bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid Thermal Oxidation of GeSi Strained Layers
Authors: Nayak D. K. , Kamjoo K. , Park J. S. , Woo J. C. S. , Wang K. L. 
Published: March 2011

ABSTRACTA cold-wall rapid thermal processor is used for the oxidation of commensurately grown GexSi1−x layers on Si substrates. It is shown for dry oxidation that the oxidation rate of GeSi is the same as that of Si. The dry oxidationrate of GeSi is independent of Ge concentration (up to 20 % considered in this study) in the GeSi layer. For wet oxidation, however, the rate of oxidation of the GexSi1−x layer is found to be significantly higher than that of pure Si, and the oxidation rate increases with the Ge concentration in GexSi1−x layer. Employing highfrequency and quasistatic Capacitance-Voltage measurements, it is found for a thin oxide that a fixed negative oxide charge density in the range of 1011 – 1012/cm2, and the interface trap level density (in the mid-gap region) of about 1012 /cm2.eV are present. Further, the density of this fixed oxide charge at the SiO2 /GeSi interface is found.to increase with the Ge concentration in the commensurately grown GeSi layers.
Properties of Interfaces between Superlattice Heterostructures and Uniform Alloy Materials as Realized by Impurity Induced Disordering
Authors: Thornton R. L. , Ponce F. A. , Anderson G. B. , Chung H. F. 
Published: March 2011

ABSTRACTIn this paper present experimental results on the quality of AIGaAs material after high concentrations of impurities have been introduced for the purpose of impurity induced disordering. A comparison between Zn and Si diffusion is presented, and the nature of the transition region between uniform alloy and as-grown periodic structure has been characterized both experimentally and theoretically. Device implications of these observations is discussed.
Microtomy of Large Particle Zeolites for Tem
Authors: Ulan J. G. , Schooley C. , Gronsky R. 
Published: March 2011

ABSTRACTUniformly thin specimens of powders, suitable for electron microscopy, can be prepared by ultramicrotomy. There is a size limit to the particles that can be studied since larger particles tend to be dislodged from the available resins when microtomed. A method is described to strengthen the binding of the organic resin to the inorganic zeolite, allowing large particles to be sectioned. The particle size limit increased from 3 μm to greater than 20 gim in diameter for FeZSM-5 aggregates. This method can be applied to a variety of oxide powder samples, extending the utility of microtomy as a materials science tool.
Preparation of Cross Sectional TEM Samples Using Lithographic Techniques and Reactive Ion Etching
Authors: Wetzel Jeffrey T. , Kavanagh K. L. 
Published: March 2011

ABSTRACTThis paper summarizes methods used to create cross-sectional samples for transmission electron microscopy and introduces another variant of the technique all of which rely upon some combination of lithographic patterning and reactive ion etching. The basic idea pursued in using these techniques was to form, from a preselected location, samples that had a large transparent area without use of mechanical polishing or ion milling. Samples were successfully prepared in this manner, but room for improvement remains due to the limited range of diffraction conditions available for imaging or diffraction pattern formation.
Chemically Assisted Ion Beam Etching (CAIBE)- a New Technique for TEM Specimen Preparation of Materials
Authors: Alani Reza , Jones Joseph , Swann Peter 
Published: March 2011

ABSTRACTChemically assisted ion beam etching (CAIBE) is widely practiced in the semiconductor industry. In the electron microscopy field, the CAIBE technique offers a new method for preparing specimens that are difficult to make by conventional inert gas milling techniques, e.g. indium containing type III-V compound semiconductors. CAIBE employs a collimated, molecular beam of a reactive species, e.g. iodine in combination with a conventional inert gas fast atom beam for thinning TEM specimens. CAIBE should not be confused with reactive ion beam etching (RIBE) which takes a chemically active species (e.g. iodine) and converts it into a beam of fast ions directed at the sample. CAIBE has three major advantages over (RIBE): i) corrosion of the ion gun components does not occur, ii) much smaller quantities of reactive gas are required and hence pump maintenance and pollution problems are minimized, iii) a wider range of chemicals may be used. Superior results are obtained if CAIBE is done on only one side of the specimen at a time. This is achieved using a new type of specimen holder post which enables very low angle milling and minimizes specimen contamination by sputtering from the holder. This new technique is described and results from iodine CAIBE milling, iodine RIBE milling and argon ion milling are compared for InP, InSb and GaAs as well as metals like tungsten. Also, the beneficial effects of very low angle (∼1°) argon ion milling in preparing specimens of silicide containing Si based IC wafers is reported.
Radiation Damage and its Annealing in Semiconductors
Authors: Narayan J. , Fletcher J. 
Published: March 2011

ABSTRACTResidual damage in the form of point defect clusters and amorphous regions has been investigated in ion and neutron irradiated silicon specimens. Annealing of this damage during conventional heating, flame annealing, and pulsed laser irradiation has been studied by plan-view and cross-section electron microscopy techniques. These results provide detailed information on annealing mechanisms, and emphasize the characterization of damage in the as-irradiated state.
Reduction of α-Particle Sensitivity in Dynamic Semiconductor Memories (16K d-RAMs) by Neutron Irradiation
Authors: Thompson Charles E. , Meese J. M. 
Published: March 2011

ABSTRACTTrace radioactive impurities found in all semiconductor devices induce soft errors in semiconductor memories by α-particle emission. Data taken on 16K d-RAMs which have been fast neutron irradiated to fluences from 1013 to 1016 n/cm2 show that soft errors in these devices can be significantly reduced while maintaining acceptable device operation. Reduction in soft error rate by factors as high as 80 are observed following irradiation and thermal annealing. The effect on device parameters is discussed as well as the defects responsible for this beneficial radiation processing. Estimates of the soft error rate improvement to be expected on higher density memory devices (64K and 256K d-RAMs) will also be presented.
Silicon-Sapphire Interface: A High Resolution Electron Microscopy Study
Authors: Ponce Fernando A. 
Published: March 2011

ABSTRACTThe structure of the silicon-sapphire interface of CVD silicon on a (1102) sapphire substrate has been studied in crøss section by high resolution transmission electron microscopy. Multibeam images of the interface region have been obtained where both the silicon and sapphire lattices are directly resolved. The interface is observed to be planar and abrupt to the instrument resolution limit of 3 Å. No interfacial phase is evident. Defects are inhomogeneously distributed at the interface: relatively defect-free regions are observed in the silicon layer in addition to regions with high concentration of defects.
The Effect of Carbon on the Precipitation of Oxygen in Czochralski Silicon
Authors: Pinizzotto R. F. , SCHAAKE H. F. 
Published: March 2011

ABSTRACTResearchers in both the U. S. and Japan have reported that carbon impurities can significantly alter the precipitation of oxygen in CZ silicon. We have employed FTIR, x-ray topography and TEM to study this phenomenon in silicon containing < 2 × 1016 C cm−3 or 1.3 × 1017 C cm−3. A single step anneal of 16 hours at 1000°C will cause oxygen precipitation to occur in the high carbon material, while a 32 hour pre-anneal at 600°C is necessary for precipitation in the low carbon material. If a single anneal of 120 hours at 750°C is used, light precipitation occurs in both types of material. A pre-anneal of 15 minutes at 1000°C followed by 120 hours at 750°C reduces precipitation in the high carbon material only slightly, but completely eliminates precipitation in the low carbon material. It can be concluded that carbon causes heterogeneous nucleation of oxygen precipitation in CZ silicon and it is proposed that it does so by lowering the interfacial energy of the precipitates.
Investigation of Defect Concentration Distributions in Ion-Implanted and Annealed GaAs
Authors: Wang K.L. , Li G.P. , Asbeck P.M. , Kirkpatrick C.G. 
Published: March 2011

ABSTRACTUncapped and Si3N4-capped annealing of GaAs grown with the horizontal Bridgman technique was investigated with deep-level transient spectroscopy. Electron trap concentration distributions were measured with a reduced noise DLTS system to ensure reliable data. Ion implantation using Se ions both prior to capping and through a Si3N4 cap was carried out. The evolution of defect energy levels and the changes in concentration distributions with anneal temperature were studied. It is concluded that the defects residing in the probed space-charge region can be annealed out with a Si3N4 cap at a temperature higher than 750 C.
Thermoelectric Power of Graphite Acceptor Compounds
Authors: Sugihara Ko 
Published: March 2011

ABSTRACTTemperature variations of the thermopower (TEP) of acceptor graphite intercalation compounds (GIC) are very different from that of pristine graphite. At low temperatures the TEP increases monotonically with T, then levels off above 150 K. This behavior is ascribed to the phonon drag effect. In the region where the TEP is nearly constant, phonon relaxation is mainly controlled by the Rayleigh scattering due to point defects or impurities. This process leads to T-independent phonon drag TEP. The importance of Rayleigh scattering is due to the large cross section diameter of the Fermi surface in GIC. At low temperatures where the boundary scattering becomes important, the TEP is proportional to T3 . Detailed calculations are carried out by solving the phonon-carrier coupled Boltzmann equation.
Low Field Galvanomagnetic Properties of Graphite Acceptor Compounds and their Relation to Trigonal Warping
Authors: Sugihara Ko 
Published: March 2011

ABSTRACTIn first stage graphite intercalation compounds with cylindrical Fermi surfaces and isotropic relaxation times, no magnetoresistance occurs. Holzwarth pointed out that trigonal band warping provides a finite magnetoresistance in first stage compounds. A calculation of the galvanomagnetic coefficients of stage-2 acceptor compounds is performed including the effect of trigonal warping on the bands. In the present problem a perturbation calculation provides a good approximation. Without trigonal warping, the stage-2 compounds exhibit a finite magnetoresistance since they have two kinds of holes. Retaining terms up to order (γ3/γ0)2, the weak field magnetoresistance is calculated in limit H→0; Δρ/ρoH2 ≍ (e/h2c)2 (τ/EF)2 (3γ0b/2)4[1/4(γ1/EF)2+57/2(γ3/γ0)2] where b = 1.42 Å is the nearest C-C distance, EF the Fermi energy and τ the carrier relaxation time. The first term in curly brackets is due to the existence of the two kinds of holes. This formula indicates that the term due to trigonal warping is much larger than the other term.
The Chemistry and Characteristics of Nitric Acid-Graphite Intercalation
Authors: Su Sophia R. , Oblas Daniel W. 
Published: March 2011

ABSTRACTGas-phase intercalation of graphite by nitric acid is a one-step process. The weight uptake of the sample is a function of nitric acid vapor pressure. A pure second stage compound was formed when the HNO3 reservoir was maintained at 17°C. Only a fourth stage compound was formed when the acid was kept at 0°C. The product gases due to intercalation and gas species evolved during deintercalation were analyzed by mass spectrometry. NO2 and H2O were the major components detected from the intercalation product gases. A small amount of oxygen was also present. The existence of O2 is probably due to the photo-chemical decomposition of nitric acid. As such, the photodecomposition of nitric acid is not a contributory factor in the intercalation chemistry.
Electrochemical Characteristics of Graphite Intercalation Compounds With Fluorine-Lithium Cells
Authors: Watanabe Nobuatsu , Touhara Hidekazu , Nakajima Tsuyoshi 
Published: March 2011

ABSTRACTThe discharge reaction mechanism for two types of graphite fluorides, (CF)n and (C2F)n cathodes of lithium cells utilizing a 1 M LiClO4-propylene carbonate (PC) system were studied by means of x-ray diffraction, ESCA, NMR and transmission electron microscopy. It has been revealed that the discharge reaction proceeds through the formation of an intermediate solvated ternary compound of (C·F·Li)·PC or (C2· F·Li)·PC, and then they decompose to graphite with low crystallinity and LiF. The decomposition process is not involved in the electrochemical reaction and this discharge reaction infers the open-circuit voltage of cells. New graphite intercalation compounds, CxF(MFn)y(MFn=AIF3, MgF2) were prepared under a fluorine atmosphere of 1 atm in the temperature range between 20 and 400°C. These compounds are highly stable even in moist air and have high electrical conductivity. The discharge potentials of CxF(MFn)y-lithium cells are 2.5–2.8 V at current densities 40–400μA, which are higher than those of (CF)n or (C2F)n-lithium cells below 300μA.
Diffusive Motion of Alkali Atoms in Graphite: A Quasielastic Neutron Scattering Study
Authors: Zabel H. , Magerl A. , Rush J.J. , Dianoux A.J. 
Published: March 2011

ABSTRACTWe have studied the diffusive motion of alkali atoms in thermodynamic equilibrium in RbC24 by quasielastic neutron scattering. The neutron spectra show Lorentzian line profiles. The widths increase with increasing temperature. In addition a ‘de Gennes’ narrowing is observed at Q=1.2 Å-1, which coincides with the first peak in the intercalant structure factor. The narrowing becomes more pronounced at higher temperatures in contrast to a normal liquid. The data can be interpreted by the motion of clusters of alkali atoms rather than by a liquid type motion. This adds a dynamical aspect to the “floating solid’ as described by Nelson and Halperin for the melting of a 2-dimensional solid.
Phase Transitions in Graphite – SbCl5Intercalates
Authors: Clarke Roy , Homma Hitoshi 
Published: March 2011

ABSTRACTInterlayer and intralayer ordering in SbCl5-GIC's are probed by X-ray diffuse scattering. A crossover from 3-d to quasi 2-d structure is observed at around stage 2. Surprisingly, different in-plane arrangements can be obtained under nominally the same preparation conditions at the same stage. A stripe-like incommensurate structure close to the √39 superperiod of graphite, and a 14×14 commensurate superlattice structure, have been observed in different samples. The formation of these groundstate structures, and their transitions to ‘disordered’ phases, are discussed in terms of the molecular degrees of freedom.
A Study of the Temperature-Dependence of Low-Frequency, Raman-Active Phonons in Stage-2 Graphite-K and Graphite-Rb Intercalation Compounds
Authors: Giergiel J. , Eklund P. C. , Al-Jishi R. , Dresselhaus G. 
Published: March 2011

ABSTRACTWe report results from a Raman scattering study of stage 2 Graphite-Rb and Graphite-K in the low frequency region (ω < 150 cm-1) as a function of temperature (80K < T < 300K). Four features are seen in the 80K spectra and are interpreted in terms of a Born– von Kármán lattice dynamics model. The temperature-dependence of the Raman spectra is discussed in connection with reported phase transitions in stage 2 alkalimetal graphite compounds.
Phonon Spectrum of Second Stage Graphite-Bromine Intercalation Compounds
Authors: Simon Ch. , Batallan F. , Rosenman I. , Lauter H. 
Published: March 2011

ABSTRACTCoherent inelastic neutron scattering results on the second-stage graphite intercalation compound C8Br are presented. Phonons polarized along the c-axis and in the basal plane were observed. A phenomenological Born-von Kármán force constant model with non-axial symmetry is used with parameters adjusted in agreement with the results. Several specific points of the phonon spectrum which are outside of the limits of the model are discussed.
Ion-Implantation Studies of Graphite
Authors: Elman B.S. , Hom M. , Maby E.W. , Dresselhaus M.S. 
Published: March 2011

ABSTRACTIon implantation of highly oriented pyrolytic graphite (HOPG) is studied using various characterization techniques, including Raman spectroscopy and Secondary Ion Mass Spectroscopy (SIMS). Particular attention is given to the annealing of the implantation-induced lattice damage using both hot substrate implantation (200 < T1< 1000°C) and postimplantation annealing. The Raman spectra provide detailed information on the implantation-induced structural disorder by analysis of the disorder-induced and Raman-allowed features in the first- and second-order spectra. SIMS measurements show that the implanted profile is essentially the same for hot substrate and room temperature implantation for the case of HOPG. It is shown that implantation at elevated temperatures prevents amorphization more effectively than implantation at room temperature and subsequent annealing at the same elevated temperature. The annealing results show that fundamentally different defects are created during room temperature and hot substrate implantation.
Specific Heat Anomaly of C24K Arising from Hydrogen Physisorption
Authors: Kondow Tauotsu , Mizutani Uichiro 
Published: March 2011

ABSTRACTHydrogen/deuterium gas was absorbed in the potassium graphite intercalation compound, C24K, at 77K and then the low temperature specific heats were measured in situ as a function of the hydrogen concentration in the temperature range 1.5–6K. Enhancement of the electronic specific heats upon hydrogen sorption indicates formation of bound states in the vicinity of the Fermi level. Increase of the Debye temperatures by introduction of hydrogen shows the hardening of the lattice. An observed specific heat anomaly was ascribed to a dispersion-less optical phonon with characteristic temperatures of about 17K.
Intercalation of Acceptors and Donors in Highly Ordered Graphite Fibers
Authors: Chieu T.C. , Timp G. , Dresselhaus M.S. 
Published: March 2011

ABSTRACTThe intercalation of various acceptors and donors into graphite fibers, prepared from benzene-derived precursor materials is investigated by Raman spectroscopy, x-ray diffraction, electron diffraction, lattice fringing, and electrical resistivity measurements. Evidence for formation of well-staged acceptor compounds is provided by Debye-Scherrer x-ray diffraction which probes the bulk fiber and by Raman spectroscopy which probes an optical skin depth (< 0.1 μm). Lattice fringing measurements provide direct observation of large regions (up to 50 Aring; × 400 Aring;) of defectfree single-staged regions. Values for the c-axis repeat distance Ic are obtained by indexing (00l) lines of the x-ray diffraction pattern. Raman results show characteristic upshifted modes for stage 1 acceptor compounds with a sharpening in linewidth as compared to the E2g2 mode of the pristine fiber. The room temperature electrical conductivity is increased about an order of magnitude upon intercalation and exhibits a metallic dependence on temperature. The highest air-stable room temperature conductivity 1.4 × 105 (Ω-cm)−l ever reported for an intercalated fiber has been achieved.
Electronic and Lattice Modes of Graphite-Cocl2
Authors: Lowe C.W. , Nicolini C. , Dresselhaus G. 
Published: March 2011

ABSTRACTReflectivity measurements on graphite-CoCl2 intercalation compounds between 0.06 eV and 2.0 eV for stages 3 and 5 show sharp Drude edges and superimposed interband structure. Stage 5 shows structure near 0.4 eV and 0.55 eV while stage 5 shows structure between 0.12 eV and 0.55 eV. The observed number of interband transitions is equal to the stage index which is consistent with a recently proposed kz-axis zone-folding model of the electronic energy bands. In addition to the electronic optical transitions, features associated with lattice vibrations are observed in the spectra. In particular, the graphite-like IR mode near 1580 cm–1 is clearly resolved in the intercalation compounds. A reflectivity minimum and splitting of this vibrational mode is observed for both stages 3 and 5 of graphite-CoCl2.
Excimer Laser Deposition of HighlY Oriented PLZT Thin Films
Authors: Petersen G.A. , Zou L.C. , Van Buren W.M. , Boyer L.L. , Mcneil J.R. 
Published: March 2011

ABSTRACTLaser ablation provides a suitable technique of ferroelectric thin film deposition. We have used this technique to produce films of Pb1−xLax(Zr1−y Tiy)1−x/4O3 (PLZT), a class of ceramic materials which has a wide range of composition dependent electro-optical properties. PLZT films of (7/0/100) and (28/0/100) composition have been deposited onto both crystalline Si <100> and amorphous fused silica substrates. Laser ablation provides high deposition rates and good crystal structure of thin ferroelectric films on silicon. The methods required to achieve proper stoichiometry in the films are also discussed.
Ferroelectric Films-Growth, Properties and Applications
Authors: Francombe M.H. , Krisknaswamy S.V. 
Published: March 2011

ABSTRACTThin films of ferroelectric and piezoelectric materials are playing a growing role as critical elements in microwave acoustic devices, infrared imagers, integrated optic circuits, optical displays and high-performance semiconductor memories. In this review, we discuss recent progress in the control of growth, structure and properties of the main candidate materials, such as piezoelectric ZnO and AlN, and ferroelectric PZT-based solid solutions, KNbO3, bismuth titanate (Bi4Ti3O12), LiNbO3, LiTaO3 and KNO3. Brief mention is also made of the role and status ferroelectric polymers and of the BaMF4 class of fluorides. The emphasis of the review is primarily on vacuum-processed films, and optimization of characteristics required for integration into solid-state or semiconductor components.
Study of Diffusion Barriers for PZT Deposited on Si for Non-Volatile Random-Access Memory Technology
Authors: Parikh Nalin R. , Stephen J. Todd , Swanson Max L. , Myers Edward R. 
Published: March 2011

ABSTRACTThin film ferroelectric structures are being investigated for use as storage capacitors for Non-volatile Random-Access Memories. To integrate ferroelectrics with standard silicon semiconductor processing, a great deal of effort must be spent identifying compatible materials. These materials must be able to withstand both ferroelectric and silicon processing steps involving different temperatures and environments.In this paper we have used Rutherford backscattering spectrometry (RBS) to study the diffusion of ferroelectric Pb(Zr.5Ti.5)O3 elements into thin films of TiOx, TiNx, ZrNx and ZrOx deposited onto thermally grown SiO2. The sample matrix was annealed at various temperatures in argon ambient and analyzed using 2 MeV He+. Diffusion profiles (concentration vs. depth profiles) of the ferroelectric constituents were determined for the different barrier films. Results indicated that ZrN is the most promising barrier layer so far, having shown the least interdiffusion at 700°C.