Showing papers on "Annealing (metallurgy) published in 1997"
TL;DR: In this paper, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE) to study the mechanisms of TED.
Abstract: Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5×1012 to 1×1014/cm2 evolves into a distribution of {311} interstitial agglomerates during the initial annealing stages at 670–815 °C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the dissolution of {311} defects during Ostwald ripening with an activation energy of 3.8±0.2 eV. The excess interstitials drive substitutional B into electric...
618 citations
TL;DR: A microscopic model for the formation of annealing twins in f.c. crystals is proposed in this article, where it is argued that Shockley partial loops nucleate on consecutive planes by growth accidents occurring on migrating {111} steps associated with a moving grain boundary.
481 citations
TL;DR: In this article, a process for making thick, stress-free, amorphous-tetrahedrally bonded carbon (a-tC) films with hardness and stiffness near that of diamond was developed.
Abstract: We have developed a process for making thick, stress-free, amorphous-tetrahedrally bonded carbon (a-tC) films with hardness and stiffness near that of diamond. Using pulsed-laser deposition, thin a-tC films (0.1–0.2 μm) were deposited at room temperature. The intrinsic stress in these films (6–8 GPa) was relieved by a short (2 min) anneal at 600 °C. Raman and electron energy-loss spectra from single-layer annealed specimens show only subtle changes from as-grown films. Subsequent deposition and annealing steps were used to build up thick layers. Films up to 1.2 μm thick have been grown that are adherent to the substrate and have low residual compressive stress (<0.2 GPa). The values of hardness and modulus determined directly from an Oliver–Pharr analysis of nanoindentation experimental data were 80.2 and 552 GPa, respectively. We used finite-element modeling of the experimental nanoindentation curves to separate the “intrinsic” film response from the measured substrate/film response. We found a hardness ...
292 citations
TL;DR: In this paper, the interfacial characteristics of Al/SiO2/n-type 6H-SiC capacitors fabricated by rapid thermal processing (RTP) with N2O and NO annealing are investigated.
Abstract: Interfacial characteristics of Al/SiO2/n-type 6H–SiC metal–oxide–semiconductor capacitors fabricated by rapid thermal processing (RTP) with N2O and NO annealing are investigated. Interface state density was measured by a conductance technique at room temperature. RTP oxidation in pure O2 leads to an excellent SiO2/n-type 6H–SiC interface with interface state density in the order of 1010–1011 eV−1 cm−2. NO annealing improves the SiO2/n-type 6H–SiC interface, while N2O annealing increases the interface state density.
291 citations
TL;DR: In this article, a simple theory which analyses discontinuous and continuous recovery, recrystallization and grain growth, and which enables the relationships between the various annealing phenomena to be explored, was extended to include the effects of a dispersion of second-phase particles.
285 citations
TL;DR: In this paper, a solution-grown crystal (SGC) of poly( l -lactide) (PLLA) was prepared from 0.01 % or 0.08% acetonitrile solution by an isothermal crystallization method and their morphology and structural features were examined by transmission electron microscope with the diffraction mode, wide-angle X-ray diffractometry and atomic force microscope.
272 citations
TL;DR: In this paper, the influence of post-deposition annealing between 300 and 1100 °C on the structural and optical properties and surface morphology of titanium oxide has been investigated.
261 citations
TL;DR: X-ray measurements show that GeO2 and Ge nanocrystals with a radius from 25 down to 1.5 nm are formed in an oxide matrix after annealing as mentioned in this paper.
Abstract: X-ray measurements show that GeO2 and Ge nanocrystals with a radius from 25 down to 1.5 nm are formed in an oxide matrix after annealing. Under ultraviolet excitation, both types of films luminesce around 3.1 eV, with identical photoluminescence (PL) line shapes and subnanosecond PL dynamics. The strongest PL intensity was found for the films containing GeO2 crystals and for the largest nanocrystals. These results are a clear indication that although the blue luminescence is without a doubt correlated with the formation of Ge (or GeO2) nanocrystals, it is not produced by the radiative recombination of excitons confined in the nanocrystals. Possible mechanisms for the luminescence include defects at the nanocrystal/matrix interface or in the matrix itself.
244 citations
TL;DR: Blueshifts in the photoluminescence emission energies from an ensemble of self-assembled InAs quantum dots are observed as a result of postgrowth thermal annealing.
Abstract: Blueshifts in the photoluminescence emission energies from an ensemble of self-assembled InAs quantum dots are observed as a result of postgrowth thermal annealing. Enhancement of the integrated photoluminescence emission and narrowing of the full width half-maxima (from 55 to 12 meV) occur together with blueshifts up to 300 meV at annealing temperatures up to 950 °C. Evidence that the structures remain as dots comes form the observation of level filling and photoluminescence excitation studies which reveal LO phonon peaks occurring at multiples of ∼30 meV from the detection energies.
236 citations
TL;DR: In this paper, textured textured WS2 and MoS2 films are obtained by the techniques of reactive sputtering and solid state reaction, as long as the substrates used are each coated with a 10-20 nm Ni layer.
234 citations
PARC1
TL;DR: In this article, the atomic and electronic structure of hydrogen-vacancy complexes in GaN was investigated with pseudopotential-density-functional calculations, and the formation energies provided information about the likelihood of incorporation of these complexes in $n-type and $p$-type material, and binding energies provided a measure for the dissociation energy.
Abstract: The atomic and electronic structure of hydrogen-vacancy complexes in GaN is investigated with pseudopotential-density-functional calculations. Calculated formation energies provide information about the likelihood of incorporation of these complexes in $n$-type and $p$-type material, and binding energies provide a measure for the dissociation energy. Vibrational frequencies yield a signature of the complex that should facilitate experimental identification. The behavior of hydrogenated nitrogen vacancies during annealing of acceptor-doped GaN is discussed, and a correlation with the frequently observed luminescence band around 420 nm is proposed.
TL;DR: In this paper, the photoluminescence (PL) and electroluminecence (EL) properties of Ge-implanted SiO2 layers thermally grown on a Si substrate were investigated and compared to those of Si-implants O2 films.
Abstract: The photoluminescence (PL) and electroluminescence (EL) properties of Ge-implanted SiO2 layers thermally grown on a Si substrate were investigated and compared to those of Si-implanted SiO2 films. The PL spectra from Ge-implanted SiO2 were recorded as a function of annealing temperature. It was found that the blue-violet PL from Ge-rich oxide layers reaches a maximum after annealing at 500 °C for 30 min, and is substantially more intense than the PL emission from Si-implanted oxides. The neutral oxygen vacancy is believed to be responsible for the observed luminescence. The EL spectrum from the Ge-implanted oxide after annealing at 1000 °C correlates very well with the PL one, and shows a linear dependence on the injected current. The EL emission was strong enough to be readily seen with the naked eye and the EL efficiency was assessed to be about 5×10−4.
TL;DR: In this paper, the pulsed laser recrystallization and doping of thin film amorphous silicon deposited on oxide-coated polyester substrates was reported. But no evidence of damage to the plastic or film delamination from the substrate was found.
Abstract: We report the pulsed laser recrystallization and doping of thin film amorphous silicon deposited on oxide-coated polyester substrates. Although our heat-flow simulation of the laser recrystallization process indicates that the plastic is briefly subjected to temperatures above its softening point, we see no evidence of damage to the plastic or film delamination from the substrate. Film grain size is found to vary up to ∼0.1 μm. Electrical characteristics obtained from simple strip line resistors and thin film transistors indicate that device-quality silicon films have been produced on an inexpensive flexible plastic substrate.
TL;DR: The Hi-Nicalon fiber as discussed by the authors consists of β-SiC nanocrystals (≈5nm) and stacked carbon layers of 2-3nm in extension, in the form of carbon network along the fibre.
Abstract: The oxygen free Si–C fibre (Hi-Nicalon) consists of β-SiC nanocrystals (≈5nm) and stacked carbon layers of 2–3nm in extension, in the form of carbon network along the fibre. This microstructure gives rise to a high density, tensile strength, stiffness and electrical conductivity. With respect to a Si–C–O fibre (Nicalon NL202), the Si–C fibres have a much greater thermal stability owing to the absence of the unstable SiOxCy phase. Despite its high chemical stability, it is nevertheless subject to a slight structural evolution at high temperatures of both SiC and free carbon phases, beginning at pyrolysis temperatures in the range 1200–1400°C and improving with increasing pyrolysis temperature and annealing time. A moderate superficial decomposition is also observed beyond 1400°C, in the form of a carbon enriched layer whose thickness increases as the pyrolysis temperature and annealing time are raised. The strength reduction at ambient for pyrolysis temperatures below 1600°C could be caused by SiC coarsening or superficial degradation. Si–C fibres have a good oxidation resistance up to 1400°C, due to the formation of a protective silica layer.
TL;DR: In this paper, small-angle X-ray scattering (SAXS) and low-frequency Raman spectroscopy experiments have been performed to study the mobility and motion of polymer chains upon annealing in a temperature range close to but below the melting temperature.
Abstract: In-situ small-angle X-ray scattering (SAXS) and low-frequency Raman spectroscopy experiments have been performed to study the mobility and motion of polymer chains upon annealing in a temperature range close to but below the melting temperature. Ultrahigh molecular weight polyethylene, UHMW-PE, was taken as the model polymer, which was crystallized from solution. Regularly stacked lamellar crystals could be obtained after drying the solution-crystallized films. SAXS studies revealed that, upon heating above 110 °C, the lamellar thickness (long period) increases to twice the initial value. This quantum increase was confirmed by transmission electron microscopy (TEM). By means of in-situ low-frequency Raman spectroscopy it was observed that during heating a shift occurs in the longitudinal acoustic (LA) Raman frequency to lower values, indicative of an increase in the thickness of the crystalline core. The combined experimental observations indicate that thickening occurs via a mutual chain rearrangement be...
TL;DR: In this paper, the effect of collision cascades on preexisting point defects in crystalline materials was studied by simulating 5 keV collision cascade in gold, copper, aluminum, platinum, and silicon.
Abstract: The effect of collision cascades on preexisting point defects in crystalline materials was studied by simulating 5 keV collision cascades in gold, copper, aluminum, platinum, and silicon. The results indicate that collision cascades do not significantly affect interstitials or vacancies outside the liquid core of the cascade, although in the fcc metals the heating of the crystal due to the cascade causes some thermal migration of the interstitials. Within the liquid cascade core, both interstitials and vacancies move towards the center of the molten region when it resolidifies and recombine or cluster there. At elevated temperatures, random jumps of interstitials during the thermal-spike phase can cause significant additional trapping of interstitials in the liquid. In contrast to the annealing effects of preexisting damage in the fcc metals, in silicon the amount of new damage created by a cascade is roughly independent of the number of initial point defects. The difference is attributed to the nature of the bonding in the materials.
TL;DR: In this article, two types of refined structure are distinguished by optical and transmission electron microscopy, one is created through intense deformation (four extrusion passes through a 90° die, e = 4.62) by dynamic rotational recrystallization and is a well-formed grain (fragmented) structure with a mean fragment or grain size of 0.2-0.4 μm.
Abstract: Submicrometer-grained (SMG) microstructures are produced in an Al–Mg–Si alloy (6061) by subjecting peak-aged and overaged billets of the alloy to intense plastic strain by a process known as equal channel angular extrusion. Two types of refined structure are distinguished by optical and transmission electron microscopy. One structure is created through intense deformation (four extrusion passes through a 90° die, e = 4.62) by dynamic rotational recrystallization and is a well-formed grain (fragmented) structure with a mean fragment or grain size of 0.2–0.4 μm. The other structure is produced by post-extrusion annealing through static migration recrystallization, resulting in a grain size of 5–15 μm. Intense deformation of peak-aged material to a true strain e of 4.62 (four passes) produces a strong, ductile, uniform, fine, and high angle grain boundary microstructure with increased stability against static recrystallization as compared to the overaged material.
TL;DR: In this paper, the effect of annealing in air and in reducing atmosphere was studied by X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR).
TL;DR: In this paper, the evolution of defect energy levels in CdS thin films, grown in cubic phase by chemical bath deposition, as a function of thermal annealing temperatures in Ar+S2 atmosphere was investigated.
Abstract: Spectral photoconductivity, photoconductive quenching, photoluminescence, and thermally stimulated current measurements, have been carried out in order to study the evolution of defect energy levels in CdS thin films, grown in cubic phase by chemical bath deposition, as a function of thermal annealing temperatures in Ar+S2 atmosphere. The results are influenced by a cubic-to-hexagonal phase transition. From those measurements, a number of trap levels and deep levels in the forbidden band are determined. The results can be explained in terms of the evolution of native and phase transition generated defects in the sample structure.
TL;DR: In this article, a model for the stress relaxation of amorphous carbon films containing high concentrations of fourfold coordinated carbon is presented, and the distribution of activation energies for this process is derived from the experimental measurements of stress relaxation and is found to range from 1 eV to over 3 eV.
Abstract: A model for the stress relaxation of amorphous carbon films containing high concentrations of fourfold coordinated carbon is presented. The onset of stress relaxation in these materials occurs following thermal annealing at temperatures as low as 100°C, and near full stress relaxation occurs after annealing at 600°C. The stress relaxation is modeled by a series of first order chemical reactions which lead to a conversion of some fourfold coordinated carbon atoms into threefold coordinated carbon atoms. The distribution of activation energies for this process is derived from the experimental measurements of stress relaxation and is found to range from 1 eV to over 3 eV. Permanent increases in the electrical conductivity of the carbon films are also found following thermal annealing. The electrical conductivity is found to be exponentially proportional to the number of additional threefold atoms which are created upon annealing, with the increase in threefold atom concentration being deduced from the stress relaxation model. This indicates that the increase in electrical conductivity and the stress relaxation originate from the same fourfold to threefold conversion process and that electrical transport through these films is dominated by a hopping conduction process.
TL;DR: In this article, a model that is based on the catalytic activities of the top electrode to dissociate hydrogen molecules into hydrogen atoms, with the latter subsequently migrating into PZT or SBT films to cause oxygen deficiency and its associated property degradation was proposed.
Abstract: Forming gas annealing causes changes in the remanent polarization (Pr), coercive field (Ec), and leakage current (I) in both PZT [Pb(Zr,Ti)O3] and SBT (SrBi2Ta2O9) samples with a variety of top electrode materials (Pt, Au, Ag, Cu, Ni, and In2O3), and the degree of degradation depends strongly on the top electrode material. These results may be explained by a model that is based on the catalytic activities of the top electrode to dissociate hydrogen molecules into hydrogen atoms, with the latter subsequently migrating into PZT or SBT films to cause oxygen deficiency and its associated property degradation. This model can be expanded to explain the recovery phenomenon resulting from oxygen annealing, which also depends on the catalytic activity of the top electrode to produce atomic oxygen from molecular oxygen.
TL;DR: In this article, the variation in the structural properties with a variation in zinc acetate concentration in the precursor solution, substrate temperature, as well as the doping concentration, were investigated by means of X-ray diffraction (XRD).
TL;DR: In this paper, the Raman scattering spectrum of stoichiometric V6O13 microcrystalline powder is compared to the spectrum obtained by annealing V2O5 and VO2 polycristallins.
Abstract: V6O13 microcrystalline powder was studied in an effort to resolve the stoichiometric effects. The Raman scattering spectrum of stoichiometric V6O13 microcrystalline powder is reported. The results are compared to the Raman scattering spectrum of V2O5 and VO2 polycrystalline materials obtained by annealing V6O13.
Nous etudions les proprietes vibratoires du compose stoechiometrique V6O13 sous forme de poudre microcristalline. Le spectre de diffusion Raman est presente. Une comparaison est menee avec les spectres des composes V2O5 and VO2 polycristallins obtenus par traitement thermique de V6O13.
TL;DR: In this article, the authors investigated strain relaxation and defect formation in Si1−xGex films grown epitaxially on (100)Si substrates by controlled annealing experiments.
Abstract: Mechanisms of strain relaxation and defect formation during surface roughening in Si1−xGex films grown epitaxially on (100)Si substrates have been investigated by controlled annealing experiments. Epitaxial films 10 nm in thickness and containing 18% Ge, which are subcritical with respect to the formation of misfit dislocations, show strain relaxation through surface roughening on annealing at 850 °C, where surface grooves are aligned along 〈100〉 directions. Other films with 22% Ge and supercritical thicknesses have also been studied, where surface grooves are aligned along 〈110〉 directions.
TL;DR: In this paper, the initial stages of facet formation on the α-alumina surface are explored through annealing vicinal single crystals for different lengths of time and characterizing the surface with atomic force microscopy.
TL;DR: In this paper, it was shown that the oxide/SiC interface would be inferior to the Si interface for both N-type and P-type SiC, if it were not for the beneficial effects of nitrogen incorporation.
Abstract: This letter addresses the question of why it is possible to grow high-quality oxide films on N-type but not on P-type SiC. It provides results which indicate that the oxide/SiC interface would be inferior to the oxide/Si interface for both N-type and P-type SiC, if it were not for the beneficial effects of nitrogen incorporation. The letter presents, for the first time, results on nitridation of thermally grown oxides in NO and N/sub 2/O. The results demonstrate that the oxides grown on P-type can be improved by NO annealing, but not by N/sub 2/O annealing.
TL;DR: In this article, Cadmium sulfide thin films have been deposited by electrodeposition using the potentiostatic method on indium tin oxide (ITO)-coated glass substrates from aqueous solution containing CdCl2 · 2H2O and Na2S2O3 at 90 °C.
TL;DR: In this paper, the formation of nanosize ferromagnetic MnAs crystallites imbedded in low-temperature grown GaAs using Mn+ ion implantation and subsequent annealing was reported.
Abstract: We report the formation of nanosize ferromagnetic MnAs crystallites imbedded in low-temperature grown GaAs using Mn+ ion implantation and subsequent annealing. The structural and magnetic properties of the crystallites have been characterized by transmission electron microscopy, electron beam induced x-ray fluorescence, and superconducting quantum interference device magnetometry. After an optimized thermal annealing at 750 °C, MnAs crystallites of 50 nm in size are formed. These nanomagnets show room temperature ferromagnetism.
Patent•
12 Jun 1997
TL;DR: In this article, a method of treating a component formed from a Ni-Ti-based shape memory alloy, so that the component exhibits super-elasticity, comprises cold working the component, annealing the alloy while the component is restrained in the configuration resulting from the cold working step, and exposing the component to a temperature that is less than the solvus temperature of the alloy and greater than the temperature to which it is exposed in the Annealing step to cause the A f temperature to be reduced.
Abstract: A method of treating a component formed from a Ni-Ti based shape memory alloy, so that the component exhibits super-elasticity, comprises cold working the component, annealing the alloy while the component is restrained in the configuration resulting from the cold working step, and exposing the component to a temperature that is less than the solvus temperature of the alloy and greater than the temperature to which it is exposed in the annealing step to cause the A f temperature to be reduced.
TL;DR: In this article, a comprehensive SAXS and DSC investigation was conducted to determine the relationship between crystallization temperature, crystallite thickness, rate of crystallization, and melting points.
Abstract: As shown by time- and temperature dependent SAXS experiments, crystals of s-PP do not change their thickness during isothermal crystallization and a subsequent heating to melting. This allows an accurate determination of the relations between crystallization temperature, crystallite thickness, rate of crystallization, and melting points. There are five main results obtained in a comprehensive SAXS and DSC investigation: (i) Crystals have greatly varying stabilities, in spite of their uniform thickness; the first crystals melt close to the crystallization temperature. (ii) Melting points are affected by the distance to neighboring crystals. (iii) Crystals perfect during heating and annealing. (iv) Recrystallization after melting, as observed for low enough heating rates, starts with crystal growth rates that are at least 2 orders of magnitude higher than for a primary crystallization, and then slows down progressively, being accompanied by an increase in crystal thickness. (v) The dynamic signals observed...