Effect Of Vacuum Annealing Research Articles

Effect of vacuum annealing on the upconversion luminescence of β-Ba2ScAlO5: Yb3+, Ho3+ phosphor

Upconversion luminescence (UCL) materials with narrow emission peaks, long fluorescence lifetime, and large anti-Stokes shift have attracted considerable attention in biomedical, display, anti-counterfeiting, and solid-state lasers. This study presents a new synthesis method, combining air sintering and vacuum annealing, to obtain intense green UCL emission β-Ba2ScAlO5: 0.15 Yb3+, 0.005Ho3+ phosphor. After vacuum annealing, the green, red, and near-infrared emissions of Ho3+ are enhanced by factors of 40, 133, and 37, respectively. The diffuse reflectance spectra demonstrate that there is a defect energy band ranging from 330 to 860 nm in the air-treated samples, and it is reduced dramatically after vacuum annealing. This defect band covers the three wavelengths of Ho3+ emissions in the visible range and results in the reabsorption of UCL by the host lattice. X-ray Rietveld refinements and EPR spectra reveal the difference in the oxygen defects of the air-synthesized and vacuum-annealed phosphors and reflect that the absorption band is related to the oxygen defects. This research provides a new approach to obtain intense UCL emission of β-Ba2ScAlO5 hosted phosphors and offers an excellent green phosphor for application in anti-counterfeiting or displays.

Effect of vacuum annealing on properties of HfO2/SiO2 reflective films

HfO2/SiO2 multilayer reflective film was prepared by electron beam evaporation assisted by ion beams in this paper. The prepared samples were annealed at different temperatures. Multilayer reflective films of HfO2/SiO2 are analyzed at various annealing temperatures in order to determine their optical and mechanical properties. The results show that annealing treatment can effectively reduce film absorption and thermal effects.

Effect of Vacuum Annealing on Orientation of Fluorite Films on Tilted-Axes Substrates

Effect of Vacuum Annealing on Orientation of Fluorite Films on Tilted-Axes Substrates

Marigold flower like Co3O4 nanoparticles as high performance electrodes for supercapacitors

Transition metal oxides promised as electrode materials for supercapacitors have received much interest, especially cobalt oxide (Co3O4) nanoparticles. However, the low intrinsic electrical conductivity and aggregation of Co3O4 nanoparticles limit their electrochemical performance and impede the commercialization of these electrode materials. The present study describes a simple, and cost-effective solution combustion approach for producing marigold Co3O4 at 300 °C. Further, the effect of vacuum annealing on the microstructural and electrochemical properties is studied to explore the nanostructured samples of Co3O4 as potential electrode material. The electrochemical nature of prepared marigold Co3O4 nanoparticles in 3 M KOH aqueous electrolyte has the highest specific capacitance of 603 Fg−1 at a scan rate of 1 mVs−1 with greater electrochemical stability even after 5000 cycles. The possible reasons for a decrease in specific capacitance on annealing of as prepared Co3O4 at 300 °C are explored in this paper and some significant reasons are highlighted.

Annealing effects on the magnetic and magnetotransport properties of iron oxide nanoparticles self-assemblies

In magnetic tunnel junctions based on iron oxide nanoparticles the disorder and the oxidation state of the surface spin as well as the nanoparticles functionalization play a crucial role in the magnetotransport properties. In this work, we report a systematic study of the effects of vacuum annealing on the structural, magnetic and transport properties of self-assembled ∼10 nm Fe3O4 nanoparticles. The high temperature treatment (from 573 to 873 K) decomposes the organic coating into amorphous carbon, reducing the electrical resistivity of the assemblies by 4 orders of magnitude. At the same time, the 3.Fe2+/(Fe3++Fe2+) ratio is reduced from 1.11 to 0.13 when the annealing temperature of the sample increases from 573 to 873 K, indicating an important surface oxidation. Although the 2 nm physical gap remains unchanged with the thermal treatment, a monotonous decrease of tunnel barrier width was obtained from the electron transport measurements when the annealing temperature increases, indicating an increment in the number of defects and hot-spots in the gap between the nanoparticles. This is reflected in the reduction of the spin dependent tunneling, which reduces the interparticle magnetoresistance. This work shows new insights about influence of the nanoparticle interfacial composition, as well their the spatial arrangement, on the tunnel transport of self-assemblies, and evidence the importance of optimizing the nanostructure fabrication for increasing the tunneling current without degrading the spin polarized current.

Vacuum annealing effects on the microstructure and properties of HfO2-based bilayer antireflective coatings by magnetron sputtering

Hafnia (HfO2) retains thermal stability, mechanical resilience, and chemical resistivity, which makes it feasible in various high-tech applications in optics and integrated circuit technology. This work presents the effects of thermal annealing on the microstructure, optical performance, and wettability of HfO2/Al2O3 and HfO2/ZrO2 bilayer thin films prepared by magnetron sputtering. The films were deposited on silicon (Si) and glass substrates and then annealed at a certain temperature (300–500 °C) in the ambient vacuum condition for 5hrs. XRD results of as-deposited and annealed films revealed the polycrystalline nature of the monoclinic phase. The core level orbitals of Hf 4f, Zr 3d, and Al 2p spectra showed the formation of stoichiometric compositions of HfO2, ZrO2, and Al2O3 films and exhibited a slight shift in binding energy after annealing. The AFM and SEM analysis were utilized to inspect the roughness and surface morphology and correlated with the change in hydrophobicity to the self-cleaning nature of the prepared bilayer coatings. The observed upsurge in refractive indexes of the coatings is allied to the packing density that causes lattice contraction and enhances the attraction between dipoles. The negligible effect of negative temperature on the antireflection efficiency makes it suitable for future applications in optoelectronic, photovoltaic devices operated in a cold or humid environment.

Strong oxygen-content dependence of the magnetic excitations in antiferromagnetic NiO nanoparticles: A Raman probe

Nanostructured antiferromagnetic (AFM) NiO has attracted much attention from both the fundamental and applied perspectives. Understanding the two-magnon (2 M) is of great significance in NiO applications such as spin valves and next-generation magnetic random access memories (MRAM). We investigated the phonon modes and antiferromagnetically ordered states of NiO nanoparticles prepared by empirically controlled measurements. An intensity enhancement of the 2 M mode was observed by Raman spectroscopy as the NiO nanoparticles were vacuum annealed at 650 ℃. The increased 2 M peak intensity in NiO nanoparticles is explained by the local symmetry conversions from NiO5 to NiO6 configurations due to the oxygen redistribution during the vacuum annealing. The change of the splitting of anisotropic transverse optical (TO) phonon with different oxygen contents was also revealed by the Raman spectroscopy. We have shown that the changes in the oxygen environment underlie both the change in the 2 M intensity and the splitting of TO phonon in the NiO nanoparticles. Our work offers an efficient avenue to strengthen the AFM ordering and emphasizes the effect of vacuum annealing of the NiO nanoparticles, opening the interesting possibility of individual parameter control in practical applications.

Air and Vacuum Annealing Effect on the Highly Conducting and Transparent Properties of the Undoped Zinc Oxide Thin Films Prepared by DC Magnetron Sputtering

In this study, we aim to investigate the effect of zinc interstitials (Zni) and oxygen vacancies (VO) on the ZnO electrical conductivity. ZnO films were synthesized via DC magnetron sputtering process using pure Zn target in gases mixture of Ar/O2 = 80/17.5 (sccm). In order to improve the optical and electrical prosperities, the obtained films were subjected to air and vacuum annealing treatment. Several techniques such as field emission scanning electron microscopy (FESEM), Grazing Incidence X-ray Diffraction (GIXRD), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible were used to study the influence of heat treatment on structural and physical properties of ZnO films. Electrical conductivity of ZnO thin films was determined by measuring the sheet resistance and thickness of the films. XRD results confirm the synthesis of annealed ZnO films of the hexagonal structure with a preferential orientation along the (002) plane. The average crystallite size is altered between 22.6 to 28.4 nm dependent on the plan orientation of the ZnO film. Morphology and crystallinity of the ZnO structure could efficiently control the transmittance, electrical resistivity and optical band gap. As deposited ZnO film showed a lower electrical resistivity of 2.72×10-3 Ωcm due to the Zn-rich conditions. Under vacuum annealing, a combination of low resistivity (1.17×10-2 Ωcm) and better optical transmittance (87 %) are obtained. ZnO films developed in this study with high transmittance and low resistivity and good electro-optical quality supports their use in transparent and conductive electrode applications. The plan presentation was visualized using Vesta, with the lattice parameter set as follows: a = b = 3.249 Å; c = 5.207 Å; α = β = 90°; γ = 120°. Based on the construction and optimization of primitive cells, the supercells were constructed and then optimized. Finally, (002) and (103) planes were cut and the planar supercell structure was constructed. In order to make a plane representation for the solid bulk with 10 Å of thickness.

Preparation and study effect of vacuum annealing on structure and optical properties of AgCuInSe2 thin film

Ag0.8Cu0.2InSe2 (ACIS) alloys and thin films have been fabricated with different vacuum annealing temperatures Thin film has been deposited by thermal evaporation method of vacuum of 1.3*10-6 Torr with thickness about 700 nm at R.T and vacuum annealing at temperatures (373,473) K for 1 hour. The deposition in a vacuum on glass substrates. The crystal structure of deposited thin film had been examined by XRD and AFM analysis, which confirms the formation of tetragonal phase in 112 direction and these films are polycrystalline in nature having ideal stoichiometric. The optical properties of these films are determined for the wavelength range 400 - 1000 nm. The band gap of the Ag0.8Cu0.2InSe2 films was evaluated to be (1.48-1.42) eV.

Effect of vacuum annealing on the optical properties of tungsten oxide films

• Annealing of WO 3– x films in vacuum initiates their coloration in blue. • Colored film absorption band is adequately described by the Breit-Wigner distribution. • Annealing temperature rise nonlinearly increases the absorption band intensity. • Decrease in the spectral line width is saturated when annealing temperature increases. • Asymptote of refractive index dispersion decreases in proportion to the temperature. In this work, the thermochromic properties of tungsten oxide films are studied. The goal of this work is to study the influence of vacuum annealing on optical properties of amorphous WO 3– x films deposited on silica glass substrates. These dependences of the absorption index were approximated using the Breit-Wigner distribution. An increase in the annealing temperature led to an increase in the intensity and a decrease in the width of the absorption band in the near infrared range of the film transmission spectrum. This changed the dispersion of absorption and refractive indices.

Tailoring structural and magnetic viz. static and dynamic properties of soft magnetic CoFeB film with Ta incorporation

Present study provides an insight of tailoring magnetic properties (static and dynamic) driven by structural modifications, with controlled incorporation of Ta in soft magnetic CoFeB films. Unlike conventional thermal annealing, stress induced in-plane uniaxial magnetic anisotropy of CoFeB have observed to be release with incorporation of Ta, as confirmed from in-plane rotation dependent magneto-optical Kerr effect (MOKE). Increasing atomic percent of Ta in CoFeB is accompanied with decreasing saturation magnetization of soft-magnetic layer and film densification, as confirmed from polarized neutron and X-ray reflectivities. Ferromagnetic resonance (FMR) confirms the reduction of effective magnetization of the samples with Ta incorporation, with rise of damping parameter because of increasing magnetic inhomogenities. Further, the effect of vacuum annealing on these films has been investigated. Post annealing measurements suggest rapid elimination of magnetic anisotropy for Ta doped CoFeB films. Annealing at a temperature beyond CoFeB crystallization temperature results in an increase of magnetization, relative to as-prepared samples, amplitude of which modifies with incorporated Ta concentration. Such enhancement is accompanied with the structural changes as confirmed from X-ray diffraction (XRD) measurements, resulting an increase of magnetic coercivity. The results are important in view of tailoring the functional properties of CoFeB films for wide range of applications.

Thermal stability of the magnetic moment in amorphous carbon thin film - An experimental and ab-initio study

The effect of vacuum annealing on the microstructure and its consequence on the thermal stability of magnetic moment in amorphous carbon (a-C) thin film is studied. The magnetic a-C thin film of thickness 8 nm is vacuum annealed for 2 h at 523 K and 923 K. Microstructural and chemical characterization using Raman spectroscopy and x-ray photoelectron spectroscopy, respectively, reveals that with increasing annealing temperature, the sp2 fraction in the film increases. The magnetic measurement carried out at room temperature (RT) using SQUID-VSM reveals a weak ferromagnetic signal in the film due to the interaction between the unpaired sp2 sites, which prevails till 923 K. In the as-deposited sample, an isolated sp2 atom surrounded by sp3 atom results in the paramagnetic contribution, and an sp2-sp2 atom with twisted π-orbitals results in weak ferromagnetic coupling. Compared with the as-deposited case, initially, the saturation magnetization increases when the sample is annealed at 523 K and later decreases when annealed at 923 K. Subsequently, the ab-initio molecular dynamics calculation predicts that due to the increase in sp2 fraction, the net magnetization of the system increases from 300 K to 523 K. π-Orbital Axis Vector (POAV) analysis shows that further annealing to 923 K enhances π-orbital overlapping, which leads to the annihilation of moments sites. The present study differentiates between the two structures that contribute to the magnetism in a-C in terms of their thermal stability. Our simulation indicates that the twisted π-orbitals structure is thermodynamically more stable than the structure where sp3 surrounds sp2 hybridized atom.

Effect of vacuum annealing and position of metal Cu on structural, optical, electrical and thermoelectrical properties of ITO/Cu/ITO multilayers prepared by RF sputtering

In this work, we study the effect of vacuum annealing and position of metal Cu on structural, optical, electrical and thermoelectrical properties of ITO/Cu/ITO multilayers prepared on glass substrates, at room temperature by Radio Frequency (RF) sputtering. ITO (80 nm)/Cu(5 nm)/ITO (80 nm) ICI(a) and ITO (150 nm)/Cu(5 nm)/ITO (10 nm) ICI(b) multilayers were studied. The effect of vacuum annealing and position of metal Cu on ITO/Cu/ITO multilayers were investigated. The structure of ICI was analyzed by X-Ray Diffraction (XRD), X-Ray Reflectivity (XRR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Moreover, the electrical and optical properties were characterized by the four-point probes method and UV–Vis–NIR transmission measurement, respectively. Effect of the annealing temperature and position of metal Cu on the structural, optical, electrical and thermoelectrical properties were investigated.

Effects of vacuum annealing on the phase constituents and mechanical properties of the AlxCrFeMn2-xNi multiprincipal component alloys

The development of high-performance Co-free multiprincipal component alloys (MPCAs) is of great significance in recent years. In the present work, eight arc-melted Co-free AlxCrFeMn2-xNi alloys were prepared and then vacuum annealed at 800 or 1000 °C for 5–10 days. Their phase constituents, microstructures and mechanical properties were investigated. The second-order L21-Ni2MnAl phase with low Cr and Fe content was confirmed and had similar contribution to the alloy hardness as B2 phase. When x ≥ 1, the as-cast AlxCrFeMn2-xNi alloys are composed of BCC + B2 phase and have an elastic modulus of ∼228 GPa. Their mechanical properties slightly change after annealing, although the phase grains are coarsened after 1000 °C annealing and small amount of FCC phase precipitated after 800 °C annealing. When x = 0.1–0.75, the BCC phase transforms into the σ phase after 800 °C annealing, which leads to greatly increased hardness and reduced ductility. The decomposition temperature of the σ phase decreased with Al content, from 1036.9 °C to 912.0 °C. Compared to the AlxCo2-xCrFeNi alloys, the similar phase constituent and similar hardness can be obtained by replacing Co with Mn. Therefore, Co-free Al–Cr–Fe–Mn–Ni MPCAs have great application prospects.

Investigation of the effect of vacuum annealing on the tribological properties of the austenite stainless steel multilayer coatings

Investigation of the effect of vacuum annealing on the tribological properties of the austenite stainless steel multilayer coatings

Effect of ALD Processes on Physical and Electrical Properties of HfO2 Dielectrics for the Surface Passivation of a CMOS Image Sensor Application

The surface passivation of a CMOS image sensor (CIS) is highly beneficial for the overall improvement of a device performance. We employed the thermal atomic layer deposition (T-ALD) and plasma enhanced (PE-ALD) techniques for the deposition of 20 nm HfO₂ as well as stacked with 3 and 5 nm Al₂O₃ thin films. The HfO₂/Si and Al₂O₃/HfO₂/Si metal-oxide-semiconductor structures were used to analyze the fixed charge density (Q_f) and interface trap density (D_it). The as-synthesized samples show high D_it and Q_f values (10¹² cm^-2eV^-1) and a minority carrier lifetime of 15-300 μs. The finite-difference time-domain simulation of high-k dielectrics confirmed that the Al₂O₃ (top)/HfO₂ stacked structures expected higher quantum efficiency for CIS application. The effect of vacuum annealing (VA) and forming gas annealing (FGA) treatments succeeded with the decomposition of the D_it and increase in carrier lifetime. The H₂ ambient FGA samples showed a remarkable decrease in the D_it values. To improve the overall performance of the device after passivation, we employed an Al₂O₃/HfO₂ bilayer structure, which showed a low D_it of 10¹¹ cm^-2eV^-1 and a minority carrier lifetime of ~3,700 μs after 400 °C and 30 min FGA. We believe that this surface passivation strategy will pave way for future CIS technology regarding the development of lower defective surface and superior performance.

Effect of vacuum annealing on the optical and electrical properties of sputtered silicon doped indium oxide thin films

Silicon doped indium oxide (SIO) thin-films were deposited on Corning glass substrates using radio frequency magnetron sputtering at room temperature. The deposited SIO thin-films were post annealed under vacuum conditions (∼3.9 × 10−4 Pa) at 100–500 °C, respectively. The XRD analysis confirmed presence of polycrystalline indium oxide (In2O3) with preferred orientation in the (400) plane. Atomic force microscopy images show root mean square roughness ranging between ∼6 and 10 nm. The SIO thin-film post annealed at 400 °C had shown the electrical resistivity, mobility carrier concentration and sheet resistance values of 3.7 × 10−4 Ω-cm, 40 cm2/V.s, 4.2 × 1020 cm−3 and 4.96 Ω/□, respectively. The average transmittance of 76.2%, in the visible region (380–750 nm) was observed for SIO thin-film post annealed at 400 °C. The obtained results confirm that SIO thin films can be used for further development of high-performance transparent electrodes by sputtering technique.

Effect of vacuum annealing on the properties of one step thermally evaporated Sb2S3thin films for photovoltaic applications

Sb2S3films were deposited on unheated glass substrates by thermal evaporation and annealed under vacuum atmosphere for 2 hours at different temperatures. Different characterization techniques were used to better understand the behavior of the Sb2S3material. XRD and Raman spectroscopy confirmed the formation of pure Sb2S3powder with orthorhombic lattices. The effect of vacuum annealing on the properties of the films was studied. XRD analysis revealed that as-deposited and annealed films at 150 °C were amorphous in nature whereas those annealed atT≥ 200 °C were polycrystalline. The crystallite size of the films showed a decrease from 75.8 to 62.9 nm with the increase of the annealing temperature from 200 to 250 °C. The Raman showed several peaks corresponding to the stibnite Sb2S3phase. The surface morphology of the films was examined by AFM. The roughness decreases slightly as the transformation from the amorphous to the crystalline phase occurs. The chemical compositions of Sb2S3films were analyzed by EDS, revealing that all films were Sb-rich. The optical parameters were estimated from the transmittance and reflectance spectra recorded by UV-Vis spectroscopy. A reduction in the band gap energy from 2.12 to 1.70 eV with the increase of annealing temperature was also found.

Effect of vacuum annealing on structural and electrical properties of germanium telluride thin films

This study investigates the effects of vacuum annealing on the structural and electrical properties of germanium telluride thin films. To this end, GeTe thin films were prepared via DC magnetron sputtering in three sets—as-prepared at 25 °C, as-prepared at 300 °C, and deposited and annealed at 300 °C for different time intervals. Post fabrication, the films were characterized using grazing-incidence X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and four-point probe measurements. The as-prepared films deposited at 25 °C were amorphous, while the remaining film types exhibited crystalline conductivity and comparable sheet-resistance values. However, the observations of this study reveal a gradual increase in the degree of crystallinity and average grain size of the annealed films. The Raman spectroscopy results reveal the increase in film crystallinity to be due to an increase in the concentration of Te-rich tetrahedra at the expense of their Ge-rich equivalents.

High thermal stability of perpendicular magnetic anisotropy in the MgO/CoFeB/W thin films

Perpendicular magnetic anisotropy (PMA) with high thermal stability is greatly essential for ultrahigh density and stable data storage devices. Here, the effect of vacuum annealing on PMA of MgO/CoFeB/W stacks was investigated. It was shown that the PMA can be well maintained after annealing at 590 °C, which is much higher than that in traditional Ta-based PMA films. Using the polarized neutron reflectometry, the Co-Fe atoms proportion of the CoFeB/W interface was deliberately determined at different temperatures. It is found that the Co and Fe atoms of CoFeB/W interface had strongly segregation after annealing at 590 °C Furthermore, the effect of different proportion of Co-Fe elements on the PMA was systematically studied by the first-principles calculation. Our first-principles calculation and further analysis reveal that different Co-Fe proportion leads to the modification of orbital hybridization between dxy and dx2-y2 orbitals at the CoFe/W interface, indicating that the interfacial segregation can enhance the PMA. These findings unveil the origin of PMA in W-based devices with high thermal stability and can promote their future industrial applications.