bluuebunny/crossref_metadata_2025_split huggingface dataset:
Melting and Laser Annealing in Semiconductors using 0.485 μm and 0.193 μm Pulsed Lasers
Authors: Narayan J. , Fletcher J. , Eby R. E. 
Published: March 2011

ABSTRACTAnnealing of displacement damage, the dissolution of boron precipitates, the formation of constitution supercooling cells, and the broadening of dopant profiles have been studied in laser annealed silicon. These samples were irradiated with a dye laser (λ = 0.485 µm, τ = 9 ns, E = 0.7–1.2 J cm−2) and an Excimer laser (λ = 0.193 µm, τ= 9 ns, E = 0.5–0.7 J cm−2) pulses. These results can be consistently interpreted by invoking melting during pulsed laser irradiation. Thus these results provide convincing evidence for the melting phenomenon.
Residual Defects after Pulsed Laser Annealing of Ion implanted Silicon
Authors: Mesli A. , Muller J.C. , Salles D. , Siffert P. 
Published: March 2011

ABSTRACTCapacitance transient spectroscopy has been used to investigate the electrically active defects subsisting, after a ruby laser pulse annealing, in ion implanted silicon. In contrast to the common view, it is shown that the identified point defects are related to residual implantation related defects buried beyond the dopant distribution and not to the laser effect.
Effect of Electric Field and Current Injection on the Main Electron Trap in Bulk GaAs
Authors: Makram–Ebeid S. 
Published: March 2011

ABSTRACTThe dark capacitive transients related to the main electron trap in bulk and VPE GaAs have been studied in detail. The low temperature low field transients are induced by electrons injected from the metal counter electrode. Both hot electron capture and impact ionization effects are observed. At high fields, a phonon assisted tunneling model accounts for the observations and yields the values of the Franck Condon Shift Sw and the energy w of the phonon coupled to the level. These values are found to be in good agreement with other independent estimates.
Imaging of Defects in Cadmium Telluride using High Resolution Transmission Electron Microscopy
Authors: Ponce F. A. , Yamashita T. , Bube R. H. , Sinclair R. 
Published: March 2011

ABSTRACTThe defect structure of cadmium telluride has been investigated using high resolution transmission electron microscopy. The variation of the TEM images with the defocus value is discussed, and defect symmetry considerations are used to correlate the image contrast characteristics with the lattice struc ture. Experimental micrographs of stacking faults and dislocations in the structure are analyzed.
A Channeling Study of Defect-Boron Complexes in Si
Authors: Swanson M.L. , Howe L.M. , Saris F.W. , Quenneville A.F. 
Published: March 2011

ABSTRACTSi crystals were doped with 0.1–0.2 at% 11B in the near surface region by ion implantation followed by thermal diffusion at 1373 K or by ruby laser annealing. The position of the B atoms in the Si lattice was determined by channeling measurements, utilizing both the yield of H+ ions (of incident energy 0.7 MeV) backscattered from Si atoms and the yield of alpha particles from the 11B(p,α)8Be nuclear reaction. Initially, 95–99% of the B atoms were substitutional. Irradiation at 35 K or 293 K with 0.7 MeV H+ displaced B atoms from lattice sites. The displacement rate was greater at 293 K than at 35 K, and was greater for diffused samples than for laser annealed samples. Following 35 K irradiations, a large increase in the fraction fdB of displaced B atoms occurred during annealing near 240 K. At higher annealing temperatures, fdB decreased over a broad temperature range from 425–825 K. Angular scans through <110> channels for the laser annealed samples after 293 K irradiation or after 35 K irradiation plus 293 K annealing showed a pronounced narrowing of the dip in 11B(p,α)8Be yields compared with the dip in yields from Si, whereas no narrowing was observed for <100> channels. These results indicate that B atoms were displaced into specific lattice sites by the migration of an interstitial B defect (the EPR G28 defect) near 240 K.
Fermi Surface and Charge Density Waves in Second-Stage Graphite-Bromine Intercalation Compounds
Authors: Batallan F. , Rosenman I. , Simon Ch. , Furdin G. 
Published: March 2011

ABSTRACTResults of de Haas van Alphen effect study on second-stage bromine graphite intercalation compound C14 Br are presented together with a two dimensional model of electronic structure and Fermi surface. The results are characterized by a mixing of de Haas-van Alphen frequencies. The nature of the coupling mechanisms between orbits is discussed. It is shown that the two dimensional Fermi surface of C14 Br contains nested parallel parts which can stabilize charge density waves. A comparison between the nesting vectors of this Fermi surface and the satellites and diffuse streaks found in structural studies shows a fair agreement between both.
Thermal Transport in Intercalated Graphite
Authors: Issi J-P. 
Published: March 2011

ABSTRACTRecent results on the temperature and stage dependence of the thermal conductivity of various graphite intercalation compounds are reported and briefly analyzed. In the lowest temperature range the in-plane thermal conductivity which is mainly electronic, is higher than that of pristine graphite. Around room temperature, in spite of an increased electronic conduction, a decrease in the total thermal conductivity relative to pristine graphite is observed. This shows that the dominant effect is the decrease of the lattice contribution due to increased phonon scattering by lattice defects. The c-axis conduction is attributed entirely to phonons and the anisotropy ratio is of order of 102 in the liquid helium range and increases up to several hundreds around room temperature. Some results on the temperature variation of the in-plane and c-axis thermopower for donor and acceptor compounds are also presented and discussed.
Single Crystal X-Ray Diffraction Study of the Phase Transitions in Graphite-Bromine Intercalation Compounds
Authors: Ghosh D. , Chung D.D.L. 
Published: March 2011

ABSTRACTReported here is the first observation of an incommensurate-commensurate phase transition at 316 ± 1 K upon heating stage-2 graphite-bromine prepared in bromine liquid. The transition during heating involved the movement of the 300 reflection toward a lower q value and the sharpening of the 010 reflection, thereby resulting in the commensurate structure characteristic of stage-2 prepared in bromine vapor. The transition was reversible. The previously reported comtmensurate-incommensurate transition occurred at 326, 329, 332, 338 and 348 K for stage 2 (in bromine liquid), stage 2 (in bromine vapor), stage 3, stage 4, and desorbed material, respectively. Disordering was observed upon completion of this transition.
C-Axis Resistivity of SbCl5-Graphite in Hopg and Single Crystal Forms
Authors: Uher C. , Morelli D.T. 
Published: March 2011

ABSTRACTC-axis electrical resistivities were measured from 2-300K on SbCl5-graphite intercalation compounds, using both HOPG and single crystals as host materials. The resistivity of these compounds is up to an order of magnitude higher (˜10−2Ωm) than that of pure HOPG graphite. Yet, for stage n≤3 (in the case of HOPG), a metallic temperature dependence of ρC is observed throughout the entire investigated range. Higher stage compounds show metallic behavior at high temperatures, but exhibit a crossover to an activated dependence as the temperature is lowered. All samples show hysteretic behavior with cycling. A model, based on defect-mediated short-circuiting channels, is proposed to account for the existence of a metallic temperature dependence in conjunction with large resistivity.
Thermodynamics Of Intercalation of Bromine in Graphite
Authors: Anderson S. H. , Chung D. D. L. 
Published: March 2011

ABSTRACTThe thermodynamics of intercalation of bromine in highly oriented pyrolytic graphite had been studied by determining the pressure-temperature equilibrium diagram for stages 2–4. The standard heat and entropy of reaction for the transformation from stage n to stage n−l (n=5, 4, 3) were found to be roughly the same, though the enthalpy of reaction became slightly more negative as the stage number increased. The heat and entropy of formation from pure graphite were thus found to be −10.9 kcal mol-1 Br2 and −30.4 cal mol−1 Br2 K−1 respectively for stage 2, −11.32 kcal mol−1 Br2 and −30.6 cal mol−1 Br2 K−1 respectively for stage 3, and −11.5 kcal mol−1 Br2 and −30.6 cal mol−1 Br2 K−1 respectively for stage 4.
Intercalation-Desorption Studies of Graphite Nitrate
Authors: Dziemianowicz T. , Leong K. , Forsman W.C. 
Published: March 2011

ABSTRACTA new model for intercalation kinetics is presented whick takes into account both nucleation of the interlaminar spaces and intercalant layer growth. For nitric acid intercalation, the nucleation constant, β, ranges from 1.25×10−3 to 10−4 sec−1 depending on graphite type (HOPG > powder > fibers); the corresponding range of effective diffusivities, D, is 2.5×10−5 to 10−10 cm2/sec. It is emphasized that effective diffusivities obtained from sorption kinetics are reaction enhanced.Stepwise isothermal desorption experiments show that the diffusivities of HNO3 neutrals are lower than the effective diffusivities on sorption. At desorptive equilibrium, intercalant retention is in the order HOPG > fibers > powder. In HOPG, resistance is constant over the desorptive transition stage II → III → IV; during the stage IV → V → VI regime (dynamic vacuum), resistance doubles. A similar resistance gain is noted on desorption of neturals from nitrated graphite fibers.
Binary and Ternary Alkali Graphite Intercalation Compounds: In-Situ X-Ray Study Of Elastic And Electrostatic Effects on Staging
Authors: Misenheimer M.E. , Chow P. , Zabel H. 
Published: March 2011

ABSTRACTWe have studied stage transformations of binary potassium-graphite intercalation compounds by in-situ x-ray (00ℓ) scans. In the transition region of stages one and two, both stages coexist and all Bragg reflections exhibit resolution limited widths. The characteristics of the stage transformation are identical in intercalated HOPG and single crystals. This implies that the stage transformation is a direct process with no need of forming intermediate structures, favoring electrostatic interaction as the dominant stabilizer for pure stage donor compounds. We have also studied the elastic distortion due to potassium atoms substitutionally dissolved in rubidium intercalant layers. From the interlayer spacing variation we find a double force tensor Pzz = 0.36 eV for potassium defects in RbC8 in the small defect concentration region.
Ultrasonic Velocity Studies of Graphite and Its Intercalation Compounds
Authors: Hwang D. M. 
Published: March 2011

ABSTRACTThe c-axis sound velocities and attenuations for HOPG, stage 3 and stage 4 SbCl5-graphite were determined by ultrasonic techniques in the temperature range between 4 and 325 *K. The temperature variation of C33 for HOPG agrees closely with the theoretical prediction based on the Lennard-Jones interlayer potential. In SbCl5-graphite, the longitudinal sound attenuation increases sharply and the transverse sound cannot propagate for temperatures above 200 °K, indicating a commensurate-to-incommensurate in-plane phase transition. The stage dependence of C33 at low temperatures indicates that the interlayer forces beyond the nearest layers can not be neglected.
Second-Order Raman Scattering in Graphite Intercalation Compounds
Authors: Giergiel J. , Eklund P. C. 
Published: March 2011

ABSTRACTThe stage dependence of various second-order Raman features observed for acceptor (FeCl3, SbCl5) and donor (Rb) Graphite Intercalation Compounds is reported and discussed in terms of recent Born-von Kármán lattice dynamics calculations of Al-Jishi and Dresselhaus.
High Resolution Electron Microscopy of A Nicl2 – Intercalated Graphite
Authors: Dorignac D. , Lahana M.J. , Jagut R. , Jouffrey B. , Flandrois S. , Hauw C. 
Published: March 2011

ABSTRACTHigh resolution electron imaging supported by computer image simulation has been carried out for a nominal “second–stage” NiCl2 graphite compound. The resulting local structure information underlines the statistical nature of the stage ordering, rarely perfectly regular. It also shows the interpenetration of differently staged regions.
Cesium State, Thermal Evolution In Csc24
Authors: Estrade-Szwarckopf H. , Conard J. , Lauginie P. , Van Der Klink J. , Lagrange P. , Guerard D. , Rousseauxl F. , Nancy L.C.M.A. , Maaroufi A. , Hermann G. 
Published: March 2011

ABSTRACTBy 133Cs and 13C NMR, EPR, susceptibility anisotropy and X-Ray diffraction,we studied the thermal evolution of Cs24 from 100 to 500 K. A smooth transition is observed near 300 K which can be interpreted in structural and electronic terms: at lower temperatures, the Cs atoms are located in a disordered manner on graphitic hexagonal sites and are almost completely ionized; in the high temperature state, the Cs atoms are completely disordered relatively to the graphitic lattice and their electrons are at least partly relocalized on the metallic s-function.
151Eu Mössbauer Studies on Graphite-EuC13
Authors: Boolchand P. , Lemon G. , Bresser W. , Mcdaniel D. , Heinz R.E. , Eklund P.C. , Stumpp E. , Nietfeld G. 
Published: March 2011

ABSTRACT151Eu Mössbauer experiments on EuC13-Alcl3 graphite flakes and HOPG samples have been performed as a function of temperature in the range 4.2K < T < 300K and indicate the presence of a narrow line characteristic of Eu3+. No evidence of Eu2+ was found. This suggests that enhanced conductivity of graphite upon intercalation with rare earth chlorides derives from a transfer of charge to the co-intercalated Cl.
X-Ray Diffraction Studies of Structural Dimensionality in Carbon Fibers
Authors: Stamatoff James , Goldberg Harris , Kalnin Ilmar 
Published: March 2011

ABSTRACTDiffraction patterns of carbon fibers have been recorded photographically using monochromatized MoKα radiation. <001> and <hk0> reflections are observed for fibers pyrolyzed at lower temperatures. The absence of <hkl> reflections suggests that the graphite planes are turbostratic. A three-dimensional structural transition is manifest in the appearance of <hkl> reflections. The results suggest that the degree of three dimensionality increases progressively through the sample as a function of increasing temperature of pyrolysis. There is no evidence for coexistence of three dimensional and tubostratic phases. It is further demonstrated that turbostratic carbon fibers may be intercalated to stage two with AsF5.
XPS Study of Alkali Graphite Intercalation Compounds
Authors: Wertheim G. K. , Dicenzo S. B. 
Published: March 2011

ABSTRACTCarbon 1s X-ray photoemission spectra of alkali graphite intercalation compounds are shown to provide detailed information about the distribution of charge among the carbon layers and atoms. The interior layers of higher stage compounds contain little charge and remain similar to graphite. The charge in the bounding layers is strongly localized to screen the alkali intercalate ions. The c-axis charge distribution in KC12n is in reasonable accord with the electrostatic screening model of Safran and Hamann.
Microstructure Characterization of Ferroelectric Thin Films used in Non-Volatile Memories - Optical and Scanning Electron Microscopy
Authors: Chapin Leo N. , Myers Sharon A. 
Published: March 2011

ABSTRACTLead zirconate titanate ferroelectric thin films have been fabricated and fully integrated with standard CMOS semiconductor technology to produce non-volatile IC memory devices, now being tested in the marketplace. Starting with an organo-metallic sol-gel and using standard IC spin-on glass and annealing technologies, perovskite type ferroelectric thin films are formed. A variety of techniques have been under study for characterizing the crystalline microstructumre of the ferroelectric layer. Presented here are observations made with optical and scanning electron microscopy, and X-ray diffraction analysis of the effects of ferroelectric composition and sinter temperatures on crystal structure.
Characterization of Chemically Prepared PZT Thin Films
Authors: Tuttle Bruce A. , Schwartz R.W. , Doughty D.H. , Voigt J.A. , Carim A.H. 
Published: March 2011

ABSTRACTWe have systematically varied processing parameters to fabricate PZT 53/47 thin films. Polycrystalline PZT thin films were fabricated by spin depositing Pt coated Sio2/Si substrates with alkoxide solutions. Our study focused on two process parameters: 1) heating rate and 2) excess Pb additions. We used rapid thermal processing techniques to vary heating rates from 3°C/min to 8400°C/min. Films were characterized with the following excess Pb additions: 0, 3, 5, and 10 mol% For all process variations, films with greater perovskite content had better ferroelectric properties. Our best films were fabricated using the following process parameters: an excess Pb addition of 5 mol%, a heating rate of 8400°C/min and annealing conditions of 700°C for 1 min. Films fabricated using these process conditions had a remanent polarization of 0.27 C/m2and a coercive field of 3.4 MV/m.
TEM Investigation of the Ferroelectric Domain Structure in Sputtered PZT Thin Films
Authors: Goral J.P. , Huffman Maria , Al-Jassim M.M. 
Published: March 2011

ABSTRACTThe ferroelectric domain structure in sputtered lead zirconate titanate (PZT) thin films has been investigated using transmission electron microscopy (TEM) and transmission electron diffraction (TED). The individual ferroelectric domains occur as {110}-type microtwins as is observed in the bulk ceramic. The arrangement and size of the ferroelectric domains is strongly dependent on the microstructure of the sputtered film.
Microstructural Characterization of Ferroelectric Thin Films for Non-Volatile Memory Applications
Authors: Myers Sharon A. , Chapin Leo N. 
Published: March 2011

ABSTRACTFerroelectric thin films are now being used in conjunction with semiconductor CMOS technology to produce non-volatile IC memory devices. Three film compositions across the lead-zirconate-titanate (PZT) phase diagram were examined by transmission electron microscopy (TEM). The films are produced using organo-metallic sol-gels and sintered using standard semiconductor processing techniques. The grain structure of these thin films differ greatly from bulk ceramic crystals and thin films prepared using other deposition techniques. For two compositions, Pb1.1 (Zr0.75Ti0. 25)O3 and Pb1.1 (Zr0.50Ti0.50)O3, the perovskite structure was found in large rosettes surrounded by the polycrystalline pyrochlore phase. In the Pb1.1(Zr0.25Ti0.75)O3 sample, perovskite grains were found with no evidence of the pyrochlore phase. Ferroelectric domains were imaged in all three samples.
Measuring Fatigue in PZT Thin Films
Authors: Johnson D. J. , Amm D. T. , Griswold E. , Sreenivas K. , Yi G. , Sayer M. 
Published: March 2011

ABSTRACTSmall signal dielectric response is reported for a variety of PZT thin film samples. Small and large signal responses, recorded simultaneously during the fatiguing of PZT thin films, are used to identify distinct fatigue mechanisms. Microcracking or electrode delamination less than 100 Å is sufficient to explain the high correlation between the dielectric permittivity and remanent polarization during fatigue.
Electrical and Mechanical Properties of PZT Films
Authors: Etzold K. F. , Roy R. A. , Saenger K. L. , Cuomo J. J. 
Published: March 2011

ABSTRACTPZT is a well known ferroelectric material which has been investigated in thin film form for memory, electro-optical and actuator applications. The electrical and electro-mechanical properties of thin PZT films deposited by opposed target RF-sputtering and laser ablation were determined. The targets were sintered and one of them had a composition near the morphotropic phase boundary (48% Ti and 52% Zr) while the other one was on the tetragonal side of the phase diagram with 60% Ti and 40% Zr. Both types had 25% excess lead. The thin films were deposited on a number of substrates (MgO, CaF2, Al2O3 and Spinel. Platinum electrodes were e-beam evaporated on Si/SiO2 as well as on the above single crystal materials). We have measured the relative dielectric constant ε, the polarization P and the electrical field to mechanical strain conversion factor d33. The values which were obtained are compatible with bulk materials but an annealing step at 575°C in oxygen is necessary after deposition. The values before anneal are often significantly lower and we have attributed the reduction to interface layers between the electrodes and the perovskite film or a surface layer on the grains. The d33 coefficients were determined by an interferometric technique which directly detects the surface displacement of the electrode dot.
Electrical Measurement of Ferroelectric Capacitors for Non-Volatile Memory Applications
Authors: Abt Norman 
Published: March 2011

ABSTRACTModified lead titanate ferroelectdc thin films are currently utilized in conjunction with silicon CMOS technology for non-volatile memory applications. The electrical measurement of ferroelectric films has been common practice for many years but the parameters necessary for optimizing their use as memory have not been routinely recorded. Remanent polarization, spontaneous polarization and their change through fatigue and ageing are still the dominant parameters but the pulsing conditions of interest are driven by the circuit requirements. The operation of a memory circuit will be discussed along with implications for testing. Memory is written by applying a pulse to the capacitor. It is read by applying a pulse and sensing whether or not the polarization switched. Read and write pulses will apply different voltages to the ferroelectric capacitor in the circuit because a sense capacitor will be in series with it during the read. A new test, pulsed hysteresis, which is based on circuit operation will be presented. Parameter space of interest will also be discussed.
Electrical Characterization of Ferroelectric Thin Films of Lithium Niobate on Silicon Substrates
Authors: Baumann Robert C. , Rost Timothy A. , Rabson Thomas A. 
Published: March 2011

ABSTRACTThin films (.1-.6 μm) of LiNbO3 have been deposited on silicon substrates by rf reactive sputtering. MFS (metal-ferroelectric-semiconductor) capacitor structures were created by a liftoff process which physically isolated small areas of LiNbO3. Standard MOS (metal-oxide-semiconductor) electrical characterization techniques were used to determine the resistivity and dielectric constant of the films. Short-circuit photocurrent measurements revealed both transient and steady state components attributed to a pyroelectric effect and a bulk photovoltaic effect respectively. The conduction processes in these films were examined and found to exhibit Frenkel-Poole characteristics. Ferroelectric switching at room temperature has also been observed in these films, however, the reversed orientation was not stable.