Annealing Properties Research Articles

Composition and annealing temperature dependent properties of Co1−xPtx(0<x⩽0.2) alloy nanowire arrays

Arrays of Co1−xPtx(0<x⩽0.2) alloy nanowires have been fabricated by electrochemical deposition of metals into anodic aluminium oxide templates. Compositional and annealing dependent properties of these samples have been investigated by a range of techniques. X-ray diffraction experiments show that the crystal structure of alloy nanowire varies with the chemical composition, ranging from predominantly c axis oriented for pure Co to textured, e.g., Co87Pt13 and to nontextured pure Pt wires. Hysteresis loops, saturation magnetization, squareness ratio (Mr∕Ms), and coercivity (perpendicular and parallel to the wire axis) have all been investigated as a function of the composition. Rapid thermal annealing treatment demonstrates that nanowires with different composition shows different response to the annealing temperatures. The annealing temperature related changes in coercivity, squareness, crystal structure, and ultraviolet-visible spectra are also presented.

Annealing properties of ZnO films grown using diethyl zinc and tertiary butanol

ZnO films were grown by atmospheric metal–organic chemical vapour deposition and annealed at900 °C in an oxygen environment. The annealing properties of the films have been characterized bymeans of x-ray diffraction, Raman scattering, Rutherford backscattering (RBS), elastic recoildetection analysis (ERDA) and photoluminescence spectra. The results indicate that highcrystal quality ZnO film has been obtained after annealing. The full width at half-maximum ofω rocking curves is only 369 arcsec. The Raman spectra show a strong high frequencyE2 mode peak comparable to that for bulk ZnO. The intensity ratio of theE1(LO) peakto E2high peak before annealing is 0.81 and after annealing 0.75. RBS and ERDA spectra indicatethat a stoichiometric ZnO film is formed and the annealing only changes the H content inthe ZnO film. After annealing all emission lines become sharper, as expected, which meansa higher quality film has been obtained.

Formation of Type I-IR and Type II-IR gratings with an ultrafast IR laser and a phase mask

The formation of two grating types in SMF-28 fiber by focusing 125 fs, 0.5-2 mJ pulses through a phase mask onto a fiber sample is studied. The first type, specified as type I-IR, occurs below the damage threshold of the medium. The scaling behavior of the type I-IR gratings with field intensity and annealing properties suggests that their formation is related to nonlinear absorption processes, possibly resulting in color center formation. The second type, denoted as type II-IR, occurs coincidentally with white light generation within the fiber. These type II-IR gratings are stable at temperatures in excess of 1000 masculineC and are most likely a consequence of damage to the medium following ionization.

The structure and annealing properties of multilayer carbon films

We investigate the structure and annealing properties of multilayer carbon films consisting of alternating layers of high density and low density amorphous carbon produced using two methods. The first method uses plasma immersion ion implantation (PIII) to create alternating high density (PIII off) and low density (PIII on) films. The second involves the formation of high and low density layers by changing the level of DC bias. Both methods allow thick films to be deposited without excessive stress build up. We use cross-sectional transmission electron microscopy (X-TEM), diffraction and electron energy loss spectroscopy (EELS) to investigate the microstructure of the films both before and after annealing to temperatures of 600 °C. High DC biases were found to cause modification of the surface of any subsequently deposited film (either low or high density). This modification can be attributed to ion implantation effects, which occur when using high DC biases. We found that the structure of high density layers in the multilayers was not greatly affected by annealing, however, low density layers develop strong preferred orientation either as a result of elevated deposition temperatures or post deposition annealing.

A novel structure of DNA repair protein RecO from Deinococcus radiodurans.

Recovery of arrested replication requires coordinated action of DNA repair, replication, and recombination machineries. Bacterial RecO protein is a member of RecF recombination repair pathway important for replication recovery. RecO possesses two distinct activities in vitro, closely resembling those of eukaryotic protein Rad52: DNA annealing and RecA-mediated DNA recombination. Here we present the crystal structure of the RecO protein from the extremely radiation resistant bacteria Deinococcus radiodurans (DrRecO) and characterize its DNA binding and strand annealing properties. The RecO structure is totally different from the Rad52 structure. DrRecO is comprised of three structural domains: an N-terminal domain which adopts an OB-fold, a novel alpha-helical domain, and an unusual zinc-binding domain. Sequence alignments suggest that the multidomain architecture is conserved between RecO proteins from other bacterial species and is suitable to elucidate sites of protein-protein and DNA-protein interactions necessary for RecO functions during the replication recovery and DNA repair.

Structure and mechanical properties of structural steel in laser resolidification processing

The structure of austenitic crystals and mechanical properties in the molten zone of a structural steel (C=2.29 at.%, Mn=0.71 at.%, Si=0.62 at.%, S=0.003 at.%, P=0.004 at.%, Cr=0.21 at.%, Ni=0.26 at.%) upon laser resolidification has been studied. The laser scan rate has been varied in the range of 0.01–0.167 m/s. The mathematical modeling of laser regimes and formation of crystal patterns in the molten zone has been provided. The results of modeling and experiments are used to develop the microstructure selection map. It is shown that the results obtained can be used for predicting the mechanical properties in the molten zone as a function of the energy parameters of a process of laser annealing and thermophysical properties of the steel.

Deep Level Transient Spectroscopy of Defects in High-Energy Light-Particle Irradiated Si

The authors review what has been learned concerning the electrical and annealing properties of point defects in high-energy electron or proton irradiated Si from deep level transient spectroscopy (DLTS). The authors have focused mainly on the properties of electron traps, and to a lesser extent on the properties of hole traps. In addition to an in-depth discussion of hydrogen-related defects in Si, this review article provides a brief tutorial on ion-solid interactions and the theory underlying DLTS. The authors also provide a few examples of the power of high resolution Laplace DLTS in analyzing radiation induced defects. The collection of results gathered in this article may provide the fundamental information for successful defect engineering in light-particle irradiated Si.

Temperature-dependent defect properties from ion-irradiation in Pu(Ga)

We report the measured decrease of electrical resistivity during isochronal-annealing of ion irradiation damage accumulated at low-temperature (10 or 20 K), and the temperature dependence of the resistance of defect populations produced by low-temperature damage-accumulation and annealing in a stabilized δ-phase plutonium alloy, Pu(3.3 at.% Ga). The normalized change in resistivity is compared for a specimen that was either self-irradiated (from Pu α-decay and the associated uranium-recoil) or 3.8 MeV proton-irradiated with a Pelletron electrostatic accelerator. Modeling of the annealing data through combined molecular dynamics (MD) and kinetic Monte Carlo (KMC) methods describes the defect populations as a function of irradiation type and annealing temperature. It is observed that interstitial clustering is extant for the self-irradiation, but that the corresponding vacancies from the uranium damage cascade appear to be more point defect-like, as exhibited by their subsequent annealing behavior and comparison with the experimental annealing properties from the proton-irradiation. We also report the temperature dependence of the resistance of defects resulting from low-temperature damage accumulation and subsequent annealing at three temperatures: 30, 150, and 250 K. For the two defect populations dominated by vacancies and vacancy clusters (150 and 250 K), we observe a temperature-dependent defect population resistance of the form − a[ln( T)]+ b suggestive of a Kondo impurity. A discussion of possible causes leading to this observation and their effects, as it might relate to the nature of the δ-phase of Pu, are presented.

Effects of O 2 annealing after etching SrBi 2Ta 2O 9 thin film in Cl 2/CF 4/Ar plasma

The etching and O 2 annealing properties of SrBi 2Ta 2O 9 (SBT) thin films were investigated. The etch rates of SBT thin films increased with 20% additive Cl 2 into CF 4/Ar plasma, which indicated that SBT thin films could be removed by chemically enhanced ion etching mechanism. The increased etch rate of SBT was due to lower boiling points of SrCl 2 and BiCl 3 than those of SrF 2 and BiF 3. The etch profile of etched SBT thin films at 20% Cl 2 in Cl 2/CF 4/Ar plasma was over 80 ° and the top corner of SBT was clean. The SBT thin films during etching process were influenced on the electrical properties of ferroelectricity by the plasma induced damages. A decreased total bismuth-oxide concentration was influenced on the electrical properties of SBT thin films. Therefore, the changes of stoichiometry on the etched surface of the SBT thin films were measured by X-ray photoelectron spectroscopy (XPS). After annealing at 700 °C in oxygen ambient, the decreased remnant polarization was recovered in the Pt/SBT/Pt capacitors.

Radiation induced defects in n-GaN, an overview

We determine, using deep level transient spectroscopy, the electronic and annealing properties of defects introduced in MOVPE grown n-GaN by high energy electron, helium-ion and proton irradiation. As in other semiconductors these three particles introduce electrically active defects in n-GaN. There are 6 electron defects (ER1-ER6) introduced in the hexagonal n-GaN. A deep lying defect (1.04 eV), ER6, was detected and characterised for the first time. Defect ER3 which exhibits a field dependent emission rate has been reported to be the nitrogen vacancy. Defect ER2 appears to have a higher introduction rate when using protons. The deeper lying defects ER4-ER6 which are positioned reasonably close to one another have peak temperature positions which differ depending on the incident particle mass.

Deep-level transient spectroscopy study of electron traps in rapid thermally annealed SiO 2-capped n-type GaAs layers grown by metalorganic chemical vapour deposition

Three dominant electron traps S1 ( E c−0.23 eV), S2* ( E c−0.53 eV), and S4 ( E c−0.74 eV) are introduced in SiO 2/n-GaAs after rapid thermal annealing (RTA). A defect S3 ( E c−0.72 eV) is observed in uncapped and annealed samples only. The S2* arises from the superposition of two defects, of which S2 ( E c−0.46 eV) can be resolved using filling pulse widths <1 ms. The intensities of S1, S2*, and S4 show Arrhenius-like dependencies on the RTA temperature. We argue that the defects are formed as a result of an increase in the ratio of As : Ga in the near-surface region of the GaAs layers. The electronic and annealing properties of S4 show that it is a member of the EL2 family of defects. The removal of S1 and S2*, as well as the introduction of secondary defects, during isochronal annealing experiments is also discussed.

A New Absorption Band and the Decomposition of the 350 nm Absorption Band of PbWO4

Single crystal PbWO 4 has been grown by the improved Bridgman method. The absorption spectra in polarized light of the sample with the crystal c-axis parallel to its surface have been measured. The absorption spectra of the as-grown crystal show a 350 nm weak band with dichroism in polarized light. Subtracting the polarized light absorption spectrum with the electric vector E parallel to the c-axis by that one with E perpendicular to the c-axis, the polarized light difference spectrum is obtained. The polarized light difference spectrum indicates that the 350 nm band has two peaks and can be decomposed into two bands peaking at 330 and 360 nm, respectively. In order to determine the detailed structure of the 350 nm band, annealing experiments in air condition of the as-grown crystal at different temperatures were performed Difference spectra of the annealed crystal have been obtained by subtracting the absorption spectra of the crystal annealed at different annealing temperatures by that one of the as-grown crystal. The absorption spectra features also indicate that the 350 nm absorption band is composed of two bands peaking at 330 and 360 nm, respectively. The annealing properties of the 330 nm and the 360 nm band are obviously different. We come to the conclusion that the 350 nm band is a composed band and can be decomposed into two bands peaking at 360 and 330 nm, respectively. The two bands are suggested to belong to different color centers.

Quantification of the common deletion in human testicular mitochondrial DNA by competitive PCR assay using a chimaeric competitor.

The "common" 4977 bp deletion in mitochondrial DNA (Delta4977) is commonly used as an indicator of tissue deterioration in ageing and bioenergetic diseases. Deletion levels are normally measured by a serial dilution polymerase chain reaction (PCR) approach, where test reactions are compared with dilutions of control amplifications of DNA from a similar sized stable region of the mitochondrial genome. The end-point of this assay is the dilution that can just detect any PCR product; however, this is an inherently unstable measure. We constructed a chimaeric DNA construct that binds to both control and deletion primers with similar annealing properties. This was used in a competitive PCR assay to quantify Delta4977 in human testicular tissues that had been well-characterized using the serial dilution approach. We found the competitive assay to be highly replicable as it compares the PCR product of the construct with that of test DNA samples during the linear growth phase of the PCR reaction. Moreover, the serial dilution assay was shown to significantly overestimate the amounts of deleted mitochondrial DNA present. The assay promises to throw new light on the role of mitochondrial DNA deletions in tissue dysfunction and ageing, as such deletions can now be determined with high accuracy and repeatability and is much cheaper to apply than real-time fluorescent quantitative PCR.

Electronic and isochronal annealing properties of electron traps in rapid thermally annealed SiO2-capped n-type GaAs epitaxial layers

We have recently shown [P. N. K. Deenapanray et al., Appl. Phys. Lett. 77, 626 (2000)] that four electron traps S1(Ec−0.23 eV), S2(Ec−0.46 eV), S3(Ec−0.72 eV), and S4(Ec−0.74 eV) are introduced in rapid thermally-annealed (RTA) SiO2-capped n-type GaAs epitaxial layers. In the present study, we have used deep level transient spectroscopy to investigate the electronic and annealing properties of these deep levels. The electron emission kinetics of S1 is enhanced by an electric field, and the activation energy of S1 decreases linearly from ∼233 to ∼199 meV when the field is increased from 7.5×104 to 13.4×104 V cm−1. The intensities of S1, S2, and S4 show Arrhenius-like dependencies on the RTA temperature, which relate to the outdiffusion of Ga atoms into the SiO2 layer. The intensity of S2(VGa–SiGa) also increases exponentially with the square of the annealing time for RTA at 800 °C. Isochronal annealing experiments show that S1 and S2 are thermally stable below 500 and 400 °C, respectively. S4, which is a member of the EL2 family, is stable up to 600 °C. Secondary defects are introduced during isochronal annealing above 400 °C, and some of these defects are thermally stable at 600 °C.

ESR characterization of the top Si layer of ion implanted SIMOX

Electron spin resonance (ESR) method was used to investigate defects produced in SIMOX by As + and B + ion implantation. Two kinds of paramagnetic defect centers were observed. One had a g-value of 2.0055 and Δ H pp= 7.0 Oe, due to a-center, which originated from Si dangling bonds at the amorphous layer. The other had a g-value of 2.0010 and Δ H pp=2.8 Oe, due to E′-center in the SiO 2 layer. These centers showed different annealing properties. The existence of an amorphous/crystalline layer at the top Si layer plays an important role for the recrystallization mechanism. However, recrystallization at the moving crystalline layer by annealing depends highly on the ion species as well as the implantation energy.

Generalized Simulated Annealing Studies on Structures and Properties of Nin(n= 2−55) Clusters

With the generalized simulated annealing algorithm (GSA), the structures and properties of Ni n (n ) 2-55) clusters have been studied. We find that besides the icosahedral-like structure, the structures of Ni clusters can be decahedral-like or fragments of the fcc crystal. The clusters with n ) 13, 38, 55 are found to be very stable. With modification of the effective coordination number model, the calculated ionization potentials of Ni clusters are in good agreement with the experimental data. The dynamical simulations show that the clusters with a closed-compact inner core have a high vibrational frequency mode, while the disordered clusters show some low vibrational frequency modes.

Iron-related defect model in n-type silicon based on the electrical and diffusion properties

We review the electrical and diffusion properties of iron-related electrically active defects (IRDs) in floating zoned (FZ) and Czochralski (CZ)-grown n-type silicon. A small fraction of iron atoms dissolved into n-type silicon forms electrically active IRDs. From in-diffusion and annealing properties, IRDs can be related to interstitial iron atoms independent of phosphorus, oxygen and hydrogen atoms. We propose a model that IRDs observed in the present study are due to intermediate states in consecutive reactions of iron-related complex formation process. IRDs observed in CZ and FZ n-type silicon are identical.

Deep levels of vacancy-hydrogen centers in silicon studied by Laplace DLTS

We identify the acceptor levels (−/0) of the VH and V2H defects in silicon from comparison of DLTS and EPR annealing data. The levels are very close to each other and close to the acceptor level of the PV defect (the E-center) as well. In order to separate them, we have applied the high-resolution technique of Laplace DLTS and compared the formation and annealing properties of defects generated by implantation of hydrogen or helium. We further applied Laplace DLTS in combination with uniaxial stress to study the acceptor level at Ec−Et=0.31eV previously assigned to a vacancy-hydrogen–oxygen defect. We find, in accordance with recent EPR measurements, that the defect displays orthorhombic-I symmetry and rule out that it contains two hydrogen atoms. The defect can be understood as a single hydrogen atom bound inside the A-center, the well-known VO defect of silicon, and we denote it VOH accordingly. The observed orthorhombic-I symmetry arises because the hydrogen atom (at T=160K) swiftly jumps among two equivalent sites across the (110) plane that contains the Si–O–Si bond. Previous studies have shown that hydrogenation of oxygen-rich electron-irradiated samples leads to the formation of VOH with simultaneous depletion of the A-center. Our structural data are in accordance with this dynamic behavior.

Oxygen-related defects in O+-implanted 6H–SiC studied by a monoenergetic positron beam

Vacancy-type defects and their annealing properties for O+- or N2+-implanted 6H–SiC were studied using a monoenergetic positron beam. For ion-implanted specimens with a dose of 1×1013 cm2, the mean size of open volume of defects was estimated to be close to the size of divacancies. Annealing processes of the damage were identified to be agglomerations of vacancy-type defects due to migrations of carbon vacancies (100–400 °C), silicon vacancies (400–800 °C), and vacancy complexes such as divacancies (800–1000 °C), and the annealing out of the open spaces adjacent to extended defects (1000–1400 °C). From a comparison between the annealing behaviors of defects for the O+-and the N2+-implanted specimens, the migration and the agglomeration of vacancy-type defects were found to be suppressed in the O+-implanted specimen. This fact was attributed to the formation of complexes between vacancy-type defects and oxygen. For ion-implanted specimens with a dose of 1×1015 cm2, annealing behaviors of amorphous regions were also studied.

Structural and optical properties of the Ba(Mg1/3Ta2/3)O3 thin films prepared by pulsed laser deposition

Single phase Ba(Mg1/3Ta2/3)O3 films were prepared on Si (100) substrates and a fused silica substrate by pulsed laser deposition. The structure and annealing properties of these films were studied by the x-ray -2 scan. The wavelength dependence of the transmittance of the films deposited on fused silica was determined. The refractive index was calculated from the transmission spectrum. The quadratic electro-optic effects of the film were successfully measured to be 8.35 × 10-18 m2 V-2 by the differential detection method at 6328 Å.