Increase Of Annealing Time Research Articles

Effects of Remanent Polarization State and Internal Field in Ferroelctric Film on the Hydrogen-Induced Degradation Characteristics in Pt/Pb(Zr,Ti)O3/Pt Capacitor

The ferroelectric properties of Pb(Zr,Ti)O<TEX>$_3$</TEX>[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

Saturation magnetostriction measurement in nearly zero magnetostrictive Co-rich glass-covered amorphous wires

The magnetostrictive behaviour of Co 68.15Fe 4.35Si 12.5B 15 glass-covered amorphous wires in the as-cast state and stress-current annealed between 20–80 mA, under 200–500 MPa, is reported. For as-cast as well as stress annealed samples the value of stress derivative α is about −0.9×10 −10 MPa −1. In the as-cast state the value of saturation magnetostriction at zero applied stress λ s(0) is about –1.11×10 −7. After stress-current annealing λ s(0) decreases in absolute value, changing continuously from small negative to small positive values when the annealing time increases. The positive magnetostriction is obtained for annealing current density higher than about 130×10 6 A/m 2.

Effect of rapid thermal annealing on the electrical properties of ion‐beam‐synthesized oxide layers using 12 keV O2+ bombardment of Si

AbstractSurface layers of SiO2 were synthesized by bombarding n‐type Si samples with 12 keV O2+ ions at 10° incidence in a SIMS instrument. The oxide layers were annealed at 950 °C for 3, 6 or 8.5 min under Ar flow in a rapid thermal annealer. Temperature‐dependent current–voltage (I–V–T) measurements were used in order to establish both the dielectric quality and the current transport mechanisms across the dielectric layers. Annealing for 8.5 min doubled the breakdown voltage while decreasing the leakage current by a factor of ∼18. The ohmic quality of the layers for the low field strengths decreased with the increasing annealing time, which is related to the removal of implantation damage as observed by high‐resolution RBS measurements. For the high field strengths, the tunnelling effect was most dominant for the oxide annealed for 8.5 min. The breakdown voltage of oxide layers exhibited an Arrhenius‐like dependence on the sample temperature, with the activation energy for breakdown decreasing with the increasing annealing time. Deep‐level transient spectroscopy (DLTS) and capacitance–voltage (C–V) measurements also were used to characterize the samples. Copyright © 2001 John Wiley &amp; Sons, Ltd.

Gasoline permeation resistance of the as‐blow‐molded and annealed polyethylene, polyethylene/polyamide, and polyethylene/modified polyamide bottles

AbstractAn investigation of the gasoline permeation resistance of the as‐blow‐molded and annealed polyethylene, polyethylene (PE)/polyamide (PA), and polyethylene/modified polyamide (MPA) bottles is reported. The gasoline permeation resistance improves dramatically after blending PA and MPA barrier resins in PE matrices during blow‐molding, and the order of barrier improvement corresponds to the order of barrier improvement of the barrier resins added in PE. Somewhat unexpectedly, the gasoline permeation rates of the annealed PE and/or PE/PA bottles annealed at 90°C or higher temperatures increase significantly with the annealing temperature and time. On the contrary, the gasoline permeation resistance of the annealed PE/MPA bottles increase significantly as the annealing temperature and/or time increase. For instance, the gasoline permeation rate of the PE/MPA bottle annealed at 120°C for 32 h is about 190 times slower than that of the as‐blow‐molded PE bottle. Further investigations found that, after blending the MPA and PA barrier resins in PE matrices, the relatively nonpolar hydrocarbon components present in the gasoline fuels were significantly blocked, without permeation during the permeation tests, in which the as‐blow‐molded PE/MPA bottle inhibited the permeation of hydrocarbon components more successfully than did the as‐blow‐molded PE/PA bottle. In contrast, the amounts of polar components that permeated through the as‐blow‐molded PE/PA and PE/MPA bottles were very small and about the same as the amount that permeated through the as‐blow‐molded PE bottle. Possible mechanisms accounting for these interesting behaviors are proposed in this study. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 81: 2827–2837, 2001

Ferrimagnetic resonance linewidths of thick barium hexaferrite films on MgO [111

C-axis oriented barium hexaferrite films having thickness from 3-30 /spl mu/m were deposited onto 0.5 mm magnesium oxide (MgO) [111] substrates by pulsed laser ablation deposition, and were characterized by magnetometry and ferrimagnetic resonance (FMR) measurements. The FMR linewidth for as-produced 30 /spl mu/m films was 0.65-0.70 kOe, while those of thinner (3 /spl mu/m) films was near 0.50 kOe. The narrowest linewidth of /spl sim/0.06 kOe was obtained for a 3 /spl mu/m film after annealing for two hours. However, increased annealing time beyond two hours caused an increase in FMR linewidth. The FMR linewidth of 30 /spl mu/m films where from 55-77% of the MgO substrate was removed decreased by 0.15-0.20 kOe compared to as-produced films. Further improvement in the FMR linewidth to 0.20 kOe was obtained by a two hour annealing. These FMR results are discussed in terms of the homogeneity, planar stress, and stoichiometry of these thick pulsed laser deposited films.

The effect of annealing on the photoacoustic and photothermal response of Al2O3-SiC-TiC ceramics with internal stresses

The Vickers indentation zones in Al2O3-SiC-TiC ceramics were studied by scanning laser photo-deflection and photoacoustic microscopy. The method of photoacoustic microscopy with piezoelectric detector (PAMPD) is sensitive to the internal stress distribution in the material. The effect of annealing on the PAMPD signal of the Al2O3-SiC-TiC ceramics was studied. An increase in the annealing time is accompanied by decrease in the PAMPD response from the vertices of radial cracks.

The effect of annealing on the junction properties of CdTe/CdS cells with carbon contacts

The effects of annealing on the properties of CdTe/CdS cells with carbon contacts are studied for CdTe sputtered cells. Both open circuit voltage and short circuit current decrease as the annealing time increases. This degradation is attributed to the diffusion of impurities that exist in the carbon paste. Results obtained from contact resistance measurement and capacitance–voltage measurement at different frequencies for annealed cells confirm this assumption.

Prediction of Microstructural Evolution during Grain Growth of a Pure Aluminum by means of Monte Carlo Simulation

The modified Monte Carlo simulation of grain growth has been performed in the model applying actual orientation data by SEM/EBSP analysis in a pure aluminum to an initial microstructure. Changes in microstructural features and textures have been compared between experimental and simulated results. The SEM/EBSP analysis reveals that the pure aluminum has a residual rolling texture after annealing. The texture becomes sharper as the annealing time increases. The simulations are carried out under various conditions of grain-boundary energy and mobility. Microstructural and textural developments in the simulation taking the dependence of grain-boundary energy on misorientation into consideration were in good agreement with those in the experiment. The present model is expected to make it possible to predict the microstructural evolutions precisely.

高純度アルミニウム中の鉛の表面偏析

Surface segregation of Pb in the annealed Al-foils has been studied by Rutherford back scattering spectroscopy (RBS) and transmission electron microscopy (TEM). High-purity Al-foils containing 100 mass-ppm Pb were heat-treated for 1 h or 4 h at 540°C. Almost all of Pb segregate in a thin layer, 0.1 μm from the surface. Lead contents in the Pb-enriched surface layers were estimated to be 0.1∼0.14 at% Pb which were about 100–fold higher than the initial bulk concentration. TEM observations show that Pb-particles are formed at foil surfaces and their size increases from about 80 nm to 240 nm when final annealing time increases from 1 h to 4 h at 540°C. The Pb particles have a cube-cube orientation relationship with Al matrix and are bounded by {100} and {111} facets.

Effects of Sr substitution on T c of Y 0.85Ca 0.15Ba 2−xSr xCu 3O y

We have studied the Ar annealing effect on T c of Y 0.85Ca 0.15Ba 2−xCu 3O y (x = 0.0, 0.5 and 1.0) samples, Ar annealing was carried out at 480°C for 15 min ∼ 10 h. As the annealing time increases, T c of the x = 0.0 and 0.5 samples first gradually increases to a maximum value, then it decreases slowly suggesting the assintered samples are in the over-doped state. However, the x = 1.0 sample shows an anomalous behavior. T c increases from 68 K to 75 K after Ar annealing for 15 ∼ 30 min, then it abruptly decreases to 40∼50 K after further Ar annealing.

Optical properties of InGaAs/InAIAs diffused double quantum wells

The effects of interdiffusion on the subbands and optical properties of InGaAs/InAIAs double quantum well (QW) have been theoretically studied. The results show that since a double QW (DQW) can be diffused to become an effectively single QW structure, the characteristic features in the subbands structure and optical properties of a strongly coupled DQW structure and that of a single QW structure can be obtained by a suitable annealing time. Moreover, the increase in separation between the first symmetric and antisymmetric heavy hole subbands and the increase in the spin splitting of the valence subbands of the diffused DQW, due to an applied electric field, diminish when annealing time increases. In optimizing the In0.53(AlaGa1−a)0.47As/In0.52Al0.48As DQW structure, the results show that symmetric DQW with no Al content in wells can provide large material gain and radiative spontaneous recombination rate. With interdiffusion, the material gain and recombination rate reduce but the reduction saturates when the DQW structure is diffused to effectively become a single graded QW. By subjecting the DQW and an as-grown single QW to the same annealing conditions (where the summation of the width of the two wells and the separation barrier of the DQW equals the well width of the single QW), the diffused DQW can provide a larger material gain and radiative recombination rate than the diffused single QW when the annealing time is short. Therefore, the short-time diffused DQW is more useful for laser applications. Besides, since Al diffuses into the wells, the transition energy of the QW structure increases so that the operating wavelength of the optical devices can be adjusted.

Biaxial orientation of poly(vinyl chloride) compounds Part 2 –Structure–property relationships and their time dependency

X-ray diffraction and thermomechanical analysis have been used, respectively, to examine structural order and shrinkage behaviour for oriented samples of rigid and flexible poly(vinyl chloride) (PVC). Results were compared with previously measured tensile properties and structure–property relationships explored. X-ray diffraction showed that drawing produces planar crystallite orientation in PVC sheets. If drawing and subsequent annealing conditions are held constant, but draw ratio is varied, there is good correlation between structural order measured by X-ray diffraction and tensile strength. Increased annealing time and temperature improve crystallite order and dimensional stability, while tensile strength is unchanged. The greatest enhancement in tensile strength is achieved by stretching PVC towards its maximum draw ratio at 90°C, but optimum thermal stability of the oriented structure is achieved when higher annealing temperatures are used. Room temperature recovery is observed for flexible PVC when the material has a glass transition temperature below ambient. This can be delayed by increased annealing time and temperature, and by increased draw ratio.

Role of Defects on the Aging Behavior of Manganese‐Doped Lead Iron Tungstate Relaxor Ceramics

The effect of oxygen annealing on the dielectric aging of manganese‐doped Pb(Fe2/3W1/3)O3 (PFW) ceramics is investigated in an attempt to clarify the role of defects on aging. Evident relaxor‐type aging is observed in as‐sintered manganese‐doped PFW samples. The degree of aging gradually decreases as the annealing time increases, and no aging is observed for 100 h of annealing, which supports the correlation between oxygen vacancies and aging.

Si (001) surface defects after extended high temperature annealing

Deep diffusion of dopants in Si 001 requires temperature annealing as high as 1250°C and more for several days, in a quasi-neutral atmosphere. We have shown that such thermal treatment strongly affects the surface morphology, creating several-micrometers long, 10–50 nm deep square-shaped pits faceted along the 110 directions, with a density of ∼10 defects/cm2 for a 50-h anneal. These kind of defects, although reported in the literature for different experimental conditions, have not been studied in details. These defects grow as the annealing time increases. A second annealing in similar conditions shows a striking difference of behavior between CZ- and FZ-grown wafers, the latter having a defect density rising up to 104/cm2. It is believed that the metallic contaminants accumulated during the first annealing precipitate during cooling and eventually dissolve during further thermal treatment, leaving small marks on the surface which grow to micron-sized squares via a surface reconstruction. Comparisons have been made between the evolution of these defects and patterns with various depths followed by a high-temperature annealing.

Effect of annealing on the microstructure of Ni 80Fe 20/Cu multilayers

[Ni 80Fe 20/Cu] 15 multilayers grown by DC-magnetron sputtering and annealed at different temperatures and/or times were investigated by low- and high-angle X-ray diffraction. Structural parameters such as superlattice period, interplane distance, average multilayer coherence length and interfacial roughness were obtained. It was found that as the annealing temperature increases the superlattice period, interplane distance, average multilayer coherence length decrease, while (1 1 1) preferred orientation of the superlattices was improved slightly. The interfacial roughness increases with increasing annealing temperature and/or time. A significant intermixing layer located in the interlayer region between the Ni 80Fe 20 and Cu layers was revealed by simulating the high-angle X-ray diffraction profiles. The thickness of the intermixing layer increases as the annealing temperature or annealing time increases.

Effect of a Thermotropic Liquid Crystalline Polymer on the Physical Ageing of PET

In this work the effect of the presence of a thermotropic liquid crystalline polymer (TLCP) on the physical ageing of poly(ethylene terephthalate) (PET) was investigated. Physical ageing of PET and its blends with a TLCP was carried out by annealing the samples at 60[ddot]C for several ageing times. Structural relaxation has been revealed by DSC through the analysis of position and magnitude of the endothermic peak superposed on the glass transition. It was found that the peak increases and shifts towards higher temperatures as the annealing time increases for all materials analysed. With respect to the PET matrix, blends submitted to physical ageing show an increase in the ageing rate by a percentage that increase with the amount of TLCP. Moreover, increasing the fraction of liquid crystalline component, a continuos decrease of the cold crystallisation temperature has been also observed.

Effect of thermal annealing on the structural and electrical properties of HgTe/CdTe superlattices

Rapid thermal annealing effects on the structural and electrical properties of the HgTe/CdTe superlattices grown on the Cd 0.96Zn 0.04Te substrates by molecular beam epitaxy have been investigated by double-crystal X-ray rocking curve (DCRC) and Van der Pauw Hall effect measurements. The sharp satellite peaks of the DCRC spectra measured on as-grown HgTe/CdTe superlattices show a periodic arrangement of the superlattice with high-quality interfaces. As the annealing time increases, the peak intensities corresponding to m=±1 of the DCRC spectra decrease dramatically. The average diffusion coefficient of the Hg in a HgTe/CdTe superlattice annealed at 220°C is approximately 10 −18 cm 2/s. After annealing, the results of the Hall effect measurements show that the carrier concentration and the mobility of the HgTe/CdTe superlattice are changed resulting from the formation of Hg vacancies and that the n-type HgTe/CdTe superlattice has converted to the p-type HgTe/CdTe superlattice with a high carrier concentration. These results indicate that the heterointerface of the HgTe/CdTe superlattice annealed at 220°C is significantly intermixed and that the monotonous variation of the intensity for the satellite peak in annealed HgTe/CdTe superlattice is attributed to a linear diffusion behavior.

Photoacoustic Studies of Annealed CdSxSe1-x (x = 0.26) Nanocrystals in a Glass Matrix

Photoacoustic (PA) spectroscopy is applied to study an optical absorption of CdSxSe1-x (x=0.26) nanocrystals in a glass matrix annealed at 700°C for different time durations. As the annealing time increases, a shift of the absorption peak (due to the quantum confinement effect) to lower energy is observed in the PA spectra at room temperatures. The observed absorption peak shifts are used to evaluate the average size of CdSxSe1-x nanocrystals in terms of a simple model. The average radius increases from 2.3 to 4.7 nm as the annealing time increases from 0 to 120 min. The PA signal intensities plotted in the semilogarithmic scale vary linearly below the fundamental absorption edges in accordance with the Urbach rule for the optical absorption coefficient. The steepness factor (slope of exponential optical absorption) of the PA spectra increases with increasing annealing time. The change of the electronic states by annealing is explained by considering that the contribution of the surface states decreases with the increase of the nanocrystal size.

The formation, structure and properties of nanocrystalline Ni-Mo-B alloys

The structure, structure evolution and microhardness of nanocrystalline Ni-Mo-B alloys were studied by X-ray diffraction, differential scanning calorimetry, transmission and high resolution electron microscopy and microhardness measurements. The nanocrystalline structure was produced by controlled crystallization of amorphous alloys. The annealed samples consist of the FCC nanocrystals with the amorphous regions between them. The grain size of the nanocrystals is about 20 nm and depends on the chemical composition of the alloy. The chemical composition of the amorphous phase between the nanocrystals changes at the annealing. A slight grain growth was observed when the annealing time increases. The diffusion of Mo and B from FCC to the amorphous phase occurs at the annealing. It results in the lattice parameter change. The microhardness of the alloys increases during the annealing. The microhardness values are the same in all alloys before the nanocrystalline structure decomposition. The microhardness is inconsistent with the Petch-Hall equation. The microhardness of the alloys is determined by the microhardness of the amorphous phase bands located between the nanocrystalline grains.

Optical properties of interacting Si nanoclusters in SiO 2 fabricated by ion implantation and annealing

A novel method for the fabrication of luminescent Si nanoclusters in an amorphous SiO 2 matrix by ion implantation and annealing, and the detailed mechanisms for the photoluminescence from implanted Si nanoclusters are reported. We have measured dose (concentration of excess Si atoms), annealing time and excitation energy dependence of the photoluminescence of Si nanoclusters in SiO 2 layers. The samples were fabricated by Si ion implantation into SiO 2 and subsequent high temperature annealing. After annealing, a photoluminescence band below 1.7 eV has been observed. The peak energy of the photoluminescence is found to be independent of annealing time and excitation energy, while the intensity of the luminescence increases as the annealing time and excitation energy increase. Moreover, we found that the peak energy of the luminescence is strongly affected by dose of implanted Si ions especially in the high dose range. These results indicate that the photons are absorbed by Si nanoclusters, for which the band-gap energy is modified by the quantum confinement effects, and the emission is not simply due to direct electron-hole recombination inside Si nanoclusters, but is related to defects probably at the interface between Si nanoclusters and SiO 2, for which the energy state is affected by Si cluster–cluster interactions. It seems that Si nanoclusters react via a thin oxide interface and the local concentrations of Si nanoclusters play an important role in the peak energy of the photoluminescence.