bluuebunny/crossref_metadata_2025 huggingface dataset:
Wavelength Tunable Random Laser
Authors: Tikhonov E. , Yashchuk Vasil P. , Prygodjuk O. , Bezrodny V.
Published: March 2009

Continuously tunable random laser basing on rhodamine 6G was achieved. Wavelength tuning was implemented by wedge-shaped sample shift relatively to the pump beam. The physical base of the tuning method is gain band shift caused by reabsorption. We ascertained that two medium thickness ranges of significantly different tune efficiency exist. The lasing characteristics of the laser were investigated depending on active medium and pump beam parameters. The feedback formation mechanisms in the random lasers of different thickness were analyzed.
Potential of Nano-Sized Rare Earth Fluorides in Optical Applications
Authors: Kynast Ulrich H. , Lezhnina Marina M. , Kätker H.
Published: March 2009

Rare earth fluorides are a class of materials with a high potential for optical applications. Fluoride lattices allow high coordination numbers for the hosted rare earth ions, but the high ionicity of the rare earth to fluorine bond leads to a wide band gap and very low vibrational energies. These two essential factors, in particular, contribute to their practicality for use in optical applications based on vacuum ultraviolet (VUV) and near infrared (NIR) excitation. The preparation and optical characteristics of rare earth fluoride nanoparticles and their embedding in polymeric, glassy or porous matrices are very promising for the eventual manufacture of transparent hybrid materials. Recent attempts to control the size of these particles down to the nano-scale and, at the same time, maintaining the performance of their macroscopic counterparts, indicate accessibility of hitherto unrealized optical properties and applications.
Ion Beam Modification of Carbon Materials
Authors: Iwaki Masaya
Published: March 2009

A study has been made of surface properties of carbon materials modified by ion beams. Substrates used were natural diamonds, glass-like carbon plates and polymer sheets. Ion species were chemically-active elements such as C, N and O, inert gas elements such as He, Ne and Ar, and metallic elements such as Cr and Ti. It was found that diamond becomes electrically conductive in ion implanted layers, which are amorphous or graphite-like structures. Electrical conductivity depends on implanted species, doses and target temperatures. It was found that glass-like carbon consisting of graphite and disordered graphite becomes amorphous due to ion beam bombardment. Amorphization causes the wear resistance to improve. The electrochemical properties changes depending on implanted species. The wear resistance and electrochemical properties depended on the target temperature during ion implantation. Ion beam bombardment to polymers has been
carried out to control the electrical conductivity, cell adhesion and bio-compatibility. The electrical
conductivity of polyimide films increases as the dose increases. The saturated sheet resistivity of
implanted layers depends on ion species, dose and dose rate. It was found that the cell adhesion can
be controlled by ion beam bombardment. The results were used in the fields of clinical
examinations. In summary, ion beam bombardment to carbon materials is useful to control the
carbon structures and surface properties depending on ion implantation conditions.
Improve Stability of Dicalcium Silicate/Zirconia Composite Coatings by Post-Spraying Heat Treatment
Authors: Xie Youtao , Chu Paul K. , Liu Xuan Yong , Ding Chuan Xian
Published: March 2009

The long-term stability of plasma-sprayed dicalcium silicate (C2S) composite coatings is determined by the phase composition, crystallinity, and other properties. Zirconia reinforcement and post-spraying heat treatment are applied to C2S coatings simultaneously in this work. The stability of the coating increases evidently by reinforcement with 70wt% zirconia and heat treatment at 800oC for 4 hours. SEM reveals that the smooth glassy surface of the as-sprayed coatings is replaced by randomly dispersed crystals. Tris-HCl immersion test results show that the dissolution rate of the composite coatings decreases after the heat treatment.
The Progress of the Research and Application of Ion Implantation Biotechnology in China
Authors: Wu Yue Jin , Zhang Ying , Yu Wang , Song Mei , Yu Zeng Liang
Published: March 2009

This paper summarizes the development of the research and application of ion implantation biotechnology on plant, animal and microorganism varieties Improvement, and it also includes the contemporary effects and utilization of ion implantation, and the application of ion implantation on trans-gene plant.
In 1980s, cooperated with Anhui Academy of Agriculture Sciences, the ion implantation was applied for crops’ improvement by Plasma Physics Research Institute of the Chinese Academy of Sciences, and made greater progress in both practice and theory, which attracted many scholars inside and outside. By using ion implantation, extensive researches had been made in different materials including plant, animal and microorganism on different levels. With combination of physics and biology, as a new cross subject and a unique technology system, the ion implantation biotechnology came into being, and created more dramatically economic and social benefit in crops improvement by transferring exogenous gene. This paper summarizes the development of the research and application of ion implantation biotechnology.
Bunch Compression of a Non-Relativistic 280-keV-He+ Beam
Authors: Junphong P. , Ano V. , Lekprasert B. , Suwannakachorn D. , Vilaithong Thiraphat , Wiedemann H.
Published: March 2009

At 150 kV-pulsed neutron generator at the Fast Neutron Researh Facility is being upgraded to produce a 280-kV-pulsed-He beam for Time-of-Flight Rutherford Backscattering Spectrometry (TOF RBS). Modification are being done by replacing the existing beamline elements by a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. Radiofrequency (RF) of 2 MHz is used for the chopper and 4 MHz for the buncher. For the buncher the RF amplitude of 13 kV is applied to two gaps, so that the ion pulse is compressed twice. An optimized geometry for the 280-keV pulsed helium ion beam is presented in this paper,. The PARMELA code has been used to optimize the space-charge effect, resulting in a excitated pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between the chopper and buncher have been included in the optimization of the bunch lengh.
Inactivation and Destruction of Bacillus Subtilis Using a Low Pressure Glow Discharge Plasma
Authors: Ramos Henry J. , Pineda Prydex H. , Siringan Ma. Auxilia T.
Published: March 2009

Radicals like atomic oxygen, the hydroxyl OH and charged particles directly affect outer membranes of biological cells such as microorganisms. Low pressure glow discharges of oxygen and hydrogen peroxide (3% concentration H2O2) produced these radicals and charged particles, and their effect on the inactivation or destruction of Bacillus subtilis were investigated. Artificially contaminated 65 cm2 Petri dishes with a pure culture of the microorganism were used to test the efficiency of the plasma treatment. Cell density of the spore suspension of a 24-hour nutrient agar containing the culture is estimated at 1.5x109 cells/ml using standard plate count techniques. The effect of varied discharge conditions (450V and 500V), gas flow rate (20-60 sccm), sample temperature and exposure time (30-60 minutes) on the decimal reduction value (DRV or D-value), that is, the time required to inactivate or destroy 90% of the original population of microorganisms were determined.
Results indicate that for the H2O2 plasma, at a discharge potential of 500V, the DRV is 11.83 minutes with a 99.6% destruction of microorganisms in 60 minutes. For oxygen plasma, the DRV is 10.57 minutes and 99.33% reduction in 60 minutes. The sample temperature in the H2O2 plasma exposure reached a maximum of 109 oC in an hour, while that in the oxygen plasma peaked at 46 oC in less than an hour. These DRV, cycle time and temperature values are much better when compared to common sterilization methods like autoclave, dry heat and gas like ethylene oxide.
Sterilization Performance of Ultraviolet Emission from Laser Plasmas
Authors: Murai K. , Miyano Yasushi , Hirotani K. , Tsukamoto Masahiro , Kikuchi Yoshio
Published: March 2009

A pulsed YAG laser beam was focused with a lens in order to produce laser plasmas by laser-induced gas breakdown inside the gas cell. The most intense UV emissions between 200 and 300 nm in wavelength was generated by the Xe gas breakdown. UV emission from laser plasma by Xe gas breakdown showed the best sterilization performance compared with those by other gas breakdown.
Intrinsic Point Defects in Silicon: a Unified View from Crystal Growth, Wafer Processing and Metal Diffusion
Authors: Voronkov Vladimir V. , Falster Robert J.
Published: March 2009

There are several phenomena where the properties of vacancies and self-interstitials in silicon are manifested in straightforward ways. These include the formation of grown-in microdefects, the diffusion of metals (such as Au, Zn), self-diffusion and the installation of vacancy depth profiles in wafers by Rapid Thermal Annealing. Combining features extracted from the analysis of these phenomena, it is possible to define the diffusivities and equilibrium concentrations of the intrinsic point defects. Their diffusivities are remarkably high, and have weak temperature dependence. Their equilibrium concentrations are very low, and have strong temperature dependence.
Precipitation Enhancement of "so Called" Defect-Free Czochralski Silicon Material
Authors: Müller Timo , Kissinger G. , Krottenthaler P. , Seuring C. , Wahlich R. , von Ammon Wilfried
Published: March 2009

Thermal treatments to enhance precipitation like RTA, ramp anneal and argon anneal were performed on low oxygen 300 mm wafers without vacancy or interstitial agglomerates (“so called” defect-free material). Best results were achieved using high temperature argon anneal leading to a homogenous BMD and denuded zone formation. Furthermore the getter efficiency was positively tested by intentional Ni-contamination. Concepts to overcome the slip danger like improved support geometries and nitrogen codoping were also evaluated and are seen to be beneficial.
Formation of the Buried Insulating SixNy Layer in the Region of Radiation Defects Created by Hydrogen Implantation in Silicon Wafer
Authors: Frantskevich A.V. , Saad Anis M. , Fedotov A.K. , Mazanik A.V. , Frantskevich N.V.
Published: March 2009

The radiation defects in 10 Ω⋅cm p-type and 4.5 Ω⋅cm n-type Cz Si were created at depth of 0.8-1 µm using 100 keV 2⋅1016 at/cm2 hydrogen implantation at room temperature. Then the introduction of nitrogen into silicon and its diffusion were carried out at different thermodynamic conditions. Finally, the samples were vacuum annealed at 800 oС during 2 h. The state of sample surfaces was studied by SEM. The depth and thickness of SixNy layer and also defect numbers were estimated by RBS method in the channeling mode. The electrical properties of the obtained structures were characterized by the transversal conductance measurements with the keep of a standard LCR-meter at a frequency of 1 MHz using the two-probe method. Our experiments have shown that the above-described method enables one to form the buried SiхNy layer with dielectric properties and the number of defects and nitrogen atoms on the silicon surface and in the near-surface region are comparable with those for the initial silicon wafers.
Metastable VO2 Complexes in Silicon: Experimental and Theoretical Modeling Studies
Authors: Murin L.I. , Lindström J. Lennart , Markevich Vladimir P. , Medvedeva I.F. , Torres Vitor , Coutinho J. , Jones R. , Briddon Patrick R.
Published: March 2009

We report on a combined experimental and theoretical study of the metastable form of the vacancy-dioxygen defect in Si labeled VO∗
2. Important new experimental observations are the detection of mixed local vibrational modes of VO∗ 2 in 16O,18O co-doped samples, the determination
of the position of LVM bands for the negatively charged defect, and an assignment of an acceptor level at about Ec − 0.05 eV. Defect energetics, electrical levels and LVM frequencies of the VO∗ 2 complex are also investigated by ab-initio density-functional modeling.We find it to be a bistable defect which accounts well for the experimental data. The metastable form produces an acceptor state at 0.05 eV
below Ec, and can be thought of as a VO defect perturbed by interstitial oxygen.
Hydrogen-Related Donors in Silicon: Centers with Negative Electronic Correlation Energy
Authors: Pokotilo Yurii M. , Petukh Alla N. , Litvinov Valentin V. , Tsvirko B.G.
Published: March 2009

The transformation of the shallow hydrogen-related donors, which have been formed in the silicon samples by irradiation of the low energy (300 keV) protons and following heat treatment under 350 0С or 450 0С was investigated. The experiment was carried out on Ag-Mo-Si Shottky diodes and diodes with shallow p+-n-junction. The concentration and distribution of these donors were defined by C-V-method at 1.2 MHz frequency. Using temperature dependence of equilibrium electron concentration it was established, that the hydrogen-related donors were charged controlled centers with negative electronic correlation energy (U<0). The transformation between both equilibrium configurations of the double hydrogen-related donor takes place when value of the Fermi level is arranged near Ec-0.30 eV. It was revealed that the donor transformation from neutral into double charged state have been stimulated by minority carriers trapping under room temperature when Fermi level was higher then level of the double electron occupation E(0/++)= Ec-0.30 eV.
Study of Au Diffusion in Nitrogen-Doped FZ Si
Authors: Yakimov Eugene B.
Published: March 2009

Depth profiles of Au in nitrogen-doped FZ p-Si have been studied by the DLTS after diffusion at 680 - 730°C. It was shown that the Au depth profile could be described by trap-limited diffusion. To explain the experimental profiles the existence of two traps with different capture radius should be assumed. A formation of new electrically active center is detected at a depth close to that of sharp decay in Au concentration. This center is assumed to be a result of Au capture by nitrogen-vacancy complexes and could be associated with the substitutional gold neighboring nitrogen and/or vacancy.
VOn (n≥3) Defects in Irradiated and Heat-Treated Silicon
Authors: Murin L.I. , Lindström J. Lennart , Svensson Bengt Gunnar , Markevich Vladimir P. , Peaker Anthony R. , Londos Charalamos A.
Published: March 2009

Local vibrational mode (LVM) spectroscopy has been used to study the evolution of vacancy-oxygen-related defects (VOn) in the temperature range 300-700°C in carbon-lean Cz-Si samples irradiated with MeV electrons or neutrons. New experimental data confirming an attribution of the absorption bands at 910, 976 and 1105 cm-1 to the VO3 complex are obtained. In particular, a correlated generation of VO3 and the oxygen trimer is observed upon irradiation of Cz- Si crystals in the temperature range 300-400°C. Strong evidence for the assignment of the bands at 991 and 1014 cm-1 to a VO4 defect is presented. The lines are found to develop very efficiently in the VO2 containing materials enriched with the oxygen dimer. In such materials the formation of VO4 is enhanced due to occurrence of the reaction O2i+VO2 ⇒ VO4. Annealing of the VO3 and VO4 defects at T ≥ 550C °C is found to result in the appearance of new defects giving rise to a number of O-related LVM bands in the range 990-1110 cm-1. These bands are suggested to arise from VO5 and/or VO6 defects. Similar bands also appear upon the annihilation of oxygen-related thermal double donors at 650°C in Cz-Si crystals pre-annealed at 450°C.
Formation and Properties of Iron-Phosphorus and Iron-Phosphorus-Hydrogen Complexes in Silicon
Authors: Mchedlidze Teimuraz
Published: March 2009

Hitherto unreported ESR signal, labeled TU10, was detected after annealing of electronirradiated silicon samples doped with phosphorus, iron and hydrogen. The ESR spectrum corresponds to a complex having monoclinic-I symmetry and S = 3/2 spin-state. Hyperfine structure of the TU10 spectrum suggests participation of two nucleus with spin I = 1/2 and 100% abundance in the core of the related defect. Doping of samples with hydrogen-deuterium mixture revealed presence of one hydrogen atom in the complex. The second nucleus with I = 1/2 is apparently a phosphorus atom. Presence of single iron atom was verified by doping with iron heaving modified isotope content. An intensity of the previously reported TU6 signal, related to iron-phosphorus complex, was significantly suppressed in hydrogen-doped samples.
General Model of Diffusion of Interstitial Oxygen in Silicon, Germanium and Silicon - Germanium Crystals
Authors: Gusakov Vasilii E.
Published: March 2009

A theoretical modelling of the oxygen diffusivity in silicon, germanium and Si1-xGex (O) crystals both at normal and high hydrostatic pressure has been carried out using molecular mechanics, semiempirical and ab initio methods. It was established that the diffusion process of an interstitial oxygen atom (Oi) is controlled by the optimum configuration of three silicon (germanium) atoms nearest to Oi. The calculated values of the activation energy Ea (Si) = 2.59 eV, Ea(Ge) = 2.05 eV and pre-exponential factor D0(Si) = 0.28 cm2 s−1, D0(Ge) = 0.39 cm2 s−1 are in good agreement with experimental ones and for the first time describe perfectly the experimental temperature dependence of the Oi diffusion constant in Si crystals (T = 350–1200 °C). Hydrostatic pressure (P ≤ 80 kbar) results in a linear decrease of the diffusion barrier (∂P Ea (P) = −4.38 × 10−3 eV kbar−1 for Si crystals). The calculated pressure dependence of Oi diffusivity in silicon crystals agrees well with the pressure-enhanced initial growth of oxygen-related thermal donors. The simulation (PM5) has revealed that in Si1-xGex crystals there are two mechanisms of variation of Oi diffusion barrier. The increase of lattice constant leads to the linear increase of the diffusion barrier. Strains around Ge atoms decrease the diffusion barrier. Formation of gradient of diffusion barrier in the volume of Si1-xGex may be responsible for the experimentally observed suppression of generation of TD in Si1-xGex (O) crystals.
Low-Temperature Radiation Enhanced Diffusion of Implanted Platinum in Silicon with Increased Controllability
Authors: Hazdra Pavel , Vobecký Jan
Published: March 2009

The in-diffusion of platinum into a low-doped n-type float zone silicon guided and enhanced by radiation damage produced by co-implantation of helium ions was investigated. The implantation of 1 MeV platinum ions at different doses ranging from 5×1011 to 3×1014 cm-2 was used to produce a finite source for platinum diffusion. Single and multiple energy implantation of helium ions with energies 7, 9, 11 and 13 MeV and doses from 5×1011 to 1×1013 cm-2 were applied to enhance and shape the diffusion of platinum atoms performed by 20 minutes annealing at 725°C in vacuum. Results show that diffusion of platinum at these conditions is fast enough to reach an equilibrium decoration of vacancy-related defects up to the depth of hundred micrometers. Analysis of the resulting platinum profiles indicates, that transformation of diffusing platinum interstitials to stable substitutional position is mainly given by Frank-Turnbull mechanism controlled by vacancy-related defects while the kick-out mechanism may play role at the peak of the radiation damage and at higher doses of helium implantation (>1012 cm-2). It is also shown that an extra annealing performed prior to helium implantation substantially increases the amount and localization of in-diffused platinum.
Formation of Vacancies and Divacancies in Plane-Stressed Silicon
Authors: Nicolaysen S. , Ganchenkova Mariya G. , Nieminen Risto M.
Published: March 2009

The effect of compressive and tensile plane-stress loading on formation energies and electronic properties of vacancies and divacancies in silicon are studied by first-principles approach for in-plane strains up to 0.7%. It is demonstrated that contributions to defect formation energies from the elastic lattice relaxation and from the band structure modification respond to stress in a different manner, leading to noticeable different behaviour of formation energies for different charges states. The most stable vacancy charge states at different Fermi level are shown to be sensitive to strain magnitude and sign. This results in the strain-induced shifts and even disappearance of some of thermal ionization levels of vacancies and divacancies in the band gap.
Selective SiGe Etching Formed by Localized Ge Implantation on SOI
Authors: Bourdon Helene , Fenouillet-Béranger Claire , Gallon Claire , Coronel Philippe , Lenoble Damien
Published: March 2009

The fully depleted SOI devices present lateral isolation issues due to the shallow trench isolation (STI) process. We propose in this paper to study a new fabrication process for integrating local isolation trenches. Germanium (Ge) implantation is used to create SiGe (Silicon-Germanium) layer on thin SOI (silicon on insulator) that can be selectively etched. The advantage is the capability of implantation to localize the SiGe area on this substrate and to avoid STI process issues. Aggressive dimensions and geometries are studied and resulting material transformation (crystallization and Ge diffusion) are apprehending via SEM (Secondary Electron Microscopy) or AFM (Atomic Force Spectroscopy) to understand the etching kinetics. After optimization, we demonstrate the capability of fabricating localized trenches on SOI without degrading the neighboring Si layer or consuming the thin BOX (buried oxide).
The Role of Silicon Interstitials in the Formation of Boron-Oxygen Defects in Crystalline Silicon
Authors: Macdonald Daniel , Deenapanray Prakash N.K. , Cuevas Andres , Diez S. , Glunz Stephan W.
Published: March 2009

Oxygen-rich crystalline silicon materials doped with boron are plagued by the presence of a well-known carrier-induced defect, usually triggered by illumination. Despite its importance in photovoltaic materials, the chemical make-up of the defect remains unclear. In this paper we examine whether the presence of excess silicon self-interstitials, introduced by ion-implantation, affects the formation of the defects under illumination. The results reveal that there is no discernible change in the carrier-induced defect concentration, although there is evidence for other defects caused by interactions between interstitials and oxygen. The insensitivity of the carrier-induced defect formation to the presence of silicon interstitials suggests that neither interstitials themselves, nor species heavily affected by their presence (such as interstitial boron), are likely to be involved in the defect structure, consistent with recent theoretical modelling.
Silicon Layers Grown on Siliconized Carbon Net: Producing and Properties
Authors: Brantov Sergei K. , Kveder Vitaly V. , Kuznetzov N.N. , Orlov Valeri I.
Published: March 2009

The paper describes the elaboration of a method for producing composite Si/SiC wafers and investigation of their properties. The known two-shaping elements (TSE) method was used to produce the material. Pilot tests show that this composite material can be used for production of solar cells. The structure of silicon grains is elongated relative to the growth direction, the dislocation density in grains is of about (5÷8) ×104 cm-2, the average lifetime of minority carriers is 4÷6 µs.
Crack Detection and Analyses Using Resonance Ultrasonic Vibrations in Full-Size Crystalline Silicon Wafers
Authors: Belyaev A.E. , Polupan O. , Dallas W. , Ostapenko Sergei S. , Hess D. , Wohlgemuth John
Published: March 2009

An experimental approach for fast crack detection and length determination in fullsize solar-grade crystalline silicon wafers using a Resonance Ultrasonic Vibrations (RUV) technique is presented. The RUV method is based on excitation of the longitudinal ultrasonic vibrations in full-size wafers. Using an external piezoelectric transducer combined with a high sensitivity ultrasonic probe and computer controlled data acquisition system, real-time frequency response analysis can be accomplished. On a set of identical crystalline Si wafers with artificially introduced periphery cracks, it was demonstrated that the crack results in a frequency shift in a selected RUV peak to a lower frequency and increases the resonance peak band width. Both characteristics were found to increase with the length of the crack. The frequency shift and bandwidth serve as reliable indicators of the crack appearance in silicon wafers and are suitable for mechanical quality control and fast wafer inspection.
Behaviour of Natural and Implanted Iron during Annealing of Multicrystalline Silicon Wafers
Authors: Macdonald Daniel , Roth Thomas , Geerligs L.J. , Cuevas Andres
Published: March 2009

Changes in the concentration of interstitial iron in multicrystalline silicon wafers after high temperature annealing (900°C) have been monitored by carrier lifetime measurements. Two cooling rates were investigated. The first was considered ‘fast’, meaning the interstitial Fe had no time to diffuse to precipitation sites, and should therefore be frozen-in, despite being far above the solubility limit at lower temperatures. A second ‘slow’ cool down to 650°C allowed ample time for the Fe to reach the surfaces or other internal precipitation sites. Surprisingly, in both cases the Fe remained in a supersaturated state. This indicates the precipitation process is not diffusion-limited, and that another energetic barrier to precipitate formation must be present. Since the slow cooling used here is similar to the cooling rate experienced by multicrystalline ingots after crystallisation, this precipitate-impeding mechanism is probably responsible for the surprisingly high interstitial Fe concentrations often found in as-grown multicrystalline silicon wafers.
Cobalt Contamination in Silicon
Authors: Polignano Maria Luisa , Caputo Daniele , Codegoni Davide , Privitera Vittorio , Riva M.
Published: March 2009

The properties of cobalt as a contaminant in p-type silicon are studied by using cobaltimplanted wafers annealed by RTP or by RTP plus a low temperature furnace annealing. It is shown that after RTP most cobalt is under the form of CoB pairs. A quantification of cobalt contamination is provided based upon SPV measurements and optical pair dissociation. However, this quantification fails in furnace-annealed wafers because of the formation of a different level. It is shown that the CoB level is located near the band edges, whereas the level formed upon a low temperature furnace annealing is located near midgap. Besides, when the cobalt concentration is high enough a small fraction of cobalt is in a level different from the CoB pair even in RTP samples. This level can probably be identified with a previously observed midgap level. It is suggested that the same level is formed in RTP plus low temperature furnace annealed samples and in high concentration RTP annealed samples, and that this level may consist in some cobalt agglomerate.
Improved Measurement of Carbon in Poly- and CZ Crystal Silicon by Means of Low Temperature FTIR
Authors: Porrini M. , Crössmann Ivo , Pretto M.G. , Scala R. , Wolf Reinhard
Published: March 2009

This work proposes some improvements over the current state-of-the-art of carbon measurement in silicon by means of Fourier Transform Infrared Spectroscopy (FTIR) at low temperature (77 K), as described in the ASTM F1391-93 (2000) standard method.
The Employment of Cathodoluminescent Method for Characterization of Silicon Oxide - Silicon Interface
Authors: Zamoryanskaya M.V. , Sokolov V.I.
Published: March 2009

In this work we studied the cathodoluminescence (CL) of thin silicon oxide and natural silicon oxide grown on different types of silicon substrates (p-silicon and n-silicon with different content of boron and phosphor). At the same time we studied the distribution of intrinsic defects on depth for thermal silicon oxide films with depth resolution 10-20 nm. The method of local cathodoluminescence was used for definition the structure defects in SiO2 think layer and control of the quality of SiO2-Si interface.
Blue Photoluminescence from Quantum Size Silicon Nanopowder
Authors: Efremov M.D. , Volodin Vladimir A. , Marin D.V. , Arzhannikova Sofia A. , Ivanov M.G. , Gorajnov S.V. , Korchagin A.I. , Cherepkov V.V. , Lavrukhin A.V. , Fadeev S.N. , Salimov R.A. , Bardakhanov S.P.
Published: March 2009

Silicon nanopowders were produced using electron-beam-induced evaporation of bulk silicon ingots in various gas atmosphere. Optical properties of the nanopowders were studied with the use of photoluminescence and Raman spectroscopy techniques. Photoluminescence peaks in the visible region of the spectrum have been detected at room temperature in silicon nanopowders, produced in argon gas atmosphere. Strong short-wavelength shift of the photoluminescence peaks can be result of quantum confinement effect for electrons and holes in small silicon nanocrystals (down to 2 nm in diameter). The size of silicon nanocrystals was estimated from Raman spectroscopy data. The calculated in frame of effective mass model optical gaps for silicon nanocrystals of spherical shape are in good correlation with experimental photoluminescence data. The attempts of deposition of silicon nanocrystal films from the nanopowders on silicon substrates were carried out.
Silicon Carbide: Defects and Devices
Authors: Roccaforte Fabrizio , Di Franco Salvatore , Giannazzo Filippo , La Via Francesco , Libertino Sebania , Raineri Vito , Saggio Mario , Zanetti Edoardo
Published: March 2009

In this paper, some basic aspects related to defects and SiC devices performances are discussed. Our recent work is reviewed and inserted in the international research scenario. In particular, some issues relative to rectifying metal/SiC contacts will be treated in more detail. In fact, establishing a correlation between material defects, processing induced defects and irradiation induced defects with the electrical behaviour of Schottky contacts is extremely important for the future optimization of almost all electronic devices, sensors and particle detectors.
Defect Removal, Dopant Diffusion and Activation Issues in Ion-Implanted Shallow Junctions Fabricated in Crystalline Germanium Substrates
Authors: Simoen Eddy , Satta A. , Meuris Marc , Janssens Tom , Clarysse T. , Benedetti A. , Demeurisse C. , Brijs B. , Hoflijk I. , Vandervorst W. , Claeys Cor
Published: March 2009

The formation of shallow junctions in germanium substrates, compatible with deep submicron CMOS processing is discussed with respect to dopant diffusion and activation and damage removal. Examples will be discussed for B and Ga and for P and As, as typical p- and n-type dopants, respectively. While 1 to 60 s Rapid Thermal Annealing at temperatures in the range 400-650oC have been utilized, in most cases, no residual extended defects have been observed by RBS and TEM. It is shown that 100% activation of B can be achieved in combination with a Ge pre-amorphisation implant. Full activation of a P-implant can also be obtained for low-dose implantations, corresponding with immobile profiles. On the other hand, for a dose above the threshold for amorphisation, a concentration-enhanced diffusion of P occurs, while a lower percentage of activation is observed. At the same time, dose loss by P out-diffusion occurs, which can be limited by employing a SiO2 cap layer.
Structural Characterization of Epitaxial Si / Pr2O3 / Si(111) Heterostructures
Authors: Zaumseil P. , Schroeder T. , Weidner G.
Published: March 2009

The use of heteroepitaxial Si / Pr2O3 / Si(111) systems as semiconductor-insulatorsemiconductor (SIS) stacks in future applications requires a detailed structural characterization. We used X-ray reflectivity (XRR) to control layer thickness and interface roughness, standard X-ray diffraction (XRD) to analyze the Pr2O3 phase, orientation and crystal perfection, and grazing incidence XRD to study the thin epitaxial Si top layer. Transmission electron microscopy (TEM) was used to prove the results by direct imaging on a microscopic scale. Pr2O3 grows epitaxially in its hexagonal phase and (0001) orientation on Si(111) substrates. An epitaxial Si overgrowth in (111) orientation and good perfection is possible, but such Si layers exhibit two stacking twins, one with the same in-plane orientation as the substrate and one rotated by 180° around the Si [111] direction.
Virtual Demonstration Tests of Large-Scale and Complex Artifacts Using an Open Source Parallel CAE System, ADVENTURE
Authors: Yoshimura Shinobu
Published: March 2009

The ADVENTURE project started as one of the research projects in the "Computational Science & Engineering" field selected for the "Research for the Future" Program sponsored by the Japan Society for the Promotion of Science during 1997-2002. Since March 2002, the project has continued as an independent project. In the project we have been developing an advanced general-purpose computational mechanics system, named ADVENTURE, running in various kinds of parallel and ditributed environments. The system is designed to be able to analyze a three-dimensional finite element model of arbitrary shape with 10-100 million DOFs mesh, and additionally to enable parametric and non-parametric shape optimization. The first version of the system has been released from the project website as open source software since March, 2002. 2,049 registered users in academia and industries have downloaded 12,827 modules and been using them, while one company has developed and released its commercial version named ADVENTUREcluster. The ADVENTURE system has been successfully implemented in various types of parallel and distributed environments including PC clusters, massively parallel processers such as Hitachi SR8000/MPP and the Earth Simulator, and Grid environments such as ITBL (IT-based Laboratory). The system has been successfully applied to solve various real world problems such as response of a full scale nuclear pressure vessel model and thermoelastic deformation of full scale electric mounting board of a mobile PC.
Numerical Modeling for the Characterization of Flow Excitation for the HDD Disk Vibration Control
Authors: Koo Ja Choon , Kang Sean W. , Han Y.S. , Choi Yeon Sun
Published: March 2009

This article presents a modeling method for air flow analysis of a hard disk drive. Air flow excitation causes disk vibration that aggravates TMR budget of the design of modern high performance hard drives. And it is the most expensive budget consumer so that controlling of the flutter becomes the primary design issue of the data storage industry. In the presented work, air flow excitation forces are characterized by LES modeling and the results are verified with experiments. A
squeeze-film-type disk damper is employed in the experiments and it is applied for a hardware design improvement for disk flutter reduction. LES and RANS are compared and alternately used in a calculation in order to minimize computational efforts.
The Effect of Surface Roughness on Wear-Life of DLC Coated Silicon Disk in Dry Sliding
Authors: Shin Kyung Seob , Cho Chung Woo , Lee Young Ze
Published: March 2009

Dry sliding wear resistance of DLC coated silicon disk with different surface roughness has been evaluated using a ball-on-disk sliding tester. It was found that the transfer layer formed on steel ball produced a low friction regime and the formation of transfer layer was more active with increasing the substrate surface roughness. The wear life of DLC coating was increased as increasing
the real area of contact.
Reliability of Buried Pipeline Using a Theory of Probability of Failure
Authors: Lee Ouk Sub , Kim Dong Hyeok , Choi Seon Soon
Published: March 2009

The reliability estimation of buried pipeline with corrosion defects is presented. The
reliability of corroded pipeline has been estimated by using a theory of probability of failure. And the reliability has been analyzed in accordance with a target safety level. The probability of failure is calculated using the FORM (first order reliability method). The changes in probability of failure corresponding to three corrosion models and eight failure pressure models are systematically investigated in detail. It is highly suggested that the plant designer should select appropriate operating
conditions and design parameters and analyze the reliability of buried pipeline with corrosion defects according to the probability of failure and a required target safety level. The normalized margin is defined and estimated accordingly. Furthermore, the normalized margin is used to predict the failure probability using the fitting lines between failure probability and normalized margin.
Excavation-Induced Buried Pipeline Failure – A Case Study
Authors: Yoo Chung Sik , Choi Byung Seok , Jung Hye Young
Published: March 2009

This paper presents a case history involving a failure of water pipeline due to a deep
excavation. The case history was analyzed using both the simplified method and more sophisticated finite element modeling. Also presented are the fundamentals of damage assessment of buried pipelines associated with deep excavation-induced ground movements. A number of ground displacement profiles pertinent to the damage assessment are introduced. The results of the analysis indicated that the excessive ground movement was the major cause for the failure. These results were
partly supported by the finite element analysis which takes the soil-pipe interaction effect account. It is demonstrated that although conservative, the simplified approach presented in this paper can be effectively used as a first-order method for excavation-induced pipeline damage.
Detection and Evaluation of Localized Damage under Creep-Fatigue Loading at 1000°F Using Acoustic Emission Technique
Authors: Oh Kwang Hwan , Jang Jun Ho , Jung C.K. , Han Kyung Seop
Published: March 2009

Acoustic emission (AE) technique was applied as a non-destructive test method to detect and evaluate the localized damage at high temperature environment. The creep-fatigue crack growth tests were carried out with the acquisition of AE signal at 1000°F. Under trapezoidal waveform loadings, AE results showed different features according to each damage mode. During the creep period, low and steady emissions were shown, while emissions were burst and high counts rate was
recorded during the fatigue loading. Based on these characteristics, damage contribution was expressed in terms of acoustic emission parameter as a part-time monitoring method. Comparisons of damage contribution with respect to lifetime showed the transient behavior from cycle-dependent to time-dependent process. In case of full-time monitoring, bilinear behavior between AE counts and life
was represented. From both monitoring results, it was confirmed that creep and fatigue damage can be characterized by means of emission features and AE is possible way to evaluate the localized damage at elevated temperature.
Corrosion Fatigue Characteristics of Artificially Sensitized Austenitic STS304
Authors: Choi Byung Bok , Bae Dong Ho
Published: March 2009

Austenitic stainless steel is a useful material for various industrial facilities such as the nuclear and steam power plant and the heavy chemical industry due to its good corrosion resistance and mechanical properties. However, it has also a large problem that austenitic stainless steel is sensitized in the welding process and its corrosion resistance and mechanical properties decreases by sensitization. Thus, in this paper, corrosion fatigue characteristics of artificially sensitized austenitic
STS304 were investigated through corrosion fatigue test. From the results, corrosion fatigue strength of sensitized STS304 was remarkably reduced compare to non-sensitized ones. And it is expected that corrosion fatigue life of TMCP steel can be nondestructively predicted using the DCPD method.
Preparation and Characterization of Porous Hydrogen Silsesquioxane by Sol-Gel Process
Authors: Cheng Yao Yi , Chang Chen Jung , Chan Chaung Chih , Peng Kuey Ming , Dai Chi An
Published: March 2009

This paper presents study on porous Hydrogen Silsesquioxane (HSQ) of dielectric constant near 2. Porous HSQ solution was spin-on coated and then treated by wet ammonia. During the treatment, HSQ film went through a sol-gel process. Pores were uniformly formed in HSQ film after a baking process to remove solvent. A solid network structure of porous HSQ was then formed after a high-temperature curing process. In this work, we compared the properties of porous HSQ with varying process time of wet ammonia treatment and curing
temperature. Change of chemical structure was analyzed by Fourier transform infrared (FTIR) spectrometry. We found that the cage structure of porous HSQ was reduced but the network structure was enhanced as treatment time of wet ammonia increased. Hardness and Young’s modulus were measured by nano-indentation technique. The adhesion strength of porous HSQ with silicon carbide was measured. Surface properties and electrical characterization of
porous HSQ with varying process conditions have also been examined.
Bioactive Gelatin-Siloxane Hybrids as Tissue Engineering Scaffold
Authors: Ren Lei , Osaka Akiyoshi , Yu B. , Shi Wei , Ge Dong Tao , Chen Song , Zhang Qi Qing
Published: March 2009

Ca2+-containing porous gelatin-siloxane hybrids were prepared using sol-gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A bone-like apatite layer was able to form in the Ca2+-containing porous gelatin-siloxane hybrids upon soaking in a stimulated body fluid. The porous gelatin-siloxane hybrids could release gentamicin sulfate which is
an antibiotic drug in bone chemotherapy. Thus, those hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.
Research on the Hybrid Fiber-Reinforced Microstructure of Chafer Cuticle
Authors: Chen Bin , Peng Xiang He , Cai C. , Dong Q.
Published: March 2009

In this paper, the microstructure of chafer cuticle is observed with a scanning electron microscope (SEM). The observation shows that the insect cuticle is a kind of biocomposite with hybrid structural characteristic of various chitin fibers embedded in protein matrix. The reinforced chitin fibers vary in size, shape, property and distribution, which are related to their location in the cuticle. Near the surface of the cuticle, the chitin fibers are smaller, stiffer, more circular, and
the orientations of the chitin-fiber plies are various. A kind of helicoidal layup is found. The dependence of fracture strength on the fiber diameter and the dependence of fracture toughness on the parameters related to helicoidal layup are experimentally investigated. It shows that the smaller fiber and the helicoidal layup endow the surface of the cuticle with higher fracture strength and toughness.
Estimation of Self-Injection Length in Heterostructures of YBa2Cu3O7-δ Superconductor and La0.67Ca0.33MnO3 Manganite
Authors: Khatua S. , Wanchoo S. , Bannerjee T. , Thakar C.M. , Malik S.K.
Published: March 2009

Epitaxial bilayers of YBa2Cu3O7-δ (YBCO) and La0.67Ca0.33MnO3 (LCMO) heterostructures have been prepared by pulsed laser deposition technique, the growth sequence being YBCO on LCMO. The length scale of the YBCO layer, which is rendered non-superconductor/insulator by selfinjection of the spin polarized quasiparticles, is estimated to be 850Å. This can be an important guiding parameter in spintronic device configuration/fabrication.
Co/CoO Hybrid Film by Post Annealing
Authors: Yi J.B. , Ding J.
Published: March 2009

Co/CoO hybrid films are prepared by annealing Co films with various ratio of oxygen of O2/Ar mixture. The nanocomposite film shows a relatively large exchange bias (5.32 kOe) and coercivity (HC-: 6.17 kOe) taken at 80 K when formed by post annealing at 473 K under 3% O2 for 1h. Both are much larger than that of Co/CoO nanocomposite by reactive sputtering with an oxygen
partial pressure. Investigation shows that the formation of interface by post annealing is of importance for the large exchange bias and enhanced coercivity. The surface CoO, grain size of CoO and composition may also contribute to magnetic properties of the post annealing film.
Effect of Surface Characteristics on Polystyrene/Clay Nanocomposite via Emulsion Polymerization
Authors: Park B.J. , Choi Hyoung Jin
Published: March 2009

Polystyrene/clay nanocomposite with organically modified montmorillonite was
synthesized via emulsion polymerization. Organic styrene monomer was first intercalated into intergalley of the clay hosts, followed by a typical emulsion polymerization with surfactant and initiator. To investigate the effect of clay loading, we also prepared PS/clay nanocomposites with different clay contents. Wide angle X-ray diffraction (XRD) and transmission electron microscopy
(TEM) showed that the emulsion polymerization of PS in the presence of clay produces partially exfoliated and intercalated nanocomposites. In order to study their rheological properties, the melt pallets of composite materials were prepared and measured via a rotational rheometer with a parallel plate geometry.
Microstructural Investigation of Particulate Reinforced Ti-Sn Metal Matrix Composites
Authors: Zhang Su Xia , Li Q.F. , Ho M.K. , Pook Siew Fei , Chandra M. , Yong M.S.
Published: March 2009

Titanium alloy is an attractive material for aerospace and automobile applications due to its lightweight and high strength. Titanium metal matrix composite (MMCs) is one of the promising materials which could be employed to enhance stiffness and wear resistance of titanium alloy. In this study, reinforcement of in-situ and ex-situ particulates has been investigated. The experimental results show that a dense microstructure with uniformly distributed in-situ TiB reinforcement phase in the Ti+B+Sn system could be obtained. It is present in either needle or blocky shape.
This process involved warm pressing of mixed powder in semi-solid stage followed
by sintering, which eliminated costly CIP and HIP processes. However, it is found
that the ex-situ particulates in the titanium metal matrix are not suitable as
reinforcements in Ti-Sn metal matrix as they either reacted with titanium during
sintering process or generated a void at the interface between the reinforcement and
the matrix.
Pillared Materials from Layer Titanosilicates?
Authors: Ferraris Giovanni
Published: March 2009

Heterophyllosilicates are mineral phases based on layers that are comparable with those of the better known TOT phyllosilicates. Precisely, the HOH layers occurring in the heterophyllosilicates are formally obtained from a TOT layer by periodically introducing five or six co-ordinated titanium in the silicatic T sheets that sandwich the octahedral O sheet. The structural analogy between smectites, from which the mesoporous pillared clays are prepared, and heterophyllosilicates suggests that in principle pillared materials based on HOH layers could be prepared. Field observations show that swelling can occur in heterophyllosilicates; however, these minerals are rare and their synthetic analogues must first be prepared before attempting pillaring, an operation that might lead to interesting results for materials science owing to the presence of titanium.