bluuebunny/crossref_metadata_2025 huggingface dataset:
Epiphytic flora on Gelidium corneum (Rhodophyta: Gelidiales) in relation to wave exposure and depth
Authors: Quintano Endika , Díez Isabel , Muguerza Nahiara , Santolaria Alberto , Gorostiaga José María
Published: October 2015

The canopy-forming macroalga Gelidium corneum (Hudson) J.V. Lamouroux plays a major role in the functioning of the subtidal ecosystem of the Cantabrian Sea (northern Spain). Despite its importance, little is known about the factors that may potentially affect the distribution pattern of its epiphytic flora. Here we examine two indirect factors: coastal orientation (N and NW) and depth (3 and 7 m), as proxies for wave exposure and light availability, respectively. We test their effects on the total epiphytic load, alpha diversity (species richness, Shannon, Simpson and evenness measures) and multivariate structure of the epiphytic flora growing on G. corneum in subtidal waters off the Basque coast. Plocamium cartilagineum, Dictyota dichotoma and Acrosorium ciliolatum were found to be the most common epiphytes. Significant interactive effect of coastal orientation and depth were observed for species composition and abundance of epiphytic flora. Increased wave exposure resulted in a lower epiphyte load and a less diverse community, suggesting that under high hydrodynamic conditions epiphytes were more likely to become dislodged from hosts. However, light availability only had a significant effect on the distribution of epiphytes below a certain threshold of wave action, with the epiphytic load being 30-40% greater on shallow bottoms.
The Development of Virtual World Tools to Enhance Learning and Real World Decision Making in the Australian Sugar Farming Industry
Authors: Cliffe Neil , Doyle Joanne , Farley Helen , Lindesay Janette , Loch Adam , Maraseni Tek , Marcussen Torben , Martin Neil , Mushtaq Shahbaz , Ostini Jenny , Reardon-Smith Kate , Stone Roger
Published: October 2015

In farming, the outcome of critical decisions to enhance productivity and profitability and so ensure the viability of farming enterprises is often influenced by seasonal conditions and weather events over the growing season. This paper reports on a project that uses cutting-edge advances in digital technologies and their application in learning environments to develop and evaluate a web-based virtual ‘discussion-support’ system for improved climate risk management in Australian sugar farming systems. Customized scripted video clips (machinima) are created in the Second Life virtual world environment. The videos use contextualized settings and lifelike avatar actors to model conversations about climate risk and key farm operational decisions relevant to the real-world lives and practices of sugarcane farmers. The tools generate new cognitive schema for farmers to access and provide stimuli for discussions around how to incorporate an understanding of climate risk into operational decision-making. They also have potential to provide cost-effective agricultural extension which simulates real world face-to-face extension services but is accessible anytime anywhere.
Reducing Noise Pollution Generated by a Hydropower Facility
Authors: Simion Sorin , Găman George Artur , Călămar Angela , Pupăzan Daniel
Published: October 2015

Environmental noise affects a growing number of people and therefore, with the passing of each day, it becomes a major environmental problem. The population is affected both physiologically and psychologically, noise influencing basic activities such as sleep, rest, study and communication. Although these effects on human health are known for a long time, recent research shows that the noise produces effects on humans at lower levels than previously thought. Exposure to noise not only leads to disturbances of hearing, irritation but also to other health problems such as cardiovascular diseases.Environmental noise, that undesirable external noise, is spreading both in urban and in rural areas. It is omnipresent, cannot be avoided and a large part of the population is influenced by its existence.This paper examines the effects produced by a hydropower facility on the surrounding areas, before and after soundproofing its elements likely to produce noise.
Effects of Structural Properties on Natural Frequencies of Axially Moving Beams with an Intermediate Support
Authors: Aksoy Şafak , Kostekci Ferid
Published: October 2015

In this study, linear vibrations of axially moving beam simply supported between the guides are examined and natural frequencies are calculated numerically. The vibrations of axially tensioned Euler-Bernoulli beam are investigated under clamped-clamped end conditions. Governing differential equations of motion are derived using Hamilton’s Principle for two regions of the beam. The boundaries at the outer ends of the beam are assumed immovable. Non-dimensional equations of motion are derived and the solutions of the linear problem are obtained. Assuming a weakly non-linear system, linear equations are obtained using the Method of Multiple Scales. First seven natural frequencies are calculated numerically based on the flexural rigidity, axial velocity and locations of the intermediate support.
The Dynamic Response of the Elastomeric Isolators Modeled as Voigt-Kelvin to the Action of the Seismic Motion
Authors: Ciuncanu Mihai
Published: October 2015

The paper presents the model of a seismic mass with viscoelastic linear connections, following the Voigt-Kelvin model, with the fundamental unidirectional harmonic kinematic excitation of an earthquake. The motion is caused by seismic action. Thus, the parameters and the motion laws of the mass, the inertial force and the force transmitted to the fixed base are determined. Also, the relations for the amplitude and the transmissibility of the motion are established in function of the elastic and viscous parameters of the composed model Voigt-Kelvin.Based on the established relations the dissipated energy function of the acceleration of the earthquake and of the dominant pulsation and the viscoelastic characteristics are determined.
Assessments in Experimental Dynamics of a Pendulum System with Application in Vibration Isolation
Authors: Potîrniche Aurora , Căpățână Gigel , Simionescu Cristian
Published: October 2015

This paper provides a starting point for further study in the domain of analysis of the behavior of the pendulum absorber systems in dynamic regime. Thus, one can determine an optimal configuration of the pendulum absorber system to ensure the efficiency for the dynamic isolation for the entire domain of variation of excitation.
The Influence of the Working Regime of Oscillations Produced by an Electrovibrator on the Sorting of Materials
Authors: Vlăduţ Valentin , Danciu Aurel , Grigore Ion , Herişanu N. , Dumitru Ilie , Sorică Cristian , Voicea Iulian , Biris S. , Duţu M. , Păunescu D. , Găgeanu Iulia
Published: October 2015

In order to be used as food supplements, materials (medicinal and aromatic plants, other materials containing active principles, etc.) need to be chopped and sorted by size, depending on the field of use: herbal tea, suspensions, tinctures, etc. The paper presents the results of research on the sorting process of some materials containing active principles (yarrow, alfalfa and willow bark) using a sorting machine provided with 2 electro vibrators fitted on each side of the framework within which 3 sieves with a mesh size of: 2.15, 4 and 8 mm are fitted, changing the oscillation regime of the sieves by adjusting the angle of the electro vibrators, in order to identify the optimal sorting regime.
Characterization of Medicinal Plants Sorting Process by Planar Sieving through Mechanical Oscillations Analysis
Authors: Pruteanu Augustina , Matache Mihai , David Ladislau , Persu Catalin , Duţu M. , Vlăduţ Valentin
Published: October 2015

The mechanical sorting process of granular and vegetal materials is a complex technological process influenced by a series of factors from which we remind: mechanical vibratory motion, geometrical measures of the sorting equipment and technological factors. Based on correlations between the presented elements one can establish the technological parameters of the sorting process so that to realize a quality separation.In the paper we present a method for determination of mechanical oscillations influence on the quality of the sorting process with planar sieves. The experiments performed on a dimensional sorter with planar sieves aimed at identification of an optimum working set-up in terms of frequency and amplitude of the sorter’s vibrators, for a quality separation degree.
A Methodology to Estimate the Center of Oscillation and the Center of Mass of a Railway Vehicle
Authors: Ghita Eugen
Published: October 2015

The paper proposes a model in order to estimate the location of the center of oscillation and mass of railway bogies or vehicles in order to place in the correct position all the equipments inside the coach. The location of this point is very important for the comfort coefficients regarding passenger coaches, as the position of the coach floor must be horizontal at every moment in order to avoid some disturbed motion as the rotation around the horizontal lateral axes. The proposal for the system of axys, the calculus algorithm and the estimation of the correct position of the Diesel engine inside the coach represent the basis of the paper.
Analysis of the Human Health and Safety Requirements to Vibration Generated Risks
Authors: Vasile Ovidiu
Published: October 2015

Having as starting point the fundamental requirements outlined in Directive 2002/44/CE in which the minimum health and safety requirements for the workers’ exposure to the risks generated by physical agents (vibrations) are established, the paper presents a concrete evaluation, based on experimental determinations, of the vibrations transmitted to the entire body of a human operator. The evaluation of the level of exposure to vibrations is based on the computation of the daily exposure, expressed over a period of eight hours. The weighted mean square acceleration will be determined function of the frequency weighting curves Wc, Wd and Wk , using a MATLAB program developed by the author. Based on the indications from SR ISO 2361-1 the evaluation of the vibrations for health, comfort, and perception are presented as experimental results. In this context, the necessity of compliance with the minimum health and safety requirements imposed by the current legislation are highlighted.
Vibroacustical Method for Measuring the Effect of Cavitation Erosion
Authors: Bereteu Liviu , Bordeaşu Ilare , Drăgănescu Gheorghe , Simoiu Dorin , Micu Lavinia , Sălceanu Cornelia
Published: October 2015

One of the most harmful effects of cavitation, with strong influence on the life of the hydraulic machines is the destruction caused by erosion Since its discovery, over 150 years ago, evaluating the degradation is achieved by mass of material removed by erosion in a given time, which in the case of rotors and blades of hydraulic machines and marine propeller blades are equivalent by amount of electrode consumption for filling the voids left by the removal of material. Laboratory research on cavitation, from the beginning until now, evaluates the intensity of cavitation erosion rate, defined as a mass of material removed by erosion at a certain time of attack.The purpose of this paper is to develop and validate a technique based on vibroacoustic signal analysis of corroded samples, and that through their natural frequencies deviations to emphasize mass loss.The experimental measurement of the vibroacustic response of corroded specimens is carried out by using a condenser microphone. The vibration responses, in free-free conditions of the specimens, are analyzed using algorithm based on Fast Fourier Transform (FFT). The results are compared with other indicators of cavitation corrosion, such as lost mass and mass loss rate.
Delimiting and Protecting Quiet Areas in an Urban Environment
Authors: Herisanu Nicolae , Bacria Vasile , Fiat Calin , Damian Ionut
Published: October 2015

This paper is concerned with the problem of quiet areas in Timisoara City. According to the strategic noise map of Timisoara City, which has been updated in 2013, there were identified some potential quiet areas, which are needed in order to comply with the European Noise Directive. We present the conditions for these potential quiet areas to become real quiet areas, delimitation and measures designed for the proposed aim, and also measures which should be implemented in the next five years to protect and preserve them. The analysis is performed with the help of predictions based on some noise maps.
Effects of Footfall Induced Vibrations on Concrete and Composite Floors
Authors: Leing Chuen Keit , Mohammed Parvez Anwar , Elleithy Wael
Published: October 2015

This paper investigates the effects of footfall induced vibrations on the floors of a 3-storey sub-frame structure. Composite and concrete floors were examined. Variables involved are floor widths, floor thicknesses, floor aspect ratios and column heights. Models are generated and analysed using the finite element method. The vibration responses were represented in terms of displacements and accelerations. Results show that higher vibration responses occurs on longer floor widths, thinner floor slabs and higher floor aspect ratios for both composite and concrete floors.
Effects of Thickness of Ultra High-Performance Fiber Concrete Wrapping on the Torsional Strength of Reinforced Concrete Beam
Authors: Jasim Mohammed Thaer , Abu Bakar Badorul Hisham , Muhamad Bunnori Norazura
Published: October 2015

Abstract: Two groups of rectangular beams, comprising of six specimens, the first group (L) were provided with four longitudinal bars, one at each corner while the second groups of beams (S) were fully reinforced with longitudinal bars and transverse reinforcement. Each group consisted of three beams. Two beams have been strengthened with ultra high performance fiber concrete (UHPFC) on four sides having a thickness of (15mm - 25mm) and one control beam. The variables considered in the experimental study include the transverse reinforcement ratios and the effect of thickness of UHPFC wrap. Experimental results show the effectiveness of the proposed technique at ultimate torque for strengthening beams and behavioral curves. Strengthened RC beams fully wrapped with a thin layer of UHPFC exhibit an enhanced torsional strength when compared to control beam. Results reveal that the transverse reinforcement ratios by 0.66%, increases the UHPFC contribution to torsional strength of strengthened beams with a 15 thick UHPFC; and by up to 7% for strengthened beams with a 25 thick UHPFC, respectively when compared to same strengthened beams without stirrup. It is found that the ultimate torque of beams with a 25 mm thin layer UHPFC is greater than beams with 15 mm by (28% and 28.3%) for the groups L and S, respectively.
Groundwater Inflows Characterization in the Pahang-Selangor Raw Water Transfer Tunnel Using δ2H and δ18O as Tracers
Authors: Syed Zainal Sharifah Farah Fariza , Mohamad Ismail Mohd Ashraf , Mostafa Roslanzairi , Azit Romziah
Published: October 2015

Groundwater inflows represent a very important element in hydrological circulation. Water inflows in Pahang-Selangor Raw Water Transfer Tunnel have been analyzed for isotopes stable of δ2H and δ18O. 61 samples were collected, including Tunnel Seepage Water (TSW), surface water and hot spring water samples within the study area which to understand the effect of multi topographical scale and geological characteristic. Deuterium (δ2H) and Oxygen-18 (δ18O) contributes the understanding of the origin and flow paths of water in the mountainous region. The δ2H and δ18O data obtained from TSW samples ranging from-45.73%0to-54.68%0and-46.01%0to-58.49%0are clustered along the local meteoric water line (LMWL) indicating that the groundwater originated from meteoric water. δ2H and δ18O data, primarily indicate the recharge altitude from 100m–550m which control by the sub vertical flow path mainly from geological structures (i.e. fractures and faults) followed by the groundwater. The altitude effect is indicated by the relation between the stable isotope values and elevation in meters highlighting a depletion of the heavy stable isotope with the increase of the tunnel overburden. The general trend obtained is δ2H and δ18O decreased with the increase of the overburden. The deviation of the δ2H and δ18O data from the expected trends may reflect the recharges are coming from the sub-horizontal flow path such as rivers or water infiltration from the valley. The results show that environmental isotopes indicates a better understanding of the complex hydrogeological system in a mountainous region and interaction between groundwater in granitic and meta-sedimentary rock formation along the tunnel project.
Comparative Study of Basic, Acid and Reactive Dyes Adsorption onto Rubber Seed-Coated Activated Carbon
Authors: Ismail Muhd Nazmi , Abdul Aziz Hamidi , Ahmad Mohd Azmier , Yusoff Nik Athirah
Published: October 2015

In this present study, rubber seed-coated activated carbon (RSCAC) was used as a natural adsorbent to remove basic (MB), acid (MR) and reactive (RBV) dyes using batch process. Each dye in the adsorption process was tested at different initial concentration from 50-500 mg/l. Different dyes showed different percentage removals. The highest removal was recorded by MB which was up to 99.9 %. The experimental data was analyzed with Langmuir and Freundlich adsorption models. The data fitted well with Langmuir. The adsorption capacity were 332.99, 210.33 and 155.37 mg/g for MB, MR and RBV, respectively.
Effect of Utilizing Different Building's Roof Material on Rainwater Harvesting System’s Payback Period, Water and Energy Savings, and Carbon Dioxide Emission Reduction
Authors: Nasif Mohammad Shakir , Roslan Rozanna
Published: October 2015

This study aims to investigate the effect of using different roofing materials in office building on rainwater harvesting system annual energy savings and carbon dioxide (CO2) emissions reduction which relates to the payback period. This paper includes modelling of different rain water harvesting concrete tank sizes for an office building which is used to supply water for toilet flushing and irrigation purposes. It is found that the optimized roof material for the catchment area is slate tiles with a 0.9 run-off coefficient. A total of 2870 MJ of energy can be saved and 830 kg of CO2 can be reduced annually with a payback period of 20 years, using a 32 m3 concrete tank.
A Study on the Characteristic and Properties of Riverbank Soil Samples as RBF Natural Materials from Sungai Perak, Kota Lama Kiri, Kuala Kangsar, Perak Darul Ridzuan, Malaysia
Authors: Adlan Mohd Nordin , Selamat Mohamad Razip , Othman Siti Zahirah
Published: October 2015

For a developing country such as Malaysia, riverbank/bed filtration (RBF) technology is still new and only few efforts have been made to understand the RBF mechanism and processes. Soil characteristics play important roles in determining the water quality and the ability of water to be abstracted from the wells during RBF process. A research has been carried out to identify the characteristic of riverbank soil at different layers in the pumping well (PW) borehole at Kota Lama Kiri, Kuala Kangsar, Perak, Malaysia. Soil samples were collected during the development of PW for RBF application. The maximum depth of PW was 8.50 metre. The soil samples were transported to Geotechnical Engineering Laboratory, School of Civil Engineering, Universiti Sains Malaysia and the properties were determined by a series of laboratory test. Soil particle size distribution (PSD) and hydraulic conductivity were obtained from sieve analyses and constant head test with reference to BS 1377: Part 1-9;2:1990. Laboratory results show that the value of Cu(coefficient of uniformity) for the soil samples within the borehole of PW was found to be within the range of 2.00 to 10.00 while the value of Cc(coefficient of gradation) lies in the ranges of 0.06-1.19. The One Way Analyses of Variance test was performed using Minitab statistical packages and the results indicate that the p-value was 0.996, where there was no significance difference between the mean sizes of soil samples within the PW. The hydraulic conductivity, k for PW ranges between 0.10-0.91 cm/s. Soil samples from depth 6.00-7.00 metres has the highest hydraulic conductivity, which is 0.91 cm/s. The overall well production from the pumping test was found 112.10 m3/hr.
Direct Determination of Groundwater Direction and Velocity Using Colloidal Borescope at Jenderam Hilir, Selangor
Authors: binti Ghazali Miskiah Fadzilah , bin Adlan Mohd Nordin , bin Samuding Kamarudin , bin Selamat Mohamad Razip
Published: October 2015

The colloidal borescope can be used for measuring groundwater flow directions and velocity. It is an integrated high-resolution flux gate compass with a high-magnification colloid-imaging camera that can measure flow at selected depths within a well. In this study, the colloidal borescope was used to determine flow direction and measure velocity during a pumping test for the riverbank filtration study in Jenderam Hilir, Selangor. During each measurement, the instrument, which monitored the movement of the suspended particles, was inserted into a well at a particular depth (screen well). The relative flow direction was determined by plotting the trajectory and speed of colloidal particles across the screen with AquaLITE Software, which determined the horizontal speed of the particles and flow speed. The groundwater flow pattern was dtermined at four boreholes in the study area, and the groundwater flow velocities were found ranging from 0.72 to 2.45 x (10-4) m/s. The direction of the groundwater flow at boreholes monitoring well 02 (MW02) and monitoring well 19 (MW19) was moved toward borehole pumping well (PW). The groundwater flow at monitoring well 01 (MW01) was moving toward the northwest of the study site which was parallel with the Langat river. The groundwater flow in borehole monitoring well A (MWA) was toward the southern part of the study site and was not affected by the pumping test activities at borehole monitoring well 03 (MW03).
Experimental Proof of the Slow Light-Induced Degradation Component in Compensated n-Type Silicon
Authors: Niewelt Tim , Schön Jonas , Broisch Juliane , Rein Stefan , Haunschild Jonas , Warta Wilhelm , Schubert Martin C.
Published: October 2015

We present new experimental data on light-induced degradation due to the boron oxygen defect in compensated n-type silicon. We are the first to show that both defect components known from p-type silicon are formed in compensated n-type silicon. A parameterization of the injection dependent recombination activity of the slower formed defect component is established. The formation kinetics of both defect components are studied and modeled under different conditions. It is found that the same rate factors as in p-type can describe the degradation, if the actual hole concentration under illumination is taken into account. The regeneration process known to permanently deactivate boron oxygen defects in p-type is successfully applied to n-type material and the illumination stability of the regenerated state is tested and proven.
Interplay of Ni and Au Atoms with Dislocations and Vacancy Defects Generated by Moving Dislocations in Si
Authors: Kveder V. , Khorosheva M. , Seibt Michael
Published: October 2015

We show experimentally that dislocations in Si crystals can generate some unknown vacancy complexes Vxtrail in their slip planes during their motion at 600°C. Most of these “dislocation trail defects” are not electrically active but can be detected by their reaction with gold atoms during in-diffusion experiments. It was also shown that contrary to gold, the Vxtrail-complexes do not react with interstitial Ni atoms. It means that the binding energy Ebind of Vxtrail complexes is quite high (Ebind>2.5eV), higher than the binding energy of vacancy complexes generated during FZ-Si crystal growth. It was also shown that Ni in-diffusion results in a strong increase of electron-hole recombination at dislocations and in a strong increase of dislocation-related DLTS C-line.
Kinetic Model of Precipitate Growth during Phase Separation in Metastable Binary Solid Solutions
Authors: SARIKOV Andrey
Published: October 2015

In this paper, the kinetics of precipitate growth in metastable binary solid solutions is analyzed considering two mechanisms: (i) diffusion of the one component from the bulk of composition matrix and its incorporation in the precipitate, and (ii) emission and outdiffusion of the second component from the interface of precipitate with surrounding matrix. A kinetic model is proposed that enables a description of these both mechanisms in a unique way. Using this model, the mechanism of oxygen emission and outdiffusion from the interface of Si precipitates with the silicon oxide surrounding is confirmed to determine the phase separation kinetics upon high temperature annealing nonstoichiometric silicon oxide films.
Determination of Activation Energy of the Iron Acceptor Pair Association and Dissociation Reaction
Authors: Lauer Kevin , Möller Christian , Debbih D. , Auge Manuel , Schulze Dirk
Published: October 2015

A method to measure the reaction rates of the iron acceptor pair association and dissociation is presented and applied. The activation energies of the dissociation and association reaction are determined for the acceptors boron, aluminum, gallium and indium. Additionally, the activation energies are reported for different illumination intensities. It is found that the activation energy of the association reaction varies for the investigated acceptors and that the activation energy of the dissociation reaction depends strongly on the illumination intensity. It is shown that neglecting of the dissociation reaction in the evaluation of relative interstitial iron content decrease causes a considerable overestimation of the activation energy of the iron acceptor association.
Boron-Related Defects in Low Temperature Irradiated Silicon
Authors: Khirunenko Ludmila , Sosnin Mikhail , Duvanskii A.V. , Abrosimov N.V. , Riemann Helge
Published: October 2015

The FTIR absorption studies of boron-doped silicon irradiated at 80 K by 5 MeV electrons have shown the recombination-enhanced migration of the interstitial boron by the Bourgoin-Corbett mechanism. The interaction of diffusing atoms of Bi with one another and with atoms of interstitial oxygen was revealed. For as-irradiated samples we observed the appearance of three LVMs at 739.4, 759.6, and 780.9 cm-1, which are attributed to BiBi complex, and the LVM at 923.5 cm-1, which are identified as BiOi complex.
Spin Relaxation Times of Donor Centers Associated with Lithium in Monoisotopic 28 Si
Authors: Ezhevskii Alexander A. , Detochenko Alexandra P. , Popkov Sergey A. , Konakov Anton A. , Soukhorukov Andrey V. , Guseinov Davud V. , Zverev Dmitry G. , Mamin Georgy V. , Abrosimov Nikolay V. , Riemann Helge
Published: October 2015

We report a detailed study of electron longitudinal and transverse spin relaxation times for Li donors in monoisotopic 28Si over the temperature range 4–20 K using continuous wave and pulsed electron paramagnetic resonance. Comparison of the obtained spin-lattice relaxation times for the states of the isolated donor center and lithium complex LiO showed that due to the presence of orbital degeneracy, relaxation is faster for single lithium than for the LiO complexes with the nondegenerate ground state. For the isolated lithium center in silicon the relaxation is well described by Blume-Orbach process, with the parameters of the spin-orbit coupling ~ 1·10-6 meV compare to Orbach process for LiO complex with spin-orbit coupling parameter ~ 1.5·10-2 meV.
The Impurity Spin-Dependent Scattering Effects in the Transport and Spin Resonance of Conduction Electrons in Bismuth Doped Silicon
Authors: Soukhorukov Andrey V. , Guseinov Davud V. , Kudrin Alexei V. , Popkov Sergey A. , Detochenko Alexandra P. , Koroleva Alexandra V. , Ezhevskii Alexander A. , Konakov Anton A. , Abrosimov Nikolai V. , Riemann Helge
Published: October 2015

Transport and spin relaxation characteristics of the conduction electrons in silicon samples doped with bismuth in the 1.1·1013 - 7.7·1015 cm-3 concentration range were studied by the Hall and electron spin resonance spectroscopy. Hall effect measurements in the temperature range 10-80 K showed a deviation from the linear dependence of the Hall resistance in the magnetic field, which is a manifestation of the anomalous Hall effect. The magnetoresistance investigation shows that with current increasing magnetoresistance may change its sign from positive to negative, which is most clearly seen when the bismuth concentration goes up to 7.7·1015 cm-3. The conduction electron spin relaxation rate dramatically increases in silicon samples with sufficiently low concentration of bismuth ~ 2·1014 cm-3. All these results can be explained in terms of the concept of spin-dependent and spin flip scattering induced by heavy bismuth impurity centers.
Analysis of EL Emitted by LEDs on Si Substrates Containing GeSn/Ge Multi Quantum Wells as Active Layers
Authors: Schwartz Bernhard , Saring Philipp , Arguirov Tzanimir , Oehme Michael , Kostecki Konrad , Kasper Erich , Schulze Joerg , Kittler Martin
Published: October 2015

We analyzed multi quantum well light emitting diodes, consisting of ten alternating GeSn/Ge-layers, were grown by molecular beam epitaxy on Si. The Ge barriers were 10 nm thick and the GeSn wells were grown with 7% Sn and thicknesses between 6 and 12 nm. Despite the high threading dislocation density of 109 to 1010 cm−2 the electroluminescence spectra measured at 300 and 80 K yield a broad and intensive luminescence band. Deconvolution revealed three major lines produced by the GeSn wells that can be interpreted in terms of quantum confinement. Biaxial compressive strain causes a splitting of light and heavy holes in the GeSn wells. We interpret the three lines to represent two direct lines, formed by transitions with the light and heavy hole band, respectively, andan indirect line.
Defect Formation in Ion-Implanted Si - Approach to Controlled Semiconductor Optical Properties
Authors: Khuchua Nina , Tigishvili Marina , Melkadze Revaz , Dolidze Nugzar , Gapishvili Nodar , Jibuti Zurab , Davbeshko Galina , Romanyuk V.
Published: October 2015

For specific modification of the fundamental optical and photoelectrical properties of silicon transparent for wavelengths beyond 1.1μm, boron ions have been implanted into n-type wafers at doses of 1 х 1013 cm-2–1 х 1015 cm-2 followed by annealing at 900 °C and 1000 °C (20 min). The IR reflection spectra, Raman spectroscopy and scanning electron microscopy data have been compared with the photosensitivity spectra (1.4–2.2 μm) and with the integrated photoresponse in the IR (1.0–4.1 μm) and UV (0.25–0.4 μm) regions. These studies allow for materials engineering to obtain new data on the influence of defect formation on the optical properties of the material and to evaluate the technological conditions for practical application of the modified material.
Defect Composition in Acceptor Doped ZnO Quantum Structures
Authors: Tchelidze Tamar , Kereselidze Tamaz
Published: October 2015

We investigated defect composition in ZnO quantum structures – quantum wells and nanowires doped with Ag impurity. We investigated the influence of space and dielectric confinement on ionization energies of acceptor and compensation donor centers. These calculations show that in nanowire there is a optimal range of radius where the creation of ionized donors compensating hole conductivity, and consequently, improvement of hole conductivity, is possible to suppress.
ZnO Nanoparticle Formation in 64Zn+ Ion Implanted Al2O3
Authors: Privezentsev Vladimir V. , Kulikauskas V.S. , Palagushkin A.N. , Steinman Edward A. , Tereshchenko A.N. , Batrakov A.A. , Ksenich S.N.
Published: October 2015

ZnO nanoparticles (NPs) formed in (-1012) sapphire substrates have been studied. The NPs were formed by implantation of 64Zn+ ions followed by furnace annealing in oxygen atmosphere for 1h at elevated temperatures. The radiation defects and Zn implant profiles were investigated by Rutherford backscattering spectroscopy of He+ ions with energy of 1.7MeV with scattering angle of 160o at Van de Graff accelerator using the ion channeling technique (RBS/CT). The surface morphology was studied by atomic force microscopy (AFM) and scan electron microscopy in secondary emission mode (SEM-SE). The distribution of Zn implant profiles was analyzed by secondary ion mass-spectrometry (SIMS). Identification of the phase content of the materials was carried out by X-ray photoelectron spectroscopy (XPS). In as implanted samples, a near-surface amorphization layer was formed, and in this layer the surface voids were created. After annealing in temperature range of 600-900°C the ZnO phase was synthesized in sapphire substrate. After annealing at 900°C one can see the phase variation from ZnO/Zn phases at sample surface to metal Zn phase in sample body at a depth of 40nm. Annealing at temperatures above 900°C leads to disappearing of ZnO phase and creating of ZnAl2O4 phase.
A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method
Authors: Gusakov Vasilii E.
Published: October 2015

Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.
Non-Visual Defect Monitoring with Surface Voltage Mapping: Application for Semiconductor IC and PV Technology
Authors: Edelman Piotr , Marinskiy Dmitriy , Savtchouk Alexandre , D'Amico John , Findlay Andrew , Wilson Marshall , Almeida Carlos , Lagowski Jacek
Published: October 2015

Non Visual Defects (NVD) is a category of defects that cause electrical failures but are not detected with visual wafer inspection tools. Our approach for NVD detection is based on the Kelvin probe surface voltage mapping technique. The detection of defects is enhanced using field-effect created in a non-contact manner by corona charge deposition on the surface of semiconductor. Precise defect location is accomplished with surface voltage gradient magnitude mapping that enhances delineation of defects. Detected defects are characterized locally using the corona-voltage technique or isothermal voltage transient decay analysis. Presented examples include: dielectric charge and interfacial defect mapping on 300mm Si wafers; deep level emission mapping on epitaxial SiC and mobile ion mapping in Si solar cells.
Impact of the Gate Material on the Deep Levels in a-Si:H/c-Si Metal-Insulator-Semiconductor Capacitors
Authors: Simoen Eddy , Ferro Valentina , O’Sullivan Barry
Published: October 2015

Deep Level Transient Spectroscopy (DLTS) has been applied to Metal-Insulator-Semiconductor (MIS) capacitors, consisting of a p+ or n+ a-Si:H gate on an intrinsic i-a-Si:H passivation layer deposited on crystalline silicon n-or p-type substrates. It is shown that the type of gate has a pronounced impact on the obtained spectra, whereby both the kind of defects (dangling bonds at the a-Si:H/(100) c-Si interface (Pb0 defects) or in the amorphous silicon layer (D defects) and their relative importance (peak amplitude) may be varied. The highest trap densities have been found for the p+ a-Si:H gate capacitors on an n-type Si substrate. In addition, the spectra may exhibit unexpected negative peaks, suggesting minority carrier capture. These features are tentatively associated with interface states at the p+ or n+ a-Si:H/i-a-Si:H interface. Their absence in Al-gate capacitors is in support of this hypothesis.
BO-Related Defects: Overcoming Bulk Lifetime Degradation in Crystalline Si by Regeneration
Authors: Hahn Giso , Wilking Svenja , Herguth Axel
Published: October 2015

Boron-oxygen related defects formed under working conditions of a c-Si solar cell can be a showstopper for new cell concepts enabling higher conversion efficiencies. The recombination activity of these defects can be reduced to negligible values by a regeneration process under elevated temperatures and in the presence of excess charge carriers in the Si bulk. It is shown that this process also relies on the presence of H in the c-Si bulk. Regeneration kinetics can be sped up by higher temperatures, higher concentrations of excess charge carriers and higher H concentration in the c-Si bulk. But care has to be taken to avoid a destabilization reaction taking place at higher temperature, resulting in the BO-related defects being again present in the recombination-active state. A 3-state model with the corresponding reaction rates between the different defects states describes the experimental findings and can be used for predictions of an optimized regeneration process.
A Comparison of Flip Chip Bump Electromigration Reliability for Cu Pillar, High Pb, SnAg, and SnPb Bump Structures
Authors: Syed Ahmer , Dhandapani Karthikeyan , Nicholls Lou , Moody Robert , Berry C. J. , Darveaux Robert
Published: October 2015

Electromigration failure in flip-chip bumps has emerged as a major reliability concern due to potential elimination of Pb from flip-chip bumps and a continuous drive to increased IO density resulting in a reduction of bump size and pitch. Traditionally, flip-chip interconnects incorporate a high Pb bump soldered with a SnPb eutectic paste to the substrate or another die. However, because of RoHS directives, the industry is responding with Pb free bump development, such as SnAg bump with SAC solder or Cu Pillar with SAC/SnAg solder.

Although a number of recent publications deal with electromigration reliability of Pb free and Cu Pillar bumps, a gap exists in terms of their performance comparison with high Pb and SnPb solder on the same bump geometry. The available test data is based on different test vehicles and it becomes difficult to determine the relative performance of these different metallurgies under accelerated test conditions. In addition, not all published data provides the essential parameters of Black's equation to determine the performance and reliability for actual use conditions.

This paper attempts to fill this gap by comparing electromigration performance of High Pb, SnPb eutectic, SnAg, and Cu Pillar bumps using the same test vehicle. A special test vehicle was designed with daisy chain structures for electromigration testing and the packages we assembled on test cards. The testing is being done using five (5) stress conditions (combination of current and temperature) to estimate the current density exponent, n, and activation energy, Ea, parameters for Black's equation. The reliability data as well as failure modes for these bump metallurgies will be presented in the paper.
NCP (Non Conductive Paste) for Narrow Gap Flip Chip Package and TSV Package
Authors: Abe Hidenori , Masuda Tomoya , Kondo Yuko , Takahashi Hiroshi
Published: October 2015

Pre-applied process followed by mounting chip and underfill at the same time is considered as promising underfill process for coming finer pitch and narrower gap flip chip package with Cu pillar and also TSV package with micro bumps. On the other hand, conventional mass reflow could introduce too much stress on low-k chip with advanced node. Pre-applied underfill process can reduce stress on low-k chip by dispersing stress into underfill material at the connection with thermal compression bonding process. One of the challenges of thermal compression bonding process with NCP is trapping material and poor connection at the bonding area. Creeping and voiding are other challenges for NCP. This presentation reports material design of a new NCP, features, and reliability results. Our newly developed NCP material was dispensed smoothly, and didn't cause creeping up on the backside of the chip. While low thixotropic NCP tends to create voids because of easier NCP spreading out when chip is mounted, this NCP material showed good performance in terms of voiding because of high thixotropic index, less spreading out even under heating condition (<80degC) and reduced out gas in this material. We explored appropriate fluxing material inside NCP, optimized filler size and distribution, viscosity, thixotropic index and curing behavior to avoid trapping issue. Cross-section of bonding area showed sufficient solder wetting and this NCP material had excellent connectivity. In addition, this NCP material can be processed in a very short time. The TV underfilled by this NCP material was subjected to reliability tests, and passed 5x reflow test (JEDEC standard preconditioning Level 3), 1000 cycles of temperature cycle test (−55degC to 125degC), and 200 hours of biased HAST test (135degC/85%RH/1.3V).
Magnetic Field Imaging for 3D applications
Authors: Gaudestad Jan , Orozco Antonio
Published: October 2015

The challenges that 3D integration present to Failure Analysis require the development of new Fault Isolation techniques that allows for non-destructive, true 3D failure localization.

By injecting a current in the device under test (DUT), the current generates a magnetic field around it and this magnetic field is detected by a sensor above the device. Magnetic field imaging (MFI) is a natural candidate for 3D Fault Isolation of complex 3D interconnected devices. This is because the magnetic field generated by the currents in the DUT passes unaffected through all materials used in device fabrication; the presence of multiple metal layers, dies or other opaque layers do not have any impact on the magnetic field signal. The limitations of the technique are not affected by the number of layers in the stacked devise in samples such as wirebonded stacked memory, Through Silicon Via (TSV) stacked die or even package on package (PoP). The sample is raster scanned and magnetic field is acquired at determined steps providing a magnetic image of the field distribution. This magnetic field data is typically processed using a standard inversion technique to obtain a current density map of the device. The resulting current map can then be compared to a circuit diagram, an optical or infrared image, or a non-failing part to determine the fault location. Today, giant-magnetoresistive (GMR) sensors have been added to the Superconducting Quantum Interference Device (SQUID) sensor to allow higher resolution and Fault Isolation (FI) I at die level.

Magnetic Field Imaging (MFI), using SQUID as the high sensitive magnetic sensor in combination with a high resolution GMR sensor. A solver algorithm capable of successfully reconstructing a 3D current path based on an acquired magnetic field image from both sensors has been developed. The generic 3D inverse problem has no unique solution. Given a particular 3D magnetic field distribution, there are an infinite number of current path distributions that will result in such magnetic field. This ill-posed problem has restricted, so far, the use of magnetic imaging to 2D. A different kind of 3D solver can be constructed, nevertheless capable of obtaining a single solution.

The 3D solver algorithm is not only capable of extracting the 3D current path, but it also provides valuable geometrical information about the device. Accurately being able to position each current segment in a layer allows the FA engineer to follow the current as it vertically moves from one die (or layer) to another. [1,2,3]
Performance Improvement of RF Inductors Using LTCC Technology
Authors: Radosavljević Goran , Marić Andrea , Smetana Walter , Živanov Ljiljana
Published: October 2015

This paper presents for the first time a parallel comparison of the performance of RF inductors realized on different substrate configurations. Presented inductors are meander type structures fabricated in Low Temperature Co-fired Ceramic (LTCC) technology. Also, chosen material is never before implemented for inductor fabrication. The performance improvement is achieved by design optimization of different substrate configurations that incorporate placement of an air-gap beneath the inductor and/or introduction of an additional shielding layer on the top. Designed structures are characterized on the basis of simulation and experimental data, achieving good correlation between obtained results. Presented results show over 30 % increase in quality factor and widening of the operating frequency range by over 55 %.
Aerosol Printing of High Resolution Films for LTCC-Multilayer Components
Authors: Ihle Martin , Partsch Uwe , Mosch Sindy , Goldberg Adrian
Published: October 2015

For the electronic packaging of sensor stable and cost-efficient fine-line printing technologies on LTCC and high frequency laminates are needed. Especially common technologies like screen printing and thin film techniques are unsuitable for fine structures or too expensive. In addition there is no direct write technology for 3D-LTCC-designs as well as for high reliability Co-firing structures. Closing this gap the aerosol printing technology is used to print high resolution conductors on planar and non-planar substrates.

Aerosol printing is a direct write non-contact printing technology of functional layers. After a pneumatic atomization the ink is transformed into 1 to 5 μm droplets. The resulting, continuous aerosol stream is focused by a sheath gas in the printing head. Thus the long standoff distance between substrate and deposition tip of max. 5 mm allows the 3D-printing on non-planar substrates. With optimized inks and printing parameters line widths of 10 μm are achievable. This paper will present applications for aerosol printed functional layers on LTCC. These are, for example, aerosol printed films embedded in co-fired LTCC, fine line structures for high frequency applications and the evaluation of printed 3D-structures like LTCC-stairways. Furthermore the 90 degree contacting of unconventional sensor designs will be presented.
LTCC Antenna Array with Integrated Liquid Crystal Phase Shifter for Satellite Communication
Authors: Heunisch Andreas , Schulz Bärbel , Rabe Torsten , Strunck Sebastian , Follmann Rüdiger , Manabe Atsutaka
Published: October 2015

Low Temperature Cofired Ceramic (LTCC) is used as a substrate material for microelectronic devices in satellite communication. Its dielectric properties and excellent variability allows a good compactness and a high level of integration. An LTCC antenna array for microwave signals operating at 30 GHz is presented. All components such as radio frequency distribution network, four waveguide phase shifters and horn antennas are integrated in one ceramic module. The phase shifters are implemented as high volume cavities in the LTCC. A tailored mixture of liquid crystal can be stored inside the cavities. By applying an electric field, the anisotropic LC-molecules are aligned. The field is provided through a biasing network with four electrodes and screen printed resistive layers with resistance values in the MΩ/□ range. The alignment and with it the phase shifting is nearly seamless. The antenna module is manufactured in multilayer technology and consists of more than 40 layers. Lamination is carried out by thermocompression in two steps. A water based adhesive is used in the second. The cofiring is done in a sintering press. Temperature and pressure profile are chosen carefully, considering the high volume of the laminate and the buried cavities inside the module. After sintering, the horn antennas are milled into the front side of the ceramic body, which is about 5 mm in height.