bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanotechnology applications: a driving force for R&D investment
Authors: Correia A. , Pérez M. , Sáenz J. J. , Serena P. A. 
Published: May 2007

AbstractNanoscience and nanotechnology represent scientific‐technical areas that in less than two decades have gone from being in the hands of a reduced group of researchers who glimpsed their great potential, to constitute one of the recognized pillars of the scientific advance for the next decades. This paper illustrates how the irruption of nanotechnology applications will directly affect human beings by substantially improving diagnosis and treatment of diseases, and also our capacities to interact with our surroundings. Worldwide governments realized the important role deserved to nanotechnology and during the last decade budgets allocated to R&D in nanotechnology have continuously increased. Following this global trend, Spanish scientists and institutions have gone from having a rather conservative attitude to promoting a number of different initiatives aiming at increasing the contribution of Spain to the development of nanoscience and nanotechnology. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative modelling of voltage oscillations and other oscillatory phenomena with the current burst model
Authors: Foca E. , Carstensen J. , Föll H. 
Published: May 2007

AbstractThe current burst model (CBM) has been extended to include more complex oscillatory phenomena of the Si electrode in aqueous HF. In particular it accounts for additional effects inherent to the voltage oscillations, i.e. capacitive effects, very small oxide thickness, etc. A powerful Monte‐Carlo implementation now allows to simulate all presently known aspects of electrodes. Besides current oscillations under potentiostatic conditions, the CBM can now quantitatively produce voltage oscillations and other more complex phenomena like driven oscillations in close agreement with experiments. New data extraction routines provide information about, e.g., correlation lengths and thus bridge the gap to general non‐linear pattern formation theories. The CBM is far simpler than competing theories, but is nevertheless the only model presently capable of quantitatively simulating all aspects of oscillatory phenomena of the Si electrode. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Different deposition behavior of copper on silicon and porous silicon surfaces during immersion plating
Authors: Kurokawa A. , Kawamura Y. L. , Sakka T. , Ogata Y. H. 
Published: May 2007

AbstractThe deposition behavior of Cu during immersion plating was investigated on Si and porous Si (PS) surfaces. The deposition of Cu could be observed on the PS surface, but not on the native Si surface. In the electrochemical characterization of the two surfaces in HF solution, a plateau of anodic current was observed at the PS structure, but not at the Si surface. The potential region of the plateau was more negative than the potential at which Si dissolution or PS formation takes place. The electrochemical measurements of the PS samples in HF solution revealed that oxidation of hydrogen remaining in the PS layer can not participate in the appearance of the anodic plateau. The different deposition behavior on the Si and PS surfaces enables selective deposition of Cu on a PS pattern drawn on n ‐type Si by laser scanning. A new patterning method of Cu on n ‐type Si by utilizing this behavior was successfully achieved. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal conductivity features of nanostructured CdS/Al2O3 composites
Authors: Nosova L. , Igamberdiev Kh. , Sokolov V. , Yuldashev Sh. , Shashkov A. G. , Khabibullaev P. K. 
Published: May 2007

AbstractHighly ordered porous alumina (Al2O3) structures with pore diameter of 60 nm were fabricated by two‐step anodization process. CdS‐nanoparticles were grown into porous alumina template kept on Al‐substrate by using SILAR (successive ion layer adsorption and reaction) technique. The temperature dependences (10–300 K) of thermal conductivity of CdS/Al2O3 nanocomposites have been measured by pulsed method of periodical heating (3ω) which is one of the most sensitive tools for nanostructure investigation. It was shown that temperature dependences of thermal conductivity of CdS/Al2O3 nanocomposites are determined by infill degree of alumina pores. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ electrochemical characterization of porous n ‐InP (100)
Authors: Santinacci L. , Gonçalves A.‐M. , David C. , Eb A. , Gerard I. , Mathieu C. , Herlem M. , Etcheberry A. 
Published: May 2007

AbstractPorous structures have been anodically grown onto n ‐InP (100) in HCl. Surface chemistry and pore morphology have been respectively studied by X‐ray photoelectron spectroscopy and scanning electron microscopy but in situ electrochemical investigations have been emphasized. Capacitance and photocurrent experiments have been performed while the porous etching occurred. No modifications of the electronic structure (flat band potential remains constant) are observed during the pore formation. However, for high dissolution charges, the photocurrent spectra are sharpened because the porous films behave like electrically “dead layers”. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous screen printed indium tin oxide (ITO) for NOx gas sensing
Authors: Mbarek H. , Saadoun M. , Bessaïs B. 
Published: May 2007

AbstractTin‐doped Indium Oxide (ITO) films were prepared by the screen printing method. Transparent and conductive ITO thin films were obtained from an organometallic based paste fired in an Infrared furnace. The Screen printed ITO films were found to be granular and porous. This specific morphology was found to be suitable for sensing different gaseous species. This work investigates the possibility of using screen printed (ITO) films as a specific material for efficient NOx gas sensing. It was found that screen printed ITO is highly sensitive and stable towards NOx, especially for gas concentration higher than 50 ppm and starting from a substrate working temperature of about 180 °C. The sensitivity of the ITO films increases with increasing NOx concentration and temperature. The sensitivity and stability of the screen printed ITO based sensors were studied within time. The ITO crystallite grain size dimension was found to be a key parameter that influencesè the gas response characteristics. Maximum gas sensitivity and minimum response time were observed for ITO films having lower crystallite size dimensions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Single crystalline GaN grown on porous Si(111) by MOVPE
Authors: Cheng Kai , Degroote S. , Leys M. , Van Daele B. , Germain M. , Van Tendeloo G. , Borghs G. 
Published: May 2007

AbstractIn this work, GaN growth on porous Si(111) will be reported. The porosity of the substrates was 30% or 50%. In the latter case, various thicknesses, from 0.6 μm to 10 μm, were investigated. The morphology of the GaN surfaces was analyzed by optical interference microscopy. The crystalline quality of the epitaxial layers was characterized by High Resolution X‐Ray Diffraction (HR‐XRD) and cross‐sectional Transmission Electron Microscopy (TEM). A Full Width at Half Maximum (FWHM) of the X‐ray symmetric rocking curve (0002) 2θ – ω scan of 290 arc sec was obtained for a 1 μm thick GaN layer, which is comparable with that of GaN grown on bulk Si(111) substrates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphology and photoluminescence of anodized aluminium‐coated 6H‐SiC samples
Authors: Keffous A. , Bourenane K. , Gabouze N. , Kechouane M. , Kerdja T. , Manseri A. , Guerbous L. , Oudjaout D. 
Published: May 2007

AbstractIn this work, we report the effect of surface modification by aluminum metallization, prior to anodization in a solution of HF/Ethylene glycol, on the morphology and photoluminescence of p‐type porous SiC. For this purpose, a thin metallic film of aluminum has been deposited on a highly resistive 6H‐SiC. The morphology of the porous SiC layer has been investigated by Scanning Electron Microscopy (SEM). The results show that aluminum play a crucial role on the dissolution of SiC; it initiates and facilitates the electrochemical etching. The photoluminescence spectra of the anodized Al‐coated samples exhibit two emission bands centered at about 430 nm and 560 nm. While for the uncoated samples, a strong luminescence with a peak located at 560 nm is observed. Finally, the role of Al on the photoluminescence mechanism is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of self‐ordered porous alumina membranes of various thicknesses
Authors: Marsal L. F. , Vojkuvka L. , Ferré‐Borrull J. , Trifonov T. , Pallarès J. 
Published: May 2007

AbstractWe present the fabrication and optical characterization of self‐ordered porous alumina membranes (PAM). The samples were fabricated by using a two‐step anodization process in 0.3 M oxalic acid at 40 V and 20 °C. PAMs of different thickness (9 μm, 24 μm and 45 μm) were obtained by applying different anodization lengths. The morphology of the PAMs was examined using a Scanning Electron Microscope in order to estimate their thickness and porosity. The optical transmission spectra of such PAMs of different thicknesses were measured by using UV‐VIS spectrometer in the range of 300–1000 nm. The refraction index and the extinction coefficient for the studied range were determined from the fitting of the measurements. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gravimetric method to find internal surface of macroporous silicon membranes
Authors: Nechitailov A. A. , Astrova E. V. , Kukushkina Yu. A. 
Published: May 2007

AbstractA simple method to evaluate the internal surface area, porosity, pore diameter and pore density of macroporous silicon membranes has been proposed and tested. The porosity p is obtained from the mass loss under anodizing, and the surface area per unit volume Sv is determined from the mass of SiO2 formed on the pore surface as a result of thermal oxidation. The average pore diameter d and pore density N can be easily calculated from the obtained Sv and p. Experimental verification of d and N was performed by means of SEM and optical microscope images; Sv was checked by BET technique. Surface area and porosity on the resistivity of initial n‐Si in the range ρ = 3–25 Ohm · cm have been studied for the samples with regular and self‐organized macropore “lattices”. The obtained values are within the limits p = 27–50%, Sv = 2800–6000 cm2/cm3, d = 1.9–6.5 μm, N = 1.4–10 × 106 cm–2, and in a good agreement with the data of microscopic characterization. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anodisation of branched and columnar macropores in n‐type silicon under front‐side illumination
Authors: Depauw V. , Kim H. J. , Beaucarne G. , Poortmans J. , Celis J.‐P. , Mertens R. 
Published: May 2007

AbstractThe growth of well‐defined regular columnar macropores under front‐side illumination on medium doped n‐type silicon has been investigated. The various morphologies observed, with branched or columnar pores, differ from those reported so far on substrates of both higher and lower resistivities. Unlike stated by the macropore growth model, current density is found to influence the pore growth rate. These observations indicate that, under the conditions used in this work, the pore growth is at the border between meso‐ and macroporous mechanism. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Commercial applications of porous Si: optical filters and components
Authors: Kochergin V. , Foell H. 
Published: May 2007

AbstractIt is shown that porous Silicon in various geometries and morphologies can be used for novel optical elements by combining theoretical insights with suitable porous structures and some pre‐ and post‐processing of the Silicon. The paper restricts itself to light propagation in the pore direction. Theoretical and experimental results will be presented for the following novel optical elements: environmentally stable optical components from mesoporous Silicon, long wave pass filters, macroporous Silicon UV Filters, and polarization components for the UV range. Either new components are presented, mostly with first experimental results, or the state‐of‐the art for previously discussed elements is considerably improved upon. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative measurements of hydro‐alcoholic binary mixtures by porous silicon optical microsensors
Authors: De Stefano Luca , Rotiroti Lucia , Rea Ilaria , Moretti Luigi , Rendina Ivo 
Published: May 2007

AbstractIn this communication, we present a simple, completely reversible and well performing optical microsensor for the quantitative determination in liquid hydro‐alcoholic binary mixtures, based on the simple and low cost porous silicon (PSi) nanotechnology. In our sensor device, the transducer element is a PSi optical microcavity (PSMC) which is constituted by a Fabry‐Pérot layer between two distributed Bragg reflectors. When the device is exposed to the mixture, the partial substitution of air in the pores changes the average refractive index of PSMC, causing a red shift of its reflectivity spectrum, characteristic of the concentration of each component. We have characterized, in the 0‐100% composition range, three hydro‐alcoholic binary mixtures (water‐Ethanol, water‐ Methanol and water‐ Isopropanol) which exhibit very different behaviour. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An integrated hybrid optical device for sensing applications
Authors: De Stefano L. , Rea I. , Rotiroti L. , Fragomeni L. , Della Corte F. G. , Rendina I. 
Published: May 2007

AbstractWe present the design and the fabrication of an integrated hybrid optical sensor for liquid and gas sensing based on the anodic bonding technique. The device is composed by three distinct elements separately realised and then joined together: a planar SOI waveguide, a porous silicon micro‐chamber and a glass slide. The presence of a liquid or gaseous substance in the reaction chamber is revealed as a change in the propagation characteristic of the guided mode. In case of exposure to methanol, the preliminary experimental results show that the propagation of the laser beam, coupled into the SOI waveguide, has been efficiently modulated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Composite structures of porous silicon and polyaniline for optoelectronic applications
Authors: Urbach B. , Korbakov N. , Bar‐david Y. , Yitzchaik S. , Sa'ar A. 
Published: May 2007

AbstractComposite structures of p‐type meso‐porous silicon (PS) and polyaniline (PAN) have been fabricated by electrochemical polymerization process. The composite structure provides a unique way to control the conduction either through the porous silicon matrix or via the polyaniline, by changing the polarity of the applied bias voltage. In addition, photoluminescence (PL) experiments revealed enhanced PL emission at the green wavelengths that are originated from the polyaniline network, rather than the porous silicon. The above composite structure can be used as a building block for improved electroluminescence and light emitting devices in a wide range of applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of UV filters from porous silicon at low temperatures
Authors: Becerra D. , Agarwal V. 
Published: May 2007

AbstractIn the present work we study the influence of the anodization temperature on the morphology and optical properties of porous silicon monolayers and multilayers. UV filters for the wavelength range of 200– 400 nm were fabricated at low temperatures and their optical response was compared with the metallic mirrors as well as with the filters made at room temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunable one‐dimensional photonic crystal structures based on grooved Si infiltrated with liquid crystal E7
Authors: Perova T. S. , Tolmachev V. A. , Astrova E. V. , Zharova Yu. A. , O'Neill S. M. 
Published: May 2007

AbstractTuning of a photonic band gap in a composite one‐dimensional photonic crystal structure infiltrated with nematic liquid crystal E7 has been evaluated by simulations. It has been found that a sufficient shift of the short wavelength edge, λ edge of a main photonic band gap can be obtained in structures with a pronounced initial alignment of the liquid crystal director in the grooves of a single crystalline Si matrix. The largest effect is predicted for the reorientation of liquid crystal molecules from planar homogeneous alignment along the grooves to homeotropic alignment with respect to the Si walls due to an electro‐optical effect. The shift in photonic band gap due to thermal tuning, resulting from the transition of liquid crystal from the mesophase to the isotropic phase, is less than for electric tuning. Thermo‐tuning has been demonstrated experimentally. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of porous silicon Thue‐Morse structures
Authors: De Stefano Luca , Rea Ilaria , Rotiroti Lucia , Moretti Luigi , Rendina Ivo 
Published: May 2007

AbstractDielectric aperiodic Thue‐Morse structures up to 128 layers have been realized by the porous silicon technology. Normal incidence reflectivity measurements have been performed to investigate the photonic properties of the devices. A partial photonic band gap region, centered at 1100 nm and 70 nm wide has been observed for the S6 and S7 Thue‐Morse structures. The S6 multilayer has been studied as sensor device on exposure to several chemical substances. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new approach based on transfer matrix formalism to characterize porous silicon layers by reflectometry
Authors: Pirasteh P. , Boucher Y. G. , Charrier J. , Dumeige Y. 
Published: May 2007

AbstractWe use reflectometry coupled to transfer matrix formalism in order to investigate the comparative effect of surface (localized) and volume (distributed) losses inside a porous silicon monolayer. Both are modeled as fictive absorption. Surface losses are described as a Dirac‐like singularity of permittivity localized at an interface whereas volume losses are described trough the imaginary part of the porous silicon complex permittivity. A good agreement with experimental data is determined by this formalism. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Capacitance method for determination of basic parameters of porous silicon
Authors: Adamyan A. , Adamian Z. , Aroutiounian V. 
Published: May 2007

AbstractMicrostructure and physical characteristics of porous silicon (PS), such as thickness, bulk porosity, dielectric permittivity, and refractive index depend directly on the production conditions, e.g., on the electrolyte composition, anodizing current density, duration of etching etc. Many various possibilities of applications of PS generate high interest towards elaboration of new or modified operative nondestructive methods for testing the microstructure characteristics of PS layer for the adjustment of its processing regimes. According to the mechanism of formation of porous silicon and experimental data on the morphology of PS layers, a porous layer represented as a structure with cylindrical pores of equal lengths piercing the silicon frame. This approximation allows considering the structure using the parallel plate model with in parallel connected capacitances of the silicon frame and the air or liquid dielectric filled pores. A method for obtaining information on the volume porosity, thickness, and dielectric permittivity of a PS layer by means of two measurements of the structure capacitance – in dry air and when the pores are filled by a condensed medium having a dielectric permittivity strongly differing from that of air (e.g., methanol) is described. Sufficiently good agreement has been revealed between the data calculated from the capacitance measurements and obtained by other methods. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance spectroscopy of in‐plane anisotropic porous silicon films
Authors: Forsh P. A. , Martyshov M. N. , Timoshenko V. Yu. , Kashkarov P. K. 
Published: May 2007

AbstractFree‐standing porous silicon films prepared from heavily boron‐doped (110) Si wafers are investigated by means of the impedance spectroscopy in the frequency range from 5 Hz to 10 MHz. The AC electrical conductivity of the films is found to be significantly larger along the [1$ \bar 1 $0] in‐plane crystallographic direction than that along the [001] one. While the AC conductivity anisotropy decreases with increasing frequency, the capacity anisotropy exhibits non‐monotonic frequency dependence. The experimental results are explained by considering potential barriers for charge carrier transport between anisotropic Si nanocrystals in porous silicon films. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of form anisotropy of silicon nanocrystals on birefringence and dichroism in porous silicon
Authors: Efimova A. I. , Krutkova E. Yu. , Golovan L. A. , Timoshenko V. Yu. , Kashkarov P. K. 
Published: May 2007

AbstractArtificial anisotropic optical media based on nanostructured silicon formed by electrochemical porosifying of Si substrates are investigated. Strong birefringence and dichroism of surface silicon‐hydrogen bonds vibrations are found in the infrared spectral range. A comprehensive analysis of the absorption bands corresponding to the deformation and stretching modes is performed. The experimental results are discussed in terms of an effective medium model, taking into account the morphological anisotropy of Si nanocrystals in porous Si layers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The birefringence level of anisotropically nanostructured silicon
Authors: Diener J. , Künzner N. , Gross E. , Kovalev D. , Timoshenko V. Yu. , Fujii M. 
Published: May 2007

AbstractWe present a detailed study of the anisotropic optical properties of mesoporous silicon layers prepared from substrates having different doping levels under various preparation conditions. It is demonstrated that the morphology of the layers strongly depends on the preparation conditions. The experimental data are explained in the framework of an effective medium model which takes into account different morphologies of the layers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An investigation of an etch‐through process on porous silicon
Authors: Kan P. Y. Y. , Finstad T. G. 
Published: May 2007

AbstractAn etch–through process on porous silicon (PS) has been investigated. A macro‐(>50 nm) and meso‐(10‐50 nm) PS were fabricated by electrochemical anodisation process. A normal electrochemical etching from the front‐side will only yield some parts of the area being etched all the way through the wafer, due to the statistical process which leads to an uneven etch front towards the back‐side of the wafer. A new method has been tried in which a thin PS layer was fabricated at the back‐side before etching. The etch‐through PS apparently shows that all the pores were past through the wafer for the whole etching area (1 cm2). The etch data were recorded and were plotted as voltage and temperature against time. An etch‐through thin meso PS membrane (10‐50 nm diameter, 50‐100 µm thick) has also been investigated. The PS were characterized by scanning electron microscopy. A proposed model for the etch‐through PS is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)