bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure mediated release of hydrogen from silicon co‐implanted with H2+ and He+
Authors: Misiuk Andrzej , Barcz Adam 
Published: May 2007

AbstractHydrogen out‐diffusion from porous‐like buried layers prepared in single crystalline Si by implantation with hydrogen (Si:H) or hydrogen and helium (Si:H, He) depends, among others, on the sequence of layers enriched with H and He and on implantation conditions. Hydrogen loss at 720–920 K decreases, increases or does not depend on hydrostatic pressure of ambient (HP, up to 1.1 GPa). This unusual effect is related to specific microstructure of Si:H, He induced under HP and to the He‐mediated energy of creation of vacancies as well as of the strength of H–Si bonds. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of Ag‐Cu nanoparticles in SiO2 films by sol‐gel process and their effect on the film properties
Authors: Díaz‐Flores L. L. , Garníca‐Romo M. G. , González‐Hernández J. , Yáñez‐Limón J. M. , Vorobiev P. , Vorobiev Y. V. 
Published: May 2007

AbstractSol‐gel thin films and microcrystalline powders of SiO2 doped with Ag and Cu were obtained under environmental conditions of pressure and temperature. The precursor material was a mixture of water, tetraethyl‐orthosilicate, ethanol and aqueous solutions of Ag and Cu salts, the components were taken in ratios known to provide SiO2 matrix material with good structure. The annealing was performed in oxidizing and reducing atmosphere, the temperature varied in the range of 100–800 °C. Formation of metal particles of 100 nm order of magnitude was confirmed by X‐ray, optical and SEM analysis. In presence of metal particles, the SiO2 matrix was crystallized in α‐cristobalite at annealing temperature as low as 500 °C, and in quartz form at 800 °C. A simple model treating the metal‐induced low‐temperature crystallization is presented. The material obtained is promising for the use as optical filter, gas sensing element and antibacterial agent. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regular patterning of PS substrates by a self‐assembled mask
Authors: Nagy N. , Pap A. E. , Deák A. , Volk J. , Horváth E. , Hórvölgyi Z. , Bársony I. 
Published: May 2007

AbstractRegularly ordered porous structures were fabricated in ion‐implanted p‐ and n‐type silicon. Mono‐layered Langmuir‐Blodgett (LB) films and a double‐layered film from Stöber silica spheres of 350 nm diameter were used as masking layers in the boron and phosphorus ion‐implantation step, providing the laterally periodic doping structure. The various ordered porous structures are obtained after the anodic etch process. The PS layer can be removed by alkaline etching. The masking LB silica layer and the resulting structures are shown in the SEM images. Using the self‐assembled nanoparticles, regular patterns of high resolution can easily be prepared in an inexpensive manner on large area silicon. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gradient‐porous structure of silicon
Authors: Starkov V. , Gavrilin E. 
Published: May 2007

AbstractSilicon membranes with through pores have been manufactured based on silicon plates with a gradient‐porous structure (GPSi), in which the pore cross section and structure varies with depth. The obtained structure can serve a basis for the development of electrodes for solid polymer fuel cells. The developed technology allows to change porosity and porous morphology on all thickness of a porous membrane. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymer supported porous TiO2: application to photo‐catalysis
Authors: Saadoun M. , Chorfi H. , Bousselmi L. , Bessaïs B. 
Published: May 2007

AbstractThis work concerns the preparation and characterization of polymer supported adhesive TiO2 films starting from the P25 TiO2 powder. For this purpose, we prepared a TiO2 based paste and used the screen printing method. The annealing temperature of the screen printed layers was chosen taking into account the variation of the composition ratio and morphology of the TiO2 powder. X‐Ray Diffraction (XRD) analyses show that the TiO2 powder conserves the same anatase/rutile composition at annealing temperatures below 600 °C, beyond the rutile TiO2 phase increases. Annealing dependence of the morphological features of the TiO2 powder was investigated by Atomic Force Microscopy (AFM). XRD and AFM investigations enabled us preparing flexible polymer supported porous TiO2 films (mostly anatase), just by choosing temperatures that allow elimination of the organic inks forming the screen printing paste. Scanning Electron Microscopy (SEM) shows that polymer supported TiO2 films are inhomogeneous and porous, which make them highly suitable for photo‐catalysis applications. The photo‐catalytic performances of the polymer supported porous TiO2 films were experienced on a typical textile dye by absorbance measurements using UV‐Visible spectroscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low refractive index porous silicon multilayer with a high reflection band
Authors: Xifré Pérez E. , Pallarès J. , Ferré‐Borrull J. , Trifonov T. , Marsal L. F. 
Published: May 2007

AbstractWe present the fabrication and characterization of a one‐dimensional photonic crystal consisting of the periodic repetition of two porous silicon layers with different refractive index. The refractive indices of the single layers have been determined from experimental measurements using two different methods. Both methods lead to the same results: the obtained average refractive index for a current density of J = 30 mA/cm2 is 1.7 and for J = 70 mA/cm2 is 1.3. The reflectivity spectrum of the studied multilayer for different angles of incidence has been measured and a good agreement with the simulation of the structure has been achieved. It has been observed that it presents a high reflectivity band in the NIR. Besides, we show that the projected band structure of the multilayer can be used for the analysis of the reflectivity results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of duty cycle and frequency on the morphology of porous silicon formed by alternating square pulse anodic etching
Authors: Escorcia J. , Agarwal V. 
Published: May 2007

AbstractIn this work we report the fabrication and characterization of porous silicon formed by alternating square pulse anodization. The effect of duty cycle (5–100%) and frequency was studied for porous silicon samples made with highly doped silicon wafers, under the same equivalent charge condition. The high resolution scanning electron microscopy images reveal that, under the same conditions of current and frequency, there exists an optimum value of duty cycle (20%), at which the structure exhibits superior characteristics. Maintaining the same charge supplied during the positive square pulse for the total anodization time, with a 10 mA/cm2 current density and 5% duty cycle, samples were fabricated at different frequencies (from constant current to 100 Hz) and the etching rate/thickness of the PSL formed at a 10 Hz frequency is found to be maximum, indicating that the response of the electrochemical reaction is maximum at this frequency. However, a reduction in the interface roughness between porous silicon and crystalline Si is obtained only at high frequencies. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐steps functionalization process to extend the novel in situ porous silicon formation‐functionalization method
Authors: Valentini V. , Mattei G. , Cattaruzza F. , Flamini A. 
Published: May 2007

AbstractRecently, we have presented a novel in situ simultaneous formation‐functionalization (FORFUN) method of porous silicon (PS) layers in which the molecules to be chemisorbed are present in the HF ethanoic solution used for the electrochemical preparation of the PS. In this work we demonstrate that is possible to extend this method to a wider group of organic molecules, in principle even to molecules not compatible with the preparation solution. First a PS single layer functionalized with methyl‐6‐heptynoate was prepared by the FORFUN method (I step) and then, after a second ex situ chemical process (II step), we obtained the correspondent tertiary alcohol bonded to the surface, as proved by the IR reflection spectra. This two‐steps process maintains all the features of the FORFUN method: simplicity, effectiveness and the possibility of confining the chemisorbed species in selected layers in a PS stack (“spatially selective functionalization”). These findings can be relevant for many applications based on PS systems and devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical vapour infiltration of nano‐structured carbon in porous silicon
Authors: Mattei G. , Valentini V. , Polini R. 
Published: May 2007

AbstractFor the first time the results of the chemical vapor infiltration (CVI) of nanostructured sp2 carbon in meso‐porous silicon layers under process conditions normally used to grow diamond films by Hot Filament Chemical Vapour Deposition (HFCVD) are presented. The combined use of micro‐Raman spectroscopy and Field Emission Gun Scanning Electron Microscopy (FEG‐SEM) clearly demonstrated that disordered graphitic carbon was infiltrated in the PS pores, thus permeating completely the PS layer. Such a nanostructured carbon infiltration provided new properties to the PS material, which are potentially of great relevance for opto‐electronics and sensors applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New type of dual macro and nano fractal structure of reaction induced vapor phase stain etched porous silicon
Authors: Stolyarova S. , Weiss S. , Levy M. , Nemirovsky Y. 
Published: May 2007

AbstractA comprehensive study of morphology of Reaction‐Induced Vapor Phase Stain Etched porous silicon was performed in order to inspect samples for fractal structure and to estimate their potential for sensing applications. A new dual fractal structure is found in porous silicon layer obtained by Reaction‐Induced Vapor Phase Stain Etch. The layer consists of two superposed fractal macro‐ and nanostructures. The macrostructure is formed due to the condensation of drops while the nanostructure is caused by the chemical reactions of the vapor molecules with the silicon surface. A comparison with morphology of porous silicon prepared by Liquid Phase Stain Etch is also presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room temperature gas sensor based on porous silicon/metal oxide structure
Authors: Arakelyan V. M. , Martirosyan Kh. S. , Galstyan V. E. , Shahnazaryan G. E. , Aroutiounian V. M. 
Published: May 2007

AbstractN‐type TiO2–x and In2O3 · SnO2 thin films were deposited onto p‐type porous silicon layer which was formed by common electrochemical anodization. The current‐voltage characteristics of obtained structures and sensitivity to different concentrations of hydrogen in air were studied. Measurements were carried out at room temperature. As shown results of measurements, an exponential growth of the current in forward branch of the current‐voltage characteristics of the device made of TiO2–x layer was detected. Higher sensitivity to hydrogen of the TiO2–x ‐porous silicon sensor in comparison to structure made of In2O3 · SnO2 film was detected at room temperature (without preheating of work body of the sensor). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐frequency noise in structures with porous silicon in different gas media
Authors: Mkhitaryan Z. H. , Shatveryan A. A. , Aroutiounian V. M. , Ghulinyan M. , Pavesi L. 
Published: May 2007

AbstractNoise properties of porous silicon/single‐crystalline silicon structures under exposure to active gases are investigated for the first time. Current‐voltage and noise characteristics of samples are measured. The Al/porous silicon/single‐crystalline Si/Al sandwich‐structures were placed in a special chamber and the influence of adsorption of various gases on low‐frequency noise of the samples was revealed. The adsorption changes the dynamics of the interaction of charge carriers with traps, i.e. the noise characteristics of the samples. The results are encouraging for practical applications of porous silicon structures as gas sensors using measurements of low‐frequency noise characteristics. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gas sensitive porous silicon sensor using rapid thermal annealing screen printing contacts
Authors: Mahmoudi Be. , Gabouze N. , Haddadi M. , Cheraga H. , Belhousse S. 
Published: May 2007

AbstractThe development of sensitive porous silicon (PS) gas sensor which utilizes screen printing for the front and back contacts metallization has been reported. Application of the thick‐film technology results in highly reproducible and economic fabrication of the contacts. We present the design, fabrication, characterization and results when devices were submitted to different gases as opposed to a controlled environment such as vacuum. The C‐V and I‐V measurements performed on metal/CHx/porous silicon/silicon structure showed that the electrical properties of the device are extraordinary sensitive to various gases, oxygen, propane, carbon dioxide at disproportionate level. The response of this device, which operates at bias voltages of 10–100 mV, is rapid and reversible. The electrically operated sensor is more sensitive to oxygen and shows an opposite behaviour if exposed to a reducing environment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensing of chemical vapor using a porous multilayer prepared from lightly doped silicon
Authors: Salem M. S. , Sailor M. J. , Harraz F. A. , Sakka T. , Ogata Y. H. 
Published: May 2007

AbstractA porous silicon rugate filter was prepared and investigated for its ability to sense ethanol vapors of different concentrations. The structure shows sensitivity to concentrations above 1% in volume up to saturation at room temperature. This sensitivity is in the form of a red shift of the characteristic peak of the filter due to capillary condensation phenomenon. Exposing the structure to saturated ethanol vapor produces partial filling of the pores with liquid. Theoretical calculations using the Bruggeman effective medium approximation and characteristic matrix method were employed to estimate the average volume fraction of ethanol molecules condensed into the pores. Electrochemical oxidation of the filter was performed. Furthermore, the oxidized structure was found to improve the durability of the filter and increase the adsorbed amount of ethanol molecules into the pores. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical sensing by simultaneous measurement of photoluminescence intensity and photoluminescence decay time of porous silicon
Authors: Dian J. , Vrkoslav V. , Jelínek I. 
Published: May 2007

AbstractSimultaneous measurement of photoluminescence intensity and photoluminescence decay time of porous silicon was used for optical detection of chemical species in gas phase. For the studied set of analytes we observed that quenching of photoluminescence intensity and shortening of photoluminescence decay time scale with the analyte concentration. Simultaneous acquisition of photoluminescence intensity and photoluminescence decay time enabled to improve reliability of the sensor response measurements. Different sensor sensitivity of photoluminescence intensity and decay time to the presence of chemical species makes possible to discriminate between various classes of organic molecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Host‐guest interactions in gas phase chemical sensing of permethyl‐6I‐alkenoylamino‐6I‐deoxy‐β‐cyclodextrin derivatized porous silicon
Authors: Jelínek I. , Vrkoslav V. , Trojan T. , Jindřich J. , Dian J. 
Published: May 2007

AbstractPorous silicon surface was modified by photochemically activated hydrosilylation reaction with permethyl‐6I‐alkenoylamino‐6I‐deoxy‐β‐cyclodextrins. In the presence of controlled amounts of various organic molecules in gas phase photoluminescence response from this derivatized porous silicon revealed formation of host‐guest complexes between β‐cyclodextrin and detected molecules. The strongest modification of photoluminescence response was observed for aromatic compounds that have optimal molecular size for strong interaction with β‐cyclodextrin cavity. For low concentrations of aromatic molecules we observed PL enhancement most probably due to electron transfer from β‐cyclodextrin‐analyte complex to porous silicon. For higher concentrations – after saturation of the β‐cyclodextrin sites – a combined response with dominant PL quenching was observed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensing with porous silicon double layers: A general approach for background suppression
Authors: Pacholski Claudia , Sailor Michael J. 
Published: May 2007

AbstractOne‐dimensional porous silicon photonic crystals can be considered as optical double layers. The reflectivity spectrum of the structure displays a strong peak corresponding to the stop band of the photonic crystal (rugate filter) and Etalon fringes due to Fabry‐Pérot interference in the porous silicon film. The intensity (reflectivity) of the rugate peak and of the peak in the Fourier transform of the Fabry‐Pérot interference spectrum changes differently upon adsorption or binding of biomolecules to the solution/porous silicon interface. Whereas the intensity of the rugate peak only tracks lamp fluctuations, bubbles, and other sources of experimental errors, the intensity of the peak in the FFT spectrum detects in addition adsorption/binding of biomolecules to the surface of the biosensor. The intensity ratio between the rugate peak (reference channel) and the peak in the FFT spectrum (sensing channel) efficiently suppresses background and improves the signal to noise ratio for the detection of biomolecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of a new microfluidic analysis system based on porous silicon as sensitive element
Authors: Miu Mihaela , Angelescu Anca , Kleps Irina , Craciunoiu Florea , Simion Monica , Bragaru Adina , Ignat Teodora 
Published: May 2007

AbstractIn this paper, a bio‐laboratory on a chip is presented, representing a new miniaturized device on silicon, utilized to monitor a variety of cellular responses. It is equipped with a glass cover wafer which contains cavities for microreservoir feeding and fluid extraction, and for optical detection. The microfluidic system contains a reaction chamber and a channel network laid‐out radially, fabricated by silicon etching process. In order to improve the cell adhesion and the detection sensitivity, the internal bottom of the reaction chamber is nanostructured by silicon porosification. Porous silicon is a biocompatible material, and the cells cultivated on its modified surface, represent a biochemical system which could be the receptor component of a biosensor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical study of microfluidic channels isolated with chemically modified porous silicon
Authors: Méry E. , Malhaire C. , Remaki B. , Barbier D. 
Published: May 2007

AbstractThis paper deals with On‐Chip‐Electrophoresis separation systems micromachined on porous silicon. The electrical insulation properties of the porous substrates were analyzed and related to physical and chemical treatments such as thermal oxidation and silanisation. From this preliminary study, microfluidic devices including silanized porous silicon layers were realized. Finally, ANSYS 3D‐Finite Element Modelling of a microfluidic device was performed using experimental data from the electrical measurements. The geometrical and electrical limitations were then discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calculation of reflectance of porous silicon double‐layer antireflection coating for silicon solar cells
Authors: Martirosyan Kh. S. , Hovhannisyan A. S. , Aroutiounian V. M. 
Published: May 2007

AbstractCalculations of the reflectance spectrum of the double‐layer porous silicon antireflection coating for silicon solar cells were carried out using optical matrix approach method. Comparison of obtained reflectance spectrum of double‐layer porous silicon with the spectra obtained experimentally without optimization of parameters of layers and for the SiO2/TiO2 antireflection coating was shown lower reflectance value for this new construction proposed by us. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reflectance spectrum of diamond‐like carbon/porous silicon double‐layer antireflection coatings designed for silicon solar cells
Authors: Aroutiounian V. M. , Martirosyan Kh. S. , Soukiassian P. G. 
Published: May 2007

AbstractIn this study, our purpose was to investigate the possibility of using a diamond‐like carbon/porous silicon double‐layer antireflection coating which is characteriazed by low reflectance, in order to enhance the performance of silicon solar cells and to protect them from various external influences. Experimental results obtained from reflectance measurements showed the possibility of achieving low reflectance value. Theoretical simulations of the reflectance spectra were carried out. The comparison of the reflectance spectrum of such diamond‐like carbon/porous silicon double layer antireflection coating with spectra obtained from other types of coating layers showed a much lower reflectance within larger energy range including the UV, visible and infrared regions of the solar spectrum. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conductivity of free‐standing porous silicon layers using Terahertz differential time‐domain spectroscopy
Authors: Ramani S. , Cheville Alan , Escorcia Garcia J. , Agarwal V. 
Published: May 2007

AbstractIn this paper, we report preliminary experimental results obtained by measuring the conductivity of free‐standing porous silicon with porosities ranging between 35% and 70%, using Terahertz Differential Time‐Domain spectroscopy (THz‐DTDS). The measured conductivity response follows sub‐linear and the super‐linear power laws in the terahertz frequency region. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Peculiarities of ozone adsorption on a porous silicon surface at low temperature
Authors: Pikulev V. B. , Tsyganenko A. A. , Kuznetsov S. N. , Saren A. A. , Gurtov V. A. 
Published: May 2007

AbstractInteraction between ozone molecules and silicon nanocrystallites in porous silicon (por‐Si) results in effective luminescence similar to optically excited emission but the mechanism still is not quite understood. To study the process the kinetics of both adsorption and oxidation of highly porous silicon surface under exposure to ozone (16O3 and 18O3) at low temperatures were measured using FTIR‐ and luminescence spectroscopy. It is shown that ozone chemisorption on por‐Si surface takes place yet at liquid oxygen temperature. The oxide coat formed instantly after ozone admission inhibits further oxidation and results in the predominance of ozone physisorption. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)