Effects Of Two-step Annealing Research Articles

Effect of two-step annealing on photoelectrochemical properties of hydrothermally prepared Ti-doped Fe2O3 films

Hematite (α-Fe2O3, bandgap ~2.1 eV) is a potential photoanode candidate for photoelectrochemical water splitting. In this work, we report the preparation of Fe2O3 with Ti4+ doping by hydrothermal treatment at 393 K and then annealing in the air at 873 K, with a second round of annealing in argon at 473 K. The two-step annealing process increased the photoelectrochemical performance of Ti-doped Fe2O3 on a fluorine-doped tin oxide (FTO)-coated glass substrate (FTO/Ti-Fe2O3) for water oxidation in 0.1 mol L−1 NaOH solution. Ti4+ doping was sourced from TiCl4 in ethanol solutions of various concentrations. An energy-dispersive X-ray spectrometer (EDS) analysis confirmed that the optimized Ti/Fe atomic ratio in the solution was ~3%, which showed the highest photocurrent densities in the linear sweep voltammetry and chronoamperometry measurements. The two-step annealed FTO/Ti-Fe2O3 generated a photocurrent density of 0.55 mA cm−2 at 1.50 V vs. reversible hydrogen electrode (RHE) under simulated one-sun illumination, which was approximately 3 times higher than that of the photoanodes annealed in air. Four-point probe resistivity measurements revealed that the two-step annealing resulted in a higher electrical conductivity than that of the samples annealed in air. The conductivity improvements induced by additional argon annealing at 473 K were ascribed to the increased donor density, which was confirmed by Mott–Schottky analysis and diffuse reflectance UV–visible–near-infrared spectra. We found that the strategy of Ti4+ doping and two-step annealing helped fabricate Fe2O3-based photoanode materials with better photocurrent density attributed to high electrical conductivity successfully.

Effect of Two-Step Annealing on High Stability of a-IGZO Thin-Film Transistor

In this article, the effects of two-step annealing at the active layer (AL) and the completed device on the electrical properties and stability of amorphous In-Ga-Zn-O (a-IGZO) thin-film transistor (TFT) are studied. The subthreshold swing (SS) and stability of a-IGZO TFT devices are greatly improved, and the hump phenomenon under the negative bias illumination stability (NIBS) is particularly well suppressed when the TFT devices are treated with an optimum two-step annealing process (200 °C of preannealing and 300 °C of postannealing). Based on the analysis of the surface morphology, internal chemical state, and electrical properties of the IGZO thin film, an improvement of two-step annealing devices may be due to hydrogen filling the oxygen vacancies in the AL and well passivating the defects between insulating layer and AL. The result illustrates that two-step annealing is a promising method for IGZO TFT, which is not only beneficial to improve the stability of the device but also suppresses the hump phenomenon in NIBS.

Effect of two-step annealing on recrystallized structure and mechanical properties in AA7075/AA1100 laminated metal composites processed by accumulative roll bonding

AA7075/AA1100 laminated metal composites (LMCs) were successfully produced by accumulative roll bonding (ARB). Also, to investigate the effect of annealing on mechanical properties and microstructure evolution, the composites were subject to annealing treatment at three different temperature (200, 300 and 400 °C) for 1 h. The microstructure evolution was evaluated by scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) and electron back scatter diffraction (EBSD). Tensile tests were performed to measure the mechanical properties of composites. It was observed that elemental diffusion occurred in the constituent layer interfaces, indicating that superior bonding was achieved between the layers with annealing temperature increased. By increasing the annealing temperature, the presentation of a relatively strong {100}<001>Cube recrystallization textures has been attributed to strain-induced boundary migration (SIBM) caused by a preference for the Cube-oriented grains to grow into adjacent S-oriented grains with higher stored energy. In addition, the effect of pre-recovery on anisotropy was discussed in detail. Tensile tests revealed that the plane anisotropy after the two-step annealing (TSA) process was evidently diminished in compare with the single annealing (SSA) process due to the reduced Cube texture strength and the formation of equiaxed crystal structures.

Beneficial Effect of Two-Step Annealing via Low Temperature of Vacancy Complexes in N-type Czochralski Silicon

We report a simple, time-saving and effective low-temperature approach to avoid the effect of intrinsic defects in n-type Czochralski silicon (Cz-Si) wafers. This approach consists of submitting Cz-Si wafers to two annealing steps. The first annealing step was conducted in the temperature range 100–200°C to dissociate phosphorus–vacancy (P-V) defects. These defects were identified through the calculation of its activation energy (Ea) of annihilation. The second annealing step was conducted in the temperature range 300–400°C to eliminate defects caused by vacancy–oxygen (V-O) pairs. The deactivation effect of the V-O pairs was highlighted using Fourier transform infrared spectroscopy and the effective minority carrier lifetime (τeff). By combining these two annealing steps, we succeeded in enhancing τeff from 180 to 2400 μs and the electrical parameters of the silicon solar cell.

Effect of two-step annealing on the performance of ternary polymer solar cells based on P3HT:PC71BM:SQ

The effect of two-step annealing, including solvent annealing and further-step thermal annealing on the inverted ternary polymer solar cells (PSCs), which are composed of poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl C71-butyric acid methyl ester (PC71BM):2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ), was systematically investigated. The film morphology of ternary blends was characterized by X-ray diffraction and atomic force microscope. The results showed that a dramatic enhancement of power conversion efficiency from 1.32% to 4.42% was obtained due to the improved light harvesting, optimized self-assembled morphology and thermally induced crystallization of ternary blends. Especially, the optimized temperature of the thermal annealing process was remarkably decreased to 80°C. It was also found that the two-step annealing process was crucial in achieving high performance, which could not only control the domain size of SQ but also maintain a well-ordered nanoscale structure within the ternary blends of P3HT:PC71BM:SQ.

Effects of Two-Step Annealing on the Magnetic Properties of Iron-Based Nanocrystalline Soft Magnetic Material

In the present paper, the effects of two-step annealing on the soft magnetic properties of nanocrystalline Fe73.5Cu1Nb3Si13.5B9 melt spun ribbons were studied. The two-step annealing comprises low-temperature preannealing (first step) for an α-Fe(Si) phase nucleation in an amorphous matrix, and a subsequent high-temperature annealing (second step) for the growth of precipitated crystallites. Compared with a nanocrystalline alloy obtained by conventional one-step annealing at 550 °C for 1 h, the grain size of α-Fe（Si）crystalline phase in the Fe73.5Cu1Nb3Si13.5B9 alloy decreased greatly after it is pre-annealed at 480°C for 1 h followed by annealing at 550°C for 40 min. It has been shown that the soft magnetic properties can be significantly improved by applying two-step annealing. The decrease of grain size of α-Fe(Si) crystalline phase may result from the nucleation rate increase during the crystallization of pre-annealed.

Effects of annealing technique and TiO 2 seed layer on the phase composition of 0.7Pb(Mg 1/3Nb 2/3)O 3–0.3PbTiO 3 film

The lead magnesium niobate–lead titanate (PMN–PT) thin films with and without the TiO 2 seed layer were prepared by a pulsed laser deposition (PLD) deposited on Pt/Ti/SiO 2/Si substrates. The films were treated by two-step annealing and normal annealing with rapid thermal annealing (RTA). The effects of two-step annealing and the TiO 2 seed layer on the phase composition of PMN–PT films were studied. The results show that the PMN–PT film with TiO 2 seed layer can gain a pure perovskite phase with a high (1 0 0) preferential orientation after the two-step annealing technique.

Effects of Two-step Annealing on Texture and Magnetic Properties by Addition of Co, Mo, or Ni in Silicon Steel

In 3Si–1.4Al electrical steel with addition of Co, Mo or Ni, the texture of hot bands is almost random except γ fiber which is dominant. After cold reduction, the texture shows the typical (111)//ND and (110)//RD fibers. When cold rolled sheets are annealed, it is clear that γ fiber of {111}‹110› and {111}‹112› decreases significantly, while, on the contrary, Goss texture increases but cube texture is not changed. Two-step annealing process was observed to be effective to increase grain size and decrease γ fiber texture resulting in lowering iron loss and its anisotropy. The combination of increasing grain size and decreasing γ texture by two-step annealing was able to improve magnetic properties.

Effects of two-step annealing on properties of Cd 1- xZn xTe single crystals

The Cd 1- x Zn x Te(CZT) single crystals were annealed by a two-step method including a vapor-environment step and a liquid-environment step in sequence. The effects of annealing on the properties of CZT were analyzed in detail. IR transmission measurement results show that IR transmission of CZT is improved dramatically after annealing. X-ray rocking curves indicate that the annealing treatment ameliorates crystal quality obviously, which is ascribed to the release of residual stress and the reduction of point defects. Photoluminescence(PL) spectra reveal that the full width at half maximum(FWHM) of the donor-bound exciton ( D 0, X) peak is reduced obviously, and the free exciton emission is weakened after annealing. Meanwhile, the intensity of the donor-acceptor pair(DAP) peak decreases to a great degree, which implies that the impurities are removed from CZT wafers. In addition, the deep defect-related emission band D complex disappears after annealing, which mean that Cd vacancies are well-compensated. The results confirm that the two-step annealing is an effective approach to improve the qualities of CZT single crystals.

Effects of two-step annealing on the microstructures and soft magnetic properties of nanocrystalline Fe86Zr7B6Cu1 ribbons

The effects of two-step annealing on the microstructures and soft magnetic properties of nanocrystalline Fe86Zr7B6Cu1 ribbons were studied. Two-step annealing results in a marked decrease of grain size and a distinct improvement of soft magnetic properties with respect to conventional annealing at 600°C for 1h. Bcc α-Fe with the grain size of 8nm is formed in ribbon after it is pre-annealed at 750°C for 2min followed by annealing at 600°C for 58min. Its coercive force Hc, initial permeability μi, and relaxation frequency f0 are 1.5A/m, 6.15×104, and 8.9×104Hz, respectively. The decrease of grain size may result from a larger value of the nucleation rate obtained during the initial stage of crystallization by annealing amorphous ribbon at higher temperatures for short duration. But pre-annealing at 800°C leads to the decrease of soft magnetic properties because of the formation of Fe3Zr.

Effects of two-step annealing on the characteristics of the low temperature polycrystalline silicon thin film transistors

The effects of two-step annealing on the device characteristics of polysilicon thin film transistors are investigated. The device characteristics such as drain current, mobility and threshold voltage of the low temperature furnace annealed polysilicon thin film transistors is improved considerably due to the reduction of in-grain defects by post-laser annealing. The post-high temperature furnace annealing (900°C) on the low temperature furnace annealed devices does not improve the device performance of polysilicon thin film transistors, due to the facts the annealing temperature of 900°C is much lower than the melting temperature (⩾ 1300°C) of polysilicon. We have also found that the activation energy and hydrogen passivation rate in two-step annealed polysilicon thin film transistors is also improved significantly by the reduction of tail states due to the elimination of in-grain defects.

Effect of two-step annealing on magnetic properties of Pr-Fe-B base hot-rolled magnet

Magnetic properties of a Pr-Fe-B base magnet produced by the hot-rolling method are improved remarkably by a characteristic two-step annealing. The relationship between magnetic properties and microstructure in the two-step annealing is investigated for a Pr/sub 15/Fe/sub 78.0/B/sub 5.5/Cu/sub 1.5/ (at.%) hot rolled magnet, and the effect of Ga replacement for Cu is investigated for Pr/sub 15/Fe/sub 79.0/B/sub 5.5/Ga/sub 0.5/ (at.%). The effect of the two-step annealing is attributed to recovery of disordered microstructure by first step annealing and development of network structure of Pr-rich phase by second-step annealing. The Ga replacement for Cu enhances the improvement of magnetic properties through formation of a more desirable microstructure by the two-step annealing. >

Effects of two-step annealing on the epitaxial growth of CoSi2 on silicon

The formation of epitaxial CoSi2 on silicon by both conventional and two-step annealing of cobalt thin films on silicon was studied by transmission electron microscopy.For two-step annealing, samples were first annealed at 350 °C for 1 h, followed by high temperature annealing at 650–950 °C for 1 h. The scheme was found to be very effective in promoting the epitaxial growth of CoSi2 on silicon as well as eliminating faceted structures on Si(111). The results are discussed in terms of the driving away of impurities from the interfaces.