images. By applying this strategy on molded-ink-on-nanostructured-surface printing, we present an industry-applicable inkjet structural color printing technique termed multilayer molded-ink-on-nanostructured-surface (M-MIONS) printing, in which structural color pixels are molded on multiple layers of nanostructured surfaces. Transparent colorless titanium dioxide nanoparticles were inkjet-printed onto three separate transparent polymer substrates, and each substrate surface has one specific subwavelength grating pattern for molding the deposited nanoparticles into structural color pixels of red, green, or blue primary color. After index-matching lamination, the three layers were vertically stacked and bonded to display a color image. Each primary color can be printed into a range of different shades controlled through a half-tone process, and full colors were achieved by mixing primary colors from three layers. In our experiments, an image size as big as 10 cm by 10 cm was effortlessly achieved, and even larger images can potentially be printed on recombined grating surfaces. In one application example, the M-MIONS technique was used for printing customizable transparent color optical variable devices for protecting personalized security documents. In another example, a transparent diffractive color image printed with the M-MIONS technique was pasted onto a transparent panel for overlaying colorful information onto one's view of reality.

Surface morphology of Al0.3Ga0.7N/Al2O3-high electron mobility transistor structure.

Science.gov (United States)

Cörekçi, S; Usanmaz, D; Tekeli, Z; Cakmak, M; Ozçelik, S; Ozbay, E

2008-02-01

We present surface properties of buffer films (AIN and GaN) and Al0.3Gao.zN/Al2O3-High Electron Mobility Transistor (HEMT) structures with/without AIN interlayer grown on High Temperature (HT)-AIN buffer/Al2O3 substrate and Al2O3 substrate. We have found that the GaN surface morphology is step-flow in character and the density of dislocations was about 10(8)-10(9) cm(-2). The AFM measurements also exhibited that the presence of atomic steps with large lateral step dimension and the surface of samples was smooth. The lateral step sizes are in the range of 100-250 nm. The typical rms values of HEMT structures were found as 0.27, 0.30, and 0.70 nm. HT-AIN buffer layer can have a significant impact on the surface morphology of Al0.3Ga0.7N/Al2O3-HEMT structures.

Structural and optical characterization of GaN heteroepitaxial films on SiC substrates

International Nuclear Information System (INIS)

Morse, M.; Wu, P.; Choi, S.; Kim, T.H.; Brown, A.S.; Losurdo, M.; Bruno, G.

2006-01-01

We have estimated the threading dislocation density and type via X-ray diffraction and Williamson-Hall analysis to elicit qualitative information directly related to the electrical and optical quality of GaN epitaxial layers grown by PAMBE on 4H- and 6H-SiC substrates. The substrate surface preparation and buffer choice, specifically: Ga flashing for SiC oxide removal, controlled nitridation of SiC, and use of AlN buffer layers all impact the resultant screw dislocation density, but do not significantly influence the edge dislocation density. We show that modification of the substrate surface strongly affects the screw dislocation density, presumably due to impact on nucleation during the initial stages of heteroepitaxy

Structural and optical characterization of GaN heteroepitaxial films on SiC substrates

Energy Technology Data Exchange (ETDEWEB)

Morse, M. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States) and Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States)]. E-mail: michael.morse@duke.edu; Wu, P. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Choi, S. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Kim, T.H. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Brown, A.S. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States) and Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States)]. E-mail: abrown@ee.duke.edu; Losurdo, M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona, 4-70126 Bari (Italy); Bruno, G. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona, 4-70126 Bari (Italy)

2006-10-31

We have estimated the threading dislocation density and type via X-ray diffraction and Williamson-Hall analysis to elicit qualitative information directly related to the electrical and optical quality of GaN epitaxial layers grown by PAMBE on 4H- and 6H-SiC substrates. The substrate surface preparation and buffer choice, specifically: Ga flashing for SiC oxide removal, controlled nitridation of SiC, and use of AlN buffer layers all impact the resultant screw dislocation density, but do not significantly influence the edge dislocation density. We show that modification of the substrate surface strongly affects the screw dislocation density, presumably due to impact on nucleation during the initial stages of heteroepitaxy.

A practical method to fabricate gold substrates for surface-enhanced Raman spectroscopy.

Science.gov (United States)

Tantra, Ratna; Brown, Richard J C; Milton, Martin J T; Gohil, Dipak

2008-09-01

We describe a practical method of fabricating surface-enhanced Raman spectroscopy (SERS) substrates based on dip-coating poly-L-lysine derivatized microscope slides in a gold colloidal suspension. The use of only commercially available starting materials in this preparation is particularly advantageous, aimed at both reducing time and the inconsistency associated with surface modification of substrates. The success of colloid deposition has been demonstrated by scanning electron microscopy (SEM) and the corresponding SERS response (giving performance comparable to the corresponding traditional colloidal SERS substrates). Reproducibility was evaluated by conducting replicate measurements across six different locations on the substrate and assessing the extent of the variability (standard deviation values of spectral parameters: peak width and height), in response to either Rhodamine 6G or Isoniazid. Of particular interest is the observation of how some peaks in a given spectrum are more susceptible to data variability than others. For example, in a Rhodamine 6G SERS spectrum, spectral parameters of the peak at 775 cm(-1) were shown to have a relative standard deviation (RSD) % of or=10%. This observation is best explained by taking into account spectral variations that arise from the effect of a chemisorption process and the local nature of chemical enhancement mechanisms, which affects the enhancement of some spectral peaks but not others (analogous to resonant Raman phenomenon).

Characterization of glassy phase at the surface of alumina ceramics substrate and its effect on laser cutting

Energy Technology Data Exchange (ETDEWEB)

Fu Renli [School of Mechanical-Electronic and Materials Engineering, China Univ. of Mining and Technology, Xuzhou, JS (China); Dept. of Ceramics and Glass Engineering, CICECO, Univ. of Aveiro, Aveiro (Portugal); Li Yanbo [School of Mechanical-Electronic and Materials Engineering, China Univ. of Mining and Technology, Xuzhou, JS (China); Xu Xin; Ferreira, J.M.F. [Dept. of Ceramics and Glass Engineering, CICECO, Univ. of Aveiro, Aveiro (Portugal)

2004-07-01

Nowadays alumina ceramic substrates are widely used for high precision applications in electronic devices, such as hybrid integrated circuits (HIC). Usually, the alumina ceramic substrates are shaped through tape casting method and sintered in continuous slab kilns. The sintering aids used to enhance densification during sintering give rise to the formation of an alumino-silicate liquid phase, which is of crucial importance in pressureless and low-temperature sintering (<1600 C) of alumina ceramics. The preferential migration of liquid phase to the surface of alumina substrates under the capillary action and its transformation into glassy phase during cooling affects the subsequent processing steps of HIC. A smoothening effect on surface with its enrichment in glassy phase is accompanied by a decrease of the surface toughness. On the other hand, the accumulated glassy phase onto the surface has a great effect on laser cutting. The high temperatures developed during laser cutting turn the superficial glassy phase into liquid again, while rapid solidification will occur after removing laser beam. The fast cooling of the liquid phase causes formation of extensive network of cracks on the surface of alumina substrate. Apparently, the presence of such faults degrades mechanical strength and thermal shock resistance of alumina substrates. Meanwhile, the recast layers and spatter deposits at the periphery of the hole has been observed. (orig.)

Effects of the crystallographic orientation of the Al2O3 substrate on the structural and the optical properties of ZnO thin films

International Nuclear Information System (INIS)

Lee, Chongmu; Park, Yeonkyu; Kim, Kyungha

2006-01-01

The structure and the optical properties of ZnO thin films grown on (0002) C-plane, (1120) A-plane, and (1012) R-plane sapphire substrates by using atomic layer epitaxy (ALE) were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and photoluminescence analysis (PL) techniques. The ZnO film grown on the C-plane sapphire substrate has the smallest full width at half maximum (FWHM) values for both the X-ray (0002) diffraction peak and the photoluminescence peak for near-band-edge emission whereas that grown on the R-plane sapphire substrate has the largest FWHM values. On the other hand, the ZnO film grown on the C-plane sapphire substrate has the strong texture of the c-axis but the roughest surface while those grown on the R- and the C-plane sapphire substrates have smoother surfaces but do not have the texture of the c-axis.

Beyond Cassie equation: Local structure of heterogeneous surfaces determines the contact angles of microdroplets

Science.gov (United States)

Zhang, Bo; Wang, Jianjun; Liu, Zhiping; Zhang, Xianren

2014-01-01

The application of Cassie equation to microscopic droplets is recently under intense debate because the microdroplet dimension is often of the same order of magnitude as the characteristic size of substrate heterogeneities, and the mechanism to describe the contact angle of microdroplets is not clear. By representing real surfaces statistically as an ensemble of patterned surfaces with randomly or regularly distributed heterogeneities (patches), lattice Boltzmann simulations here show that the contact angle of microdroplets has a wide distribution, either continuous or discrete, depending on the patch size. The origin of multiple contact angles observed is ascribed to the contact line pinning effect induced by substrate heterogeneities. We demonstrate that the local feature of substrate structure near the contact line determines the range of contact angles that can be stabilized, while the certain contact angle observed is closely related to the contact line width. PMID:25059292

Enhancing the Properties of Carbon and Gold Substrates by Surface Modification

Energy Technology Data Exchange (ETDEWEB)

Harnisch, Jennifer Anne [Iowa State Univ., Ames, IA (United States)

2001-01-01

The properties of both carbon and gold substrates are easily affected by the judicious choice of a surface modification protocol. Several such processes for altering surface composition have been published in literature. The research presented in this thesis primarily focuses on the development of on-column methods to modify carbon stationary phases used in electrochemically modulated liquid chromatography (EMLC). To this end, both porous graphitic carbon (PGC) and glassy carbon (GC) particles have been modified on-column by the electroreduction of arenediazonium salts and the oxidation of arylacetate anions (the Kolbe reaction). Once modified, the carbon stationary phases show enhanced chromatographic performance both in conventional liquid chromatographic columns and EMLC columns. Additionally, one may also exploit the creation of aryl films to by electroreduction of arenediazonium salts in the creation of nanostructured materials. The formation of mercaptobenzene film on the surface of a GC electrode provides a linking platform for the chemisorption of gold nanoparticles. After deposition of nanoparticles, the surface chemistry of the gold can be further altered by self-assembled monolayer (SAM) formation via the chemisorption of a second thiol species. Finally, the properties of gold films can be altered such that they display carbon-like behavior through the formation of benzenehexathiol (BHT) SAMs. BHT chemisorbs to the gold surface in a previously unprecedented planar fashion. Carbon and gold substrates can be chemically altered by several methodologies resulting in new surface properties. The development of modification protocols and their application in the analytical arena is considered herein.

Surface wettability of silicon substrates enhanced by laser ablation

Energy Technology Data Exchange (ETDEWEB)

Tseng, Shih-Feng [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China); Hsiao, Wen-Tse; Huang, Kuo-Cheng; Hsiao, Sheng-Yi [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); Chen, Ming-Fei [National Changhua University of Education, Department of Mechatronics Engineering, Changhua (China); Lin, Yung-Sheng [Hungkuang University, Department of Applied Cosmetology and Graduate Institute of Cosmetic Science, Taichung (China); Chou, Chang-Pin [National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China)

2010-11-15

Laser-ablation techniques have been widely applied for removing material from a solid surface using a laser-beam irradiating apparatus. This paper presents a surface-texturing technique to create rough patterns on a silicon substrate using a pulsed Nd:YAG laser system. The different degrees of microstructure and surface roughness were adjusted by the laser fluence and laser pulse duration. A scanning electron microscope (SEM) and a 3D confocal laser-scanning microscope are used to measure the surface micrograph and roughness of the patterns, respectively. The contact angle variations between droplets on the textured surface were measured using an FTA 188 video contact angle analyzer. The results indicate that increasing the values of laser fluence and laser pulse duration pushes more molten slag piled around these patterns to create micro-sized craters and leads to an increase in the crater height and surface roughness. A typical example of a droplet on a laser-textured surface shows that the droplet spreads very quickly and almost disappears within 0.5167 s, compared to a contact angle of 47.9 on an untextured surface. This processing technique can also be applied to fabricating Si solar panels to increase the absorption efficiency of light. (orig.)

Influence of substrate and film thickness on polymer LIPSS formation

Energy Technology Data Exchange (ETDEWEB)

Cui, Jing; Nogales, Aurora; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, Madrid 28006 (Spain); Rebollar, Esther, E-mail: e.rebollar@csic.es [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, Madrid 28006 (Spain)

2017-02-01

Highlights: • The estimation of temperature upon pulse accumulation shows that a small positive offset is caused by each individual pulse. • Number of pulses needed for LIPSS formation in PS thin films depends on polymer thickness. • Thermal conductivity and diffusivity of supporting substrate influence the onset for LIPSS formation and their quality. • Quality of LIPSS is affected by the substrate optical properties. - Abstract: Here we focus on the influence of both, substrate and film thickness on polymer Laser Induced Periodic Surface Structures (LIPSS) formation in polymer films. For this aim a morphological description of ripples structures generated on spin-coated polystyrene (PS) films by a linearly polarized laser beam with a wavelength of 266 nm is presented. The influence of different parameters on the quality and characteristics of the formed laser-induced periodic surface structures (LIPSS) was investigated. We found that well-ordered LIPSS are formed either on PS films thinner than 200 nm or thicker than 400 nm supported on silicon substrates as well as on thicker free standing films. However less-ordered ripples are formed on silicon supported films with intermediate thicknesses in the range of 200–380 nm. The effect of the thermal and optical properties of the substrate on the quality of LIPSS was analyzed. Differences observed in the fluence and number of pulses needed for the onset of surface morphological modifications is explained considering two main effects which are: (1) The temperature increase on polymer surface induced by the action of cumulative laser irradiation and (2) The differences in thermal conductivity between the polymer and the substrate which strongly affect the heat dissipation generated by irradiation.

Investigation of microstructure and morphology for the Ge on porous silicon/Si substrate hetero-structure obtained by molecular beam epitaxy

International Nuclear Information System (INIS)

Gouder, S.; Mahamdi, R.; Aouassa, M.; Escoubas, S.; Favre, L.; Ronda, A.; Berbezier, I.

2014-01-01

Thick porous silicon (PS) buffer layers are used as sacrificial layers to epitaxially grow planar and fully relaxed Ge membranes. The single crystal Ge layers have been deposited by molecular beam epitaxy (MBE) on PS substrate. During deposition, the pore network of PS layers has been filled with Ge. We investigate the structure and morphology of PS as fabricated and after annealing at various temperatures. We show that the PS crystalline lattice is distorted and expanded in the direction perpendicular to the substrate plane due to the presence of chemisorbed –OH. An annealing at high temperature (> 500 °C), greatly changes the PS morphology and structure. This change is marked by an increase of the pore diameter while the lattice parameter becomes tensily strained in the plane (compressed in the direction perpendicular). The morphology and structure of Ge layers are investigated by transmission electron microscopy, high resolution X-ray diffraction and atomic force microscopy as a function of the deposition temperature and deposited thickness. The results show that the surface roughness, level of relaxation and Si-Ge intermixing (Ge content) depend on the growth temperature and deposited thickness. Two sub-layers are distinguished: the layer incorporated inside the PS pores (high level of intermixing) and the layer on top of the PS surface (low level of intermixing). When deposited at temperature > 500 °C, the Ge layers are fully relaxed with a top Si 1−x Ge x layer x = 0.74 and a very flat surface. Such layer can serve as fully relaxed ultra-thin SiGe pseudo-substrate with high Ge content. The epitaxy of Ge on sacrificial soft PS pseudo-substrate in the experimental conditions described here provides an easy way to fabricate fully relaxed SiGe pseudo-substrates. Moreover, Ge thin films epitaxially deposited by MBE on PS could be used as relaxed pseudo-substrate in conventional microelectronic technology. - Highlights: • We have developed a rapid and low

Structural and electrical characterization of HBr/O2 plasma damage to Si substrate

International Nuclear Information System (INIS)

Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya

2011-01-01

Silicon substrate damage caused by HBr/O 2 plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H 2 , Ar, and O 2 plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O 2 plasma exposure, hydrogen generated the deep damaged layer (∼10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

Surface Structures Formed by a Copper(II Complex of Alkyl-Derivatized Indigo

Directory of Open Access Journals (Sweden)

Akinori Honda

2016-10-01

Full Text Available Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM analysis revealed that the copper(II complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed.

Effect of the nand p-type Si(100) substrates with a SiC buffer layer on the growth mechanism and structure of epitaxial layers of semipolar AlN and GaN

Science.gov (United States)

Bessolov, V. N.; Grashchenko, A. S.; Konenkova, E. V.; Myasoedov, A. V.; Osipov, A. V.; Red'kov, A. V.; Rodin, S. N.; Rubets, V. P.; Kukushkin, S. A.

2015-10-01

A new effect of the n-and p-type doping of the Si(100) substrate with a SiC film on the growth mechanism and structure of AlN and GaN epitaxial layers has been revealed. It has been experimentally shown that the mechanism of AlN and GaN layer growth on the surface of a SiC layer synthesized by substituting atoms on n- and p-Si substrates is fundamentally different. It has been found that semipolar AlN and GaN layers on the SiC/Si(100) surface grow in the epitaxial and polycrystalline structures on p-Si and n-Si substrates, respectively. A new method for synthesizing epitaxial semipolar AlN and GaN layers by chloride-hydride epitaxy on silicon substrates has been proposed.

Dielectrophoretic deformation of thin liquid films induced by surface charge patterns on dielectric substrates

NARCIS (Netherlands)

Berendsen, C.W.J.; Kuijpers, C.J.; Zeegers, J.C.H.; Darhuber, A.A.

2013-01-01

We studied the deformation of thin liquid films induced by surface charge patterns at the solid–liquid interface quantitatively by experiments and numerical simulations. We deposited a surface charge distribution on dielectric substrates by applying potential differences between a conductive liquid

COATING OF POLYMERIC SUBSTRATE CATALYSTS ON METALLIC SURFACES

Directory of Open Access Journals (Sweden)

H. HOSSEINI

2010-12-01

Full Text Available This article presents results of a study on coating of a polymeric substrate ca-talyst on metallic surface. Stability of coating on metallic surfaces is a proper specification. Sol-gel technology was used to synthesize adhesion promoters of polysilane compounds that act as a mediator. The intermediate layer was coated by synthesized sulfonated polystyrene-divinylbenzene as a catalyst for production of MTBE in catalytic distillation process. Swelling of catalyst and its separation from the metal surface was improved by i increasing the quantity of divinylbenzene in the resin’s production process and ii applying adhesion pro¬moters based on the sol-gel process. The rate of ethyl silicate hydrolysis was intensified by increasing the concentration of utilized acid while the conden¬sation polymerization was enhanced in the presence of OH–. Sol was formed at pH 2, while the pH should be 8 for the formation of gel. By setting the ratio of the initial concentrations of water to ethyl silicate to 8, the gel formation time was minimized.

Template-controlled mineralization: Determining film granularity and structure by surface functionality patterns

Directory of Open Access Journals (Sweden)

Nina J. Blumenstein

2015-08-01

Full Text Available We present a promising first example towards controlling the properties of a self-assembling mineral film by means of the functionality and polarity of a substrate template. In the presented case, a zinc oxide film is deposited by chemical bath deposition on a nearly topography-free template structure composed of a pattern of two self-assembled monolayers with different chemical functionality. We demonstrate the template-modulated morphological properties of the growing film, as the surface functionality dictates the granularity of the growing film. This, in turn, is a key property influencing other film properties such as conductivity, piezoelectric activity and the mechanical properties. A very pronounced contrast is observed between areas with an underlying fluorinated, low energy template surface, showing a much more (almost two orders of magnitude coarse-grained film with a typical agglomerate size of around 75 nm. In contrast, amino-functionalized surface areas induce the growth of a very smooth, fine-grained surface with a roughness of around 1 nm. The observed influence of the template on the resulting clear contrast in morphology of the growing film could be explained by a contrast in surface adhesion energies and surface diffusion rates of the nanoparticles, which nucleate in solution and subsequently deposit on the functionalized substrate.

Electronic structure of graphene on Ni surfaces with different orientation

International Nuclear Information System (INIS)

Pudikov, D.A.; Zhizhin, E.V.; Rybkin, A.G.; Rybkina, A.A.; Zhukov, Y.M.; Vilkov, O. Yu.; Shikin, A.M.

2016-01-01

An experimental study of the graphene, synthesized by propylene cracking on Ni surfaces with different orientation: (100) and (111), using angle-resolved photoemission, has been performed. It has been shown that graphene on Ni(111) had a perfect lateral structure due to consistency of their lattices, whereas graphene/Ni(100) consisted of a lot of domains. For both systems electronic structure was quite similar and demonstrated a strong bonding of graphene to the underlying Ni surface. After Au intercalation the electronic structure of graphene in both systems was shifted to the Fermi level and became linear in the vicinity of the K point of the Brillouin zone. - Highlights: • Graphene on Ni(111) is well-ordered, whereas on Ni(100) – multi-domain. • Graphene on Ni(111) and Ni(100) is strongly bonded with substrate. • Intercalation of Au atoms restores the linearity in dispersion and makes graphene quasi-free on both Ni(100) and Ni(111).

Influence of substrate bias on the structure and properties of (Ti, Al)N films deposited by filtered cathodic vacuum arc

International Nuclear Information System (INIS)

Cheng, Y.H.; Tay, B.K.; Lau, S.P.; Shi, X.

2001-01-01

(Ti, Al)N films were deposited by an off-plane, double-bend, filtered cathodic vacuum arc technique in N 2 atmosphere at room temperature. The (Ti, Al)N films deposited are atomically smooth. The influence of substrate negative bias at the wide range (0-1000 V) on the deposition rate, surface morphology, crystal structure, internal stress, and mechanical properties of (Ti, Al)N films were systematically studied. Increasing substrate bias results in the decrease of deposition rate and the increase of surface roughness monotonically. At the bias of 0 V, (Ti, Al)N films are amorphous, and the internal stress, hardness, and Young's modulus for the deposited films are fairly low. With increasing substrate bias to 200 V, single-phase face-centered cubic-type nanocrystalline (Ti, Al)N films can be obtained, and the internal stress, hardness, and Young's modulus increase to the maximum of 7 GPa, 28 GPa, and 240 GPa, respectively. Further increase of substrate bias results in the decrease of intensity and the broadening of x-ray diffraction lines, and the gradual decrease of internal stress, hardness, and Young's modulus in (Ti, Al)N films

Morphology, structure, and electrical properties of YBa{sub 2}Cu{sub 3}O{sub x} thin films on tilted NdGaO{sub 3} substrates, deposited by DC-sputtering

Energy Technology Data Exchange (ETDEWEB)

Mozhaev, Peter B. [Institute of Radio Engineering and Electronics RAS, Moscow 125009 (Russian Federation)]. E-mail: pbmozh@nm.ru; Kotelyanskii, Iosif M. [Institute of Radio Engineering and Electronics RAS, Moscow 125009 (Russian Federation); Luzanov, Valery A. [Institute of Radio Engineering and Electronics RAS, Moscow 125009 (Russian Federation); Mozhaeva, Julia E. [Institute of Radio Engineering and Electronics RAS, Moscow 125009 (Russian Federation); Donchev, Todor [Institute of Electronics BAS, Sofia (Bulgaria); Mateev, Emil [Institute of Electronics BAS, Sofia (Bulgaria); Nurgaliev, Timur [Institute of Electronics BAS, Sofia (Bulgaria); Bdikin, Igor K. [Institute of Solid State Physics RAS, Chernogolovka, Moscow 142432 (Russian Federation); Department of Ceramic and Glass Engineering, CICECO, University of Aveiro, Aveiro 3810-193 (Portugal); Narymbetov, Bakhyt Zh. [Complex Institute of Natural Sciences UzAS, Nukus (Uzbekistan)

2005-02-15

Thin YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) films were deposited using DC-sputtering technique on NdGaO{sub 3} substrates, tilted from (1 1 0) orientation by 0-26 deg . The structure and surface quality of the substrates were carefully characterized to obtain reliable results of thin films deposition. Structural, morphological and electrical properties of the YBCO thin films show three different ranges of inclination angle: vicinal, intermediate and high. In the vicinal range the properties of the film are generally the same as of the standard films deposited on (1 1 0) NdGaO{sub 3} substrate. An increase of the inclination angle to the intermediate range results in a significant improvement of morphology and structural quality of the film. Best electrical parameters are measured for the films of the intermediate range also. Probable reason for such behavior is simultaneous and regular seeding of the film in the joints of facets on the substrate surface. Further increase of inclination angle leads to step bunching and oxygen out-diffusion, destroying both structural and electrical perfection of the tilted-axes YBCO film.

Modification of Surface Roughness and Area of FeCrAl Substrate for Catalytic Converter using Ultrasonic Treatment

Directory of Open Access Journals (Sweden)

Yanuandri Putrasari

2012-03-01

Full Text Available Surface roughness and area play important role especially in deposition and reaction of the catalyst in the catalytic converter substrate. The aim of this paper is to show the modification of surface roughness and area of FeCrAl substrate for catalytic converter using ultrasonic method. The method was conducted by agitating the FeCrAl in 10 minutes 35 kHz ultrasonic cleaning bath. The  surface roughness, morphology, and chemical components of FeCrAl catalytic converter substrate after ultrasonic treatment were analyzed using atomic force microscope (AFM and examined with scanning electron microscope (SEM in combination with energy dispersive X-ray spectroscopy (EDS. The ultrasonic treatment assisted with Al2O3 powders successfully increased the roughness and surface area of FeCrAl better than SiC powders. 

Three-dimensionally structured silicon as a substrate for the MOVPE growth of GaN nanoLEDs

Energy Technology Data Exchange (ETDEWEB)

Fuendling, Soenke; Li, Shunfeng; Soekmen, Uensal; Merzsch, Stephan; Peiner, Erwin; Wehmann, Hergo-Heinrich; Waag, Andreas [Institut fuer Halbleitertechnik, TU Braunschweig, Braunschweig (Germany); Hinze, Peter; Weimann, Thomas [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Jahn, Uwe; Trampert, Achim; Riechert, Henning [Paul-Drude-Institut fuer Festkoerperelektronik, Berlin (Germany)

2009-06-15

Three-dimensionally patterned Si(111) substrates are used to grow GaN based heterostructures by metalorganic vapour phase epitaxy, with the goal of fabricating well controlled, defect reduced GaN-based nanoLEDs. In contrast to other approaches to achieve GaN nanorods, we employed silicon substrates with deep etched nanopillars to control the GaN nanorods growth by varying the size and distance of the Si pillars. The small footprint of GaN nanorods grown on Si pillars minimise the influence of the lattice mismatched substrate and improve the material quality. For the Si pillars an inductively coupled plasma dry-etching process at cryogenic temperature has been developed. An InGaN/GaN multi quantum well (MQW) structure has been incorporated into the GaN nanorods. We found GaN nanostructures grown on top of the silicon pillars with a pyramidal shape. This shape results from a competitive growth on different facets as well as from surface diffusion of the growth species. Spatially resolved optical properties of the structures are analysed by cathodoluminescence. Strongly spatial-dependent MQW emission spectra indicate the growth rate differences on top of the rods. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effect of strain on geometric and electronic structures of graphene on a Ru(0001) surface

Institute of Scientific and Technical Information of China (English)

Sun Jia-Tao; Du Shi-Xuan; Xiao Wen-De; Hu Hao; Zhang Yu-Yang; Li Guo; Gao Hong-Jun

2009-01-01

The atomic and electronic structures of a graphene monolayer on a Ru(0001) surface under compressive strain are investigated by using first-principles calculations. Three models of graphene monolayers with different carbon periodicities due to the lattice mismatch are proposed in the presence and the. absence of the Ru(0001) substrate separately. Considering the strain induced by the lattice mismatch, we optimize the atomic structures and investigate the electronic properties of the graphene. Our calculation results show that the graphene layers turn into periodic corrugations and there exist strong chemical bonds in the interface between the graphene N x N superlattice and the substrate. The strain does not induce significant changes in electronic structure. Furthermore, the results calculated in the local density approximation (LDA) are compared with those obtained in the generalized gradient approximation (GGA), showing that the LDA results are more reasonable than the GGA results when only two substrate layers are used in calculation.

Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate

Energy Technology Data Exchange (ETDEWEB)

Sarycheva, Asia [Drexel Univ., Philadelphia, PA (United States); Makaryan, Taron [Drexel Univ., Philadelphia, PA (United States); Maleski, Kathleen [Drexel Univ., Philadelphia, PA (United States); Satheeshkumar, Elumalai [National Cheng Kung Univ., Tainan (Taiwan); National Institute of Technology-Trichy, Tamil Nadu (India); Melikyan, Armen [Russian-Armenian (Slavonic) State Univ., Yerevan (Armenia); Minassian, Hayk [A. Alikhanian National Science Lab., Yerevan (Armenia); Yoshimura, Masahiro [National Cheng Kung Univ., Tainan (Taiwan); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

2017-08-22

Here, noble metal (gold or silver) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic conductivity and plasmon resonance in the visible or near-infrared range, making them promising candidates for a wide variety of applications. Herein, we show that 2D titanium carbide, Ti₃C₂T_x, enhances Raman signal from organic dyes on a substrate and in solution. As a proof of concept, MXene SERS substrates were manufactured by spray-coating and used to detect several common dyes, with calculated enhancement factors reaching ~10⁶. Titanium carbide MXene demonstrates SERS effect in aqueous colloidal solutions, suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance positively charged molecules.

Substrate Misorientation Effects On (A1,Ga)As And (Al,Ga)As/GaAs Structures Grown By Molecular Beam Epitaxy

Science.gov (United States)

Tsui, Raymond K.; Kramer, Gary D.; Curless, J. A.; Peffley, Marilyn S.

1987-04-01

(Al,Ga)As layers have rough surface morphologies when deposited under certain growth conditions in molecular beam epitaxy (MBE). This leads to poor interfaces between (A1,Ga)- As and GaAs and degraded performance in heterojunction devices. We have observed that by misorienting the substrate slightly from (100), in a manner specific to the growth conditions, smooth (Al,Ga)As layers 3-4 μm thick can be grown at a rate of ≍ 1 μm/h for various AlAs mole fractions, x. Similar conditions for nominal (100) result in a rough, textured morphology. Experiments were carried out using flat substrates of specific misorientations as well as lens-shaped substrates. The lenticular substrates allowed all orientations within 14° of (100) [i.e., out to (511)] to be evaluated in one growth run. Deposition conditions that were varied included x, substrate temperature, and V/III beam flux ratio. Smooth layers obtained using optimal misorientations showed superior optical characteris-tics as determined from low-temperature photoluminescence (PL) measurements. The 4.2K PL spectra of smooth layers exhibit well-resolved exciton-related peaks, and do not have the deeper-level defect-related peaks observed in the spectra of rough layers. Single quantum well structures with A10.3Ga0.7As barriers and a 100 A-wide GaAs well deposited on mis-oriented substrates also have superior optical properties compared to a structure grown on nominal (100). Such findings may have significant implications for the performance of heterojunction device structures grown by MBE.

Simple method to transfer graphene from metallic catalytic substrates to flexible surfaces without chemical etching

International Nuclear Information System (INIS)

Ko, P J; Takahashi, H; Sakai, H; Thu, T V; Okada, H; Sandhu, A; Koide, S

2013-01-01

Graphene shows promise for applications in flexible electronics. Here, we describe our procedure to transfer graphene grown on copper substrates by chemical vapor deposition to polydimethylsiloxane (PDMS) and SiO 2 /Si surfaces. The transfer of graphene was achieved by a simple, etching-free method onto flexible PDMS substrates.

The lateral In2O3 nanowires and pyramid networks manipulation by controlled substrate surface energy in annealing evolution

Science.gov (United States)

Shariati, Mohsen; Darjani, Mojtaba

2016-02-01

The continuous laterally aligned growth of In2O3 nanocrystal networks extended with nanowire and pyramid connections under annealing influence has been reported. These nanostructures have been grown on Si substrate by using oxygen-assisted annealing process through PVD growth technique. The formation of In2O3 nanocrystals has been achieved by the successive growth of critical self-nucleated condensation in three orientations. The preferred direction was the route between two pyramids especially in the smallest surface energy. The effects of substrate temperature in annealing process on the morphological properties of the as-grown nanostructures were investigated. The annealing technique showed that by controlling the surface energy, the morphology of structures was changed from unregulated array to defined nanostructures; especially nanowires 50 nm in width. The obtained nanostructures also were investigated by the (transmission electron microscopy) TEM, Raman spectrum and the (X-ray diffraction) XRD patterns. They indicated that the self-assembled In2O3 nanocrystal networks have been fabricated by the vapor-solid (VS) growth mechanism. The growth mechanism process was prompted to attribute the relationship among the kinetics parameters, surface diffusion and morphology of nanostructures.

Development of novel series and parallel sensing system based on nanostructured surface enhanced Raman scattering substrate for biomedical application

Science.gov (United States)

Chang, Te-Wei

With the advance of nanofabrication, the capability of nanoscale metallic structure fabrication opens a whole new study in nanoplasmonics, which is defined as the investigation of photon-electron interaction in the vicinity of nanoscale metallic structures. The strong oscillation of free electrons at the interface between metal and surrounding dielectric material caused by propagating surface plasmon resonance (SPR) or localized surface plasmon resonance (LSPR) enables a variety of new applications in different areas, especially biological sensing techniques. One of the promising biological sensing applications by surface resonance polariton is surface enhanced Raman spectroscopy (SERS), which significantly reinforces the feeble signal of traditional Raman scattering by at least 104 times. It enables highly sensitive and precise molecule identification with the assistance of a SERS substrate. Until now, the design of new SERS substrate fabrication process is still thriving since no dominant design has emerged yet. The ideal process should be able to achieve both a high sensitivity and low cost device in a simple and reliable way. In this thesis two promising approaches for fabricating nanostructured SERS substrate are proposed: thermal dewetting technique and nanoimprint replica technique. These two techniques are demonstrated to show the capability of fabricating high performance SERS substrate in a reliable and cost efficient fashion. In addition, these two techniques have their own unique characteristics and can be integrated with other sensing techniques to build a serial or parallel sensing system. The breakthrough of a combination system with different sensing techniques overcomes the inherent limitations of SERS detection and leverages it to a whole new level of systematic sensing. The development of a sensing platform based on thermal dewetting technique is covered as the first half of this thesis. The process optimization, selection of substrate material

Tuning the adhesion between polyimide substrate and MWCNTs/epoxy nanocomposite by surface treatment

Science.gov (United States)

Bouhamed, Ayda; Kia, Alireza Mohammadian; Naifar, Slim; Dzhagan, Volodymyr; Müller, Christian; Zahn, Dietrich R. T.; Choura, Slim; Kanoun, Olfa

2017-11-01

MWCNTs/epoxy nanocomposite thin films are coated on the polyimide (PI) flexible substrate, to be used as a strain sensor. Previous studies showed that the adhesion between polyimide and other materials are very poor. In this work, two approaches, oxygen plasma cleaning and simple solvent cleaning are performed for activation of the polyimide surface. In order to understand the impact of both cleaning techniques, the physicochemical properties of PI are measured and characterized using contact angle measurements (CAMs), X-ray photoelectron spectroscopy(XPS), and atomic force microscopy (AFM). In addition, the adhesion properties of PI/[MWCNTs/epoxy] systems by varying surface treatment time are investigated and evaluated using force-distance measurements by AFM. The results illustrate that the activated surface exhibits higher surface energy for oxygen plasma cleaning in comparison with the solvent cleaning method. The improvement can be related to the increase of oxygen concentration, which is accompanied by the enhancement of the polar component to 53.79 mN/m due to the formation of functional groups on the surface and the change of the substrate surface roughness from 1.72 nm to 15.5 nm. As a result, improved adhesion was observed from force-distance measurement between PI/[MWCNTs/epoxy] systems due to oxygen plasma effects.

DNA origami deposition on native and passivated molybdenum disulfide substrates

Directory of Open Access Journals (Sweden)

Xiaoning Zhang

2014-04-01

Full Text Available Maintaining the structural fidelity of DNA origami structures on substrates is a prerequisite for the successful fabrication of hybrid DNA origami/semiconductor-based biomedical sensor devices. Molybdenum disulfide (MoS2 is an ideal substrate for such future sensors due to its exceptional electrical, mechanical and structural properties. In this work, we performed the first investigations into the interaction of DNA origami with the MoS2 surface. In contrast to the structure-preserving interaction of DNA origami with mica, another atomically flat surface, it was observed that DNA origami structures rapidly lose their structural integrity upon interaction with MoS2. In a further series of studies, pyrene and 1-pyrenemethylamine, were evaluated as surface modifications which might mitigate this effect. While both species were found to form adsorption layers on MoS2 via physisorption, 1-pyrenemethylamine serves as a better protective agent and preserves the structures for significantly longer times. These findings will be beneficial for the fabrication of future DNA origami/MoS2 hybrid electronic structures.

Electrical properties of transparent CNT and ITO coatings on PET substrate including nano-structural aspects

Science.gov (United States)

Park, Joung-Man; Wang, Zuo-Jia; Kwon, Dong-Jun; Gu, Ga-Young; Lawrence DeVries, K.

2013-01-01

Ultraviolet (UV)-visible spectra and surface resistance measurement were used to investigate optical transmittance and conductive properties of carbon nanotube (CNT) and indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates. Conductive CNT and ITO coatings were successfully fabricated on PET by a spray-coating method. Thin coatings of both materials exhibited good conductivity and transparency. Changes in electrical and optical properties of the coatings were studied as a function of the coating suspension concentration. Interfacial durability of the coatings on PET substrates was also investigated under fatigue and bending loads. CNT coated substrates, with high aspect ratios, exhibited no detectable change in surface resistance up to 2000 cyclic loadings, whereas the ITO coated substrates exhibited a substantial increase in surface resistance at 1000 loading cycles. This change in resistance is attributed to a reduction in the number and effectiveness of the electrical contact points due to the inherent brittle nature of ITO.

Structural and optical characteristics of in-situ sputtered highly oriented 15R-SiC thin films on different substrates

Science.gov (United States)

Mourya, Satyendra; Jaiswal, Jyoti; Malik, Gaurav; Kumar, Brijesh; Chandra, Ramesh

2018-01-01

In this work, we have reported the in-situ fabrication of nanocrystalline rhombohedral silicon carbide (15R-SiC) thin films by RF-magnetron sputtering at 800 °C substrate temperature. The structural and optical properties were investigated for the films grown on four different substrates (ZrO2, MgO, SiC, and Si). The contact angle measurement was performed on all the substrates to investigate the role of interfacial surface energy in nucleation and growth of the films. The XRD measurement revealed the growth of (1 0 10) orientation for all the samples and demonstrated better crystallinity on Si substrate, which was further corroborated by the TEM results. The Raman spectroscopy confirmed the growth of rhombohedral phase with 15R polytype. Surface characteristics of the films have been investigated by energy dispersive x-ray spectroscopy, FTIR, and atomic force microscope (AFM) to account for chemical composition, bonding, and root mean square surface roughness (δrms). The optical dispersion behavior of 15R-SiC thin films was examined by variable angle spectroscopic ellipsometry in the wide spectral range (246-1688 nm), including the surface characteristics in the optical model. The non-linear optical parameters (χ3 and n2) of the samples have been calculated by the Tichy and Ticha relation using a single effective oscillator model of Wemple and Didomenico. Additionally, our optical results provided an alternative way to measure the ratio of carrier concentration to the effective mass (N/m*). These investigated optical parameters allow one to design and fabricate optoelectronic, photonic, and telecommunication devices for deployment in extreme environment.

X-ray structures of the Pseudomonas cichorii D-tagatose 3-epimerase mutant form C66S recognizing deoxy sugars as substrates.

Science.gov (United States)

Yoshida, Hiromi; Yoshihara, Akihide; Ishii, Tomohiko; Izumori, Ken; Kamitori, Shigehiro

2016-12-01

Pseudomonas cichorii D-tagatose 3-epimerase (PcDTE), which has a broad substrate specificity, efficiently catalyzes the epimerization of not only D-tagatose to D-sorbose but also D-fructose to D-psicose (D-allulose) and also recognizes the deoxy sugars as substrates. In an attempt to elucidate the substrate recognition and catalytic reaction mechanisms of PcDTE for deoxy sugars, the X-ray structures of the PcDTE mutant form with the replacement of Cys66 by Ser (PcDTE_C66S) in complexes with deoxy sugars were determined. These X-ray structures showed that substrate recognition by the enzyme at the 1-, 2-, and 3-positions is responsible for enzymatic activity and that substrate-enzyme interactions at the 4-, 5-, and 6-positions are not essential for the catalytic reaction of the enzyme leading to the broad substrate specificity of PcDTE. They also showed that the epimerization site of 1-deoxy 3-keto D-galactitol is shifted from C3 to C4 and that 1-deoxy sugars may bind to the catalytic site in the inhibitor-binding mode. The hydrophobic groove that acts as an accessible surface for substrate binding is formed through the dimerization of PcDTE. In PcDTE_C66S/deoxy sugar complex structures, bound ligand molecules in both the linear and ring forms were detected in the hydrophobic groove, while bound ligand molecules in the catalytic site were in the linear form. This result suggests that the sugar-ring opening of a substrate may occur in the hydrophobic groove and also that the narrow channel of the passageway to the catalytic site allows a substrate in the linear form to pass through.

Effect of sulfur passivation of InSb (0 0 1) substrates on molecular-beam homoepitaxy

Energy Technology Data Exchange (ETDEWEB)

Solov’ev, V.A., E-mail: vasol@beam.ioffe.ru; Sedova, I.V.; Lvova, T.V.; Lebedev, M.V.; Dement’ev, P.A.; Sitnikova, A.A.; Semenov, A.N.; Ivanov, S.V.

2015-11-30

Highlights: • Treatment of InSb (0 0 1) substrate with 1 M aqueous Na{sub 2}S solution results in nearly complete removal of native oxides. • A sulfide protective layer formed by the S-treatment is desorbed at much lower temperatures than the native oxide layer. • The bulk InSb epilayers grown on the S-treated substrates have very smooth surface (RMS ∼0.1 nm). • Good structural quality of the homointerfaces formed at the S-treated substrates is confirmed by TEM. - Abstract: The aqueous sodium sulfide solution has been used for pre-epitaxial preparation of epi-ready InSb (0 0 1) substrates for molecular beam epitaxy (MBE) of InSb layers. X-ray photoemission spectroscopy study shows that the S-treated surface of InSb (0 0 1) substrate generally does not contain a native oxide layer and is covered with a sulfide protecting overlayer. Atomic-force microscopy and transmission electron microscopy have been applied to compare surface topography and structural properties of InSb layers grown by MBE on S-treated and untreated epi-ready InSb (0 0 1) substrates. The MBE growth of InSb layers with very smooth surface possessing the root-mean-square roughness as low as 0.1 nm and good structural quality has been demonstrated on the S-treated substrates.

A study of the substrate surface chemical states at the interface TiN/Si by X-Ray Photoelectron Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Antunes, Vinicius Gabriel; Alvarez, Fernando, E-mail: vi.antunes@gmail.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Fisica Gleb Wataghin; Figueroa, Carlos Alejandro [Universidade de Caxias do Sul, RS (Brazil)

2016-07-01

Full text: Titanium-based thin films are used for a great number of applications, such as hard coating in cutting tools, catalyst diffusion barriers, and in microelectronic devices. Although the understanding of the film adhesion mechanisms onto different substrates continue being a challenge and its atomic bonding properties are not fully understood. Furthermore, as the interface determines many characteristics of the final film by prompting the bulk properties of the grown material, a detailed study of the first atomic layers is an interesting route to gain physical inside on the adhesion properties of the coating. Also, it is important to remark that the presence of residual oxygen in standards deposition chambers is sometime unavoidable and its influence on the films properties is important to be taking in account. In this work the influence of the chemical state of the silicon surface at the interface TiN/Si have been studied. In order to this, a few atomic layers of TiN were deposited on mirror polished c-Si by ion beam deposition (IBD) sputtering of a pure Ti target in a nitrogen atmosphere during 5s (T=350C). In this conditions, a 3Å average thickness, as estimated by the material deposition rate, is obtained. The local electronic structure at the interface TiN/Si was scrutinized by XPS (X-ray photoelectron spectroscopy, 1485.6eV) in a UHV chamber attached to the IBD system, i.e the studied samples are free from atmospheric contamination. The study indicates the presence of Ti-Si, Ti-O, Si-O, Ti-N and Si-N bonds at the TiN/Si interface, where the oxygen stems from the residual chamber pressure. The nano-structuration of the Si substrate surface by noble gas ion bombardment during the pre-cleaning procedure of the substrate and its influence on the bonding structures at the TiN/Si interface will be also presented and discussed. Finally, the oxygen reduction effect obtained by introducing H2 on the interface structure is presented and discussed. (author)

Ceramic substrate including thin film multilayer surface conductor

Science.gov (United States)

Wolf, Joseph Ambrose; Peterson, Kenneth A.

2017-05-09

A ceramic substrate comprises a plurality of ceramic sheets, a plurality of inner conductive layers, a plurality of vias, and an upper conductive layer. The ceramic sheets are stacked one on top of another and include a top ceramic sheet. The inner conductive layers include electrically conductive material that forms electrically conductive features on an upper surface of each ceramic sheet excluding the top ceramic sheet. The vias are formed in each of the ceramic sheets with each via being filled with electrically conductive material. The upper conductive layer includes electrically conductive material that forms electrically conductive features on an upper surface of the top ceramic sheet. The upper conductive layer is constructed from a stack of four sublayers. A first sublayer is formed from titanium. A second sublayer is formed from copper. A third sublayer is formed from platinum. A fourth sublayer is formed from gold.

Silver nanoparticles deposited on anodic aluminum oxide template using magnetron sputtering for surface-enhanced Raman scattering substrate

Energy Technology Data Exchange (ETDEWEB)

Wong-ek, Krongkamol [Nanoscience and Technology Program, Chulalongkorn University, Bangkok 10330 (Thailand); Eiamchai, Pitak; Horprathum, Mati; Patthanasettakul, Viyapol [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Limnonthakul, Puenisara [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Chindaudom, Pongpan [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Nuntawong, Noppadon, E-mail: noppadon.nuntawong@nectec.or.t [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand)

2010-09-30

Low-cost and highly sensitive surface-enhanced Raman scattering (SERS) substrates have been fabricated by a simple anodizing process and a magnetron sputtering deposition. The substrates, which consist of silver nanoparticles embedded on anodic aluminum oxide (AAO) templates, are investigated by a scanning electron microscope and a confocal Raman spectroscopy. The SERS activities are demonstrated by Raman scattering from adsorbed solutions of methylene blue and pyridine on the SERS substrate surface. The most optimized SERS substrate contains the silver nanoparticles, with a size distribution of 10-30 nm, deposited on the AAO template. From a calculation, the SERS enhancement factor is as high as 8.5 x 10{sup 7}, which suggests strong potentials for direct applications in the chemical detection and analyses.

Molecular-beam epitaxial growth of insulating AlN on surface-controlled 6H-SiC substrate by HCl gas etching

International Nuclear Information System (INIS)

Onojima, Norio; Suda, Jun; Matsunami, Hiroyuki

2002-01-01

Insulating AlN layers were grown on surface-controlled 6H-SiC subtrates by molecular-beam epitaxy (MBE) using elemental Al and rf plasma-excited nitrogen (N*). HCl gas etching was introduced as an effective pretreatment method of substrate for MBE growth of AlN. 6H-SiC substrates pretreated by HCl gas etching had no surface polishing scratches and an atomically flat surface. In addition, evident ( 3 √x 3 √)R30 deg. surface reconstruction was observed even before thermal cleaning. AlN layers grown on this substrate had no defects related to surface polishing scratches and excellent insulating characteristics

Structural and kinetic basis for substrate selectivity in Populus tremuloides sinapyl alcohol dehydrogenase.

Science.gov (United States)

Bomati, Erin K; Noel, Joseph P

2005-05-01

We describe the three-dimensional structure of sinapyl alcohol dehydrogenase (SAD) from Populus tremuloides (aspen), a member of the NADP(H)-dependent dehydrogenase family that catalyzes the last reductive step in the formation of monolignols. The active site topology revealed by the crystal structure substantiates kinetic results indicating that SAD maintains highest specificity for the substrate sinapaldehyde. We also report substantial substrate inhibition kinetics for the SAD-catalyzed reduction of hydroxycinnamaldehydes. Although SAD and classical cinnamyl alcohol dehydrogenases (CADs) catalyze the same reaction and share some sequence identity, the active site topology of SAD is strikingly different from that predicted for classical CADs. Kinetic analyses of wild-type SAD and several active site mutants demonstrate the complexity of defining determinants of substrate specificity in these enzymes. These results, along with a phylogenetic analysis, support the inclusion of SAD in a plant alcohol dehydrogenase subfamily that includes cinnamaldehyde and benzaldehyde dehydrogenases. We used the SAD three-dimensional structure to model several of these SAD-like enzymes, and although their active site topologies largely mirror that of SAD, we describe a correlation between substrate specificity and amino acid substitution patterns in their active sites. The SAD structure thus provides a framework for understanding substrate specificity in this family of enzymes and for engineering new enzyme specificities.

Controlling the anisotropy and domain structure with oblique deposition and substrate rotation

Directory of Open Access Journals (Sweden)

N. Chowdhury

2014-02-01

Full Text Available Effect of substrate rotation on anisotropy and domain structure for a thin ferromagnetic film has been investigated in this work. For this purpose Co films with 10 nm thickness have been prepared by sputtering with oblique angle of incidence for various substrate rotations. This method of preparation induces a uniaxial anisotropy due to shadow deposition effect. The magnetization reversal is studied by magneto-optic Kerr effect (MOKE based microscope in the longitudinal geometry. The Co films prepared by rotating the substrate with 10 and 20 rpm weakens the anisotropy but does not completely give isotropic films. But this leads to high dispersion in local grain anisotropy resulting in ripple and labyrinth domains. It is observed that the substrate rotation has moderate effect on uniaxial anisotropy but has significant effect on the magnetization reversal process and the domain structure.

Surface engineering of biaxial Gd2Zr2O7 thin films deposited on Ni–5at%W substrates by a chemical solution method

DEFF Research Database (Denmark)

Yue, Zhao; Grivel, Jean-Claude; Liu, Min

2012-01-01

crystal structure along the film thickness observed by a transmission electron microscope. On the basis of the enhanced understanding of the crystallization processes, we demonstrate a possibility of engineering the surface morphology and texture in the film deposited on technical substrates using...... a chemical solution deposition route....

DC heating induced shape transformation of Ge structures on ultraclean Si(5 5 12) surfaces.

Science.gov (United States)

Dash, J K; Rath, A; Juluri, R R; Raman, P Santhana; Müller, K; Rosenauer, A; Satyam, P V

2011-04-06

We report the growth of Ge nanostructures and microstructures on ultraclean, high vicinal angle silicon surfaces and show that self-assembled growth at optimum thickness of the overlayer leads to interesting shape transformations, namely from nanoparticle to trapezoidal structures, at higher thickness values. Thin films of Ge of varying thickness from 3 to 12 ML were grown under ultrahigh vacuum conditions on a Si(5 5 12) substrate while keeping the substrate at a temperature of 600 °C. The substrate heating was achieved by two methods: (i) by heating a filament under the substrate (radiative heating, RH) and (ii) by passing direct current through the samples in three directions (perpendicular, parallel and at 45° to the (110) direction of the substrate). We find irregular, more spherical-like island structures under RH conditions. The shape transformations have been found under DC heating conditions and for Ge deposition more than 8 ML thick. The longer sides of the trapezoid structures are found to be along (110) irrespective of the DC current direction. We also show the absence of such a shape transformation in the case of Ge deposition on Si(111) substrates. Scanning transmission electron microscopy measurements suggested the mixing of Ge and Si. This has been confirmed with a quantitative estimation of the intermixing using Rutherford backscattering spectrometry (RBS) measurements. The role of DC heating in the formation of aligned structures is discussed. Although the RBS simulations show the presence of a possible SiO(x) layer, under the experimental conditions of the present study, the oxide layer would not play a role in determining the formation of the various structures that were reported here.

Conformal dip-coating of patterned surfaces for capillary die-to-substrate self-assembly

International Nuclear Information System (INIS)

Mastrangeli, M; Ruythooren, W; Van Hoof, C; Celis, J-P

2009-01-01

Capillarity-driven self-assembly of small chips onto planar target substrates is a promising alternative to robotic pick-and-place assembly. It critically relies on the selective deposition of thin fluid films on patterned binding sites, which is anyway normally non-conformal. We found that the addition of a thin wetting sidewall, surrounding the entire site perimeter, enables the conformal fluid coverage of arbitrarily shaped sites through dip-coating, significantly improves the reproducibility of the coating process and strongly reduces its sensitivity to surface defects. In this paper we support the feasibility and potential of this method by demonstrating the conformal dip-coating of square and triangular sites conditioned with combinations of different hydrophobic and hydrophilic surface chemistries. We present both experimental and simulative evidence of the advantages brought by the introduction of the wetting boundary on film coverage accuracy. Application of our surface preparation method to capillary self-assembly could result in higher precision in die-to-substrate registration and larger freedom in site shape design

Experimental and simulation study of growth of TiO2 films on different substrates and its applications

Science.gov (United States)

Ghogare, Trupti T.; Kartha, Moses J.; Kendre, Subhash D.; Pathan, Habib M.

2018-04-01

Monte-Carlo Ballistic Deposition simulations have done on substrates with different initial roughness. The grown films were observed to be porous. The initial growths of the films with seed like initiations are observed for substrate with high initial roughness. In order to confirm this effect TiO2 films were deposited on different substrates using chemical bath deposition. The surface morphological and optical properties were measured using scanning electron microscopy and a UV-Vis spectrophotometer. Flower like porous structure are obtained on glass substrate and continuous porous morphology is formed on ITO substrate. The morphology of the surfaces was successfully reconstructed and the surface porosity was calculated after digitalising images and reconstructed the surfaces. The TiO2 film formed on ITO is observed to be 10% more porous than on the film formed on glass substrate. Diffusion Limited Aggregation simulations with multiple seeds confirms that the observed flower like structure formed are due to the screening effects of the diffusing ion by already deposited particles.

Fabrication and Corrosion Resistance of Superhydrophobic Hydroxide Zinc Carbonate Film on Aluminum Substrates

Directory of Open Access Journals (Sweden)

Jin Liang

2013-01-01

Full Text Available Superhydrophobic hydroxide zinc carbonate (HZC films were fabricated on aluminum substrate through a convenient in situ deposition process. Firstly, HZC films with different morphologies were deposited on aluminum substrates through immersing the aluminum substrates perpendicularly into aqueous solution containing zinc nitrate hexahydrate and urea. Secondly, the films were then modified with fluoroalkylsilane (FAS: CH3(CF26(CH23Si(OCH33 molecules by immersing in absolute ethanol solution containing FAS. The morphologies, hydrophobicity, chemical compositions, and bonding states of the films were analyzed by scanning electron microscopy (SEM, water contact angle measurement (CA, Fourier transform infrared spectrometer (FTIR, and X-ray photoelectron spectroscopy (XPS, respectively. It was shown by surface morphological observation that HZC films displayed different microstructures such as microporous structure, rose petal-like structure, block-shaped structure, and pinecone-like structure by altering the deposition condition. A highest water contact angle of 156.2° was obtained after FAS modification. Moreover, the corrosion resistance of the superhydrophobic surface on aluminum substrate was investigated using electrochemical impedance spectroscopy (EIS measurements. The EIS measurements’ results revealed that the superhydrophobic surface considerably improved the corrosion resistance of aluminum.

Improved electrochemical properties of morphology-controlled titania/titanate nanostructures prepared by in-situ hydrothermal surface modification of self-source Ti substrate for high-performance supercapacitors.

Science.gov (United States)

Banerjee, Arghya Narayan; Anitha, V C; Joo, Sang W

2017-10-16

Ti substrate surface is modified into two-dimensional (2D) TiO 2 nanoplatelet or one-dimensional (1D) nanorod/nanofiber (or a mixture of both) structure in a controlled manner via a simple KOH-based hydrothermal technique. Depending on the KOH concentration, different types of TiO 2 nanostructures (2D platelets, 1D nanorods/nanofibers and a 2D+1D mixed sample) are fabricated directly onto the Ti substrate surface. The novelty of this technique is the in-situ modification of the self-source Ti surface into titania nanostructures, and its direct use as the electrochemical microelectrode without any modifications. This leads to considerable improvement in the interfacial properties between metallic Ti and semiconducting TiO 2 . Since interfacial states/defects have profound effect on charge transport properties of electronic/electrochemical devices, therefore this near-defect-free interfacial property of Ti-TiO 2 microelectrode has shown high supercapacitive performances for superior charge-storage devices. Additionally, by hydrothermally tuning the morphology of titania nanostructures, the electrochemical properties of the electrodes are also tuned. A Ti-TiO 2 electrode comprising of a mixture of 2D-platelet+1D-nanorod structure reveals very high specific capacitance values (~7.4 mF.cm -2 ) due to the unique mixed morphology which manifests higher active sites (hence, higher utilization of the active materials) in terms of greater roughness at the 2D-platelet structures and higher surface-to-volume-ratio in the 1D-nanorod structures.

CONICAL EQUIPOTENTIAL SUBSTRATE FOR LIQUID METAL SOURCES

OpenAIRE

Kubby , J.; Siegel , B.

1986-01-01

Morphological changes that occur at an ion bombarded surface as a result of erosion by sputtering can be utilized for the machining of cylindrically symmetric submicron structures. Such structuring has produced tungsten field emitters of conical configuration with variable cone half angle. A conical equipotential surface with an included half angle of 49.3° would be a useful emitter substrate for experiments designed to produce an equilibrium conical interface to a conducting fluid in an appl...

Effects of substrate material on carbon films grown by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Liu, M.; Xu, X.Y.; Man, B.Y.; Kong, D.M.; Xu, S.C.

2012-01-01

Highlights: ► We prepared tri-layers by laser molecular beam epitaxy (LMBE) on sapphire substrate. ► We found that the formation of the graphene film has a strong relation to the structure and properties of the substrate. ► The different carbon film formation mechanism of the buffer layers can affect the morphology of the film. - Abstract: The carbon thin films were grown on different substrates with different buffer layers by laser molecular beam epitaxy (LMBE) with a high purity graphite carbon target. A UV pulsed KrF excimer laser with a wavelength of 248 nm was used as laser source. The structure, surface morphology and other properties of the carbon thin films were characterized by Raman spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and atomic force microscopy (AFM). The results show that the properties of the carbon thin films and the formation of the graphene film have a strong relation to the structure and properties of the substrate. The substrate with a hexagonal wurtzite structure which is similar to the hexagonal honeycomb structure of the carbon atoms arranged in the graphene is more beneficial for the formation of the graphene thin film. In our experiment conditions, the carbon films grown on sapphire substrates with different buffer layers have an ordered structure and a smooth surface, and form high quality tri-layer graphene films.

Investigation of photocatalytic activity of titanium dioxide deposited on metallic substrates by DC magnetron sputtering

DEFF Research Database (Denmark)

Daviðsdóttir, Svava; Canulescu, Stela; Dirscherl, Kai

2013-01-01

The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology of the c......The photocatalytic properties of titanium dioxide (TiO2) coating in the anatase crystalline structure deposited on aluminium AA1050 alloy and stainless steel S316L substrates were investigated. The coating was prepared by DC magnetron sputtering. The microstructure and surface morphology...... sweep voltammetry, impedance measurements. The microstructure and surface morphology of the coating were similar irrespective of the nature of the substrate, while the photocatalytic behaviour was found to vary depending on the substrate type. In general the TiO2 coating on stainless steel was shown...

Facile Synthesis of Micron-Sized Hollow Silver Spheres as Substrates for Surface-Enhanced Raman Scattering

Directory of Open Access Journals (Sweden)

Lixin Xia

2014-01-01

Full Text Available A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering. 4 Å molecular sieves were employed as a removable solid template. [Ag(NH32]+ was absorbed as the precursor on the surface of the molecular sieve. Formaldehyde was selected as a reducing agent to reduce [Ag(NH32]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves. The micron-sized hollow silver spheres were obtained by removing the molecular sieve template. SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres. The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106. This synthetic process represents a promising method for preparing various hollow metal nanoparticles.

Influence of substrate on structural, morphological and optical ...

Indian Academy of Sciences (India)

Administrator

differences in crystallite sizes, microstrain and texture coefficient with respect to the employed substrates. The morphology of ... perties of ZnO thin films, the real effect on the structural ... related to the piezoelectric property, which is an impor- tant issue on ..... ceramics (New York: Springer Berlin Heidelberg) 2nd edn. Bai S N ...

Nanostructuration of self-assembled poly(styrene-b-isoprene-b-styrene) block copolymer thin films in a highly oriented pyrolytic graphite substrate

Energy Technology Data Exchange (ETDEWEB)

Zalakain, Inaki; Ramos, Jose Angel; Fernandez, Raquel; Etxeberria, Haritz; Mondragon, Inaki, E-mail: inaki.mondragon@ehu.e

2011-01-03

Highly oriented pyrolitic graphite (HOPG) is a useful substrate to visualize epitaxial formation due to its crystallographic structure. The morphology of a poly(styrene-b-isoprene-b-styrene) block copolymer thin film on a HOPG substrate was investigated by atomic force microscopy. Block copolymer domains generated a morphology with triangular regularity. This arrangement was induced by the HOPG substrate structure due to van der Waals attraction between the HOPG {pi}-conjugated system and aromatic ring of polystyrene domains. However, increasing the film thickness, the substrate effect on the surface morphology decreased. As a consequence, film surfaces showed the coexistence of different structures such as highly aligned cylinders and perforated lamellae. When film thickness exceeded a threshold value, the substrate did not have effect in the surface arrangements and the surface showed a similar morphology to that existing in bulk.

Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

Energy Technology Data Exchange (ETDEWEB)

Cai, Tanhong [Iowa State Univ., Ames, IA (United States)

2001-01-01

Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

Comparison of different pathways in metamorphic graded buffers on GaAs substrate: Indium incorporation with surface roughness

International Nuclear Information System (INIS)

Kumar, Rahul; Mukhopadhyay, P.; Bag, A.; Jana, S. Kr.; Chakraborty, A.; Das, S.; Mahata, M. Kr.; Biswas, D.

2015-01-01

Highlights: • In(Al,Ga)As metamorphic buffers on GaAs have been grown. • Surface morphology, strain relaxation and compositional variation have been studied. • Al containing buffers shows inferior surface roughness. • Surface roughness modulates the indium incorporation rate. - Abstract: In this work, compositionally graded In(Al,Ga)As metamorphic buffers (MBs) on GaAs substrate have been grown by MBE through three different paths. A comparative study has been done to comprehend the effect of underlying MB on the constant composition InAlAs healing layer by analyzing the relaxation behaviour, composition and surface morphology of the grown structures. The compositional variation between the constant composition healing layers on top of graded MB has been observed in all three samples although the growth conditions have been kept same. Indium incorporation rate has been found to be dependent on underlying MB. By combining the result of atomic force microscopy, photo-luminescence and X-ray reciprocal space mapping, varying surface roughness has been proposed as the probable driving force behind different Indium incorporation rate

Comparison of different pathways in metamorphic graded buffers on GaAs substrate: Indium incorporation with surface roughness

Energy Technology Data Exchange (ETDEWEB)

Kumar, Rahul, E-mail: rkp203@gmail.com [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Mukhopadhyay, P. [Rajendra Mishra School of Engineering Entrepreneurship, Indian Institute of Technology, Kharagpur 721302 (India); Bag, A.; Jana, S. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Chakraborty, A. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India); Das, S.; Mahata, M. Kr. [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur 721302 (India); Biswas, D. [Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)

2015-01-01

Highlights: • In(Al,Ga)As metamorphic buffers on GaAs have been grown. • Surface morphology, strain relaxation and compositional variation have been studied. • Al containing buffers shows inferior surface roughness. • Surface roughness modulates the indium incorporation rate. - Abstract: In this work, compositionally graded In(Al,Ga)As metamorphic buffers (MBs) on GaAs substrate have been grown by MBE through three different paths. A comparative study has been done to comprehend the effect of underlying MB on the constant composition InAlAs healing layer by analyzing the relaxation behaviour, composition and surface morphology of the grown structures. The compositional variation between the constant composition healing layers on top of graded MB has been observed in all three samples although the growth conditions have been kept same. Indium incorporation rate has been found to be dependent on underlying MB. By combining the result of atomic force microscopy, photo-luminescence and X-ray reciprocal space mapping, varying surface roughness has been proposed as the probable driving force behind different Indium incorporation rate.

Gecko Adhesion on Wet and Dry Patterned Substrates.

Directory of Open Access Journals (Sweden)

Alyssa Y Stark

Full Text Available Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough. Although many studies have investigated the effect of environmental challenges on performance, the interaction of multiple, potentially compromising variables is studied less often. Here we focus on substrate structure and surface water, both of which are highly relevant to the biological system and to synthetic design. To do this we utilized a highly controlled, patterned substrate (Sharklet®, by Sharklet® Technologies Inc.. This allowed us to test independently and jointly the effects of reduced surface area substrates, with a defined pattern, on adhesion in both air and water. Our results show that adhesion is not significantly impaired in air, whereas surface area and pattern significantly affect adhesion in water. These findings highlight the need to study multiple parameters that are relevant to the gecko adhesive system to further improve our understanding of the biological system and to design better, more versatile synthetics.

Crystal Structure and Substrate Specificity of Drosophila 3,4-Dihydroxyphenylalanine Decarboxylase

Energy Technology Data Exchange (ETDEWEB)

Han, Q.; Ding, H; Robinson, H; Christensen, B; Li, J

2010-01-01

3,4-Dihydroxyphenylalanine decarboxylase (DDC), also known as aromatic L-amino acid decarboxylase, catalyzes the decarboxylation of a number of aromatic L-amino acids. Physiologically, DDC is responsible for the production of dopamine and serotonin through the decarboxylation of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively. In insects, both dopamine and serotonin serve as classical neurotransmitters, neuromodulators, or neurohormones, and dopamine is also involved in insect cuticle formation, eggshell hardening, and immune responses. In this study, we expressed a typical DDC enzyme from Drosophila melanogaster, critically analyzed its substrate specificity and biochemical properties, determined its crystal structure at 1.75 Angstrom resolution, and evaluated the roles residues T82 and H192 play in substrate binding and enzyme catalysis through site-directed mutagenesis of the enzyme. Our results establish that this DDC functions exclusively on the production of dopamine and serotonin, with no activity to tyrosine or tryptophan and catalyzes the formation of serotonin more efficiently than dopamine. The crystal structure of Drosophila DDC and the site-directed mutagenesis study of the enzyme demonstrate that T82 is involved in substrate binding and that H192 is used not only for substrate interaction, but for cofactor binding of drDDC as well. Through comparative analysis, the results also provide insight into the structure-function relationship of other insect DDC-like proteins.

Crystal structure and substrate specificity of Drosophila 3,4-dihydroxyphenylalanine decarboxylase.

Directory of Open Access Journals (Sweden)

Qian Han

2010-01-01

Full Text Available 3,4-Dihydroxyphenylalanine decarboxylase (DDC, also known as aromatic L-amino acid decarboxylase, catalyzes the decarboxylation of a number of aromatic L-amino acids. Physiologically, DDC is responsible for the production of dopamine and serotonin through the decarboxylation of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively. In insects, both dopamine and serotonin serve as classical neurotransmitters, neuromodulators, or neurohormones, and dopamine is also involved in insect cuticle formation, eggshell hardening, and immune responses.In this study, we expressed a typical DDC enzyme from Drosophila melanogaster, critically analyzed its substrate specificity and biochemical properties, determined its crystal structure at 1.75 Angstrom resolution, and evaluated the roles residues T82 and H192 play in substrate binding and enzyme catalysis through site-directed mutagenesis of the enzyme. Our results establish that this DDC functions exclusively on the production of dopamine and serotonin, with no activity to tyrosine or tryptophan and catalyzes the formation of serotonin more efficiently than dopamine.The crystal structure of Drosophila DDC and the site-directed mutagenesis study of the enzyme demonstrate that T82 is involved in substrate binding and that H192 is used not only for substrate interaction, but for cofactor binding of drDDC as well. Through comparative analysis, the results also provide insight into the structure-function relationship of other insect DDC-like proteins.

Wetting morphologies and their transitions in grooved substrates

Energy Technology Data Exchange (ETDEWEB)

Seemann, Ralf; Bommer, Stefan; Herrmann, Carsten; Michler, Dominik [Experimental Physics, Saarland University, D-66123 Saarbruecken (Germany); Brinkmann, Martin; Herminghaus, Stephan; Khare, Krishnacharya; Kostourou, Konstantina; Gurevich, Evgeny [Max Planck Institute for Dynamics and Self-Organization, D-37073 Goettingen (Germany); Law, Bruce M; McBride, Sean, E-mail: r.seemann@physik.uni-saarland.de [Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)

2011-05-11

When exposed to a partially wetting liquid, many natural and artificial surfaces equipped with complex topographies display a rich variety of liquid interfacial morphologies. In the present article, we focus on a few simple paradigmatic surface topographies and elaborate on the statics and dynamics of the resulting wetting morphologies. It is demonstrated that the spectrum of wetting morphologies increases with increasing complexity of the groove structure. On elastically deformable substrates, additional structures in the liquid morphologies can be observed, which are caused by deformations of the groove geometry in the presence of capillary forces. The emergence of certain liquid morphologies in grooves can be actively controlled by changes in wettability and geometry. For electrically conducting solid substrates, the apparent contact angle can be varied by electrowetting. This allows, depending on groove geometry, a reversible or irreversible transport of liquid along surface grooves. In the case of irreversible liquid transport in triangular grooves, the dynamics of the emerging instability is sensitive to the apparent hydrodynamic slip at the substrate. On elastic substrates, the geometry can be varied in a straightforward manner by stretching or relaxing the sample. The imbibition velocity in deformable grooves is significantly reduced compared to solid grooves, which is a result of the microscopic deformation of the elastic groove material close to the three phase contact line.

Electron microscopy study of the microstructure of Ni–W substrate surface

Energy Technology Data Exchange (ETDEWEB)

Ovcharov, A. V.; Karateev, I. A.; Mikhutkin, A. A. [National Research Centre “Kurchatov Institute,” (Russian Federation); Orekhov, A. S. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics,” (Russian Federation); Presniakov, M. Yu.; Chernykh, I. A.; Zanaveskin, M. L.; Kovalchuk, M. V.; Vasiliev, A. L., E-mail: a.vasiliev56@gmail.com [National Research Centre “Kurchatov Institute,” (Russian Federation)

2016-11-15

The surface microstructure of Ni–W alloy tapes, which are used as substrates to form films of high-temperature superconductors and photovoltaic devices, has been studied. Several samples of a Ni{sub 95}W{sub 5} tape (Evico) annealed under different conditions were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, electron diffraction, and electron energy-loss spectroscopy. NiWO{sub 4} precipitates are found on the surface of annealed samples. The growth of precipitates at a temperature of 950°C is accompanied by the formation of pores on the surface or under an oxide film. Depressions with a wedge-shaped profile are found at the grain boundaries. Annealing in a reducing atmosphere using a specially prepared chamber allows one to form a surface free of nickel tungstate precipitates.

Fabrication of a Large-Area Superhydrophobic SiO2 Nanorod Structured Surface Using Glancing Angle Deposition

Directory of Open Access Journals (Sweden)

Xun Lu

2017-01-01

Full Text Available A glancing angle deposition (GLAD technique was used to generate SiO2 nanorods on a glass substrate to fabricate a low-cost superhydrophobic functional nanostructured surface. GLAD-deposited SiO2 nanorod structures were fabricated using various deposition rates, substrate rotating speeds, oblique angles, and deposition times to analyze the effects of processing conditions on the characteristics of the fabricated functional nanostructures. The wettability of the surface was measured after surface modification with a self-assembled monolayer (SAM. The measured water contact angles were primarily affected by substrate rotation speed and oblique angle because the surface fraction of the GLAD nanostructure was mainly affected by these parameters. A maximum contact angle of 157° was obtained from the GLAD sample fabricated at a rotation speed of 5 rpm and an oblique angle of 87°. Although the deposition thickness (height of the nanorods was not a dominant factor for determining the wettability, we selected a deposition thickness of 260 nm as the optimum processing condition based on the measured optical transmittance of the samples because optically transparent films can serve as superhydrophobic functional nanostructures for optical applications.

Friction characteristics of submicrometre-structured surfaces fabricated by particle-assisted near-field enhancement with femtosecond laser

International Nuclear Information System (INIS)

Sakai, Tetsuo; Nedyalkov, Nikolay; Obara, Minoru

2007-01-01

We present friction characteristics of sliding textured silicon surfaces at the submicrometre scale. A two-dimensional submicrometre dimple array on the Si surface is fabricated by femtosecond laser processing. Direct femtosecond laser nano-structuring of the Si (1 0 0) substrate by polystyrene particle-assisted near-field enhancement is used. In the investigated hole diameter domain from 229 to 548 nm, an increase in the friction coefficient with the decrease in the hole size is found experimentally. The fabricated submicrometre dimples act evidently as lubricant reservoirs to supply lubricants and traps to capture wear debris. The fluctuation of the friction coefficient is also increased by reducing the dimple size. The lowest friction coefficient of 1.41 x 10 -2 is achieved with the dimple array having a diameter of about 550 nm. This value is 2.6 times lower than that of non-structured substrates

Novel metal ion surface modification technique

International Nuclear Information System (INIS)

Brown, I.G.; Godechot, X.; Yu, K.M.

1990-10-01

We describe a method for applying metal ions to the near-surface region of solid materials. The added species can be energetically implanted below the surface or built up as a surface film with an atomically mixed interface with the substrate; the metal ion species can be the same as the substrate species or different from it, and more than one kind of metal species can be applied, either simultaneously or sequentially. Surface structures can be fabricated, including coatings and thin films of single metals, tailored alloys, or metallic multilayers, and they can be implanted or added onto the surface and ion beam mixed. We report two simple demonstrations of the method: implantation of yttrium into a silicon substrate at a mean energy of 70 keV and a dose of 1 x 10 16 atoms/cm 2 , and the formation of a titanium-yttrium multilayer structure with ion beam mixing to the substrate. 17 refs., 3 figs

Effect of substrate type on the electrical and structural properties of TiO2 thin films deposited by reactive DC sputtering

Science.gov (United States)

Cheng, Xuemei; Gotoh, Kazuhiro; Nakagawa, Yoshihiko; Usami, Noritaka

2018-06-01

Electrical and structural properties of TiO2 thin films deposited at room temperature by reactive DC sputtering have been investigated on three different substrates: high resistivity (>1000 Ω cm) float zone Si(1 1 1), float zone Si(1 0 0) and alkali free glass. As-deposited TiO2 films on glass substrate showed extremely high resistivity of (∼5.5 × 103 Ω cm). In contrast, lower resistivities of ∼2 Ω cm and ∼5 Ω cm were obtained for films on Si(1 1 1) and Si(1 0 0), respectively. The as-deposited films were found to be oxygen-rich amorphous TiO2 for all the substrates as evidenced by X-ray photoemission spectroscopy and X-ray diffraction. Subsequent annealing led to appearance of anatase TiO2 on Si but not on glass. The surface of as-deposited TiO2 on Si was found to be rougher than that on glass. These results suggest that the big difference of electrical resistivity of TiO2 would be related with existence of more anatase nuclei forming on crystalline substrates, which is consistent with the theory of charged clusters that smaller clusters tend to adopt the substrate structure.

Co thin film with metastable bcc structure formed on GaAs(111 substrate

Directory of Open Access Journals (Sweden)

Minakawa Shigeyuki

2014-07-01

Full Text Available Co thin films are prepared on GaAs(111 substrates at temperatures ranging from room temperature to 600 ºC by radio-frequency magnetron sputtering. The growth behavior and the detailed resulting film structure are investigated by in-situ reflection high-energy electron diffraction and X-ray diffraction. In early stages of film growth at temperatures lower than 200 ºC, Co crystals with metastable A2 (bcc structure are formed, where the crystal structure is stabilized through hetero-epitaxial growth. With increasing the film thickness beyond 2 nm, the metastable structure starts to transform into more stable A1 (fcc structure through atomic displacements parallel to the A2{110} close-packed planes. The crystallographic orientation relationship between the A2 and the transformed A1 crystals is A1{111} || A2{110}. When the substrate temperature is higher than 400 ºC, Ga atoms of substrate diffuse into the Co films and a Co-Ga alloy with bcc-based ordered structure of B2 is formed.

Analysis of the electrodeposition and surface chemistry of CdTe, CdSe, and CdS thin films through substrate-overlayer surface-enhanced Raman spectroscopy.

Science.gov (United States)

Gu, Junsi; Fahrenkrug, Eli; Maldonado, Stephen

2014-09-02

The substrate-overlayer approach has been used to acquire surface enhanced Raman spectra (SERS) during and after electrochemical atomic layer deposition (ECALD) of CdSe, CdTe, and CdS thin films. The collected data suggest that SERS measurements performed with off-resonance (i.e. far from the surface plasmonic wavelength of the underlying SERS substrate) laser excitation do not introduce perturbations to the ECALD processes. Spectra acquired in this way afford rapid insight on the quality of the semiconductor film during the course of an ECALD process. For example, SERS data are used to highlight ECALD conditions that yield crystalline CdSe and CdS films. In contrast, SERS measurements with short wavelength laser excitation show evidence of photoelectrochemical effects that were not germane to the intended ECALD process. Using the semiconductor films prepared by ECALD, the substrate-overlayer SERS approach also affords analysis of semiconductor surface adsorbates. Specifically, Raman spectra of benzenethiol adsorbed onto CdSe, CdTe, and CdS films are detailed. Spectral shifts in the vibronic features of adsorbate bonding suggest subtle differences in substrate-adsorbate interactions, highlighting the sensitivity of this methodology.

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

Directory of Open Access Journals (Sweden)

Alan H. Chin

2018-04-01

Full Text Available Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in the open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. This observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell.

Impact of layer and substrate properties on the surface acoustic wave velocity in scandium doped aluminum nitride based SAW devices on sapphire

Energy Technology Data Exchange (ETDEWEB)

Gillinger, M., E-mail: manuel.gillinger@tuwien.ac.at; Knobloch, T.; Schneider, M.; Schmid, U. [Institute of Sensor and Actuator Systems, TU Wien, 1040 Vienna (Austria); Shaposhnikov, K.; Kaltenbacher, M. [Institute of Mechanics and Mechatronics, TU Wien, 1040 Vienna (Austria)

2016-06-06

This paper investigates the performance of surface acoustic wave (SAW) devices consisting of reactively sputter deposited scandium doped aluminum nitride (Sc{sub x}Al{sub 1-x}N) thin films as piezoelectric layers on sapphire substrates for wireless sensor or for RF-MEMS applications. To investigate the influence of piezoelectric film thickness on the device properties, samples with thickness ranging from 500 nm up to 3000 nm are fabricated. S{sub 21} measurements and simulations demonstrate that the phase velocity is predominantly influenced by the mass density of the electrode material rather than by the thickness of the piezoelectric film. Additionally, the wave propagation direction is varied by rotating the interdigital transducer structures with respect to the crystal orientation of the substrate. The phase velocity is about 2.5% higher for a-direction compared to m-direction of the sapphire substrate, which is in excellent agreement with the difference in the anisotropic Young's modulus of the substrate corresponding to these directions.

Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique

International Nuclear Information System (INIS)

Hazra, Purnima; Singh, Satyendra Kumar; Jit, Satyabrata

2015-01-01

In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak in the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance ( 20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the output current rating is about 130 times larger compared to their planar

Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique

Energy Technology Data Exchange (ETDEWEB)

Hazra, Purnima; Singh, Satyendra Kumar [Department of Electronics and Communication Engineering, Motilal Neheru National Institute of Technology, Allahabad 211004 (India); Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in [Department of Electronics Engineering, Indian Institute of Technology (BHU), Varanasi 221005 (India)

2015-01-01

In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak in the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance (<3%) in the visible wavelength region compared to Si/ZnO heterojunctions (>20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the

Determination of three-dimensional interfacial strain - A novel method of probing interface structure with X-ray Bragg-surface diffraction

International Nuclear Information System (INIS)

Sun, W.-C.; Chu, C.-H.; Chang, H.-C.; Wu, B.-K.; Chen, Y.-R.; Cheng, C.-W.; Chiu, M.-S.; Shen, Y.-C.; Wu, H.-H.; Hung, Y.-S.; Chang, S.-L.; Hong, M.-H.; Tang, M.-T.; Stetsko, Yu.P.

2007-01-01

A new X-ray diffraction technique is developed to probe structural variations at the interfaces between epitaxy thin films and single-crystal substrates. The technique utilizes three-wave Bragg-surface diffraction, where a symmetric Bragg reflection and an asymmetric surface reflection are involved. The propagation of the latter along the interfaces conveys structural information about the interfacial region between the substrate and epi-layers. The sample systems of Au/GaAs(001) are subject to the three-wave diffraction investigation using synchrotron radiation. The GaAs three-wave Bragg-surface diffractions (006)/(11-bar3) and (006)/(1-bar1-bar3), are employed. The images of the surface diffracted waves are recorded with an image plate. The obtained images show relative positions of diffraction spots near the image of the interfacial boundary, which give the variation of lattice constant along the surface normal and in-plane directions. With the aid of grazing-incidence diffraction, three-dimensional mapping of strain field at the interfaces is possible. Details about this diffraction technique and the analysis procedures are discussed

Patterned growth of carbon nanotubes on Si substrates without predeposition of metal catalysts

Science.gov (United States)

Chen, Y.; Yu, J.

2005-07-01

Aligned carbon nanotubes (CNTs) can be readily synthesized on quartz or silicon-oxide-coated Si substrates using a chemical vapor deposition method, but it is difficult to grow them on pure Si substrates without predeposition of metal catalysts. We report that aligned CNTs were grown by pyrolysis of iron phthalocyanine at 1000°C on the templates created on Si substrates with simple mechanical scratching. Scanning electron microscopy and x-ray energy spectroscopy analysis revealed that the trenches and patterns created on the surface of Si substrates were preferred nucleation sites for nanotube growth due to a high surface energy, metastable surface structure, and possible capillarity effect. A two-step pyrolysis process maintained Fe as an active catalyst.

Influence of substrate bias voltage on structure and properties of the CrAlN films deposited by unbalanced magnetron sputtering

Science.gov (United States)

Lv, Yanhong; Ji, Li; Liu, Xiaohong; Li, Hongxuan; Zhou, Huidi; Chen, Jianmin

2012-02-01

The CrAlN films were deposited on silicon and stainless steel substrates by unbalanced magnetron sputtering system. The influence of substrate bias on deposition rate, composition, structure, morphology and properties of the CrAlN films was investigated. The results showed that, with the increase of the substrate bias voltage, the deposition rate decreased accompanied by a change of the preferred orientation of the CrAlN film from (2 2 0) to (2 0 0). The grain size and the average surface roughness of the CrAlN films declined as the bias voltage increases above -100 V. The morphology of the films changed from obviously columnar to dense glass-like structure with the increase of the bias voltage from -50 to -250 V. Meanwhile, the films deposited at moderate bias voltage had better mechanical and tribological properties, while the films deposited at higher bias voltage showed better corrosion resistance. It was found that the corrosion resistance improvement was not only attributed to the low pinhole density of the film, but also to chemical composition of films.

Effect of gradient dielectric coefficient in a functionally graded material (FGM) substrate on the propagation behavior of love waves in an FGM-piezoelectric layered structure.

Science.gov (United States)

Cao, Xiaoshan; Shi, Junping; Jin, Feng

2012-06-01

The propagation behavior of Love waves in a layered structure that includes a functionally graded material (FGM) substrate carrying a piezoelectric thin film is investigated. Analytical solutions are obtained for both constant and gradient dielectric coefficients in the FGM substrate. Numerical results show that the gradient dielectric coefficient decreases phase velocity in any mode, and the electromechanical coupling factor significantly increases in the first- and secondorder modes. In some modes, the difference in Love waves' phase velocity between these two types of structure might be more than 1%, resulting in significant differences in frequency of the surface acoustic wave devices.

Studies on polyurethane adhesives and surface modification of hydrophobic substrates

Science.gov (United States)

Krishnamoorthy, Jayaraman

studies involved making functionalized, thickness-controlled, wettability-controlled multilayers on hydrophobic substrates and the adsorption of carboxylic acid-terminated poly(styrene-b-isoprene) on alumina/silica substrates. Poly(vinyl alcohol) has been shown to adsorb onto hydrophobic surfaces irreversibly due to hydrophobic interactions. This thin semicrystalline coating is chemically modified using acid chlorides, butyl isocyanate and butanal to form thicker and hydrophobic coatings. The products of the modification reactions allow adsorption of a subsequent layer of poly(vinyl alcohol) that could subsequently be hydrophobized. This 2-step (adsorption/chemical modification) allows layer-by-layer deposition to prepare coatings with thickness, chemical structure and wettability control on any hydrophobic surface. Research on adsorption characteristics of carboxylic acid-terminated poly(styrene-b-isoprene) involved syntheses of block copolymers with the functional group present at specific ends. Comparative adsorption studies for carboxylic acid-terminated and hydrogen-terminated block copolymers was carried out on alumina and silica substrates.

Substrate binding and specificity of rhomboid intramembrane protease revealed by substrate-peptide complex structures

Czech Academy of Sciences Publication Activity Database

Zoll, Sebastian; Stanchev, Stancho; Began, Jakub; Škerle, Jan; Lepšík, Martin; Peclinovská, Lucie; Majer, Pavel; Stříšovský, Kvido

2014-01-01

Roč. 33, č. 20 (2014), s. 2408-2421 ISSN 0261-4189 R&D Projects: GA ČR GAP305/11/1886; GA MŠk(CZ) LK11206; GA MŠk LO1302; GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : intramembrane protease * rhomboid family * rhomboid protease * structure * substrate recognition Subject RIV: CE - Biochemistry Impact factor: 10.434, year: 2014

Structural, optical and electrical characteristics of ITO thin films deposited by sputtering on different polyester substrates

International Nuclear Information System (INIS)

Guillen, C.; Herrero, J.

2008-01-01

Indium tin oxide (ITO) thin films were deposited by sputtering at room temperature on glass and different polyester substrates; namely polyarylate (PA), polycarbonate (PC) and polyethylene terephtalate (PET). The influence of the substrate on the structural, optical and electrical characteristics of the ITO layers was investigated. The sputtered films exhibited crystallization in the (2 2 2) orientation, with higher mean crystallite size and lower structural distortion onto PET than onto PA, PC or glass substrates. ITO films deposited onto PET showed also higher band gap energy, higher carrier concentration and lower resistivity than the ITO layers onto the other tested substrates. These optical and electrical characteristics have been related to the structural distortion that was found dependent on the specific polyester substrate

Preparation of triangular and hexagonal silver nanoplates on the surface of quartz substrate

International Nuclear Information System (INIS)

Jia Huiying; Zeng Jianbo; An Jing; Song Wei; Xu Weiqing; Zhao Bing

2008-01-01

In this paper, triangular and hexagonal silver nanoplates were prepared on the surface of quartz substrate using photoreduction of silver ions in the presence of silver seeds. The obtained silver nanoplates were characterized by atomic force microscopy and UV-vis spectroscopy. It was found that the silver seeds played an important role in the formation of triangular and hexagonal silver nanoplates. By varying the irradiation time, nanoplates with different sizes and shapes could be obtained. The growth mechanism for triangular and hexagonal nanoplates prepared on quartz substrate was discussed

Potential energy surfaces of adsorbates on periodic substrates: Application of the Morse theory

Czech Academy of Sciences Publication Activity Database

Pick, Štěpán

2009-01-01

Roč. 79, č. 4 (2009), 045403-1-5 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z40400503 Keywords : adsorbed layers * Morse potential * potential energy surfaces * substrates Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.475, year: 2009

Wettability of eutectic NaLiCO3 salt on magnesium oxide substrates at 778 K

Science.gov (United States)

Li, Chuan; Li, Qi; Cao, Hui; Leng, Guanghui; Li, Yongliang; Wang, Li; Zheng, Lifang; Ding, Yulong

2018-06-01

We investigated the wetting behavior of a eutectic carbonate salt of NaLiCO3 on MgO substrates at an elevated temperature of 778 K by measuring contact angle with a sessile drop method. Both sintered and non-sintered MgO were prepared and used as the substrates. The sintered substrates were obtained by sintering compacted MgO powders at 500-1300 °C. For comparison purposes, a single crystal MgO substrate was also used in the work. The different sintering temperatures provided MgO substrates with different structures, allowing their effects on salt penetration and hence wettability and surface energy to be investigated. A scanning electron microscope equipped with energy dispersive spectrometry and an atomic force microscope were used to observe the morphology and structures of the MgO substrates as well as the salt penetration. The results showed a good wettability of the carbonate salt on both the sintered and non-sintered MgO substrates and the wettability depended strongly on the structure of the substrates. The non-sintered MgO substrate has a loose surface particle packing with large pores and crevices, leading to significant salt infiltration, and the corresponding contact angle was measured to be ∼25°. The contact angle of the salt on the sintered MgO substrates increased with an increase in the sintering temperature of the MgO substrate, and the contact angle of the salt on the single crystal substrate was the highest at ∼40°. The effect of the sintering temperature for making the MgO substrate could be linked to the surface energy, and the linkage is validated by the AFM measurements of the adhesion forces of the MgO substrates.

Synthesis of ceria based superhydrophobic coating on Ni20Cr substrate via cathodic electrodeposition.

Science.gov (United States)

Pedraza, F; Mahadik, S A; Bouchaud, B

2015-12-21

In this work, superhydrophobic cerium oxide coating surface (111) with dual scale texture on Ni20Cr substrate is obtained by combination of electropolishing the substrate and subsequent cathodic electrodeposition and long-term UVH surface relaxation. To form hierarchical structures of CeO2 is controllable by varying the substrate roughness, and electropolishing period. The results indicated that at the optimal condition, the surface of the cerium oxide coating showed a superhydrophobicity with a great water contact angle (151.0 ± 1.4°) with Gecko state. An interface model for electropolishing of substrate surface in cerium nitrate medium is proposed. We expect that this facile process can be readily and widely adopted for the design of superhydrophobic coating on engineering materials.

The role of substrate surface alteration in the fabrication of vertically aligned CdTe nanowires

International Nuclear Information System (INIS)

Neretina, S; Devenyi, G A; Preston, J S; Mascher, P; Hughes, R A; Sochinskii, N V

2008-01-01

Previously we have described the deposition of vertically aligned wurtzite CdTe nanowires derived from an unusual catalytically driven growth mode. This growth mode could only proceed when the surface of the substrate was corrupted with an alcohol layer, although the role of the corruption was not fully understood. Here, we present a study detailing the remarkable role that this substrate surface alteration plays in the development of CdTe nanowires; it dramatically improves the size uniformity and largely eliminates lateral growth. These effects are demonstrated to arise from the altered surface's ability to limit Ostwald ripening of the catalytic seed material and by providing a surface unable to promote the epitaxial relationship needed to sustain a lateral growth mode. The axial growth of the CdTe nanowires is found to be exclusively driven through the direct impingement of adatoms onto the catalytic seeds leading to a self-limiting wire height associated with the sublimation of material from the sidewall facets. The work presented furthers the development of the mechanisms needed to promote high quality substrate-based vertically aligned CdTe nanowires. With our present understanding of the growth mechanism being a combination of selective area epitaxy and a catalytically driven vapour-liquid-solid growth mode, these results also raise the intriguing possibility of employing this growth mode in other material systems in an effort to produce superior nanowires

Interfacial Structure and Photocatalytic Activity of Magnetron Sputtered TiO2 on Conducting Metal Substrates

DEFF Research Database (Denmark)

Daviðsdóttir, Svava; Petit, Jean-Pierre; Mermoux, Michel

2014-01-01

The photocatalytic behavior of magnetron sputtered anatase TiO2 coatings on copper, nickel, and gold was investigated with the aim of understanding the effect of the metallic substrate and coating-substrate interface structure. Stoichiometry and nanoscale structure of the coating were investigated...

Substrate texture properties induce triatomine probing on bitten warm surfaces

Directory of Open Access Journals (Sweden)

Lorenzo Marcelo G

2011-06-01

Full Text Available Abstract Background In this work we initially evaluated whether the biting process of Rhodnius prolixus relies on the detection of mechanical properties of the substrate. A linear thermal source was used to simulate the presence of a blood vessel under the skin of a host. This apparatus consisted of an aluminium plate and a nickel-chrome wire, both thermostatized and presented at 33 and 36°C, respectively. To evaluate whether mechanical properties of the substrate affect the biting behaviour of bugs, this apparatus was covered by a latex membrane. Additionally, we evaluated whether the expression of probing depends on the integration of bilateral thermal inputs from the antennae. Results The presence of a latex cover on a thermal source induced a change in the biting pattern shown by bugs. In fact, with latex covered sources it was possible to observe long bites that were never performed in response to warm metal surfaces. The total number of bites was higher in intact versus unilaterally antennectomized insects. These bites were significantly longer in intact than in unilaterally antennectomized insects. Conclusions Our results suggest that substrate recognition by simultaneous input through thermal and mechanical modalities is required for triggering maxillary probing activity.

Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

Energy Technology Data Exchange (ETDEWEB)

Latifi, Afrooz, E-mail: afroozlatifi@yahoo.com [Department of Biomaterials, Biomedical Engineering Faculty, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Imani, Mohammad [Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of); Khorasani, Mohammad Taghi [Biomaterials Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/159, Tehran (Iran, Islamic Republic of); Daliri Joupari, Morteza [Animal and Marine Biotechnology Dept., National Institute of Genetic Engineering and Biotechnology, P.O. Box 14965/161, Tehran (Iran, Islamic Republic of)

2014-11-30

Highlights: • Stainless steel 316L was surface modified by plasma surface oxidation (PSO) and silicone rubber (SR) coating. • On the PSO substrates, concentration of oxide species was increased ca. 2.5 times comparing to non-PSO substrates. • The surface wettability was improved to 12.5°, in terms of water contact angle, after PSO. • Adhesion strength of SR coating on the PSO substrates was improved by more than two times comparing to non-PSO ones. • After pull-off test, the fractured area patterns for SR coating were dependent on the type of surface modifications received. - Abstract: Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m{sup −1}), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer–metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

Substrate matters: Magnetic tuning of the Fe monolayer

Energy Technology Data Exchange (ETDEWEB)

Ramanathan, A.A.; Khalifeh, J.M.

2017-03-15

The effect of substrate on the magnetism of the Fe monolayer (ML) is investigated using the total energy DFT calculations with the local spin density approximation (LSDA). The results show an in plane ferromagnetic coupling (FM) and a magnetic moment of 1.78 µ{sub B} for the relaxed Fe ML in the presence of the vanadium substrate. In comparison, the surface Fe(001) magnetic moment ranges between 2.97–3.01 µ{sub B}. This difference in the Fe surface moment of more than 1 µ{sub B} in the presence or absence of Vanadium allows tuning of the Fe magnetic moment and has great potential as a magnetic switch and in spintronic devices. The surface magnetic quenching of Fe with V is much more pronounced than with other transition metal substrates like Molybdenum or Tungsten. We have a reduction of 40.5% of the Fe (001) surface moment which is more than double the reduction obtained with the Fe/Mo(001) or the Fe/W(001) systems. The magnetic quenching is due to the strong hybridization between the Fe and V d bands. This is supported by the observed charge density redistribution and large inward relaxation of 18.37% for the Fe surface upon structural relaxation. The Fe ML is antiferromagnetically (AF) coupled with the V interfacial layer, which has an appreciable induced magnetic moment of 0.48 µ{sub B}. - Highlights: • We report the magnetic quenching of a Fe ML on V(001) substrate. • Almost double as compared to Mo and W substrates. • The Fe surface ML on V(001) shows FM ordering as opposed to AF ordering for Fe ML on Mo(001) and W(001) substrates.

Optical performance of random anti-reflection structured surfaces (rARSS) on spherical lenses

Science.gov (United States)

Taylor, Courtney D.

Random anti-reflection structured surfaces (rARSS) have been reported to improve transmittance of optical-grade fused silica planar substrates to values greater than 99%. These textures are fabricated directly on the substrates using reactive-ion/inductively-coupled plasma etching (RIE/ICP) techniques, and often result in transmitted spectra with no measurable interference effects (fringes) for a wide range of wavelengths. The RIE/ICP processes used in the fabrication process to etch the rARSS is anisotropic and thus well suited for planar components. The improvement in spectral transmission has been found to be independent of optical incidence angles for values from 0° to +/-30°. Qualifying and quantifying the rARSS performance on curved substrates, such as convex lenses, is required to optimize the fabrication of the desired AR effect on optical-power elements. In this work, rARSS was fabricated on fused silica plano-convex (PCX) and plano-concave (PCV) lenses using a planar-substrate optimized RIE process to maximize optical transmission in the range from 500 to 1100 nm. An additional set of lenses were etched in a non-optimized ICP process to provide additional comparisons. Results are presented from optical transmission and beam propagation tests (optimized lenses only) of rARSS lenses for both TE and TM incident polarizations at a wavelength of 633 nm and over a 70° full field of view in both singlet and doublet configurations. These results suggest optimization of the fabrication process is not required, mainly due to the wide angle-of-incidence AR tolerance performance of the rARSS lenses. Non-optimized recipe lenses showed low transmission enhancement, and confirmed the need to optimized etch recipes prior to process transfer of PCX/PCV lenses. Beam propagation tests indicated no major beam degradation through the optimized lens elements. Scanning electron microscopy (SEM) images confirmed different structure between optimized and non-optimized samples

Structural and electrical characterization of HBr/O{sub 2} plasma damage to Si substrate

Energy Technology Data Exchange (ETDEWEB)

Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya [Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan)

2011-07-15

Silicon substrate damage caused by HBr/O{sub 2} plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H{sub 2}, Ar, and O{sub 2} plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O{sub 2} plasma exposure, hydrogen generated the deep damaged layer ({approx}10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

Influence of pulsed substrate bias on the structure and properties of Ti-Al-N films deposited by cathodic vacuum arc

Energy Technology Data Exchange (ETDEWEB)

Zhang, G.P., E-mail: princeterry@163.com [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Gao, G.J. [Changchun University of Science and Technology, College of Science, Changchun 130000 (China); Wang, X.Q.; Lv, G.H.; Zhou, L.; Chen, H.; Pang, H.; Yang, S.Z. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

2012-07-15

Ti-Al-N films were deposited by cathodic vacuum arc (CVA) technique in N{sub 2} atmosphere with different pulsed substrate bias. The influence of pulsed substrate bias (0 to -800 V) on the deposition rate, surface morphology, crystal structure, and mechanical properties of the Ti-Al-N films were systematically investigated. Increasing pulsed bias voltage resulted in the decrease of deposition rate but the increase of surface roughness. It was found that there was a strong correlation between the pulsed bias and film structure. All the films studied in this paper were composed of TiN, AlN, and Ti-Al-N ternary phases. The grains changed from equiaxial to columnar and exhibited preferred orientation when the pulsed bias increased. With the increase of pulsed bias voltage, the atomic ratio of Ti to Al element increased gradually, while the N to (Ti + Al) ratio decreased. The composite films present an enhanced nanohardness compared with binary TiN and ZrN films. The film deposited with pulsed bias of -200 V possessed the maximum scratch critical load and nanohardness. The minimum friction coefficient with pulsed bias of -300 V was obtained.

Structural and optical properties of Ag-doped copper oxide thin films on polyethylene napthalate substrate prepared by low temperature microwave annealing

Energy Technology Data Exchange (ETDEWEB)

Das, Sayantan; Alford, T. L. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, USA and School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

2013-06-28

Silver doped cupric oxide thin films are prepared on polyethylene naphthalate (flexible polymer) substrates. Thin films Ag-doped CuO are deposited on the substrate by co-sputtering followed by microwave assisted oxidation of the metal films. The low temperature tolerance of the polymer substrates led to the search for innovative low temperature processing techniques. Cupric oxide is a p-type semiconductor with an indirect band gap and is used as selective absorption layer solar cells. X-ray diffraction identifies the CuO phases. Rutherford backscattering spectrometry measurements confirm the stoichiometry of each copper oxide formed. The surface morphology is determined by atomic force microscopy. The microstructural properties such as crystallite size and the microstrain for (-111) and (111) planes are calculated and discussed. Incorporation of Ag led to the lowering of band gap in CuO. Consequently, it is determined that Ag addition has a strong effect on the structural, morphological, surface, and optical properties of CuO grown on flexible substrates by microwave annealing. Tauc's plot is used to determine the optical band gap of CuO and Ag doped CuO films. The values of the indirect and direct band gap for CuO are found to be 2.02 eV and 3.19 eV, respectively.

Silicene on metal substrates: A first-principles study on the emergence of a hierarchy of honeycomb structures

International Nuclear Information System (INIS)

Kaltsas, D.; Tsetseris, L.; Dimoulas, A.

2014-01-01

Experimental studies have reported several types of Si monolayer structures that are formed on metal surfaces. These structures typically show the topology of a honeycomb bonding network, but differ in terms of corrugation and surface coverage. Using first-principles calculations, we identify atomic-scale mechanisms that underlie the appearance of different configurations as coverage increases during Si deposition on silver. The key point is that any extra Si adatoms that land on preformed silicene films can be incorporated in the honeycomb network and form bonds with underlying Ag atoms. As a result, the corrugation profile changes, giving rise to varying overlayer geometries. We also show that the same set of mechanisms control the appearance of silicene films on an iridium substrate. The results address available experimental data, but also probe the stability and properties of silicene wetting films that have not been observed yet.

Lithography-Free Fabrication of Reconfigurable Substrate Topography For Contact Guidance

Science.gov (United States)

Pholpabu, Pitirat; Kustra, Stephen; Wu, Haosheng; Balasubramanian, Aditya; Bettinger, Christopher J.

2014-01-01

Mammalian cells detect and respond to topographical cues presented in natural and synthetic biomaterials both in vivo and in vitro. Micro- and nano-structures influence the adhesion, morphology, proliferation, migration, and differentiation of many phenotypes. Although the mechanisms that underpin cell-topography interactions remain elusive, synthetic substrates with well-defined micro- and nano-structures are important tools to elucidate the origin of these responses. Substrates with reconfigurable topography are desirable because programmable cues can be harmonized with dynamic cellular responses. Here we present a lithography-free fabrication technique that can reversibly present topographical cues using an actuation mechanism that minimizes the confounding effects of applied stimuli. This method utilizes strain-induced buckling instabilities in bi-layer substrate materials with rigid uniform silicon oxide membranes that are thermally deposited on elastomeric substrates. The resulting surfaces are capable of reversible of substrates between three distinct states: flat substrates (A = 1.53 ± 0.55 nm, Rms = 0.317 ± 0.048 nm); parallel wavy grating arrays (A|| = 483.6 ± 7.8 nm and λ|| = 4.78 ± 0.16 μm); perpendicular wavy grating arrays (A⊥ = 429.3 ± 5.8 nm; λ⊥ = 4.95 ± 0.36 μm). The cytoskeleton dynamics of 3T3 fibroblasts in response to these surfaces was measured using optical microscopy. Fibroblasts cultured on dynamic substrates that are switched from flat to topographic features (FLAT-WAVY) exhibit a robust and rapid change in gross morphology as measured by a reduction in circularity from 0.30 ± 0.13 to 0.15 ± 0.08 after 5 min. Conversely, dynamic substrate sequences of FLAT-WAVY-FLAT do not significantly alter the gross steady-state morphology. Taken together, substrates that present topographic structures reversibly can elucidate dynamic aspects of cell-topography interactions. PMID:25468368

Study of the oxygen and substrate bias effects on the defect structure of reactive sputter-deposited SnOx films

International Nuclear Information System (INIS)

Misheva, M.; Nancheva, N.; Docheva, P.; Hadjijska, P.; Djourelov, N.; Elenkov, D.

1999-01-01

The effects of oxygen and substrate bias on the defect structure of reactive sputter-deposited SnOx films were investigated. Samples were analysed using transmission electron microscopy (TEM), transmission electron diffraction (TED), X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS). The oxygen played an important role in the film growth and surface morphology. TEM, TED and XRD showed that increasing of the oxygen partial pressure leads to the formation of films with different crystal phases. The void sizes also depended on oxygen partial pressure. The positron lifetimes and their relative intensities depended on the void concentration, the partial annealing of the vacancies and oxidation of SnO to SnOx. This investigation also showed that the mechanical strength of the films obtained at negative substrate bias is higher and the concentration of vacancy defects is smaller, than in the films, prepared without substrate bias. (author)

Growth of surface structures correlated with structural and mechanical modifications of brass by laser-induced Si plasma ions implantation

Science.gov (United States)

Ahmad, Shahbaz; Bashir, Shazia; Rafique, M. Shahid; Yousaf, Daniel

2017-04-01

Laser-produced Si plasma is employed as an ion source for implantation on the brass substrate for its surface, structural, and mechanical modifications. Thomson parabola technique is employed for the measurement of energy and flux of Si ions using CR-39. In response to stepwise increase in number of laser pulses from 3000 to 12000, four brass substrates were implanted by laser-induced Si plasma ions of energy 290 keV at different fluxes ranging from 45 × 1012 to 75 × 1015 ions/cm2. SEM analysis reveals the formation of nano/micro-sized irregular shaped cavities and pores for the various ion fluxes for varying numbers of laser pulses from 3000 to 9000. At the maximum ion flux for 12,000 pulses, distinct and organized grains with hexagonal and irregular shaped morphology are revealed. X-ray diffractometer (XRD) analysis exhibits that a new phase of CuSi (311) is identified which confirms the implantation of Si ions in brass substrate. A significant decrease in mechanical properties of implanted brass, such as Yield Stress (YS), Ultimate Tensile Strength (UTS), and hardness, with increasing laser pulses from 3000 to 6000 is observed. However, with increasing laser pulses from 9000 to a maximum value of 12,000, an increase in mechanical properties like hardness, YS, and UTS is observed. The generation as well as annihilation of defects, recrystallization, and intermixing of Si precipitates with brass matrix is considered to be responsible for variations in surface, structural, and mechanical modifications of brass.

Natural printed silk substrate circuit fabricated via surface modification using one step thermal transfer and reduction graphene oxide

Science.gov (United States)

Cao, Jiliang; Huang, Zhan; Wang, Chaoxia

2018-05-01

Graphene conductive silk substrate is a preferred material because of its biocompatibility, flexibility and comfort. A flexible natural printed silk substrate circuit was fabricated by one step transfer of graphene oxide (GO) paste from transfer paper to the surface of silk fabric and reduction of the GO to reduced graphene oxide (RGO) using a simple hot press treatment. The GO paste was obtained through ultrasonic stirring exfoliation under low temperature, and presented excellent printing rheological properties at high concentration. The silk fabric was obtained a surface electric resistance as low as 12.15 KΩ cm-1, in the concentration of GO 50 g L-1 and hot press at 220 °C for 120 s. Though the whiteness and strength decreased with the increasing of hot press temperature and time slowly, the electric conductivity of RGO surface modification silk substrate improved obviously. The surface electric resistance of RGO/silk fabrics increased from 12.15 KΩ cm-1 to 18.05 KΩ cm-1, 28.54 KΩ cm-1 and 32.53 KΩ cm-1 after 10, 20 and 30 washing cycles, respectively. The results showed that the printed silk substrate circuit has excellent washability. This process requires no chemical reductant, and the reduction efficiency and reduction degree of GO is high. This time-effective and environmentally-friendly one step thermal transfer and reduction graphene oxide onto natural silk substrate method can be easily used to production of reduced graphene oxide (RGO) based flexible printed circuit.

Low energy ion scattering (LEIS) and the compositional and structural analysis of solid surfaces

International Nuclear Information System (INIS)

Berg, J.A. van den; Armour, D.G.

1981-01-01

The physics of Low Energy Ion Scattering (LEIS) and its application as a surface analytical technique are reviewed. It is shown that compositional and short-range structural information can be obtained by choosing experimental conditions which optimize the contributions of single and double (or multiple) collisions, respectively. The LEIS technique allows mass analysis in a straightforward way, possesses a high surface selectivity but is unable to provide quantitative information in isolation due to scattering cross-section uncertainties and not easily quantifiable charge exchange effects. Structural information regarding adsorbate positions on single crystal surfaces and the short-range substrate structure (including damaged and reconstructed surfaces) can be obtained by exploiting shadowing and/or multiple scattering phenomena. The progress made in recent years in this area is charted. It is shown that computer simulations often play an important role in this type of study. Effects, such as charge exchange, inelastic energy loss and ion beam surface perturbations, which complicate the use of low energy ion scattering for surface analysis are discussed in detail. The present status of the technique in the different areas of study is indicated. (author)

Surface-enhanced Raman scattering of amorphous silica gel adsorbed on gold substrates for optical fiber sensors

Science.gov (United States)

Degioanni, S.; Jurdyc, A. M.; Cheap, A.; Champagnon, B.; Bessueille, F.; Coulm, J.; Bois, L.; Vouagner, D.

2015-10-01

Two kinds of gold substrates are used to produce surface-enhanced Raman scattering (SERS) of amorphous silica obtained via the sol-gel route using tetraethoxysilane Si(OC2H5)4 (TEOS) solution. The first substrate consists of a gold nanometric film elaborated on a glass slide by sputter deposition, controlling the desired gold thickness and sputtering current intensity. The second substrate consists of an array of micrometer-sized gold inverted pyramidal pits able to confine surface plasmon (SP) enhancing electric field, which results in a distribution of electromagnetic energy inside the cavities. These substrates are optically characterized to observe SPR with, respectively, extinction and reflectance spectrometries. Once coated with thin layers of amorphous silica (SiO2) gel, these samples show Raman amplification of amorphous SiO2 bands. This enhancement can occur in SERS sensors using amorphous SiO2 gel as shells, spacers, protective coatings, or waveguides, and represents particularly a potential interest in the field of Raman distributed sensors, which use the amorphous SiO2 core of optical fibers as a transducer to make temperature measurements.

Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

Energy Technology Data Exchange (ETDEWEB)

Numazawa, Satoshi

2012-11-01

This work addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and {approx}1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements

Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

Energy Technology Data Exchange (ETDEWEB)

Numazawa, Satoshi

2012-11-01

This work addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism. Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO{sub 2} surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature. An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and {approx}1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns. The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements

Surface morphology modelling for the resistivity analysis of low temperature sputtered indium tin oxide thin films on polymer substrates

International Nuclear Information System (INIS)

Yin Xuesong; Tang Wu; Weng Xiaolong; Deng Longjiang

2009-01-01

Amorphous or weakly crystalline indium tin oxide (ITO) thin film samples have been prepared on polymethylmethacrylate and polyethylene terephthalate substrates by RF-magnetron sputtering at a low substrate temperature. The surface morphological and electrical properties of the ITO layers were measured by atomic force microscopy (AFM) and a standard four-point probe measurement. The effect of surface morphology on the resistivity of ITO thin films was studied, which presented some different variations from crystalline films. Then, a simplified film system model, including the substrate, continuous ITO layer and ITO surface grain, was proposed to deal with these correlations. Based on this thin film model and the AFM images, a quadratic potential was introduced to simulate the characteristics of the ITO surface morphology, and the classical Kronig-Penney model, the semiconductor electrical theory and the modified Neugebauer-Webb model were used to expound the detailed experimental results. The modelling equation was highly in accord with the experimental variations of the resistivity on the characteristics of the surface morphology.