Effect Of Post-annealing Process Research Articles

Template-assisted growth of Ga-based nanoparticle clusters on Si: effect of post-annealing process on the Ga ion beam exposed 2D arrays fabricated by focused ion beam nanolithography

We demonstrate template-assisted growth of gallium-based nanoparticle clusters on silicon substrate using a focused ion beam (FIB) nanolithography technique. The nanolithography counterpart of the technique steers a focussed 30 kV accelerated gallium ion beam on the surface of Si to create template patterns of two-dimensional dot arrays. Growth of the nanoparticles is governed by two vital steps namely implantation of gallium into the substrate via gallium beam exposure and formation of the stable nanoparticles on the surface of the substrate by subsequent annealing at elevated temperature in ammonia atmosphere. The growth primarily depends on the dose of implanted gallium which is in the order of 107 atoms per spot and it is also critically influenced by the temperature and duration of the post-annealing treatment. By controlling the growth parameters, it is possible to obtain one particle per spot and particle densities as high as 109 particles per square centimetre could be achieved in this case. The demonstrated growth process, utilizing the advantages of FIB nanolithography, is categorized under the guided organization approach as it combines both the classical top-down and bottom-up approaches. Patterned growth of the particles could be utilized as templates or nucleation sites for the growth of an organized array of nanostructures or quantum dot structures.

Effect of post annealing process on structural, magnetic and spin dynamics properties of MnFe2O4 nanoparticles

The present research work focuses on the one-step and cost-effective hydrothermal synthesis and characterization of manganese ferrite (MnFe2O4) magnetic nanoparticles (MNPs). To investigate the effect of different annealing temperatures on the structural, magnetic and spin dynamics properties of the as-synthesized MNPs, samples were annealed at 200°C, 400°C, and 600°C. X-ray diffraction (XRD) analysis showed that all samples had a cubic spinel phase structure with space group Fd-3 m (227), with minor impurities of α-Fe2O3 and α-Mn2O3 phase are present. The average crystallite size of the MNPs increased with increasing annealing temperature, due to grain growth. The molecular dynamics, bond stretching, and cubic spinel phase of all samples were analyzed through IR spectroscopy. Furthermore, the post-annealing process resulted in a decrease in saturation magnetization from 44.04 emu/g to 29.01 emu/g, which increased to 33.79 emu/g as the annealing temperature was raised from 200°C to 400°C and further to 600°C. Ferromagnetic resonance spectroscopy was utilized to validate the magnetic characteristics, unveiling the presence of unpaired electrons and assessing the resonant magnetic field, g-factor and peak-to-peak line width.The broad resonance signal observed in the room temperature spin dynamics indicated a strong dipolar-dipolar interactions interaction between magnetic ions through oxygen ions. The obtained results indicate that the synthesized MnFe2O4 MNPs have the potential to be used in various biomedical applications, including targeted drug delivery and magnetic hyperthermia treatment, owing to their biocompatibility, excellent magnetic properties, and facile synthesis method. This study paves the way for further research on the applications of MnFe2O4 MNPs in the field of nanomedicine.

Investigating the effect of hot extrusion and annealing to the functional fatigue behavior of Ni50Ti30Hf20 high temperature shape memory alloy

This study reveals the functional fatigue properties of hot extruded and the effect of post annealing process to the cyclic stability and fatigue properties of Ni50Ti30Hf20 (at.%) alloy. Samples were cut from the hot extruded billet and three of them were randomly selected for functional fatigue experiments. Variation in the shape memory properties such as transformation temperatures, actuation and accumulated irrecoverable strain values was observed. Additionally, the samples showed 580, 754 and 1738 thermal cycles under 200 MPa in fatigue experiments. Six more samples were cut through the cross section of another piece of the extruded billet and enumerated for further fatigue testing to investigate the reason of the variation in the properties. The edges of the gauge sections of enumerated fatigue test samples were ground to remove the surface roughness. Although the fatigue life times were increased by 3–6 times with the edge grinding the differences in the values of the shape memory properties were still observed and this observation was attributed to the deformation variation and the residual stresses induced by hot extrusion. To overcome this problem, hot extruded samples were annealed and the fatigue experiments were repeated. All annealed samples exhibited the same transformation temperatures, actuation and accumulated irrecoverable strain values. Moreover, the transformation temperatures were stabilized and the fatigue life was increased to almost 12 000 cycles.

The Effects of Post Annealing Process on the Electrical Performance and Stability of Al-Zn-O Thin-Film Transistors

In this work, we studied the effects of post annealing process on the electrical performance and positive bias stability (PBS) of aluminum-zinc-oxide (AZO) thin film transistors (TFTs). Among all the devices, the TFT annealed in vacuum atmosphere exhibits excellent I-V characteristics, such as a saturation mobility (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> ) of 45.90 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V·s, a steep subthreshold swing of 263 mV/decade, a high I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ratio of 7.56 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> because of its excellent film quality. In addition, the positive bias stability of TFTs annealed in different atmosphere under positive bias (+5V, 2000s) were also conveyed. The threshold voltage shift (ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) was 0.3V (mixed gas, Ar:O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 3 : 3), 0.9V (vacuum), 1.0V (O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). These results can be explained by the O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">II</sub> /O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">total</sub> of the AZO films. The AZO film annealed in mixed gas (Ar:O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 3 : 3) has the least oxygen vacancy density that leads to the least ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> under positive bias.

Electrochemical behavior of AISI316L stainless steel parts produced by laser-based powder bed fusion process and the effect of post annealing process

This paper presents the investigation of the corrosion behavior of AISI316L samples prepared by laser-based powder bed fusion additive manufacturing (AM) method. Both AM and conventional stainless steel 316L samples were examined in NaCl 3.5% solution before and after the annealing process using Tafel curves, Electrochemical Impedance Spectroscopy, and X-ray diffraction. The results indicate that the AM parts have an improved corrosion behavior than the conventional wrought samples. Besides, the heat treatment process is found to further decrease the corrosion rate of the AM parts through the relieving of the residual stress. In contrast, the post annealing induced improvement to corrosion resistance for the wrought samples is due to the elimination of martensite phase which almost always exists after the plastic deformation during their production process.

Improved field emission properties of ZnO NRs using Al-doped and post oxygen annealing

In this paper, we synthesized Al doped ZnO (AZO) nanorods (NRs) and characterized their field emission properties. In addition, we considered the effect of post annealing process on the field emission characteristics of pure and doped ZnO NRs. Our results show that the field emission properties improve with the increased Al doping concentration in ZnO NRs. The field enhancement factor β is enhanced by ∼ 25% through 4% (weight ratio) Al doping. The field emission properties can be further improved by annealing in oxygen environment. Oxygen annealing modified the crystal structure of ZnO NRs and improves their field emission properties. Therefore, the 4 wt% Al doped sample with oxygen post annealing demonstrates the best field emission performance.

High-Voltage LiNi0.5Mn1.5O4 Thin Film Cathode Prepared By RF Sputtering

Introduction Lithium ion battery is dominant in secondary battery market due to its long cycle life and high energy density compared to other batteries such as nickel hydride and lead acid batteries and thus has been widely used in electronic devices. However, present lithium ion battery, which uses olivine LiFePO4, spinel LiMn2O4 or layered LiCoO2 as cathode materials, cannot meet the requirement of the power sources for transportation applications. With the development of electric vehicles, lithium ion battery with higher energy density is needed. One of the effective ways to enhance the energy density of lithium ion battery is to employ high voltage cathode materials. LiNi0.5Mn1.5O4 cathode has received a great attention for its high potential plateau at around 4.7 V (vs. Li/Li+) and its low price due to enough manganese resource. In this work, LiNi0.5Mn1.5O4 cathode films were deposited by reactive radio-frequency (RF) sputtering on stainless steel substrate. The effects of post-annealing process on the crystallinity and electrochemical performance were examined. As the post-annealed temperature increases, the crystallinity of the thin film becomes better. However, the electrochemical properties did not show the corresponding results. The metal inter-diffusion between stainless steel and LiNi0.5Mn1.5O4film was observed in the annealing process at 600 ℃ or more. Experimental LiNi0.5Mn1.5O4 thin films were fabricated on Stainless Steel substrates. 400 nm-thick LiNi0.5Mn1.5O4 cathode layers were deposited by reactive sputtering using LiNi0.5Mn1.5O4 target. After the deposition, the cathode thin film on stainless steel was crystallized according to various post-annealing temperatures. The electrochemical cell consisted of a Li-metal foil counter electrode, and 1mol/L LiPF6 in a 1:1 solvent mixture of ethylene carbonate and diethyl carbonate as the electrolyte. The cells were assembled in an argon-filled glove box. The structure and crystallinity of the films were investigated using X-ray diffraction (XRD) with Cu Ka radiation. Charge / discharge tests were performed between 2.5 and 5.0 V in the current-rate of 0.05C. The secondary ion mass spectroscopy (SIMS) depth profile measurements were used to analyze the LiNi0.5Mn1.5O4thin films. Results and Discussion The XRD examination of the LiNi0.5Mn1.5O4 thin film on stainless steel substrate obtained from Rf-sputtering method confirmed the spinel crystal structure (Fig. 1). Charge / discharge profiles showed typical curves of spinels such as LiMn2O4 and LiNi0.5Mn1.5O4 at the 1st and 30th cycles (Fig. 2). Among the various post-annealed samples, the 500 °C sample exhibited the best characteristics. The low plateau at about 4 V corresponds to the redox reaction of Mn3+/Mn4+, while the high plateau at about 4.7 V corresponds to the redox reactions of Ni2+/Ni3+ and Ni3+/Ni4+. To investigate the inter-diffusion between the film and the substrate, SIMS depth profile measurements were performed on LiNi0.5Mn1.5O4 thin films at the different post-annealed temperatures (Fig. 3). Above 600 °C, Fe ion and Cr ion were observed in the LiNi0.5Mn1.5O4region. Conclusions Spinel LiNi0.5Mn1.5O4 thin films were successfully prepared on stainless steel substrates by sputtering method. The post-annealed temperature plays an important role in the formation of the LiNi0.5Mn1.5O4film. As the post-annealed temperature increased, the crystallinity of the thin film increased. However, at 600 °C or higher, inter-diffusion occurred between the substrate and the thin film, and secondary phases were formed. As a result, the electrochemical characteristics were deteriorated due to these characteristics. Figure 1

Effect of Post-Deposition Annealing Process on the Resistive Switching Behaviour of TiO&lt;sub&gt;2&lt;/sub&gt; Thin Films by Sol-Gel Method

The paper presents the memristive behaviour of spin-coated titania thin films on ITO substrate. The sample was annealed in air ambient at different annealing temperature and duration of 250 and 450 °C for 20 and 60 min. The effect of post-annealing process to the physical thickness and crystallinity of the films towards switching behaviour was studied. It was found that the thickness and crystallinity of the films increases as the post annealing process increases. Sample annealed at 250 °C for 20 min with thinner film showed better switching behaviour even though the sample is still in amorphous form. Thus, in our work, we believed that the crystallinity of the films does not affect the switching behaviour of the sample. The reliability of device performance was studied by repeating the measurement for three times.

Effect of post-annealing process on the optical properties of lateral composition-modulated GaInP structure grown by molecular beam epitaxy

We report the molecular beam epitaxy growth of lateral composition-modulated (LCM) GaInP structures induced by GaP/InP short-period superlattice (SPS), and the effect of post-annealing process on their optical properties. The samples are structurally analyzed using cross-sectional transmission electron microscopy which reveals the formation of SPS-induced LCM-GaInP just above the substrate and bulk-like weakly phase separated LCM-GaInP towards the sample surface. The bulk-like features are formed due to strain accumulation and relaxation during SPS growth. The grown samples are annealed under different annealing conditions and optically characterized by low-temperature photoluminescence (LT-PL) and Raman spectroscopy. LT-PL reveals a lower energy PL peak originating from LCM-GaInP and a higher energy PL peak originating from weakly phase separated LCM-GaInP. These peaks red-shift with increase in annealing duration and temperature, and the higher energy PL peak approach towards the lower energy PL peak indicating enhanced phase separation of In-rich GaInP and Ga-rich GaInP vertical layers of the constituent LCM-GaInP structure. Also there exists an optimum annealing temperature and duration at which the PL intensity of the LCM-GaInP increases. More importantly, our results suggest that post-annealing process is a viable technique to enhance the optical properties of LCM-GaInP structures.

Fabrication and characterization of transparent p–n and p–i–n heterojunctions prepared by spray pyrolysis technique: Effect of post-annealing process and intrinsic middle layer

In this paper, p–n and p–i–n heterojunctions based on transparent semiconducting oxides are fabricated employing the spray pyrolysis technique. The prepared p-NiO:Li/n-SnO 2:F (bi-layer) and p-NiO:Li/i-ZnO/n-SnO 2:F (tri-layer) junctions are structurally, electrically and optically characterized, and the effect of insertion of the intrinsic buffer layer (i-ZnO) followed by post-annealing is investigated through I– V measurements. The measurement results for the proposed p-NiO:Li/n-SnO 2:F device show that the forward threshold and the reverse breakdown voltages are about 0.4 and −2.8 V, respectively. By applying the middle layer, the forward threshold and reverse breakdown voltages reach ∼1 and −4.2 V; then by post-annealing this element at 700 °C for 30 min, the mentioned voltages reach about 1.6 and −3.1 V, respectively.

Preparation of C-axis textured LiNbO 3 thin films on SiO 2/Si substrates with a ZnO buffer layer by pulsed laser deposition process

Highly C-axis textured LiNbO 3 thin films were grown on SiO 2/Si substrates with a ZnO buffer layer by XeCl excimer pulsed laser deposition technique. We fixed the target–substrate spacing at 40 mm, oxygen flow rate of 20 sccm and the repetition rate of 5 Hz, and then changed the substrate temperature, energy density and oxygen pressure to obtain the optimum deposition conditions. The effect of post-annealing process on improving the structural properties of the as-deposited LiNbO 3 thin films was also studied. The ZnO buffer layers and LiNbO 3 films were characterized by X-ray diffraction (XRD), atomic force microscopy and scanning electron microscopy to analyze their crystalline structure, surface roughness and surface morphology, respectively. For the optimum deposition parameters such as substrate temperature of 700 °C, energy density of 4.6 J/cm 2 and oxygen pressure of 150 Pa, the full width at half maximum intensity (FWHM) of LiNbO 3(0 0 6) peak was 0.22°. The FWHM of LiNbO 3(0 0 6) peak was further reduced to 0.19° via. in-situ post-treatment at 750 °C for 30 min. The results could be useful for integrating the surface acoustic wave device, optical waveguide and semiconductor device on the same Si substrate.

The effect of post-annealing process in NdGaO 3 new seed layer for LPE

Novel porous NdGaO 3 (NGO) thin film was fabricated as a new seed layer for liquid phase epitaxy growth of YBa 2Cu 3O 7− δ . The microstructure and crystallization mechanism of NGO new seed layer due to post-annealing temperature were revealed by high resolution SEM. Amorphous NGO layers on LaAlO 3 single crystalline substrate obtained by pulsed laser deposition method at room temperature and this layer shows the very porous and columnar structure. And this amorphous NGO layers were annealed at wide temperature range below 1300 °C in air. Amorphous NGO layer begins to crystallize by post-annealed at 750 °C and its orientation gets better with increased annealing temperature. The thickness of NGO layers decrease with increased annealing temperature above 500 °C and the well-oriented NGO layers were obtained between 900 and 1300 °C. The NGO layers annealed at above 1100 °C show very dense film.