bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergism of electrochemical and mechanical factors in porous silicon growth
Authors: Parkhutik Vitali , Udagawa Masayuki , Harima Yutaka 
Published: June 2005

AbstractHere we report new data on mechanical properties of porous silicon films that support a model where both electrochemistry of local dissolution of silicon and mechanical stress factors are playing roles. Using micro‐Raman spectroscopy allowed us to establish the presence of rather high tensile stress in monocrystalline Si in the close vicinity of the interface with porous silicon that supports our assumption of stress‐enhanced pore growth. Our recent data on spontaneous layering of porous silicon films under steady‐state conditions of p‐Si growth also show that the mechanical stress is a key factor in formation of the structure of porous silicon additionally to conventional electrochemical factors. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light propagation in a porous silicon waveguide: an optical modes analysis in near‐field
Authors: Bruyant A. , Stefanon I. , Lerondel G. , Blaize S. , Aubert S. , Bachelot R. , Royer P. , Pirasteh P. , Charrier J. , Joubert P. 
Published: June 2005

AbstractWe report on the first near‐field observation of light propagation in a porous silicon planar waveguide. The observation has been made possible using a scattering‐type scanning near field optical microscope (s‐SNOM). Optical constants of the propating modes are retrieved by two methods first, from the intensity profile and then from the complex field profile, the latter being obtained with a heterodyne interferometric setup. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous silicon substrates for neurons culturing and bio‐photonic sensing
Authors: de‐Leon S. Ben‐Tabou , Oren R. , Spira M. E. , Korbakov N. , Yitzchaik S. , Sa'ar A. 
Published: June 2005

AbstractIn this work we report on culturing of Aplysia neurons and vertebrate cells to porous silicon substrates and on the first steps toward characterizing porous silicon as a biosensor of neural activity. Neurons cultured on porous silicon substrates survived for at least one week showing normal passive membrane properties and generation of action potentials. We have investigated several mechanisms that take advantage of the optical properties of porous silicon for transducing both electrical and chemical neuronal activities into photonic signals. For example, the photoluminescence response to voltage and the reflectivity response to chemical changes were investigated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sum‐frequency generation from surface species in porous silicon
Authors: Mattei G. , Valentini V. , Yakovlev V. A. , Mani A. A. , Sartenaer Y. , Thiry P. A. , Peremans A. , Caudano Y. , Dreesen L. , Humbert C. , Busson B. , Vidal F. , Tadjeddine A. 
Published: June 2005

AbstractFor the first time, the sum‐frequency generation (SFG) spectra of surface species have been measured in porous silicon (PS) layers. The range of the vibrations 2000–2300 cm–1 for the native species Si–Hx has been explored. Furthermore for the studied mesoporous materials, it has been found that, as opposed to the infrared absorption, the SFG signal increases with porosity. Finally, the angular dependence and the enhancement of the SFG signal were measured in a one‐dimensional PS photonic crystal structure with a defect producing an energy level in the photonic band gap. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of semiconductor nanowires by pulsed current electrodeposition of metal with subsequent sulfurization
Authors: Gavrilov S. , Nosova L. , Sieber I. , Belaidi A. , Dloczik L. , Dittrich Th. 
Published: June 2005

AbstractSemiconductor nanowires of CdS and CuxS were embedded into porous anodic alumina (PAA) by sulfurization of the metal precursors. Pores of PAA were filled with Cd and Cu by ac electrochemical preparation while the PAA layers remained on the Al‐substrate. Deposited metal and semiconductor wires were characterized by scanning electron microscopy and X‐ray diffraction. Photovoltage spectroscopy was applied to demonstrate semiconductor behaviour of CdS nanowires manufactured by the proposed technique. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence mechanisms of Tb3+‐doped porous GaP
Authors: Elhouichet H. , Oueslati M. , Lorrain N. , Langa S. , Tiginyanu I. M. , Föll H. 
Published: June 2005

AbstractPorous GaP (por‐GaP) samples are doped with terbium ions (Tb3+) by simple impregnation followed by high‐temperature annealing. From scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) analysis, we show that the por‐GaP skeleton is conserved and the Tb3+ ions are uniformly distributed in the host. The influence of annealing temperature on the luminescence intensity is explored. The photoluminescence (PL) intensity is found to be constant at temperatures lower than 130 K and quenches weakly for temperatures higher than 130 K. A quantitative model for excitation and de‐excitation processes of Tb3+ in por‐GaP based on the recombination of bound excitons to a Tb‐related trap site is proposed that shows good agreement with experimental results. We show that the PL quenching above 130 K can be interpreted in terms of both a back transfer of Tb3+ excitation to the host and a weak thermalization of bound electrons to the conduction band. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo simulation of electrochemical oscillations in the electropolishing regime
Authors: Foca E. , Carstensen J. , Föll H. 
Published: June 2005

AbstractCurrent oscillations, and for the first time, voltage oscillations too, which occur at the Si electrode in a HF electrolyte in the electropolishing regime, are quantitatively calculated using Monte Carlo simulations based on the current burst model. Results obtained for relatively large areas comprise stable, unstable and damped oscillations, the formation of synchronized domains, and the influence of external voltage modulations, always in conjunction with all other parameters like oxide thickness and roughness behavior, or electrode capacitance. The results show good quantitative agreement in all respects with the experiments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio study of birefringent porous silicon
Authors: Bonder Yuri , Wang Chumin 
Published: June 2005

AbstractOptical properties of birefringent porous‐silicon layers are studied within the density functional theory. Starting from a (110)‐oriented supercell of 32 silicon atoms, elliptic columns of atoms in [100] and [010] directions are removed. The dangling bonds are saturated with hydrogen atoms. The results show an in‐plane anisotropy in the refractive index and in the absorption coefficient, i.e., a birefringence response. The difference Δn defined as $ n_{[1\bar 10]} $–$ n_{[001]} $ is compared with experimental data and a good agreement is observed. Also, the calculated absorption coefficients behave very closely to the measured ones. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐Raman study of columnar GaAs nanostructures
Authors: Prunici Pavel , Irmer Gert , Monecke Jochen , Sirbu Lilian , Tiginyanu Ion 
Published: June 2005

AbstractMicro‐Raman scattering spectra of bulk and porous GaAs and of individual nanocolumns were studied. The GaAs nanocolumns have radii of 50–100 nm and lengths between 5 and 25 µm. The experimental data are compared with the results of calculations predicting coupled LO‐phonon–plasmon and coupled Fröhlich‐plasmon modes using a dielectric function derived on the basis of an appropriate two‐dimensional effective medium theory. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boron passivation and its reactivation in mesoporous silicon: a “chemical” model
Authors: Garrone E. , Geobaldo F. , Rivolo P. , Salvador G. P. , Pallavidino L. , Boarino L. , Amato G. , Giamello E. , Chiesa M. , Gobetto R. , Ugliengo P. 
Published: June 2005

AbstractA chemical model is proposed to explain the passivation of carriers upon etching and their reactivation by the presence of gases in p+‐type mesoporous silicon (m‐PS). The model is based on the results obtained by means of FTIR, EPR, NMR spectroscopies and ab‐initio calculations. This chemical description accounts for the behaviour of mPS when contacted with NO2 or NH3. B atoms in subsurface location play a prominent role. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spontaneous layering of porous silicon layers formed at high current densities
Authors: Parkhutik Vitali , Curiel‐Esparza Jorge , Millan Mari‐Carmen , Albella Jose 
Published: June 2005

AbstractWe report here a curious effect of spontaneous fracturing of the silicon layers formed in galvanostatic conditions at medium and high current densities. Instead of formation of homogeneous p‐Si layer as at low currents, a stack of thin layers is formed. Each layer is nearly separated from others and possesses rather flat interfaces. The effects is observed using p+‐Si wafers for the p‐Si formation and starts being noticeable at above 100 mA/cm2.We interpret these results in terms of the porous silicon growth model where generation of dynamic mechanical stress during the p‐Si growth causes sharp changes in Si dissolution mechanism from anisotropic etching of individual needle‐like pores in silicon to their branching and isotropic etching. At this moment p‐Si layer loses its adhesion to the surface of Si wafer and another p‐Si layer starts growing. One of the mechanisms triggering on the separation of p‐Si layers from one another is a fluctuation of local anodic current in the pore bottoms associated with gas bubble evolution during the p‐Si formation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of NO2 molecule adsorption on free charge carriers and spin centers in porous silicon
Authors: Konstantinova E. A. , Osminkina L. A. , Sharov C. S. , Timoshenko V. Yu. , Kashkarov P. K. 
Published: June 2005

AbstractThe effect of nitrogen dioxide (NO2) adsorption on free charge carriers and spin centers in porous silicon has been studied by FTIR and ESR spectroscopy. The silicon dangling bond (Pb1‐center) density rises with increasing NO2 pressure (P) while free charge carrier concentration depends on P nonmonotonically. The experimental results are explained by a microscopic model taking into account both the formation of P–(NO2)– donor–acceptor pairs and NO2‐induced oxidation of Si nanocrystal surfaces. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman measurements on nanocolumnar ZnO crystals
Authors: Marí B. , Cembrero J. , Manjón F. J. , Mollar M. , Gómez R. 
Published: June 2005

AbstractHexagonal zinc oxide nanocolumns have been grown on conducting F‐doped SnO2 substrates by galvanostatic electrodeposition. Raman and photoluminescence spectra of the ZnO nanocolumns have been measured in several samples with different size distributions as a function of the annealing temperature. Photoluminescence properties of ZnO nanocolumns are strongly influenced by the crystalline quality of the samples. The dependence of the crystalline quality of the samples on the growth parameters and annealing temperature is discussed. In particular, the Raman spectra of as‐grown samples exhibit broad bands that correlate perfectly with the one‐phonon density of states obtained from recent ab initio calculations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical vapour etching of silicon and porous silicon: silicon solar cells and micromachining applications
Authors: Ben Jaballah A. , Hassen M. , Hajji M. , Saadoun M. , Bessais B. , Ezzaouia H. 
Published: June 2005

AbstractIn this work, we used HNO3/HF Vapour Etching (VE) of silicon (Si) wafers for the formation of different porous structures. Depending on the volume ratio of the HNO3/HF acid mixture, we can obtain Porous Silicon (PS) layers or a (NH4)2SiF6 like powder phase. These two kind of porous structures may be used in silicon solar cells and in micromachining applications. The VE technique allows producing thick porous layers (>100 µm) in short times. Simple masking films enable to selectively groove Si wafers, leading to the formation of holes and channels of different sizes suitable for their application in micromachining. The various grooving profiles were investigated by Scanning electron microscopy (SEM). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous GaAs as a possible antireflective coating and optical diffusor for III–V solar cells
Authors: Flamand Giovanni , Poortmans Jef 
Published: June 2005

AbstractWe have studied the possibility of using (nano‐)porous GaAs top layers as antireflective coating and optical diffusor in high‐efficiency III‐V solar cells. Antireflective coating behaviour of thin, nanoporous GaAs layers has been demonstrated, whereas initial experiments on applying these porous layers on top of a GaAs solar cell structure also suggest an optical diffusion of the incident light in the porous layer. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Painting a rainbow on silicon – a simple method to generate a porous silicon band filter gradient
Authors: Li Yang Yang , Kim Peter , Sailor Michael J. 
Published: June 2005

AbstractA band filter gradient structure was obtained in porous Si by electrochemically etching a rugate structure into a Si wafer using an asymmetrically placed counter electrode. The resulting porous Si film displays a rejection band whose wavelength maximum varies spatially due to the uneven distribution of current across the wafer during the etch. The rainbow‐like band filter can be converted to a porous SiO2 graded band filter by thermal oxidization. A robust and flexible composite silicone/porous silicon gradient structure is achieved by impregnation with a silicone polymer. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A low‐power sensor for volatile organic compounds based on porous silicon photonic crystals
Authors: Dorvee Jason , Sailor Michael J. 
Published: June 2005

AbstractA miniaturized, low‐power chemical sensor for volatile organic compounds using a porous Si photonic crystal is demonstrated. The device uses simple electronic circuitry a light‐emitting diode, a phototransistor, and thin film of a 1‐dimensional photonic crystal of porous Si, drawing 0.5 W of power. Integration of the freestanding porous silicon film with the conventional circuitry is discussed as well as the current detection limits for ethanol vapor in air. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of porous membrane filter from p‐type silicon
Authors: Grigoras K. , Franssila S. , Sikanen T. , Kotiaho T. , Kostiainen R. 
Published: June 2005

AbstractMacropore formation and applications of low‐doped p‐type silicon have been studied. Traditional hydrofluoric acid/ethanol/water electrolyte and organic electrolytes containing dimethyl sulfoxide and hydrofluoric acid were used, and different anodization current densities were applied in order to optimize the pore formation and prevent cracking of the layer. Thin crystalline membranes were prepared by anisotropic wet etching from the backside, using a silicon nitride layer as a mask. A similar silicon nitride layer was used to define the area of the membrane to be porosified. Macroporous silicon membranes have been fabricated and tested as a filter for biomedical samples. Fluorescently labeled polystyrene beads, 1 µm in diameter, were succesfully used to demonstrate filter action. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐aspect‐ratio silicon dioxide pillars
Authors: Trifonov T. , Rodríguez A. , Servera F. , Marsal L. F. , Pallarès J. , Alcubilla R. 
Published: June 2005

AbstractThis paper presents a technique for fabricating high‐aspect‐ratio silicon dioxide pillars by electrochemical etching of n‐type silicon in hydrofluoric acid (HF) solutions. Basic process flow and etching conditions are described, which make it possible to obtain high‐aspect‐ratio pillar arrays with good uniformity. Pillar arrays of different dimensions (i.e. diameter and separation) and of different arrangements can be produced in a single etch step on the same wafer. The large surface area makes these pillar arrays possible candidates for applications in biological sensing. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photodetectors from Porous Silicon
Authors: Rossi A. M. , Bohn H. G. 
Published: June 2005

AbstractA metal–semiconductor–metal photoconductive detector has been fabricated from porous silicon. To that aim low conductive p‐type Si (20 Ω cm) has been porosified and several rapid‐thermal treatment steps applied before deposition of Al‐contacts. The photo response was investigated in the wavelength range of 350–800 nm. A responsivity of up to 4 A/W was observed at 600 nm which is about 13 times higher than that of a commercial photodiode. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser local oxidation of porous silicon: a FTIR spectroscopy investigation
Authors: Rocchia M. , Rossi A. M. , Borini S. , Boarino L. , Amato G. 
Published: June 2005

AbstractThe local oxidation of porous silicon (PS), induced by a focused laser beam, could represent an alternative method for patterning PS through direct writing. Important phase changes take place on PS when irradiated by a focused laser beam and moreover a complete confinement of the oxidized areas can be achieved due to the very low thermal conductivity of PS. We present a detailed Fourier Transform InfraRed (FTIR) study of the irradiated areas to understand the degree of oxidation and the type of oxide obtained at different laser powers. An interpretation of the low wavenumber range, below 1300 cm–1, in terms of Fröhlich interactions will be discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ observation of the evolution of porous silicon interference filter characteristics
Authors: Volk J. , Ferencz K. , Ramsden J. J. , Tóth A. L. , Bársony I. 
Published: June 2005

AbstractPorous silicon multilayer formation was observed by in situ monitoring of the reflectivity spectra in the visible range. In order to reproduce the formation process optical model simulation was carried out. For demonstration of this method a 24‐layer microcavity structure was selected. Although in this low wavelengths region some absorption and scattering effects complicate the overall picture, the combined analysis throws new light upon the evolution of the porous silicon multilayer. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light propagation and scattering in porous silicon nanocomposite waveguides
Authors: Pirasteh P. , Charrier J. , Dumeige Y. , Joubert P. , Haesaert S. , Chaillou A. , Haji L. , Le Rendu P. , Nguyen T. P. 
Published: June 2005

AbstractPlanar waveguides have been achieved from oxidised porous silicon layers (OPS) which have been impregnated by solvents, Congo Red (CR) dye and poly(p‐phenylene vinylene) (PPV) polymer. Optical loss has been investigated by a simple technique based on surface optical scattering measurements. Optical loss has been studied as a function of the wavelength, impregnation type and CR concentration. The main sources of attenuation, such as absorption, scattering from interface roughness, scattering from nano‐ crystallites and modification of the refractive indexes after filling are discussed. Optical loss measured at 0.633 µm is about 1.8 dB/cm for the OPS waveguides The optical loss decreases with wavelength. Otherwise, the optical loss increases with the concentration of Congo Red dye which is absorbent at this wavelength. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excimer VUV formation of erbium‐doped silica layers
Authors: Yu J. J. , Boyd I. W. 
Published: June 2005

AbstractErbium‐doped silica sol–gel layers with post‐process excimer VUV irradiation at a low temperature of 400 °C have exhibited a strong room temperature Er luminescence at ∼1.53 µm. The VUV irradiation has led to the formation of Er oxides in the silica matrix while significantly reducing nonradiative decay channels associated with the OH groups in the sol–gel layers. High‐resolution transmission electron micros‐copy results revealed the formation of Er2O3 crystallites in the silica layers. The Er–O coordination and crystallisation altered the chemical environment of the Er ions in the silica while possibly reducing the quenching effect of the Er–Er cross‐relaxation, resulting in the strong Er luminescence emitted. Moreover, the low temperature VUV process would not produce the luminescence background offset which was found to be present in all the luminescence spectra of the silica layers processed thermally at 900 °C. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A simple inverse problem in solitonic chain deformations
Authors: Ferrer Rodrigo 
Published: June 2005

AbstractWe present a method that permits to obtain the nearest neighbor interaction potential starting from the shape of a spatial deformation of the chain of atoms. The deformations are considered to be traveling pulses. This potential does not necessarily have an analytical expression. Most of this work is focused on the usual formalism for solving Hamilton equations of motion. The concept of dual systems provides a highly efficient method to relate displacements from the equilibrium with generalized momenta and interaction potentials. We introduce generating functions from which sinusoidal waves and solitons are generated; then the corresponding interaction potentials are found. We arrive at the Hamiltonian and the energy of the system. A new kind of solitonic deformations is found for nonlinear chains which corresponds to an interaction potential similar to the Toda exponential potential but with a different dispersion relation to the speed of long‐wavelength sinusoidal waves. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Checklist for GCP compliance investigation (Medical institution)
Authors: Hirayama Kiyomi , Fukuda Naohisa , Satoh Hitoshi , Itoh Katsumi , Chiba Kiyoshi , Nakae Yutaka , Takezawa Masayuki , Gotoh Kuniko 
Published: June 2005

AbstractThis checklist is an English translation of the Good Clinical Practice (GCP) compliance checklist prepared by the Japanese agency for on‐site inspections of medical institutions. Please note that the checklist was translated by the authors and has not received official review by any Japanese agency including the Organization for Pharmaceutical Safety and Research (OPSR).This checklist is an addendum to a previously published article on the evaluation of overseas GCP inspections by the Japanese Regulatory Agency [1]. Copyright © 2005 John Wiley & Sons, Ltd.
What's New?
Authors: Hattemer‐Apostel Rita , Broughton Harold Steven 
Published: June 2005

AbstractThe What's New? section in the Quality Assurance Journal aims to draw attention to items of importance to QA professionals. There is usually a three‐month interval between final submission of manuscripts and distribution of the journal. For this issue, the entries in the What's New? section arise from the period of 1 December 2004 to 28 February 2005. If you feel that there is any other new information that should be brought to the attention of readers, please let us know by e‐mailing rha@verdandi.ch. Copyright © 2005 John Wiley & Sons, Ltd.