bluuebunny/crossref_metadata_2025 huggingface dataset:
Texture Transition in Ag-Pd Alloy Substrate for Superconducting Tapes
Authors: Zhang Zheng Rong , Sekine Kazuyoshi
Published: March 2009

In order to demonstrate the effect of deformation temperature on texture formation in silver alloy sheet for superconducting types, the deformation and annealing textures of Ag-10 at% Pd alloy rolled at the temperatures from -1960C to 1600C and subsequently annealed were examined. A single Copper type texture with high intensity in ODFs has been realized in this study. Based on the experimental results, a metallurgical processing to get a sharp single orientation type texture in Ag-Pd alloy has been presented for manufacturing highly oriented superconducting substrate tapes.
Biaxially Aligned Yttria Stabilized Zirconia and Titanium Nitride Layers Deposited by Unbalanced Magnetron Sputtering
Authors: Mahieu Stijn , Ghekiere Pieter , De Winter Griet , De Gryse Roger , Depla Diederik , Lebedev Oleg I.
Published: March 2009

Control of the texture and the biaxial alignment of sputter deposited films has provoked a great deal of interest due to its technological importance. Indeed, many physical properties of thin films are influenced by the biaxial alignment. In this context, extensive research has been established to understand the growth mechanism of biaxially aligned Yttria Stabilized Zirconia (YSZ) as a buffer layer for high temperature superconducting copper oxides. In this work, the growth mechanism in general and the mechanism responsible of the biaxial alignment in detail were investigated for thin films of YSZ and TiN deposited by unbalanced magnetron sputtering using non-aligned polycrystalline stainless steel substrates. The mechanism responsible for the preferential out-of-plane alignment has been investigated by performing depositions on a non-tilted substrate. However, to study the in-plane alignment a tilted substrate was used. The microstructure of the deposited layers was characterised by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The crystallographic alignment has been investigated by X-ray diffraction (XRD) (angular scans and pole figures) and by Selective Area Diffraction (SAD). It was observed that the deposited layers show a zone T or zone II structure and the layers with a zone T structure consist of faceted grains. There seems to be a correlation between the crystal habit of these faceted grains and the measured biaxial alignment. A model for the preferential out-ofplane orientation, the in-plane alignment and the correlation between the microstructure and the biaxial alignment is proposed.
Texture Analysis with Area Detectors
Authors: Helming Kurt , Preckwinkel Uwe
Published: March 2009

Starting from simple geometric considerations concerning directions and orientations, intelligent strategies for pole figure measurements were developed for the area detector. The amount and quality of texture information contained in measured or available data sets can be directly controlled. The texture approximation is done by the component method. The method does not have any restrictions concerning the grids of sample directions in the pole figures. An almost constant information depth can be obtained at a low angle of incidence of the primary beam for the study of thin surface layers.
Use of Neutron Diffraction for Describing Texture of Isostatically-Pressed Molybdite Powders
Authors: Sitepu H. , Brokmeier Heinz Günter
Published: March 2009

The modelling and/or describing of texture (i.e. preferred crystallographic orientation (PO)) is of critical importance in powder diffraction analysis - for structural study and phase composition. In the present study, the GSAS Rietveld refinement with generalized spherical harmonic (GSH) was used for describing isostatically-pressed molybdite powders neutron powder diffraction data collected in the ILL D1A instrument. The results showed that for texture in a single ND data of molybdite the reasonable crystal structure parameters may be obtained when applying corrections to intensities using the GSH description. Furthermore, the WIMV method was used to extract the texture description directly from a simultaneous refinement with 1368 whole neutron diffraction patterns taken from the sample held in a variety of orientations in the ILL D1B texture goniometer. The results provided a quantitative description of the texture refined simultaneously with the crystal structure. Finally, the (002) molybdite pole-figures were measured using the GKSS TEX2 texture goniometer. The results showed that neutron diffraction is an excellent tool to investigate the texture in molybdite.
Reaction Stresses among the Grains during Tensile Deformation of Polycrystalline Metals
Authors: Mao Wei Min , Chen Leng , Yang Ping , Yu Yong Ning
Published: March 2009

A new model describing the reaction stresses during plastic deformation of metals is proposed in which the reaction stresses among the grains and their accumulation are calculated. The model could overcome the shortages of the Sachs and Taylor deformation model. According to the model, the plastic strain tensor induced by activation of slip systems will produce certain elastic reaction stress in the surrounding matrix, which influences the choice of further activation of slip systems as well as the orientation evolution. The model gives more attention to both of the stress and strain compatibility among the grains. The simulation on the tensile deformation of pure copper indicates that the model could exhibit the main characteristics of the real deformation process.
Formation of Core-Shell Nanoparticles by Laser Ablation of Copper and Brass in Liquids
Authors: Kazakevich P.V. , Simakin A.V. , Voronov V.V. , Shafeev G.A. , Starikov D. , Bensaoula A.
Published: March 2009

Experimental results are presented on the ablation of copper and brass targets in a liquid environment: ethanol, acetone, or water by irradiation with either a pulsed copper vapour laser (0.51 μm) or a pulsed Nd:YAG laser (1.06 μm). The ablated material was ejected into the surrounding liquid as nanoparticles of average size 20 nm. The nanoparticle composition depends on the nature of the liquid. Ablation of 60%Cu, 40%Zn brass in ethanol results in formation of core-shell nanoparticles. Brass nanoparticles were characterized by a well-defined plasmon peak at 510-520 nm.
Plasma Treatment of Silk
Authors: Riccardi Claudia , Barni R. , Esena P.
Published: March 2009

Silk, as most of the natural textile fibres, shows many excellent qualities but also some defects. In particular natural fibres are in general delicate and cannot be treated under extreme conditions, for instance at high temperatures or in reactive solutions. This makes silk a very promising object for cold plasma treatment, which happens at room temperature in absence of solvents. A review of the different experimental results obtained at the research center PlasmaPrometeo on the surface modification of silk by various plasma processing will be presented.
Deposition of TiC on γ-TiAl Alloys by Directly Applying Voltages
Authors: Boonruang Chatdanai , Thongtem Titipun , McNallan Michael J. , Singkarat Somsorn , Thongtem Somchai
Published: March 2009

Two γ-TiAl alloys, Ti-47Al-2Nb-2Cr (MJ12) and Ti-47Al-2Nb-2Mn-0.8TiB2 (MJ47), were pressed in C powder to form rods and carburized by directly applying electrical power through them at 274.3 ± 26.4 W, 80 A for MJ12 and at 293.4 ± 16.8 W, 80 A for MJ47 in Ar atmosphere. The alloys were analysed using an x-ray diffractometer (XRD), a scanning electron microscope (SEM) equipped with an energy dispersive x-ray (EDX) analyser and a Rutherford backscattering spectrometer (RBS) incorporated with NUSDAN solfware. Knoop hardness and wear resistance were improved and found to be in accord with the analytical results.
A New Design and Computer Simulation of a 5-Electrode Ion Extraction/Focusing System
Authors: Medhisuwakul M. , Vilaithong Thiraphat , Engemann Jürgen
Published: March 2009

A 13.56 MHz radio-frequency (rf) driven multicusp ion source has been constructed [1] to produce a high argon ion current density. Milliampere-range argon ion current can be extracted from the source. An in-waveguide microwave plasma source has been utilized as the ion beam neutralizer [2]. The neutralization source was placed 20 cm downstream from the extraction system. With the former extraction system, comprised of extraction electrodes and an Einzel lens, the electrons from the neutralizer were attracted to the high positive potential of the lens. Consequently, the potential of the lens drops and the beam is diverged. To suppress electrons from being accelerated to the Einzel lens a negatively biased electrode was placed before the last electrode, which is grounded, to produce a retarding electric field for electrons. The hole of the electrode was made small to make sure that the potential at the center is negative enough to suppress electrons. All simulations have been performed with the KOBRA3-INP simulation software. The results of the beam shape from the simulation will be presented.
Formation of Aluminum Nitride Film for High Power Soft X-Ray Source Using Ion-Beam Assisted Deposition Method
Authors: Matsutani Takaomi , Kiuchi Masato , Shirouzu Kiyotaka , Yoshioka Akihiro , Shimizu Ryuichi , Takahashi Sadayuki
Published: March 2009

An aluminum nitride (AlN) target for Al-Kα X-ray source with high power and long service life has been developed by N2 + ions assisted Al vapor deposition method (IBAD). The AlN film formations were carried out at the Al deposition rate varied from 2.0 nm/s to 0.15 nm/s with a fixed low-energy N2 + ion of 1 keV. The films were deposited on Cu substrate at room temperature. The AlN films were characterized by an X-ray diffraction, an electron probe X-ray microanalysis and a Knoop-hardness measurement. The AlN deposited at the Al deposition rate of 0.5 nm has a N/Al ratio of 0.4, a Knoop-hardness of ~1500 and a low resistance of ~0.2 . Comparison of durability test between the AlN target and a conventional Al target was performed. It has been revealed, after 500 hours under an electron bombardment of 300 mA at 20 kV, that there were no change of morphology and X-ray intensity on the AlN-surface whilst cracks due to the heat-cycle fatigue covered the Al-surface.
Development of In Situ Atomic Force Microscopy for Study of Ion Beam Interaction with Biological Cell Surface
Authors: Sangyuenyongpipat S. , Vilaithong Thiraphat , Yu L.D. , Yimnirun Rattikorn , Singjai Pisith , Brown Ian G.
Published: March 2009

The interaction between ion beam and biological cells has been studied to apply ionbeam- induced mutation to breeding of crops and gene transfer in cells. Formation of micro-craters has been observed after ion bombardment of plant cells and they are suspected to act as pathways for exogenous macromolecule transfer in the cells. A technique of in-situ atomic force microscopy (AFM) in the ion beam line is being developed to observe ion bombardment effects on cell surface morphology during ion bombardment. A commercial AFM is designed to place inside the target chamber of the bioengineering ion beam line at Chiang Mai University. In order to allow the ion beam to properly bombard the sample without the risk of damaging the scanning tip and affecting normal operation of AFM, geometrical factors have been calculated for tilting the AFM with 35 degree from the normal. In order to avoid vibrations from external sources, mechanical designs have been done for a vibration isolation system. Construction and installation of the in-situ AFM facility to the beam line have been completed and are reported in details.
Ion Beam Synthesis of Silicon Carbide
Authors: Intarasiri S. , Hallén Anders , Razpet A. , Singkarat Somsorn , Possnert G.
Published: March 2009

Formation and crystallization of a thin near-surface layer of silicon carbide on a silicon substrate, created by ion-beam synthesis (IBS), are discussed. 80 and 40 keV carbon ions were implanted into a (1 0 0) high-purity p-type silicon substrate at room temperature and 400 oC, respectively, using doses in excess of 1017 ions/cm2. Elastic recoil detection analysis (ERDA) technique, developed for routine atomic depth profiling at the Angstrom laboratory, Uppsala University, Sweden, was used to investigate the depth distributions of implanted-ions. Infrared transmittance measurement was used as an indication of SiC in the implanted Si substrate. For the samples implanted at high temperature, the results show the existence of a peak at 797 cm-1, indicating the presence of β-SiC, already directly formed during the implantation without postimplantation annealing. While for the samples implanted at room temperature, starting with the band of amorphous Si-C network, the crystalline SiC appears at the annealing temperature as low as 900 oC. In both cases, during further annealing in vacuum, the peak grows in height and narrows in width (according to the measured FWHM) with increasing annealing temperature, indicating a further growth of the SiC layer. However, for thermal annealing at 1000 oC in a vacuum furnace the SiC crystallization was not completed and crystal imperfection where still present. Complementary to IR, Raman scattering measurements were performed. Although no direct evidence of SiC vibrations were observed, the appearance and disappearance of both Si-Si and C-C related bands points out to the formation of silicon and carbon clusters in the implanted layer.
Seeing Inside a Hot Plasma: Photoionization of Ions
Authors: Schlachter A.S.
Published: March 2009

Photoionization of ions is an important atomic process in very hot extended plasmas, for example, in objects of astrophysical interest. Planetary nebulae as a stage in the evolution of stars are one significant example. Modeling of their formation and composition requires detailed information about atomic processes in a very highly ionized plasma, including cross sections for photoionization of ions.
Study of Multicellular Living Organisms by SXCM (Soft X-Ray Contact Microscopy)
Authors: Poletti G. , Orsini F. , Batani D.
Published: March 2009

Soft X-ray Contact Microscopy (SXCM) of Caenorhabditis elegans nematodes wit typical length 800 μm and diameter 30 μm has been performed using the PALS laser source of wavelength λ = 1.314 μm and pulse duration τ (FWHM) = 400 ps. Pulsed soft X-rays were generated using molybdenum and gold targets with laser intensities I ≥ 1014 W/cm2. Images have been recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Cuticle features and several internal organs have been identified in the SXCM images including lateral field, cuticle annuli, pharynx, and hypodermal and neuronal cell nuclei.
DLC-Film Schottky Barrier Diodes
Authors: Paosawatyanyong Boonchoat , Honglertsakul K. , Reinhard D.K.
Published: March 2009

A microwave plasma reactor (MPR) is constructed as a facility for the plasma assisted chemical vapor deposition (PACVD) process. The reactor is a mode-adjustable resonance cavity of cylindrical shape. A 2.45 GHz microwave generator is used to ignite the plasma inside the lengthadjustable cavity. The diamond-like carbon (DLC) thin film depositions onto the silicon substrates are carried out using H2–CH4 discharge. The Schottky barrier diodes (SBD) are then formed on to the DLC films. The responses of DLC-SBD to DC and time varying signals have been studied as a function of frequency. The frequency dependent response results are compared to the computer models, which includes as input parameters the bulk series resistance, the capacitance associated with the bulk material between the space-charge layer and the ohmic contact, the space-charge layer capacitance, and the diode dynamic resistance.
Development of High Voltage High Frequency Resonant Inverter Power Supply for Atmospheric Surface Glow Barrier Discharges
Authors: Nisoa M. , Srinoum D. , Kerdthongmee P.
Published: March 2009

High-voltage high-frequency power supply using voltage-fed load resonant inverter with a series-compensated resonant inductor has been developed for efficient atmospheric surface glow barrier discharges(ASGBD). It produces a controllable frequency and sinusoidal alternating voltage output. The maximum output voltage is about 6 kV peak to peak. Resonant power converter can be tune easily to the resonant frequency of the load. Operating frequency varies according to the load and voltage level typically in the range of 10 kHz and 1 MHz range. The output voltage is controlled by using pulse width modulation technique. The power supply developed in this paper is applied successfully for ozoniser that can produce high concentrate ozone by using ASGBD for agricultural industry applications.
Electrical Properties of Clustered and Precipitated Iron in Silicon
Authors: Khalil R. , Kveder Vitaly V. , Schröter Wolfgang , Seibt Michael
Published: March 2009

Deep electronic states associated with iron silicide precipitates have been studied by means of deep-level transient spectroscopy. The observed spectra show the characteristic features of bandlike states at extended defects. From the stability of the states on annealing at moderate temperature they are tentatively attributed to precipitate-matrix interfaces.
Gettering Mechanism of Cu in Silicon Calculated from First Principles
Authors: Matsukawa Kazuhito , Hattori Nobusuke , Maegawa Shigeto , Shirai Koun , Katayama-Yoshida Hiroshi
Published: March 2009

The binding energy between 3d transition metals (TM) such as iron (Fe), nickel (Ni) and copper (Cu), and boron (B) in Si are studied using first-principles molecular dynamics method. The binding energies of between each TM for Fe, Ni, Cu and B are 0.64,0.57,and 0.44eV respectively, and the binding energy of Fe and B is the largest, on the other hand, binding energy of Ni and B is the smallest. This result is well in agreement with the experiment fact that Fe and Cu exist as a positive charge in P+ silicon, so it is easy to combine with the B, which has a negative charge, on the other hand, Ni exists in the state of neutrality electrically in P+ silicon, so it can not combine with B atom.
The Influence of Nitrogen on Dislocation Locking in Float-Zone Silicon
Authors: Murphy John D. , Giannattasio A. , Alpass Charles R. , Senkader Semih , Falster Robert J. , Wilshaw Peter R.
Published: March 2009

Dislocation locking by nitrogen impurities has been investigated in float-zone silicon with nitrogen concentrations of 2.2 x 1015cm-3 and 3 x 1014cm-3. The stress required to unlock dislocations pinned by nitrogen impurities was measured as a function of annealing time (0 to 2500 hours) and temperature (550 to 830°C). For all conditions investigated the locking effect was found to increase linearly with annealing time before saturating. It is assumed that the rate of increase of unlocking stress with annealing time is a measure of transport of nitrogen to the dislocation core. This rate of increase was found to depend linearly on nitrogen concentration, which is consistent with transport by a dimeric species, whose activation energy for diffusion is approximately 1.4eV. The saturation unlocking stress has been found to be dependent on the nitrogen concentration. Additionally, the temperature dependence of the stress required to move dislocations immobilised by nitrogen impurities has been studied. By assuming a value for the binding energy of the nitrogen to the dislocation, the density of the locking species at the dislocation core has been calculated.
Impact of Low Temperature Hydrogenation on Recombination Activity of Dislocations in Silicon
Authors: Vyvenko O.F. , Kittler Martin , Seifert Winfried
Published: March 2009

Silicon samples doped with gallium and intentionally contaminated with iron have been studied by means of electron beam current (EBIC), capacitance voltage (CV) and deep level transient spectroscopy (DLTS) methods. Reverse bias anneal (RBA) treatments at temperatures of 390-420K were used to move hydrogen and dissolved iron atoms away from the surface. A new procedure was developed to find dislocations lying on desirable depth from the surface and to analyze the depth distribution of their recombination contrast. Iron contaminated dislocations do not noticeably change their recombination activity when kept in an electrical field as high as 104 V/cm at 420K for several hours. This implies a tight binding of iron atoms at dislocations. The binding energy of iron with dislocations seems to be much larger than for Fe-Ga and H-Ga pairs. Low temperature hydrogenation of iron contaminated dislocations does not produce any passivation effect. In opposite, the recombination activity of the dislocations significantly increases after RBA treatment.
FTIR Study of Precipitation of Implanted Nitrogen in CZ-Si Annealed under High Hydrostatic Pressure
Authors: Akhmetov V.D. , Misiuk Andrzej , Richter Hans
Published: March 2009

The evolution of nitrogen related infrared vibrational spectra of CZ-Si implanted with nitrogen, with doses 1017 ion/cm2 and 1018 ion/cm2, at 140 keV, was studied after annealing at 1130°C/5h under different hydrostatic pressures, from 1 bar to 10.7 kbar. It was found for each pressure applied, that the increased nitrogen dose leads to transformation of broadband spectra to the fine structure ones, corresponding to crystalline silicon nitride. The spectral position of observed sharp peaks in the investigated pressure region is red shifted in comparison to the peaks of crystalline silicon oxynitride found recently by other investigators in nitrogen-containing poly-Si as well as in a residual melt of nitrogen-doped CZ-Si. The application of pressure during annealing results in further red shift of the nitrogen-related bands. The observed decrease of frequency of vibrational bands is explained in terms of the pressure induced lowered incorporation of oxygen into growing oxynitride phase.
Influence of Magnetic Field on the Unlocking Stress for Dislocation Motion in Cz-Si Depending on Pre-Annealing Time
Authors: Badylevich M. , Kveder Vitaly V. , Orlov Valeri I. , Osipyan Yu.
Published: March 2009

We investigated the effect of magnetic field on the unlocking stress for dislocations in Cz-Si, measured at 600oC, depending on the thermal prehistory of samples. The effect increases with increasing of the duration of sample annealing at 600oC before the magnetic field treatment. The experimental data are consistent with the assumption that the magnetic field stimulate some changes in configuration of oxygen accumulated at dislocations before the magnetic field treatment, but not the state of oxygen in a bulk.
Influence of Neutron Irradiation on Stress - Induced Oxygen Precipitation in Cz-Si
Authors: Bak-Misiuk Jadwiga , Misiuk Andrzej , Surma Barbara , Shalimov Artem , Londos Charalamos A.
Published: March 2009

Oxygen precipitation and creation of defects in Czochralski grown silicon with interstitial oxygen concentration 9.4·1017 cm-3, subjected to irradiation with neutrons (5 MeV, dose 1x1017 cm-2) and subsequently treated for 5 h under atmospheric and high hydrostatic pressures (HP, up to 1.1 GPa) at 1270 / 1400 K, were investigated by spectroscopic and X - Ray methods. Point defects created by neutron irradiation stimulate oxygen precipitation and creation of dislocations under HP, especially at 1270 K. The effect of pressure treatment is related to changed concentration and mobility of silicon interstitials and vacancies as well as of the VnOm – type defects.
Oxygen Precipitation in Nitrogen Doped CZ Silicon
Authors: Kissinger G. , Müller Timo , Sattler Andreas , Häckl W. , Weber M. , Lambert U. , Huber A. , Krottenthaler P. , Richter Hans , von Ammon Wilfried
Published: March 2009

Nitrogen doping of CZ silicon results in an early formation of large precipitate nuclei during crystal cooling, which are stable at 900°C. These are prone to develop stacking faults and high densities of defects inside defect denuded zones of CZ silicon wafers. Simultaneous doping of FZ silicon with nitrogen and oxygen results in two main stages of precipitate nucleation during crystal cooling, an enhanced nucleation around 800°C, which is nitrogen induced, and a second enhancement around 600°C, which depends on the concentration of residual oxygen on interstitial sites. A combined technique of ramping with 1K/min from 500-1000°C with a final anneal at 1000°C for 2h and lateral BMD measurement by SIRM provides a possibility to delineate v/G on nitrogen-doped silicon wafers. Surface segregation of nitrogen and oxygen during out-diffusion can explain the enhanced BMD formation in about 105m depth and the suppressed BMD formation in about 405m depth below the surface. The precipitate growth is enhanced in regions where nitrogen is filled up again after a preceding out-diffusion.
Control of Oxygen Precipitation in Silicon by Infrared Laser Irradiation
Authors: Yamada-Kaneta Hiroshi , Tanahashi K.
Published: March 2009

We have investigated the effect of infrared laser irradiation on the oxygen precipitation in silicon crystals during the heat-treatments. The laser light of the wave numbers of 1085 cm-1 was adopted, which is close to the wave number of the infrared absorption by oxygen in silicon (Si-O-Si) at high temperature. We have found that for the high-temperature anneals around 1200 °C for 1-2 h, the infrared laser irradiation during the anneals significantly (almost completely) suppresses the oxygen precipitation.
From Continuous to Quantized Charging Phenomena in Few Nanocrystals MOS Structures
Authors: Benassayag G. , Shalchian M. , Grisolia Jeremie , Bonafos Caroline , Atarodi S.M. , Claverie A.
Published: March 2009

In this paper, we present a study on the contribution of silicon nanocrystals to the electrical transport characteristics of large (100 m x 100 m) and small (100 nm x 100 nm) metaloxide- semiconductor (MOS) capacitors at room temperature. A layer of silicon nanocrystals is synthesized within the oxide of these capacitors by ultra-low energy ion implantation and annealing. Several features including negative differential resistance (NDR), sharp current peaks and random telegraph signal (RTS) are demonstrated in the current-voltage and current-time characteristics of these capacitors. These features have been associated to charge storage in silicon nanocrystals and to the resulting Coulomb interaction between the stored charges and the tunneling current. Clear transition from a continuous response of large capacitors to a discrete response of small capacitors reveals the quantized nature of the charge storage phenomenon in these nanocrystalline dots. The effect of the nanocrystal density from nearly continuous layer to isolated nanodots is also presented.
Electronic Properties and Thermal Stability of Defects Induced by MeV Electron/Ion Irradiations in Unstrained Germanium and SiGe Alloys
Authors: Markevich Vladimir P. , Peaker Anthony R. , Murin L.I. , Emtsev Valentin V. , Litvinov Valentin V. , Abrosimov Nikolay V. , Dobaczewski L.
Published: March 2009

Deep states produced during γ irradiation of germanium have been compared with the defects produced by 1 and 3MeV silicon ion implantation. The deep states have been studied using DLTS and Laplace DLTS techniques. Isochronal annealing has been used to investigate the defect evolution and stability over the range 100 to 500°C. It is found that while irradiation damage can be removed with a very low thermal budget, the implantation damage is more complex and much more difficult to remove. By comparing low (1010cm-2) and high (1012cm-2) implantation doses it appears that both the complexity and stability of defects increases with increasing dose. Similar experiments have been performed on Ge rich Si1-xGex (x=0.992). The focus of this work has been on vacancy related defects. It is believed that the diffusion of both acceptors and donors is vacancy mediated in Ge and so vacancy clusters rather than interstitial clusters are expected to be the technologically significant defect in enhanced diffusion. The significance in terms of junction leakage and generation currents are discussed in the paper in the context of the observed defect reactions.
Electronic Properties and Structure of a Complex Incorporating a Self-Interstitial and two Oxygen Atoms in Silicon
Authors: Markevich Vladimir P. , Murin L.I. , Lastovskii Stanislav B. , Medvedeva I.F. , Lindström J. Lennart , Peaker Anthony R. , Coutinho J. , Jones R. , Torres Vitor , Öberg Sven , Briddon Patrick R.
Published: March 2009

The electronic properties and structure of a complex incorporating a self-interstitial (I) and two oxygen atoms are presented by a combination of deep level transient spectroscopy (DLTS), infrared absorption spectroscopy and ab-initio modeling studies. It is argued that the IO2 complex in Si can exist in four charge states (IO−
2 , IO02 , IO+ 2 , and IO++ 2 ). The first and the second donor levels of the IO2 complex show an inverted location order in the gap, leading to a E(0/ + +) occupancy level at Ev + 0.255 eV. Activation energies for hole emission, transformation barriers between different structures, and positions of LVM lines for different configurations and charge states have been determined. These observables were calculated by density-functional calculations, which show that they are accounted for if we consider at least two charge-dependent defect structures.
Novel Low-K Dielectric Obtained by Xenon Implantation in SiO2
Authors: Assaf H. , Ntsoenzok E. , Ruault M.O. , Kaïtasov O.
Published: March 2009

We implanted 300keV Xenon in silicon oxide at doses ranging from 1x1016 to 5x1016/cm2. For the first time, we reported the formation and the thermal evolution of bubbles/cavities in SiO2. Characterization by cross-section transmission electron microscopy (XTEM) and Rutherford backscattering spectrometry (RBS) showed that bubbles/cavities remain present even after a 1100°C annealing, while Xe strongly desorbs out at that temperature. Our measurements provides unexpected dielectric constant (k) lower than 1.6. These results make this technique very attractive for low-k applications in Si technology. Keywords: low-k dielectric, rare gas implantation, silicon oxid.
Bulk Radiation Damage Induced in Thin Epitaxial Silicon Detectors by 24 GeV Protons
Authors: Khomenkov V. , Bisello D. , Boscardin M. , Bruzzi Mara , Candelori A. , Dalla Betta G.-F. , Litovchenko A.P. , Piemonte C. , Rando R. , Ravotti F. , Zorzi N.
Published: March 2009

Radiation hardness of silicon detectors based on thin epitaxial layer for the LHC upgrade was studied. No type inversion was observed after irradiation by 24 GeV protons in the fluence range (1.5–10)⋅1015 cm–2 due to overcompensating donor generation. After long-term annealing highly irradiated devices show decrease of effective doping concentration and then undergo type inversion. All mentioned means that thin epitaxial devices might be used for innermost layers of vertex detectors and need moderate cooling during beam off time. Properly chosen scenario might help to restore their working characteristics.
Electrical Passivation of Silicon Wafers
Authors: Kunst M. , Wünsch Frank , Abdallah O. , Citarella G.
Published: March 2009

Surface passivation in silicon wafers is investigated by contactless photoconductance measurements. It is shown that the deposition of a-Si:H layers on top of c-Si wafers leads to passivation of the c-Si surface. Passivation by Si3N4 of the p c-Si surface is at least partially due to the depletion layer at the interface. The separation of excess charge carriers by the depletion field is responsible for a relatively slowly decaying part of the signal not directly related to bulk recombination. An HF dip is not sufficient for an appropriate passivation of p c-Si but immersion in I2/ethanol solution is promising.
Point Defects Interaction with Extended Defects and Impurities and Its Influence on the Si-SiO2 System Properties
Authors: Kropman Daniel , Abru U. , Kärner Tiit , Ugaste U. , Mellikov E. , Kauk M. , Heinmaa Ivo , Samoson A. , Medvid Arthur
Published: March 2009

The type and density of the point defects that are generated in the Si surface layer during thermal oxidation depend on the oxidation condition: temperature, cooling rate, oxidation time, impurity content. The interaction between point defects with extended defects and impurities affect the Si-SiO2 interface properties. The influence of point defects may be diminished and the interface properties improved by an appropriate choice of oxidation conditions.
A New Approach to Study the Damage Induced by Inert Gases Implantation in Silicon
Authors: Peripolli S. , Beaufort Marie France , Babonneau David , Rousselet Sophie , Fichtner P.F.P. , Amaral L. , Oliviero Erwan , Barbot Jean François , Donnelly S.E.
Published: March 2009

In the present work, we report on the effects of the implantation temperature on the formation of bubbles and extended defects in Ne+-implanted Si(001) substrates. The implantations were performed at 50 keV to a fluence of 5x1016 cm-2, for distinct implantation temperatures within the 250°C≤Ti≤800°C interval. The samples are investigated using a combination of cross-sectional and plan-view Transmission Electron Microscopy (TEM) observations and Grazing Incidence Small-Angle X-ray Scattering (GISAXS)measurements. In comparison with similar He implants, we demonstrate that the Ne implants can lead to the formation of a much denser bubble system.
First Principles Calculation for Point Defect Behavior, Oxygen Precipitation and Cu Gettering in Czochralski Silicon
Authors: Sueoka Koji , Shiba S. , Fukutani S.
Published: March 2009

Theoretical consideration for technologically important phenomena in defect engineering of Czochralski silicon was performed with first principles calculation. (i) Point defect behaviour during crystal growth, (ii) enhanced oxygen precipitation in p/p+ epitaxial wafers, and (iii) Cu gettering by impurities are main topics in this work. Following results are obtained. (i) Interstitial Si I is dominant in p type Si while vacancy V is dominant in n type Si during crystal growth when dopant concentration is higher than about 1x1019atoms/cm3. (ii) In initial stage of oxygen precipitation including a few interstitial oxygen (O) atoms, BOn complex is more stable than On complex. The diffusion barrier of O atom in p+ Si is reduced to about 2.2eV compared with the barrier of about 2.5eV in intrinsic Si. (iii) In substitutional B, Sb, As, P and C atoms, only B atom can be an effective gettering center for Cu.
The Properties of Hydrostatically Strained Ge and Si Nanocrystals in Silicon Dioxide Matrix
Authors: Tyschenko Ida E. , Talochkin A.B. , Vandyshev E.N. , Cherkov A.G. , Misiuk Andrzej
Published: March 2009

The properties of Si and Ge nanocrystals with uniformly strained Si-Si and Ge-Ge bonds have been studied. The strained Si and Ge nanocrystals were produced by the implantation of Ge+ or Si+ ions in thermally grown SiO2 films subsequently annealed under hydrostatic pressure ranging from 1 bar to 12 kbar. Correlation between the formation of the hydrostatically strained nanocrystals and the features of the photoluminescence spectra has been observed. The obtained results are discussed in terms of broadening energy gap between the levels of electron states of the hydrostatically strained nanocrystals. This effect brings about direct radiative recombination.
Effect of Self-Interstitials – Nanovoids Interaction on Two-Dimensional Diffusion and Activation of Implanted B in Si
Authors: Giannazzo Filippo , Bruno E. , Mirabella S. , Impellizzeri G. , Napolitani E. , Raineri Vito , Priolo F. , Alquier Daniel
Published: March 2009

In this work, we investigate the effect of performing a high dose 20 keV He+ implant before the implantation of B at low energy (3 keV) in silicon and the subsequent thermal annealing at 800 °C. The implants were performed in laterally confined regions defined by opening windows in a SiO2 mask, in order to evidence the impact on a realistic configuration used in device fabrication. High resolution quantitative scanning capacitance microscopy (SCM) combined with cross-section transmission electron microscopy (XTEM) allowed to clarify the role of the voids distribution produced during the thermal annealing on the diffusion and electrical activation of implanted B in Si. Particular evidence was given to the effect of the uniform nanovoids distribution, which forms in the region between the surface and the buried cavity layer.
Defect Interaction Mechanisms between Antimony and Indium in Silicon
Authors: Souza M.M. De , Chakravarthi Srinivasan , Jain Amitabh
Published: March 2009

Heavy species such as Sb, In, and Ge are required to meet the challenges of future dopant engineering in planar CMOS technology. An understanding of the interactions of these species with each other and with conventional dopants is urgently required in order to meet aggressive criteria for junction control in sub-sixty nanometer technology nodes. In the current work, the interactions between Sb and In have been explored as a function of ion implantation dose and annealing treatment. The data shows strong interaction between the two species which prevents the dissolution of an as-implanted In profile even after high temperature anneal. The nature of the interaction is probed with fundamental calculations using plane wave density functional theory. A strong binding for an Sb-In-vacancy complex is revealed. Band structure analysis indicates that this defect complex introduces several unoccupied states primarily in the upper half of the bandgap. The two species contribute with nearly equal magnitude to the top valence band.
Characterization of SiGe Layer on Insulator by In-Plane Diffraction Method
Authors: Imai M. , Miyamura Y. , Murata D. , Ogi A.
Published: March 2009

Four types of SGOI (SiGe on Insulator) wafers were fabricated by the combination of SiGe epitaxial growth, SIMOX (Separation by Implanted Oxygen) processes and oxidation. By the cross-sectional TEM (Transmission Electron Microscopy) and EDS (Energy Dispersive Spectroscopy), it is confirmed that each wafer has smooth interface between a top layer (Si or SiGe) and a BOX (buried oxide) layer and Ge atoms in SiGe layer distribute homogeneously for SGOI_A and SGOI_B.
Using high-resolution X-ray diffractometry, the crystallographic properties of SiGe layer are characterized with in-plane and out of plane diffraction methods. The lattice constants are calculated for the planes of perpendicular and parallel to wafer surface and the degree of relaxation are estimated for the SiGe layer of each wafer. The rocking curve measurements reveal that the lattice turbulence of SiGe layer is influenced by SIMOX process conditions, Ge content and the layer thickness.
Сavity Effect in Hydrogen Ion Implanted Silicon-On-Insulator Structures
Authors: Tyschenko Ida E. , Zhuravlev K.S. , Cherkov A.G. , Misiuk Andrzej , Popov V.P.
Published: March 2009

Cavity effect on the room-temperature (RT) photoluminescence (PL) from emitting centers in the top silicon layer of silicon-on-insulator (SOI) structure has been studied. The lightemitting centers were produced by the implantation of H+ ions and subsequent annealing at the temperatures Ta = 450-1000 oC for 5 h in an Ar ambient under pressure P = 1 - 1.2×104 bar. It has been obtained that annealing under hydrostatic pressure higher than 6 kbar prevented the outdiffusion of hydrogen in the form of gas bubbles, which took place after annealing at Ta≥600 oC under atmospheric conditions. Absence of micro-pores and gas bubbles in the top surface region creates the conditions to retain the mirror quality of the SOI/air interface. A wavelength-selective effect of the formed cavity on visible PL has been observed from the H+ ion implanted SOI structures annealed under pressure of 12 kbar. The cavity enhancement of PL emission for 23-40 times has been found at the wavelength of 515 and 560 nm.
Misfit Dislocations in SiGe/Si Heterostructures: Nucleation - Propagation - Multiplication
Authors: Vdovin V.I. , Mil'vidskii M.G. , Rzaev M.M. , Schäffler Friedrich
Published: March 2009

We present experimental data on the effect of low-temperature buffer layers on the dislocation structure formation in SiGe/Si strained-layer heterostructures under thermal annealing. Specific subjects include mechanisms of misfit dislocation nucleation, propagation and multiplication as well as the role of intrinsic point defects in these processes. Samples with lowtemperature Si (400°C) and SiGe (250°C) buffer layers were grown by MBE. In general, the processes of MD generation occur similarly in the heterostructures studied independently of the alloy composition (Ge content: 0.15, 0.30) and kind of buffer layer. Intrinsic point defects related to the low-temperature epitaxial growth influence mainly the rate of misfit dislocation nucleation.
Investigation of Defects in the Edge Region of Multicrystalline Solar Silicon Ingots
Authors: Rossberg M. , Naumann M. , Irmscher K. , Juda U. , Lüdge A. , Ghosh Michael , Müller Armin
Published: March 2009

The structural and electrical properties of as grown multicrystalline (mc) solar silicon have been characterized with special emphasis on the ingot's edge regions. For this purpose a vertical cross section of an mc-Si Bridgman ingot was investigated by Fourier transform infrared spectroscopy (FTIR), laser scattering tomography (LST), lateral photovoltage scanning (LPS), infrared microscopy and microwave detected photoconductivity decay (&PCD). Images of the distribution of dislocations, grain boundaries, precipitates, impurities (O, N, C) and the minority charge carrier lifetime were obtained, partly differentiating the defects by their electrical activity. In particular the LPS method displays dopant striations indicating the shape of the phase boundary. Deviations of the phase boundary from a slightly convex shape in the middle of the ingot to a concave one in the vicinity of the side walls could be observed. The existence of an horizontal temperature gradient deduced from this shape is the reason for convection in the melt. The influence on the concentration profiles of interstitial oxygen and the correlation with the minority charge carrier lifetime are discussed.
Local Measurements of Diffusion Length and Chemical Character of Metal Clusters in Multicrystalline Silicon
Authors: Buonassisi Tonio , Istratov Andrei A. , Marcus M.A. , Heuer Matthias , Pickett M.D. , Lai B. , Cai Z. , Heald Steve M. , Weber Eicke R.
Published: March 2009

We present a comprehensive description of synchrotron-based analytical microprobe techniques used to locally measure the diffusion length and chemical character of metal clusters in multicrystalline silicon (mc-Si) solar cell material. The techniques discussed are (a) X-ray fluorescence microscopy, capable of determining the spatial distribution, elemental nature, size, morphology, and depth of metal-rich particles as small as 30 nm in diameter; (b) X-ray absorption microspectroscopy, capable of determining the chemical states of these metal-rich precipitates, (c) X-ray beam induced current (XBIC), which maps the minority carrier recombination activity, and (d) Spectrally-resolved XBIC, which maps the minority carrier diffusion length. Sensitivity limits, optimal synchrotron characteristics, and experimental flowcharts are discussed. These techniques have elucidated the nature and effects of metal-rich particles in mc-Si and the physical mechanisms limiting metal gettering from mc-Si, and have opened several promising new research directions.
Comparison of Efficiencies of Different Surface Passivations Applied to Crystalline Silicon
Authors: Palais Olivier , Lemiti Mustapha , Lelievre Jean-Francois , Martinuzzi Santo
Published: March 2009

In this work the efficiencies of different surface passivation techniques are compared. This paper emphasizes on the passivation provided by SiNx:H layers that is commonly used in photovolaic industry as surface passivation and anti reflection layer. The method used to evaluate the surface recombination velocity is detailed and discussed. It is shown that light phosphorus diffusion at 850°C – 20 min provides good surface passivation of n-type silicon surface and noticeable passivation of p-type, that can be improved by SiNx:H Layer.
Stability of Emission Properties of Silicon Nanostructures
Authors: Baran M. , Khomenkova L. , Korsunska N. , Stara T. , Sheinkman Moissei K. , Yukhymchuk V. , Khomenkov V. , Goldstein Y. , Jedrzejewski J. , Savir E.
Published: March 2009

The aging process of silicon nanostructures obtained by magnetron sputtering and electrochemical etching is investigated by photoluminescence and Raman scattering methods. It is shown that oxidation of silicon crystallites takes place in both types of structures and results in appearance of additional emission bands. However the degree of oxidation in etched structures exceeds significantly this value for sputtered samples. It is found that the intensity and spectral position of the emission band caused by exciton recombination in Si crystallites do not change practically during aging in sputtered structures in contrast to etched ones. It is shown that the oxidation of silicon amorphous phase occur during aging in sputtered structures.
The Build-Up of Strain Fields in Czochralski-Si Observed in Real Time by High Energy X-Ray Diffraction
Authors: Stockmeier Matthias , Weisser Matthias , Hock Rainer , Magerl Andreas
Published: March 2009

The build-up of strain fields caused by the precipitation of oxygen in Czochralski-silicon during annealing up to 1200°C and for process times up to 70 hours has been observed in real time by high energy x-ray diffraction. Five different processes are distinguished in the temperature evolution of the intensity and of the rocking width of the silicon 220-reflection. These features are attributed to different precipitation mechanisms. A fit to part of the data with a diffusion limited precipitation model leads to an activation energy for oxygen diffusion in silicon of 2.2 eV in the temperature range from 700°C to 950°C.