Influence Of Thermal Annealing Research Articles

Fluorine Free Surface Modification of Microfibrillated Cellulose-Clay Composite Films: Effect of Hydrophobicity on Gas Barrier Performance

Diffusion barrier composite films based on microfibrillated cellulose (MFC) and clay were developed with attention paid to the influence of thermal annealing and a fluorine-free surface silylation on their microstructure, water contact angle (WCA), mechanical properties, oxygen transmission rate (OTR), and water vapor transmission rate (WVTR). The OTR of MFC at 23 °C increased from 1.2 to 25.3 cm3/m2/day/bar as relative humidity increased from 50% to 80%. Annealing increased the film’s crystallinity, surface roughness, and hydrophobicity, while decreasing its OTR by 20% at 80%RH. The addition of clay led to a 30% decrease of OTR at 80%RH due to partial exfoliation and to a 50% decrease when combined with annealing. Silylation increased the hydrophobicity of surface of the film and its combination with clay and annealing led to a WCA of 146.5°. The combination of clay, annealing, and silylation considerably reduced the OTR at 80%RH to a value of 8 cm3/m2/day/bar, and the WVTR at 23 °C and 50%RH from 49 g/m2/day for MFC to 22 g/m2/day. The reduction of OTR and WVTR was found to correlate with the increase in surface hydrophobicity of the film, which was attributed to the reduced access of water molecules within the MFC network.

Influence of thermal annealing on microstructure, energetic landscape and device performance of P3HT:PCBM-based organic solar cells

Thermal annealing alters the morphology of organic donor-acceptor bulk-heterojunction thin films used in organic solar cells. Here, we studied the influence of thermal annealing on blends of amorphous regio-random (RRa) and semi-crystalline regio-regular (RR) poly (3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C60-butyric acid methyl ester. Since the P3HT:PCBM blend is one of the most studied in the OPV community, the existing research provides a solid foundation for us to compare and benchmark our innovative characterization techniques that have been previously under-utilized to investigate bulk heterojunction organic thin films. Here, we combine advanced novel microscopies and spectroscopies, including polarized light microscopy, photo-deflection spectroscopy, hyperspectral photoluminescence imaging, and energy resolved-electrochemical impedance spectroscopy, with structural characterization techniques, including grazing-incidence wide-angle x-ray scattering, grazing-incidence x-ray diffraction, and Raman spectroscopy, in order to reveal the impact of thermal annealing on the microstructural crystallinity and morphology of the photoactive layer in organic solar cells. Coupled transfer matrix and drift-diffusion simulations were used to study the impact of the density of states on the solar cells’ device performance parameters, namely the short-circuit current (J SC), open circuit voltage (V OC), fill factor (FF), and power conversion efficiency (PCE).

Influence of Thermal Annealing on Mechanical and Optical Property of SiO2 Film Produced by ALD.

The application range of fused silica optical components can be expanded and the cost of fused silica components can be reduced by depositing the same material film on fused silica substrate. However, due to the different manufacturing process, the performance of ALD SiO2 film is lower than that of fused silica substrate, which also limits the use of this process. In this paper, ALD SiO2 film with different thicknesses were deposited, and then the structure and properties were tested. Finally, the ALD SiO2 film was treated via the annealing process. Transmission electron microscopy (TEM) showed that the ALD SiO2 film had good compactness and substrate adhesion. The Raman spectra showed that the ALD SiO2 film and substrate had the same structure, with only slight differences. The XRD pattern showed that ALD-fused silica did not crystallize before or after annealing. The infrared spectra showed that there was an obvious Si-OH defect in the ALD SiO2 film. The laser damage showed that the ALD SiO2 film had a much lower damage threshold than the fused silica substrate. The nanoindentation showed that the mechanical properties of the ALD SiO2 film were much lower than those of the fused silica substrate. After a low-temperature annealing treatment, the ALD SiO2 film Si-OH defect was reduced, the ALD SiO2 film four-member ring content was increased, the elastic modulus of the ALD SiO2 film was increased from 45.025 GPa to 68.025 GPa, the hardness was increased from 5.240 GPa to 9.528 GPa, and the ALD SiO2 film damage threshold was decreased from 5.5 J/cm2 to 1.3 J/cm2.

Effect of thermal annealing on the magnetization reversal and spin dynamics in ferrimagnetic TbCo thin films

“Ferrimagnetic rare earth-transition metal alloys are promising materials for high-speed and low-power spintronic device applications due to their wide tunability in magnetic properties as a function of temperature and composition. Here, we report the influence of thermal annealing on the magnetization reversal and spin dynamics of ferrimagnetic Tb10Co90 thin films. We have used the co-sputtering technique for the deposition of two different thicknesses (20 nm and 25 nm) of the TbCo films. Annealing of the samples has been carried out in the vacuum at 350 °C for 1 h. The magnetization reversal and dynamic properties of the as-deposited and annealed films are studied using the magneto-optical Kerr effect and broadband ferromagnetic resonance measurements at room temperature, respectively. The hysteresis loops reveal an anisotropic reversal process. The anisotropy field reduces from 66 Oe to 38 Oe for 20-nm-thick films and 98 Oe to 31 Oe for 25-nm-thick films upon annealing. Consequently, thermal annealing has led to a large reduction (∼70 %) in inhomogeneous linewidth broadening of the ferromagnetic resonance modes. Gilbert damping constant is found to decrease from 0.027 to 0.021 for 20-nm-thick films, whereas it decreases from 0.043 to 0.019 for 25-nm-thick films. The results have been attributed to the enhanced crystallinity of the films as observed in the structural analysis using grazing incidence X-ray diffraction.”

The Effect of Thermal Annealing on the Electrophysical Properties of Samples n-Si<Ni,Сu>

This paper presents the results of studies of the effect of isothermal annealing at temperatures T = 673¸1473 K in the time interval 5¸60 minutes on the electrical properties of silicon, simultaneously alloyed with nickel and copper. Samples of n-Si<Ni,Cu> were obtained on the basis of the starting material - single-crystal silicon, grown by the Czochralski method with the initial resistivity r = 0.3 Ohm×cm. Diffusion was carried out at a temperature of 1523 K for 2 hours. After that, the samples were cooled at a rate of 0.1 K/s. The morphological parameters of impurity nickel and copper atom clusters formed in the bulk of silicon were measured by electron probe microanalysis on a modern Superprobe JXA-8800R setup. As it turned out, in the volume of n-Si<Ni,Cu> samples, clusters of impurity atoms with different geometric shapes are formed, the sizes of which reach up to 500 nm. The electrical properties of the samples were studied by the Hall effect method using an Ecopia HMS-7000 instrument. It was revealed that under the influence of thermal annealing (TA) at T≥1273 K, impurity clusters decompose, which leads to an increase in the resistivity of n‑Si<Ni,Cu> samples. After exposure to TA at Т=1273 K for 15 minutes, the density of impurity nanoaccumulations of acicular and lenticular shapes sharply decreases in the sample volume. Under the influence of TA at T = 1473 K for 10 minutes in the volume of the sample, the decay of impurity nanoclusters with a spherical shape is observed. Also presented are the results of changes in the density of impurity clusters, as well as structural analyzes of the samples before and after exposure to thermal annealing.

Physical properties of thermal annealing induced In2O3 thin films for sensing layer applications

Detection and monitoring of flammable, toxic and explosive gases are crucial, where active research on nanostructured metal oxide materials and thin films is enthusiastically performed to explore new paths for improving the characteristic parameters of sensors. The higher stability and appropriate electrical properties along with wide band gap of In2O3 material make it suitable for active layer to gas sensors where properties of In2O3 films could be engineered by post treatments. The present work demonstrates an influence of thermal annealing on structural, optical, topographical, morphological, elemental and electrical properties of In2O3 films for gas sensor applications. The In2O3 films of thickness 500 nm are grown onto soda lime glass and conducting ITO substrates employing physical vapor deposition based thermal evaporation technique followed by thermal annealing at 200 °C, 300 °C and 400 °C for one hour in air atmosphere. The XRD analysis indicated phase transformation from metastable rhombohedral to stable cubic phase where crystallite size corresponding to associated preferred (110) and (222) peaks is tuned in range of 32–51 nm with annealing. Optical analysis unveiled higher transmittance in ultraviolet and visible regions whereas absorbance of films is fluctuated with thermal annealing. All the In2O3 films indicated the Ohmic nature where the resistivity is detected to be enhanced with annealing. EDS patterns confirmed deposition of the films. The SEM analysis showed nanospheres like grain morphology and such well connected nanospheric features offer large surface area and stimulate adsorption of gas effectively. Hence structural, optical, electrical and morphological properties of gas sensitive In2O3 layers are greatly stimulated by thermal annealing.

Elimination of Secondary Oxide Phases in CdTe Nanostructured Thin Films Prepared by Conventional Spray Pyrolysis, and the Influence of Thermal Annealing

Elimination of Secondary Oxide Phases in CdTe Nanostructured Thin Films Prepared by Conventional Spray Pyrolysis, and the Influence of Thermal Annealing

Influence of thermal annealing and of the substrate on sputter-deposited thin films from EUROFER97 on tungsten

The modification of sputter-deposited films from EUROFER97 on tungsten during and after annealing were investigated in-situ and ex-situ. The annealing resulted in a densification of the film, formation of large grains, segregation of W at the surface, and the formation of Fe-W compounds at the interfacial region. Similar structural modifications were observed also for a film annealed on a MgO substrate, with an exception to the change in composition (no increase of W concentration). Results indicate that the substrate significantly affects thermally induced modifications of re-deposited EUROFER97.

Easy method to prepare copper oxides with good photocurrent values

The influence of thermal annealing on the microstructure of copper oxide thin films has been investigated. The copper hydroxide (Cu(OH)2) nanowires were synthesized using a wet chemical (immersion) method. The aqueous solution was prepared by mixing 1 M NaOH and 0.1 M (NH4)2S2O8 and 30 ml of distilled water. The copper substrate was well polished, then immersed into the growth solution for 10 min, rinsed with distilled water, then dried in air, and finally annealed at different temperatures for 1 h in air. This structure can be used for many applications such as photoelectrochemical water splitting and photo-catalysis.The obtained materials were characterized by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM).The results revealed the formation of cupric oxide (CuO) and cuprous oxide (Cu2O), observed on the surface of the thin films annealed at different temperatures. The morphology of these two oxides was found to depend on annealing temperature. The resulting of a copper-oxide (CuO) photoelectrode exhibited an enhanced photocurrent density under light illumination compared to the heterostructure (CuO and Cu2O) photoelectrode. This result indicates a good conductivity of the CuO phase and a good charge separation due to the band structure realignement at the interface.

Burn-in effect in InGaP/GaAs HBT with intrinsically or extrinsically carbon doped base layer

InGaP/GaAs heterojunction bipolar transistors (HBTs) with intrinsically or extrinsically carbon doped base layers were grown by metal-organic chemical vapor deposition. Burn-in effect and the influence of thermal annealing at different temperatures on these devices were investigated. Results show that the intrinsically-carbon-doped HBTs demonstrate a higher current gain of 155 and a burn-in value of 24.0%, while the extrinsically-carbon-doped HBTs show a current gain of 92 and a burn-in value of 5.3%. Thermal annealing after exposing the base layer decreases the burn-in value from 24.0% to 5.7% and from 5.3% to 1.3% for intrinsically and extrinsically carbon doped HBTs, respectively, proved to be an effective method to eliminate the burn-in effect of HBT devices by hydrogen out diffusion. However, it also damages the base layer quality, leading to increased base recombination current and decreased current gain.

High mobility amorphous InSnO thin film transistors via low-temperature annealing

In this article, we fabricated amorphous InSnO thin film transistors (TFTs) with exceedingly high mobility and low thermal budget. The device is annealed only at a low temperature of 150 °C, a field-effect mobility (μFE) of 70.53 cm2/V s, a subthreshold swing of 0.25 V/decade, an on/off current ratio over 108, and a reasonable threshold voltage shift under negative bias stress. The influence of thermal annealing on amorphous InSnO TFTs was investigated by systematically analyzing the crystallization, surface morphology, internal chemical state, and energy band relationship of the InSnO thin film. Amorphous InSnO films deposited at room temperature have a sparse and porous loose structure, which has carrier scattering caused by poor film quality, resulting in low mobility and few free carriers in the film. With the increase in the annealing temperature, the In and Sn metal cations are further oxidized, increasing the carrier concentration in the film and forming a dense M–O–M network when annealed at 150 °C. With the further increase in the annealing temperature, a large number of thermally excited free electrons make the device appear metal like conductivity. This paper expands the research on a high electron concentration InSnO material as the active layer and promotes the development of amorphous oxide semiconductors in high mobility and flexible TFTs.

Investigation of the effect of thermal annealing of Ni-cobaltite nanoparticles on their structure, electronic properties and performance as catalysts for the total oxidation of dimethyl ether

Herein, we report the influence of thermal annealing on the structural and redox properties, optical band gap and electrical conductivity of Ni-doped Co3O4 NPs and the consequence on their catalytic performance in the DME total oxidation.

Sensing performance of sub-100-nm vanadium oxide films for room temperature thermal detection applications

Vanadium oxide films are widely employed as thermal detectors in uncooled infrared detection systems due to their high temperature coefficient of resistance near room temperature. One strategy toward maximizing detectivity and reducing the thermal time constant in these systems is to minimize the system platform dimensions. This approach necessitates thinner film thicknesses (≪100 nm), for which there is little information regarding thermal sensing performance. Herein, we report on the sensitivity of reactively sputtered vanadium oxide thin film resistive thermometers nominally ranging from 100 to 25 nm and assess the influence of thermal annealing. We demonstrate that films in this minimum limit of thickness maintain a high temperature coefficient while additionally providing an enhancement in characteristics of the noise equivalent power.

Effect of heat treatment on structure, surface morphology, linear and nonlinear optical properties of Na2Pc films for optoelectronic applications

In this paper, we study the influence of thermal annealing on the structural and optical properties of disodium phthalocyanine (Na2Pc) films. Thermal evaporation method under vacuum has been successfully used to deposit thin films of Na2Pc onto quartz and glass substrates. XRD analysis indicated that the pristine film has an amorphous structure and turns into a polycrystalline upon thermal annealing. SEM technique was used to investigate the morphological properties of thin films. The linear and nonlinear optical parameters of pristine and annealed films have been investigated in the wavelength range 200–2500 nm via spectrophotometric measurements of T(λ) and R(λ). The extinction coefficient of Na2Pc films exhibited four electronic transitions, namely, the Q, N, L and C bands. By applying a single oscillator model, many spectral dispersion parameters have been estimated in the transparent region of the spectrum. The dielectric constants, dissipation factor and optical conductivity were calculated and discussed. The optical transition type, energy gaps and Urbach energy of Na2Pc films were determined by the absorption band edges analysis. Also, the nonlinear refractive index and nonlinear optical susceptibility were evaluated from the linear refractive index results. The results of this investigation indicated the possibility of using Na2Pc films in optoelectronic device applications.

Effects of Thermal Annealing on The Morphology and Structural Characteristics of Zinc Oxide Nanopowders for Triboelectric Nanogenerator Applications

The influence of thermal annealing on the surface morphologies and structural characteristics of zinc oxide (ZnO) nanopowders synthesized via the solution immersion method for triboelectric nanogenerator applications is reported in this paper. The ZnO nanopowders were thermally treated at different temperatures of annealing in the ranges between 300°C to 700°C for 1 hour, and their surface morphologies and structural properties were studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The ZnO nanopowders have a polycrystalline, hexagonal wurtzite structure and are composed of ZnO nanoparticles and hexagonal nanorods. ZnO based tribolectric nanogenerators were fabricated with these nanopowders and their performance was assessed in terms of the output voltage. It is found that the ZnO based triboelectric nanogenerator fabricated with ZnO nanopowders annealed at 500°C has superior performance compared with the other nanogenerators, with an average output voltage of 1.95 V. This corresponds to a fourfold increase in output voltage relative to that of the ZnO based triboelectric nanogenerator fabricated with as-deposited ZnO nanopowders. In conclusion, thermal annealing significantly influences particle size and crystallinity of ZnO nanopowders, which in turn, influences the output voltage of ZnO based triboelectric nanogenerators.

Evaluation of the influence of thermal annealing on the performance of vertical topological insulator p-n heterojunction broadband photodetector

The rapid progress and continuum search for new broadband photodetectors generation with ultrafast response synchronizes with the conductive surface electronic structure and the strong broadband absorption properties of 3D topological insulators. Here, we introduce the fabrication of a vertical p-n heterojunction based on thermally evaporated thin films of Sb2Te3/Bi2Te3 on Si substrate for broadband photodetection. The realization of these characteristics dictated us to study the structural, optical absorption, and morphological properties of each layer in the fabricated device as a function of annealing temperature using XRD, spectrophotometric measurements, and FE-SEM techniques, respectively. The annealing process up to T = 423 K enhanced the film’s crystallinity, and grain growth process besides improving the film quality and surface roughness. Furthermore, the optoelectronic characterizations showed that all fabricated photodetectors exhibit a good response to halogen light illumination in the wavelength range (310–1100) nm with different intensities (10–50) mW/cm2. Whilst the 423 K annealed photodetector showed the highest photosensitivity with a conspicuous stable and fast response. The main device parameters, including spectral responsivity, specific detectivity, and response times were determined in addition to explaining the forward and reverse bias conduction mechanisms. The estimated spectral responsivity of the fabricated devices was about 0.247, 0.397, and 0.148 A/W for the as fabricated and 423 K and 573 K, respectively. This significant improvement of the device’s performance rather than other topological insulator devices may be due to the strong built-in field at the topological insulators’ interfaces. Moreover, the fabricated photodetectors showed improved and repeatable ON/OFF transient switching behavior with 85.23 ms and 84.66 ms as a rise and fall time, respectively. According to the prominent results in addition to the simple architecture of the fabricated photodetectors, this topological insulator photosensor can be considered a potential candidate in prospective high-performance optoelectronics.

Thermal Annealing Effect on the Structure, Optical and Electrical Properties of Lanthanum Manganite Thin Films Prepared by Reactive Co-Sputtering

Lanthanum manganite (LMO) thin films were deposited by co-sputtering La and Mn targets in an Ar and O2 gas mixture. The films were synthesized on silicon and fused silica substrates. The influences of thermal annealing on the structure, optical and electrical properties of LMO films were investigated. The results exhibited a correlation between these properties. In the amorphous state, an increase in annealing temperature improved the optical transmission and decreased the electrical capacitance. The beginning of crystallization at 600 °C was manifested by a strong increase in the capacitance and a decrease in the optical transmission. At higher annealing temperature, polycrystalline films were obtained with different optical and electrical characteristics. On the other hand, the annealed LMO films showed a photocurrent effect during exposure to a weak LED light.

Influence of thermal annealing on the optical and electrical properties of Ag-Al ultrathin film-based sandwich-like transparent conductor

Heating process is always needed and sometimes inevitable in fabricating high-performance transparent conductors. In this work, the thermal stabilities of the optoelectronic properties of the annealed Ag-Al ultrathin film and the sandwich-like structure of TiO2/Ag-Al/aluminum-doped zinc oxide (AZO) are systematically investigated under different annealing temperatures and durations. After annealing at 200 °C for 20 min, the pure Ag layer dewets into isolated islands completely, but the Ag-Al alloy ultrathin film retains continuous film morphology with low sheet resistance, demonstrating alloying with Al element can effectively improve the thermal stability of the Ag layer. However, increasing the annealing duration further upon Ag-Agl alloy film will lead to serious dewetting, agglomeration, and increased resistance. The TiO2/Ag-Al/AZO sample has a high optical transmittance, which can be maintained after annealing at 200 °C for 60 min. Nevertheless, when annealing at 300 °C its sandwiched structure is destroyed as a result of the agglomeration of the Ag-Al layer. The annealed TiO2/Ag-Al/AZO structure has an average transmittance of about 85.4% in the range of 400–700 nm and a sheet resistance of 12.5 Ω.sq−1, indicating the potential for the high-performance transparent conductor application.

Magnetism of Co-rich clusters embedded in nanoporous Pd prepared by electrochemical dealloying — Influence of thermal annealing

Nanoporous palladium samples containing superparamagnetic Co-rich clusters were prepared by electrochemical dealloying and the magnetic properties were subsequently varied by thermal annealing at different temperatures. It is shown that in this way porous magnetic nanomaterials exhibiting various magnetic characteristics can be obtained. The as-dealloyed, unannealed sample is ferromagnetic at 4.2 K and superparamagnetic at 300 K, with a blocking temperature TB of 100 K. The observed general decrease of the magnetization with increased annealing temperature is explained by the redistribution of Co from the Co-rich superparamagnetic clusters into the Pd matrix, leading to a shrinkage of the clusters and the formation of a diluted Co–Pd alloy phase. As a consequence of the smaller magnetic cluster size a down-shift of TB occurs for annealing temperatures of 373 K and 573 K. After annealing at 773 K the stronger dissolution of Co from the clusters into the Pd-matrix reduces TB further down to 35 K. Additionally, a second blocked magnetic phase with much higher TB emerges, which leads to ferromagnetic behavior at room temperature. The occurrence of this phase is attributed to the formation of larger magnetic entities consisting of Co-rich clusters lying close together and a Co–Pd alloy phase with relatively high Co concentration in between these clusters. After high temperature annealing at 973 K a weakly ferromagnetic phase is obtained at 4.2 K and at 300 K, which can be explained by the nearly completed dissolution of the Co in the Pd matrix.

THERMAL ANNEALING EFFECTS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE Ta-W-Ta SOLID PHASE JOINTS FOR NEUTRON PRODUCING TARGETS OF THE RESEARCH NUCLEAR FACILITY “SOURCE OF NEUTRONS”

The paper considers the neutron-producing tantalum-tungsten-tantalum target using a niobium interlayer manufacturing variant by means of vacuum hot roll bonding for the research nuclear facility «Source of Neutrons». The metallography results and the Ta-W-Ta solid-phase junction specimens mechanical testing ones obtained by hot roll bonding in vacuum, both immediately after production and after the heat treatment in the temperature range of 900…1300°C after roll bonding, are presented. The influence of thermal annealing on the interaction nature of the clad layers with each other and with the core tungsten material of the Ta-W-Ta solid-phase junctions with Nb interlayers obtained by vacuum hot roll bonding has been studied.