bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Formation of Defects Degrading Gate Oxide Integrity During CZ-Si Crystal Growth
Authors: Tsumori Y. , Nakai K. , Iwasaki T. , Haga H. , Kojima K. , Nakashizu T. 
Published: April 2011

AbstractThe formation of grown-in defects degrading the gate oxide integrity (GOI) has been studied. The growth-halting experiments were carried out to investigate the temperature ranges at which the formation of the defects was promoted or suppressed. GOI is improved in the crystal regions slowly cooled above 1330°C and between 1060°C and 1100°C. It is degraded in the crystal regions held below 1060°C. In the peripheral of the crystals, those temperature ranges are about 30°C lower. The defects are formed and grown below 1060°C in the center part of the crystal. The defect density is decreased with cooling time between 1060°C and 1100°C. These phenomena are considered to be closely related with reactions of intrinsic point defects, that is, the pair annihilation or the aggregation. The temperatures at which the pair annihilation and the aggregation of the point defects occur are dependent upon the supersaturation of the point defects.
External Gettering Comparison and Structural Characterization of Single and Polycrystalline Silicon
Authors: Hieslmair Henry , McHugo Scott , Weber Eicke 
Published: April 2011

AbstractVarious silicon samples, both single and polycrystalline, were intentionally contaminated and externally gettered using phosphorus, aluminum and co- phosphorus/aluminum gettering. Gettering efficiencies were quantified via diffusion length improvements. Structural characterization was used to correlate defects with low gettering efficiencies. External gettering was found to be particularly effective at recovering diffusion length in large grain polycrystalline silicon and solar grade single crystal silicon despite Fe contamination and high defect densities. One of two explanations is possible, 1) the structural defects are initially undecorated and are completely gettered after Fe contamination, or 2) metal decoration on as-grown structural defects are structurally and/or chemically different from intentional Fe decoration.
Theory of Defects in Wide-Band-Gap Semiconductors
Authors: Van de Walle Chris G , Neugebauer Jörg 
Published: April 2011

AbstractWe discuss the application of state-of-the-art first-principles calculations to the problem of defects, impurities, and doping levels in semiconductors. Since doping problems are of particular relevance in wide-band-gap materials, we focus here on studies of ZnSe and GaN. For ZnSe, we discuss our latest insights in the influence of compensation and dopant solubility on the experimentally observed limitation of the free carrier concentration in p-type ZnSe. For GaN, we focus on the role of native defects in doping or compensation of the material, with particular emphasis on the n-type conductivity of as-grown GaN.
Photoluminescence Studies of GaN and AlGaN Layers Under Hydrostatic Pressure
Authors: Wetzel C. , Walukiewicz W. , Haller E. E. , Amano H. , Akasaki I. 
Published: April 2011

AbstractWide bandgap GaN very often shows a high electron concentration. Although several impurities such as O and Si have been identified, the concentration is not high enough to account for the number of free carriers. As a consequence native defects namely the nitrogen vacancies are widely considered to be present at high densities. Several calculations predict different energy levels of this strongly localized defect. We present photoluminescence experiments of wurtzite GaN and AlGaN layers under large hydrostatic pressure to search for localized defects within the questionable energy range of 3 .0 to 3 .8 eV above the valence band edge.
Local Vibrational Mode (LVM) Spectroscopy of Semiconductors
Authors: Haller Eugene E. 
Published: April 2011

AbstractImpurities and defects with masses smaller than the masses of the host semiconductor crystal atoms typically exhibit vibrational frequencies well above the phonon frequency spectrum. These vibrational modes produce sharp spectral absorption features in the infrared. Because of their strong spatial localization these modes are not affected by neighboring impurities and/or defects with concentrations up to 1019 cm−3. This insensitivity is especially advantageous when the free carrier concentration must be reduced through the introduction of electron irradiation defects or when highly doped thin layers must be investigated. LVM spectroscopy with perturbations such as polarization of the probe light, uniaxial and hydrostatic stress, and isotope substitution has been highly successful in identifying the structure and composition of a large number of defect complexes. Hydrogen, in particular, forming a wide variety of complexes in elemental and compound semiconductors has been extensively studied with LVM spectroscopy. For example, it has been shown recently that nitrogen acceptors are hydrogen passivated in MOCVD grown ZnSe. Carbon and oxygen have been investigated in all major semiconductors with LVM spectroscopy. The extreme simplification of the spectrum of bond centered oxygen through isotope enrichment of several Ge crystals has been demonstrated. Additional recent investigations of importance to the currently much studied semiconductors will be reviewed.
Effect of RF Power on the Characteristic Parameters of W/n-GaAs Schottky Contacts Fabricated by RF Sputtering
Authors: Singh A. , Aroca G. , Velásquez L. 
Published: April 2011

AbstractW/n-GaAs/In Schottky contacts of area 1.75 mm2 were fabricated by deposition of W on (100) n-GaAs by rf Sputtering using rf power values in the range 200–400 Watt. The I-V and high frequency C-V measurements at 300 K, in the 200 Watt W/n-GaAs Schottky contact indicated that W formed a good rectifying contact to n-GaAs, with a rectification ratio (r) of 270, ideality factor (n) of 1.39, reverse saturation current (Io) of 1.2×10−6 A and the C-V barrier height (φbo) of 1.6 V. However, n and Io increased, whereas r and φbo decreased for the W/n-GaAs Schottky contacts prepared using higher rf power. For the 300 Watt W/n-GaAs contact, the values of 70, 1.70, 6.3}10−6 A, and 1.2V for r, n, Io and φbo, respectively, were estimated. The low frequency forward bias capacitance (or surface defect density) was an order of magnitude higher in the 300 Watt contact than in the 200 Watt contact. This fact suggested that the degradation in the quality of W/n-GaAs Schottky contacts fabricated by using high rf power was caused by high density surface defects created during sputter deposition of W on n-GaAs.
A Systematic Study of the Structural and Luminescence Properties of P-Type Porous Silicon
Authors: Yoon H. , Goorsky M. S. 
Published: April 2011

AbstractThe structural and luminescence properties of (001) p-type porous silicon samples (p∼0.1-0.2 Ω•cm) fabricated electrochemically under various conditions were investigated using high resolution double and triple axis diffraction and photoluminescence spectroscopy. We show the sensitivity of the structure of the porous silicon to the current density in the range of 10-50 mA/cm2, HF acid concentration in the range of 15% - 30%, and the evolution of the structure with time. We have found a systematic dependence of the amount of strain in the porous silicon layer (PSL) on the current density. The effect of the HF concentration is such that at 25% and 30% HF, PSLs are formed which are crystalline and strained, but at a lower HF concentration (15%), strained layers are not formed. The perpendicular strain in the layer increases linearly with storage time but the in-plane lattice constant of the porous silicon remains matched to the substrate. Further, we utilized x-ray reciprocal space maps to observe that, with storage time, there is an increase in the diffuse scattering from the PSL due to an increase in the range of tilts in the layer. Room temperature photoluminescence emission was observed for all 15% and 25% HF samples, but not for all 30% HF samples. Higher peak luminescence energy was obtained with lower HF concentration. Finally, we note the relationship between the strain in the PSL and the luminescence properties.
Chemistry of Point Defect in Silicon and its Applications in Semiconductor Technology
Authors: Pizzini S. , Binetti S. , Acciarri M. 
Published: April 2011

AbstractThe chemistry of the interactions between point defects and impurities is discussed by considering first the general thermodynamic and kinetic aspects of these reactions, deserving major attention to the identity of of the stable chemical species eventually formed and to the boundary conditions for diffusion controlled and reaction controlled interaction processes.The second part of the paper is instead dedicated to the analysis of the chemistry of carbon, oxygen, hydrogen and point defects in silicon, which is a system of major technological interest.We postulate that at low enough temperatures, when homogeneous nucleation processes are slow, spinodal decomposition assists oxygen aggregation phenomena. We postulate, also, on the basis of the existing knowledge, that carbon and hydrogen favour alternative reaction paths for oxygen in the due of clustering processes and discuss the hydrogen-enhanced oxygen diffusivity in the frame of a conventional trapping model.
Low Temperature Anneal of the Divacancy in P-Type Silicon
Authors: Trauwaert M.-A. , Vanhellemont J. , Maes H. E. , Van Bavel A.-M. , Langouche G. , Stesmans A. , Clauws P. 
Published: April 2011

AbstractResults are reported of a Deep Level Transient Spectroscopy (DLTS) study of the conversion of the divacancy, with energy level at Ev+0.19eV, to a level at Ev+0.24eV after anneal at temperatures below its dissociation temperature (300°C). In literature both levels have been associated with the donor level of the divacancy.Diodes processed on p-type Float Zone (FZ) and Czochralski (Cz) silicon wafers with boron concentration between 0.2 and 3E15 cm−3 are irradiated with 2 MeV electrons. Before and after anneal (200°C and 250°C) DLTS spectra are recorded to get a full electrical characterisation of the induced defects.The observed conversion is proposed to be a gradual transformation of the divacancy to a divacancy-oxygen complex.
Superlattice Nanowires
Authors: Attenborough K. , Hart R. , Schwarzacher W. , Ansermet J-PH. , Blondel A. , Doudin B. , Meier J.P. 
Published: April 2011

ABSTRACTCoNiCu/Cu superlattice nanowires have been grown by electrodeposition in nuclear tracketched nanoporous membranes. Transmission electron microscopy (TEM) images show a good layer structure and allow an estimate of the current efficiency. Current perpendicular to plane (CPP) giant magnetoresistance of up to 22%, at ambient temperature, has been measured but appears to be limited by defects, giving rise to ferromagnetic interlayer coupling, at low nonmagnetic layer thicknesses. Magnetic properties of the superlattice nanowires are influenced by in-plane anisotropy and magnetostatic coupling.
Reactions of Defined Oxidized Carbon Fiber Surfaces with Model Compounds and Polyurethane Elastomers
Authors: Pittman Charles U. , Gardner Steven D. , He Guoren , Wang Lichang , Wu Zhihong , Singamsetty C. , Wu Biahua , Booth Glyn 
Published: April 2011

ABSTRACTEx-PAN carbon fiber surfaces, oxidized to varying degrees by HNO3, have been characterized by NaOH, dye and HCl uptake, ion scattering spectroscopy (ISS), and angleresolved X-ray photoelectron spectroscopy (ARXPS). Subsequent treatments with tetraethylenepentamine to introduce amino groups or epichlorohydrin to introduce epoxy groups have been thoroughly characterized. The efficiency of using these surface functions to bond polymers onto fiber surfaces has been investigated using model anhydrides and isocyanates (for amines) and diols and diamines (for epoxides). The fraction of surface-bound groups which react drops with an increase in molecular size of the species being grafted. Crosslinked elastomeric polyurethane layers with designed modulus values and thicknesses have been bonded to these fibers. Composites have been prepared (epoxy matrices). The impact strengths and interlaminar shear strengths (ILSS) were studied as a function of the interphase modulus and thickness. Impact strengths increased (even at 500–1500 Å thicknesses). ILSS values depend on interphase modulus.
On the Microstructure of the Epoxy/Adherend Interphase
Authors: Libera M. , Zukas W. , Wentworth S. , Patel A. 
Published: April 2011

ABSTRACTIt is now recognized that there is a region at the epoxy/adherend interface known as the interphase whose chemistry and structure are different from those of bulk epoxy. There is, however, no adequate understanding of its microstructure. This paper describes differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) studies of the interphase between an aromatic amine cured epoxy and alumina/oxidized-aluminum surfaces. DSC results show dramatic differences in resin-cure behavior in the presence of particulate alumina. TEM results on microtomed cross-sectional specimens of anodized aluminum wire embedded in epoxy show regions of incomplete epoxy infiltration and interfacial stress. RuO4 staining combined with high-angle annular-dark-field STEM imaging indicates that there are structural variations within the bulk epoxy at lengths of ∼10–30nm. The magnitude of these fluctuations decreases in the near the adherend interface, and there is a simultaneous variation in the average epoxy structure. A plausible interpretation of these observations is that the interphase region suffers a variation in curing-agent concentration of unknown magnitude and there is a higher concentration of homopolymerized epoxy there relative to the bulk.
Post-CMP Cleaning of W and SiO2: A Model Study
Authors: Malik Igor J. , Zhang Jackie , Jensen Alan J. , Farber Jeffrey J. , Krusell Wilbur C. , Raghavan Srini , Rajhunath Chilkunda 
Published: April 2011

ABSTRACTChemical-Mechanical Planarization (CMP) of SiO2 is performed using alkaline silica slurries while CMP of tungsten (W) utilizes acidic slurries with alumina as the abrasive. Proposed mechanisms for the two CMP processes, with more emphasis on SiO2-CMP, have been discussed in literature. However, much less is known about the removal mechanism of residual slurry particles from the planarized surfaces - a crucial step for subsequent device processing. We discuss the chemical and physical basis of post-CMP cleaning by double-side scrubbing using polyvinyl alcohol (PVA) brushes and show how the interactions between the wafer surface, slurry, and the brush material affect the overall cleaning efficiency. Using the zeta potential concept the common features for cleaning surfaces after SiO2-CMP and W-CMP are established and the differences between these two systems are highlighted. We present surface particle levels for two model systems as a function of cleaning chemistries and discuss their influence on post-CMP surface metal levels.
Effect of SC-1 Process Parameters on Particle Removal and Surface Metallic Contamination
Authors: Hall R. Mark , Rosato John J. , Jarvis Taura , Parry Thad , Lindquist Paul G. 
Published: April 2011

ABSTRACTThe effect of bath temperature, megasonic power, and NH4-OH:H2O ratio are studied for particle removal efficiency, surface roughness, and surface Fe concentration in SC-1 cleaning solutions. Experimental results are presented which show removal efficiencies better than 97% on bare silicon wafers for optimized process conditions. These results are related to the etch rate of thermal oxides and a model is developed for reducing surface roughness and minimizing Fe contamination levels while maximizing particle removal efficiency.
Adsorption and Desorption of Contaminant Metals on Si Wafer Surface in SC1 Solution
Authors: Maeda G. , Takahashi I. , Kondo H. , Ryuta J. , Shingyouji T. 
Published: April 2011

ABSTRACTVariation in the surface concentration of Fe, Ni, Cu and Zn on Si wafers due to treatment in NH4OH/H2aO2/H2O solution called SC1 is investigated. The metal concentration on the wafer surface depends on the initial surface concentration, concentration in the solution, adsorption probability, desorption rate constant and the treatment time. The surface metal concentration behavior is explained by taking into account the effects of these parameters. The variation in the desorption rate constant with the metal species, the concentration in the solution, treatment temperature and mixing ratio of SC1 is discussed.
Reduced-Pressure UV Photo-Oxidation of Organic Contaminants on Si Surfaces
Authors: Bedge Satish , Lamb H. Henry 
Published: April 2011

ABSTRACTA reduced-pressure ultraviolet (UV) photo-oxidation process is described for the removal of organic contamination from Si surfaces with concomitant growth of an ultra-thin oxide passivation layer. As in situ photo-generation of ozone (O3) from dioxygen (O2) is impractical at millitorr pressures, a 2% O3/O2 mixture from an ozone generator is fed to the surface conditioning chamber. UV/O3 surface conditioning employing simultaneous 254/185 nm UV irradiation results in essentially complete removal of carbon contamination in 180 s at 100 mTorr and 100–200°C. Kinetics studies employing cyclohexane-contaminated Si(100) surfaces suggest that carbon removal occurs via two consecutive first-order processes: initial fast photo-oxidation of adsorbed cyclohexane to readily desorbed products and slower photo-oxidation of adsorbed carbonyl intermediates to CO2 and H2O. The activation energies for both processes are 2–3 kcal/mol, consistent with the involvement of photo-generated atomic oxygen species. Self-limiting growth of an ultra-thin oxide passivation layer occurs concomitantly with carbon removal. At saturation, the oxide layer is only 3–4 Å thick, and the growth kinetics are described by a first-order Langmuirian adsorption model.
Silicon Surface Chemistry By IR Spectroscopy in the Mid- To Far-IR Region: H2O And Ethanol On Si(100)
Authors: Struck L. M. , Eng J. , Bent B. E. , Chabal Y. J. , Williams G. P. , White A. E. , Christman S. , Chaban E. E. , Raghavachari K. , Flynn G. W. , Radermacher K. , Mantl S. 
Published: April 2011

ABSTRACTThe technique of external reflection infrared (IR) spectroscopy is used to study silicon surface chemistry. External reflection is enhanced by implanting a buried cobalt silicide layer in silicon to act as an infrared reflector. The preparation of clean well-ordered surfaces from the ion implanted substrates is demonstrated. The reactions of water and ethanol with Si(100) are investigated.
Vapor Breakdown During ablation by Nanosecond Laser Pulses
Authors: Liu C. L. , Leboeuf J. N. , Wood R. F. , Geohegan D. B. , Donato J. M. , Chen K. R. , Puretzky A. A. 
Published: April 2011

AbstractPlasma generation through vapor breakdown during ablation of a Si target by nanosecond KrF laser pulses is modeled using 0-dimensional rate equations. although there is some previous work on vapor breakdown by microsecond laser pulses, there have been no successful attempts reported on the same subject by nanosecond laser pulses. This work intends to fill the gap. a kinetic model is developed considering the following factors: (1) temperatures of both electrons and heavy-body particles (ions, neutrals, and excited states of neutrals), (2) absorption mechanisms of the laser energy such as inverse bremstrahlung (IB) processes and photoionization of excited states, (3) ionization acceleration mechanisms that include electron-impact excitation of ground state neutrals, electron-impact ionization of excited states of neutrals, photoionization of excited states of neutrals, and all necessary reverse processes. the rates of various processes considered are calculated using a second order predictor-corrector numerical scheme. the rate equations are solved for five quantities, namely, densities of electrons, neutrals, and excited states of neutrals, and the temperatures of electrons and heavy-body particles. the total breakdown times (sum of evaporation time and vapor breakdown time) at different energy fluences are then calculated. the results are compared with experimental observations of Si target ablation using a KrF laser.
Substrate Heating Measurements in Pulsed Ion Beam Film Deposition
Authors: Olson J. C. , Thompson M. O. , Davis H. A. , Rej D. J. , Waganaar W. J. , Tallant D. R. 
Published: April 2011

AbstractDiamond-like Carbon(DLC) films have been deposited at Los alamos National Laboratory by pulsed ion beam ablation of graphite targets. the targets are illuminated by an intense beam of hydrogen, carbon, and oxygen ions at a fluence of 15-45 J/cm2. Ion energies are on the order of 350 keV, with beam current rising to 35 kA over a 400 ns ion current pulse.Raman spectra of the deposited films indicate an increasing ratio of sp3 to sp2 bonding as the substrate is moved further away from the target and further off the target normal. Using a thin film platinum resistor at various positions, we have measured the heating of the substrate surface due to the kinetic energy and heat of condensation of the ablated material. Plume power density and energy input are inferred from the temperature measurements. This information is used to determine if substrate heating is responsible for the lack of DLC in positions close to the target and near the target normal.
Laser-Solid Interaction and Dynamics of the Laser-Ablated Materials
Authors: Chen K. R. , Leboeuf J. N. , Geohegan D. B. , Wood R. F. , Donato J. M. , Liu C. L. , Puretzky A. A. 
Published: April 2011

AbstractRapid transformations through the liquid and vapor phases induced by laser-solid interactions are described by our thermal model with the Clausius-Clapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic equations. these two models are coupled. Modeling results show that lower background pressure results lower laser energy density threshold for vaporization. the ablation rate and the amount of materials removed are proportional to the laser energy density above its threshold. We also demonstrate a dynamic source effect that accelerates the unsteady expansion of laser-ablated material in the direction perpendicular to the solid. a dynamic partial ionization effect is studied as well. a self-similar theory shows that the maximum expansion velocity is proportional to cs/α, where 1 – α is the slope of the velocity profile. Numerical hydrodynamic modeling is in good agreement with the theory. With these effects, α. is reduced. therefore, the expansion front velocity is significantly higher than that from conventional models. the results are consistent with experiments. We further study the plume propagates in high background gas condition. Under appropriate conditions, the plume is slowed down, separates with the background, is backward moving, and hits the solid surface. then, it splits to be two parts when it rebounds from the surface. the results from the modeling will be compared with experimental observations where possible.
Properties of Low-Resistivity Undoped indium-Oxide Films Grown by Reactive Ion Plating and Electrochromic Tungsten-Oxide Films Grown by Electron-Beam Evaporation
Authors: Lee Y. P. , Jeong J. I. , Moon J. H. , Hong J. H. , Kang J. S. 
Published: April 2011

AbstractThe use of gaseous discharge for ion plating and related techniques have been well known to improve coating properties in several ways. IN the arc-induced ion plating (AIIP), the ionization efficiency for the evaporants is so enhanced without any introduction of inert gases that the bias voltage for, and the temperature of the substrate are reduced in the preparation of the coatings. Highly transparent (> 90% transmission in the visible range) and highly conductive (resistivity ≅ 1.5 x 10-4 Ω cm) in-oxide films were deposited at a rate of 500 - 900 Å/min by aIIP of pure in in an O2 atmosphere of 10-4 Torr. Hall-effect measurement revealed that the observed low resistivity is due primarily to the excellent electron mobilty (≥ 70 cm2 / V sec) with carrier density up to 7 х 1020/cm3. Electrochromic WO3 films were also prepared and characterized.