Effect Of Annealing Conditions Research Articles

Effect of annealing conditions on resistive switching in hafnium oxide-based MIM devices for low-power RRAM

Abstract This work presents resistive switching (RS) behaviour in HfO2-based low-power resistive random-access memory (RRAM) devices. A metal-insulator-metal (MIM) structure (Au/HfO2/Pt) was fabricated by sandwiching a thin insulating layer of HfO2 between Pt and Au electrodes. HfO2 films deposited by RF sputtering at room temperature were rapid thermally annealed in N2 ambient at 400 °C and 500 °C. Grazing angle x-ray diffraction (GIXRD), Field emission gun-scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) were employed to analyse the phase, crystal structure, morphology, surface roughness and chemical composition of the HfO2 films. The bipolar RS could be observed in both as-deposited and annealed HfO2 film-based devices from I–V characteristics measured using a source meter. We have investigated the effect of annealing temperature and annealing ambient on the phase formation of HfO2 as well as the RS characteristics and compared with as-deposited film-based device. Annealed HfO2 film-based devices exhibited improved electrical characteristics, including stable and repeatable RS at significantly lower switching voltages (<1 V) which indicates low power consumption in these devices. The relatively lower processing temperature of the HfO2 films and that too in the films deposited by physical vapor deposition (PVD) technique-RF magnetron sputtering makes this study significantly useful for resistive switching based non-volatile memories.

Effect of annealing conditions on surface morphology and ferroelectric domain structures of BiFeO3 thin films

Ferroelectric materials are widely used in the applications of electronic devices due to their robust spontaneous polarization. The surface roughness of ferroelectric thin films, which is closely related to the morphology, can play an important role in determining the ferroelectric domain structures. In this work, we have investigated the influence of annealing conditions on the surface morphology of epitaxial BiFeO3 and SrRuO3 thin films prepared by pulsed laser deposition on SrTiO3 (001) substrates. It is found that the morphology of the thin films is sensitive to the annealing time and cooling rate, and the corresponding surface roughness decreases with increasing annealing time and decreasing cooling rate. In addition, the ferroelectric domain structures of BiFeO3 films have been investigated by piezoelectric force microscopy, which shows a significant improvement in domain size and reverse piezoelectric response in the thin films with decreasing surface roughness. This work provides a simple way to predict and improve the ferroelectric domain structures by in situ annealing.

Effect of annealing conditions on the luminescence properties and thermometric performance of Sr3Al2O5Cl2:Eu2+ and SrAl2O4:Eu2+ phosphors.

We report on the synthesis, photoluminescence optimization and thermometric properties of Sr3Al2O5Cl2:Eu2+ and SrAl2O4:Eu2+ phosphor powders. The photoluminescence of Sr2.9Al2O5Cl2:0.1Eu2+ phosphors exhibits a blue-shift with an increasing annealing temperature owing to a decrease in the crystal field strength of the host caused by evaporation of Cl from the material. The quenching of the blue band in favour of the red band observed in the luminescence spectra of Sr2.9Al2O5Cl2:0.1Eu2+ with an increased annealing temperature was explained using the mechanism of the Landau-Zener transitions. The quantum yield and the lifetime of the phosphors depend on the annealing temperature. Phosphor samples annealed at 850 °C, 1000 °C, 1200 °C and 1500 °C were found to be potential luminescence thermometers using the luminescence spectral method. For Sr3Al2O5Cl2:Eu2+ annealed at 1000 °C, the temperature-dependent dual-band intensity ratio demonstrated a high-temperature sensitivity of ∼1.47%/°C in the temperature range of 23 °C to 40 °C which is superior to other reported phosphors with a microsecond decay time, suggesting that the material has potential for sensitive thermometry applications at ambient temperatures.

Towards High-Temperature MEMS: Two-Step Annealing Suppressed Recrystallization in Thin Multilayer Pt-Rh/Zr Films.

Platinum-based thin films are widely used to create microelectronic devices operating at temperatures above 500 °C. One of the most effective ways to increase the high-temperature stability of platinum-based films involves incorporating refractory metal oxides (e.g., ZrO2, HfO2). In such structures, refractory oxide is located along the metal grain boundaries and hinders the mobility of Pt atoms. However, the effect of annealing conditions on the morphology and functional properties of such multiphase systems is rarely studied. Here, we show that the two-step annealing of 250-nm-thick Pt-Rh/Zr multilayer films instead of the widely used isothermal annealing leads to a more uniform film morphology without voids and hillocks. The composition and morphology of as-deposited and annealed films were investigated using X-ray diffraction and scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy. At the first annealing step at 450 °C, zirconium oxidation was observed. The second high-temperature annealing at 800-1000 °C resulted in the recrystallization of the Pt-Rh alloy. In comparison to the one-step annealing of Pt-Rh and Pt-Rh/Zr films, after two-step annealing, the metal phase in the Pt-Rh/Zr films has a smaller grain size and a less pronounced texture in the <111> direction, manifesting enhanced high-temperature stability. After two-step annealing at 450/900 °C, the Pt-Rh/Zr thin film possessed a grain size of 60 ± 27 nm and a resistivity of 17 × 10-6 Ω·m. The proposed annealing protocol can be used to create thin-film MEMS devices for operation at elevated temperatures, e.g., microheater-based gas sensors.

Effects of annealing conditions on structural and ferroelectric properties of CeO2-HfO2 solid solution thin films on InAs substrates fabricated by chemical solution deposition

CeO2-HfO2 solid solution thin films are fabricated on (100) InAs substrates by chemical solution deposition (CSD) method. The effects of annealing conditions (annealing temperature and atmosphere) on the structural and ferroelectric properties of CeO2-HfO2 solid solution thin films are studied. The results verified that ferroelectric phase of CeO2-HfO2 solid solution thin film could be induced on InAs substrate. In the temperature range studied (550 – 700 ºC), higher annealing temperature profits suppressing nonferroelectric monoclinic phase and promoting ferroelectric orthorhombic phase, and therefore improves ferroelectric polarization. For film annealed at 700 ºC, annealing in N2 leads to an enhanced ferroelectric polarization (2Pr of 33.9 μC/cm2) compared with annealing in O2. Importantly, all films can survive 1 × 108 cycles at an applied voltage of 20 V, and do not show significant retention losses, which are benificial for further application. This work highlights the feasibility of integrating CeO2-HfO2 ferroelectric thin films on III-V platform technology.

Investigation of the annealing treatment on the performance of TiO2 photoanode

Developing low-cost semiconductor photoanode toward efficient and stable oxygen evolution reaction (OER) is highly desirable for photoelectrochemical (PEC) water splitting. Herein, nanoparticulate titanium dioxide (TiO2) electrodes were prepared using Degussa P25 powders by spin-coating method. The effects of annealing conditions on the PEC performance of the nanoparticulate TiO2 photoanode was systematically investigated including temperature, annealing time and atmosphere. The results demonstrate that the TiO2/fluorine-doped tin oxide substrates (FTO/TiO2) electrode annealed at argon (Ar) atmosphere under 450 °C shows the highest PEC performance. The photocurrent density of FTO/TiO2 annealed in Ar for only 0.5 h reached to 120 μA/cm2 at 0.3 V vs. Hg/HgO which is about 10 times higher than that of the unannealed one. The X-ray photoelectron spectroscopy (XPS) results show the thermal treatment can produce oxygen vacancies on the surface of TiO2 which reduce the recombination of photogenerated electron-hole pairs and expanding the visible light absorption by introducing defective energy levels. The electrochemical impedance spectroscopy (EIS) approves that appropriate annealing treatment can effectively enhance the electron conductivity resulting in low charge transfer resistance. All these factors contribute to improving the PEC activity of TiO2 photoanode.

Effect of annealing conditions on the physicochemical and photocatalytic properties of a nanopowder based on Fe2TiO5

The current research deals with the urgent task of creating highly efficient photocatalysts for wastewater treatment from various organic pollutants. For these purposes, we carried out a mechanochemical synthesis, heat treatment, and study of a non-toxic, thermally and chemically stable catalysts with a heterostructure based on Fe2TiO5 pseudobrookite. The morphology and the properties of the as-prepared composites were characterized through different techniques. The chemical reactions occurring during the step-by-step heat treatment of the samples were proposed using info from XRD analysis, IR spectroscopy, thermal analysis, and mass spectra. The influence of the gaseous medium on the phase composition and the degree of crystallinity of materials has been established. The analysis of the elemental composition and morphology of powder particles was carried out at an annealing temperature in the range from 100 to 1000 °C in air. The photocatalytic activity of pseudobrookite was studied during the decomposition of the organic dye Rhodamine B, and the mechanism of photocatalysis associated with the absorption of photons and the formation of an electron-hole pair was considered. It was found that samples thermally treated in nitrogen were demonstrated greater catalytic activity than those treated in air.

Effects of annealing conditions on temperature coefficient of resistance of Pt/AlOx thin-film thermistors

Effects of annealing conditions on temperature coefficient of resistance of Pt/AlOx thin-film thermistors

Effect of annealing conditions on structural and magnetic properties of 36Ni-64Fe laminates

Different aspects of contemporary life directly or indirectly make use of magnetic materials, including both soft and hard magnets.Magnetically soft Nickel-Iron (Ni-Fe) alloys are used as magnetic core materials for the pulsed magnets of accelerators. Fe-based alloys are widely used as magnetic cores for accelerator and experiment magnets. For magnetization rates as high as 105 T/s to 107 T/s, crystalline materials would perform best in terms of minimizing losses. The processing conditions for Ni-Fe laminations and C-shaped punched cores having sizes of 70 mm × 70 mm × 0.1 mm in a hydrogen environment were optimized in this study. The structural, magnetic, and electrical characterizations of non-annealed and annealed Ni-Fe laminations were carried out under a hydrogen atmosphere by varying process parameters such as annealing as well as oxidation temperature and holding time. With the scanning Kelvin probe (SKP) method, the electrical properties, including work function, were examined. These characteristics were found to be correlated with the microstructural characteristics under various annealing conditions. Under various annealing conditions, magnetic characteristics such as remanence, coercivity, and saturation magnetization are measured. To enhance the magnetic performance of soft magnet cores after heat treatment, the microstructure-magnetic property correlation investigation is carried out.

Effect of annealing conditions on VO2 thin films prepared by sol-gel method

Vanadium dioxide has attracted considerable attention because of the semiconductor-metal transition at 68 °C. This reversible transition changes crystal structure from monoclinic to rutile resulting in tremendously change of transmittance and reflectance of infrared wavelength and electrical resistance making VO2 thin film potential candidate for energy-saving smart windows—automatically block heat. However, the preparation is very challenging due to the multivalence of vanadium element. In this study, we explored different annealing conditions for thin films synthesized by sol-gel method which has advantage over other methods such as lower cost, simpler process, and ability to make large scale thin films. In the experiment, vanadium (V) triisopropoxy oxide (VO(OC3H7)3) was used as precursor. The annealing conditions explored are annealing temperature and annealing time of thin films in argon rich environment. The spin-coated films were annealed at 300-500 °C for 30 minutes, while another set was annealed at 450 °C for 30, 60, 90, and 120 minutes, respectively. Then the films were characterized with Raman spectroscopy and temperature dependent resistance measurement. The results show that the longer the annealing time and the higher the annealing temperature are better for film formation—closer to VO2 (higher V:O ratio). In addition, the effect of various substrate types was also explored, another set of thin films was coated on c-plane sapphire (c-Al2O3) and soda lime glass (mostly SiO2) to compare the effect. Then the films were characterized with Raman spectroscopy and X-Ray Diffraction (XRD). The result showed that sapphire substrate yielded better film formation.

Effects of annealing conditions and multifold morphology on photocatalytic properties of TiO2 nanorods

Effects of annealing conditions and multifold morphology on photocatalytic properties of TiO2 nanorods

Effects of molecular weight and annealing conditions on the essential work of fracture of polycarbonate

AbstractThe effects of annealing conditions and molecular weight on the energies required for cracking and plastic deformation were investigated by the essential work of fracture (EWF) method. We found that the energy required for plastic deformation, βwp, regardless of the molecular weight, decreased upon annealing, and the energy required for cracking, we, did not change. On the basis of these results, it is suggested that annealing affects βwp because the density fluctuation is amplified by annealing, and as a result, the strain in the plastic region is concentrated. Moreover, both βwp and we increased with the molecular weight because the increase of molecular weight increases the number of entanglements formed by a molecular chain. In addition, comparing the values of the J‐integral (Jc), we found that we obtained from the EWF and Jc was almost the same, indicating that we obtained from the EWF also involves the energy required for plastic deformation when the deformation around the notch changes from biaxial stretching to uniaxial stretching.

Enhancement of magnetic properties and microstructural changes in TbCu7-type Sm-Fe-Co-Nb-B melt-spun ribbons

The effects of annealing conditions on magnetic properties, phase, and microstructural changes in Sm-Fe-Co-Nb-B melt-spun ribbons were investigated, and the dependence of magnetic properties on Sm and B composition was also investigated. SmxFe80.9−(x+y)Co16.4Nb2.7By amorphous ribbons were prepared by melt-spinning and then annealing. After annealing at 625 °C, the Sm6.2Fe66.4Co16.4Nb2.7B8.3 ribbons exhibited crystallization of hard-magnetic TbCu7-type phase, and the coercivity increased as the annealing time was increased to 9 h. The grain size of the TbCu7-type phase as estimated from transmission electron microscopy (TEM) images was 20–50 nm for ribbons annealed for 9 h. Three-dimensional atom probe (3DAP) analysis revealed that Nb and B became enriched at grain boundaries and tended to condense at the grain boundaries with increasing annealing time. Non-magnetic Nb and B enrichment at the grain boundaries in fine TbCu7-type grains thus promotes magnetic decoupling between TbCu7-type phases and suppresses domain wall propagation, resulting in high coercivity. Composition dependence on magnetic properties was investigated. Optimum annealing time tended to increase with increasing Sm content. The Sm6.7Fe65.9Co16.4Nb2.7B8.3 ribbons exhibited a maximum coercivity of 695 kA⋅m−1 by annealing at 625 °C for 21 h and subsequent slow cooling at a cooling rate of 4 °C⋅h−1. As B content decreased, coercivity decreased and remanence increased. The Sm6.2Fe68.7Co16.4Nb2.7B6.0 ribbons exhibited a high σr of 100 A⋅m2⋅kg−1 and moderate HcJ of 540 kA⋅m−1 after optimal annealing. An isotropic bonded magnet was fabricated from this ribbon. The bonded magnet exhibited high magnetic properties of Br = 0.82 T, HcJ = 538 kA⋅m−1, and (BH)max = 98 kJ⋅m−3, and small temperature coefficients of α(Br) = −0.06%⋅°C−1 and β(HcJ) = −0.27%⋅°C−1.

Formation, evolution, and prevention of thermally induced defects on germanium and silicon upon high-temperature vacuum annealing

This Letter reports the formation, evolution, and prevention of thermally induced defects on germanium upon high-temperature (up to 890 °C) vacuum (2×10−6 Torr or 2.67×10−6 mbar) annealing. It is found that the shape of defects evolves depending on the annealing temperature and duration. The defect shape can be classified into three groups (pyramid, expanded pyramid, and doughnut), considering the interplay of chemical desorption and surface diffusion. The effects of annealing conditions on the density and size of defects are also investigated with scanning electron microscopy and atomic force microscopy. To prevent thermally induced defects, a simple covering method is proposed and demonstrated. In addition, formation and prevention of defects resulting from high-temperature (1150 °C) vacuum annealing are applied to silicon.

Manipulating Crystallization for Simultaneous Improvement of Impact Strength and Heat Resistance of Plasticized Poly(l-lactic acid) and Poly(butylene succinate) Blends.

Crystalline morphology and phase structure play a decisive role in determining the properties of polymer blends. In this research, biodegradable blends of poly(l-lactic acid) (PLLA) and poly(butylene succinate) (PBS) have been prepared by melt-extrusion and molded into specimens with rapid cooling. The crystalline morphology (e.g., crystallinity, crystal type and perfection) is manipulated by annealing the molded products from solid-state within a short time. This work emphasizes on the effects of annealing conditions on crystallization and properties of the blends, especially impact toughness and thermal stability. Phase-separation morphology with PBS dispersed particles smaller than 1 μm is created in the blends. The blend properties are successfully dictated by controlling the crystalline morphology. Increasing crystallinity alone does not ensure the enhancement of impact toughness. A great improvement of impact strength and heat resistance is achieved when the PLLA/PBS (80/20) blends are plasticized with 5% medium molecular-weight poly(ethylene glycol), and simultaneously heat-treated at a temperature close to the cold-crystallization of PLLA. The plasticized blend annealed at 92 °C for only 10 min exhibits ten-fold impact strength over the starting PLLA and slightly higher heat distortion temperature. The microscopic study demonstrates the fracture mechanism changes from crazing to shear yielding in this annealed sample.

Alleviation of Negative-Bias Temperature Instability in Si p-FinFETs With ALD W Gate-Filling Metal by Annealing Process Optimization

In this article, we present an experimental study on the impact of post-metallization annealing conditions on the negative-bias temperature instability (NBTI) of Si p-channel fin field-effect transistors (p-FinFETs) with atomic layer deposition tungsten (ALD W) as the gate-filling metal. The effects of annealing conditions on the tensile stress of the W film, impurity element concentration in the gate stack, fresh interface quality, threshold voltage shift ( ${\Delta }$ V $_{T}$ ), pre-existing traps ( ${\Delta } {N} _{\mathrm {HT}}$ ), generated traps, and their relative contributions were studied. The time exponents of ${\Delta }$ V $_{T}$ , the impacts of stress bias and temperature on NBTI degradation, and the recovery kinetics of the generated traps were analyzed. For devices with a B2H6-based W-filling metal, a 34% reduction in the fresh interface states, reduced ${\Delta }$ V $_{T}$ , and a 29% improvement in the operation overdrive voltage could be achieved by optimizing the annealing conditions. The NBTI is alleviated mainly because of the reduction in the generated traps, while the energy distribution of ${\Delta } {N} _{\mathrm {HT}}$ is insensitive to the annealing conditions. Furthermore, the relative contribution of the generated bulk insulator traps to the total number of generated traps could be reduced by optimizing the annealing conditions.

Effect of Annealing Process on Microstructure and Mechanical Properties in Microalloyed Medium Manganese Steel

The effects of annealing conditions on microstructure evolution and strengthening mechanisms are investigated based on microalloyed medium manganese steel. The diffusion of C and Mn atoms is altered with increase in annealing temperatures or annealing time. Microstructure and mechanical properties are studied. It is found that the retained austenite generated by the reverse transformation of martensite is used to improve the strength and ductility during the intercritical temperature region. The total elongation (TE) is related to the fraction and stability of retained austenite. High strength is also obtained when there is almost no retained austenite below Ac1 temperature.

Carbonaceous minerals as corrosion products on the surface of bottles

During the corrosion process, as the ion exchange between the surface of the glass and the water progresses, the chemical structure of the surface changes and different structural layers are formed. These layers are characterised by various analytical techniques such as EPMA, XRD, FT-IR, TG-DTA and ICP-OES. Three carbonate mineral species namely calcite (CaCO3), shortite (Na2Ca2(CO3)3) and nyerereite (Na2Ca(CO3)2) have been identified at the outermost deposition layer. Critical parameters that affect the formation of the alkali depleted and silica enriched gel layer are investigated using some special test methods. Methylene blue solution reacts with the silanol groups of gel layer leaving a blue tint behind, the intensity of which varies with the extent of corrosion as the amount of silanol groups outcropped due to the increase of the porous structure area. A colour scale is developed to determine the level of corrosion and the results are correlated with the results of other known chemical analysis methods. The effect of annealing conditions on the chemical resistance of the surfaces and the role of the shape of the bottles on the water condensation at humid atmosphere are studied. The results of acid treatment and re-annealing of the corroded surfaces are described.

Effect of Simulated Annealing Conditions on Scale Formation and Neutral Electrolytic Pickling

Scale formation of AISI 304 stainless steel during annealing at temperatures between 1100 and 1200 °C under a water vapor‐containing atmosphere is studied. Characterization of the oxide scale is performed with field‐emission scanning electron microscopy–energy dispersive spectroscopy (FESEM–EDS) and glow discharge optical emission spectroscopy (GDOES) and removal of oxide scale is done via neutral electrolyte pickling. The pickling conditions are kept constant and the effect of the annealing conditions and scale properties on the pickling result are examined. The effectiveness of pickling is evaluated using analysis FESEM images taken on polished sections of pickled surfaces. Research shows that the thickness, morphology, and composition of the oxide scale are dependent on annealing temperature and time. The thicknesses of the scale formed under the established conditions vary from 0.2 to over 30 μm, and morphologies between the chromium rich oxide layer and layered scale structure formed by breakaway oxidation. The pickling response of oxide scales remains good at all annealing temperatures with the shortest exposure time.

Enhancement of hard magnetic properties in rapidly quenched Zr–Co–Fe–B ribbons through vacuum annealing

In the present work, the importance of vacuum annealing on the nanostructured Zr2Co9.5Fe1.5B ribbons fabricated through rapid solidification method was investigated for their hard magnetic properties. Optimized vacuum annealing promotes the formation of rhombohedral Co5.1Zr hard magnetic phase, in addition to the orthorhombic Co5.1Zr, fcc-Co, Co23Zr6 and Co3ZrB2 phases, which were formed via melt spinning. Remanent magnetization (Mr) and coercivity (HC) was found to enhance post-annealing from 22.8 emu/g and 1.24 kOe in as melt-spun (MS) ribbons to 50.3 emu/g and 1.64 kOe for the ribbons annealed at 550 °C/1 h. Furthermore, the optimally annealed ribbons contribute towards an increase in magnetic energy product (BH)max ~ 2 MGOe in comparison to as-spun ribbons having 0.7 MGOe. Annealing process leads to enhancement of hard magnetic properties through the crystallization of rhombohedral Co5.1Zr hard magnetic phase. To account for an increase in coercivity, the coercivity mechanism of the annealed optimized ribbon was also studied and is attributed to the nucleation mechanism as deduced from the measurement of minor loops. The effect of annealing conditions on the phase evolution, microstructure and magnetic behaviour of Zr2Co9.5Fe1.5B MS ribbons, indicates that appropriate control of the thermal annealing schedule is a key to achieve high remanence, coercivity as well as magnetic energy product. The nanostructured Zr2Co9.5Fe1.5B MS ribbons could serve as a potential candidate for rare-earth free permanent magnet materials.