Increase Of Post-annealing Temperature Research Articles

Large-scale fabrication of thulium iron garnet film with perpendicular magnetic anisotropy using RF magnetron sputtering

Large-scale fabrication of thulium iron garnet (TmIG) films on gadolinium gallium garnet (GGG) substrates, with a total area of 25 cm2, has been demonstrated by rotating substrate holders during on-axis sputtering. By optimizing the growth parameters based on the pressure and flow rate of the oxygen ratio, a Tm/Fe ratio of 0.65 was obtained, which is close to the stoichiometry of TmIG. The increase in post-annealing temperature has induced the growth of the TmIG structure by the strain of the lattice constant mechanism. At the highest post-annealing temperature, the crystal structure of TmIG (444) and the perpendicular magnetic anisotropy (PMA) were obtained. This result demonstrates the potential method for large-scale fabrication of TmIG film with PMA.

Post-annealing in ultra-high vacuum or nitrogen plasma for MoS2 thin films deposited by magnetron sputtering

The thin films of amorphous molybdenum disulfide were deposited at room temperature by magnetron sputtering technique. Post-annealing process in ultra-high vacuum (∼10−8 Pa) or nitrogen plasma environments at the temperatures of 300, 400, 500, and 700 °C have been first proposed to enhance the microstructure and optical properties of MoS2 thin films. The phase transformation of MoS2 thin films from amorphous to polycrystalline was characterized by in situ reflection high-energy electron diffraction during the post-annealing process. The microstructure of MoS2 thin films was also analyzed by Raman spectrum and X-ray diffractometer after the post-annealing process. In addition, the thermal analysis of the differential scanning calorimeter and optical measurement of photoreflectance confirmed the phase transformation of MoS2 thin films. The analysis of photoreflectance also estimated the exciton transition at the bandgap energy of 2.038 eV at 0 K, attributed by the crystalline MoS2 film annealed at 700 °C in ultra-high vacuum. The surface chemical composition of MoS2 thin films has been identified by X-ray photoelectron spectroscopy, but the desulfurization of MoS2 was observed after post-annealing in ultra-high vacuum. Moreover, the preferred orientation of (004) plane in the MoS2 films was performed as the increase in post-annealing temperature.

Annealing Effect on the Contact Angle, Surface Energy, Electric Property, and Nanomechanical Characteristics of Co40Fe40W20 Thin Films

This study investigated Co40Fe40W20 single-layer thin films according to their corresponding structure, grain size, contact angle, and surface energy characteristics. Co40Fe40W20 alloy thin films of different thicknesses, ranging from 10 to 50 nm, were sputtered on Si(100) substrates by DC magnetron sputtering. The thin films were annealed under three conditions: as-deposited, 250 °C, and 350 °C temperatures, respectively. The Scherrer equation was applied to calculate the grain size of Co40Fe40W20 thin films. The results show that the grain size of CoFe(110) increased simultaneously with the increase of post-annealing temperature, suggesting that the crystallinity of Co40Fe40W20 thin films increased with the post-annealing temperature. Moreover, the contact angles of all Co40Fe40W20 thin films were all less than 90°, suggesting that Co40Fe40W20 thin films show changes in the direction of higher hydrophilicity. However, we found that their contact angles decreased as the grain size of CoFe increased. Finally, the Young equation was applied to calculate the surface energy of Co40Fe40W20 thin films. After post-annealing, the surface energy of Co40Fe40W20 thin films increased with the rising post-annealing temperature. This is the highest value of surface energy observed for 350 °C. In addition, the surface energy increased as the contact angle of Co40Fe40W20 thin films decreased. The high surface energy means stronger adhesion, allowing the formation of multilayer thin films with magnetic tunneling junctions (MTJs). The sheet resistance of the as-deposited and thinner CoFeW films is larger than annealed and thicker CoFeW films. When the thickness is from 10 nm to 50 nm, the hardness and Young’s modulus of the CoFeW film also show a saturation trend.

Synthesis and thermal expansion behaviors of spin-coated Sc2Mo3O12 thin films

Orthorhombic Sc2Mo3O12 films have been successfully prepared via spin coating technique followed by annealing at 500–750 °C. The phase composition, microstructure, morphology and negative thermal behavior of the synthesized Sc2Mo3O12 films were investigated. XRD and XPS analysis indicate that as-deposited film is amorphous. Orthorhombic Sc2Mo3O12 films can be prepared after post-annealing at 500–750 °C for 1 h. The crystallinity of Sc2Mo3O12 films gradually improved with the increase of post-annealing temperature. SEM analysis shows as-deposited film is smooth and compact, and the grain size of Sc2Mo3O12 film grows up as the post-annealing temperature increases. Variable temperature XRD analysis demonstrates that the synthesized orthorhombic Sc2Mo3O12 films show stable thermo-chemical and anisotropic NTE property in 25–700 °C. The corresponding coefficients of thermal expansion (CTEs) of the orthorhombic Sc2Mo3O12 film in a, b and c directions are −6.68 × 10−6 °C−1, 5.08 × 10−6 °C−1 and −4.76 × 10−6 °C−1, respectively. The whole unit cell of the orthorhombic Sc2Mo3O12 film shrinks and the volumetric CTE of the Sc2Mo3O12 thin film is −6.36 × 10−6 °C−1, and the linear CTE is about −2.12 × 10−6 °C−1 (αv = 3αl).

Study of compositional stability and related optical properties of perovskite CH3NH3PbBr3 films fabricated via two-step sol-gel process using weakly coordinating isopropanol solvent

Compositional stability of perovskites is crucial for perovskite solar cells (PSCs) application because of directly affecting the performance of PSCs. Highly crystallized perovskite MAPbBr3 (MA = CH3NH3) with micronscale crystallites are usually fabricated via the one-step sol-gel process that uses strongly coordinating organic solvents. The two-step sol-gel process using weakly coordinating organic solvent is rarely used to fabricate MAPbBr3 films with relatively small crystallites. However, the two-step sol-gel process is preferred to fabricate PSCs because the residual PbBr2 can prevent the direct contact between electron- and hole-transporting layers. Thus in this work, perovskite MAPbBr3 films are fabricated via two-step sol-gel process using weakly coordinating isopropanol solvent. The compositional stability in dry ambient air and related optical properties of the films are intensively studied by a technique of post-annealing. A compositional transition from MAPbBr3 to PbBr2 occurs with increase of post-annealing temperature (Tpa). The product PbBr2 begins to form in the MAPbBr3 films at approximately 130 °C Tpa, and MAPbBr3 is fully thermally degraded to PbBr2 at 170 °C Tpa. The compositional stability of the films in dry air is inherently determined by instable organic cations (MA)+ and small electronegativity of Br−. The perovskite film initially shows a redshifted and then a blueshifted optical absorption edge with increase of Tpa, which is due to the decrease in film tensile stress and to the enhancement in thermal degradation to PbBr2, respectively. The increase in number of PbBr2 particles and defects in the films remarkably reduces the intensity of the green emission of MAPbBr3.

Rapid and Scalable Wire-bar Strategy for Coating of TiO2 Thin-films: Effect of Post-Annealing Temperatures on Structures and Catalytic Dye-Degradation.

Titanium dioxide (TiO2) thin films were rapidly coated on Corning glass substrates from the precursor solution using the wire-bar technique at the room temperature and then post-annealed at 400, 500 and 600 °C for 1 h under atmospheric conditions. The structural, morphological, optical, wettability and photocatalytic properties of the films were studied. X-ray diffraction analysis confirmed the formation of an anatase TiO2 structure irrespective of the post-annealing temperatures. The optical transparency of the films in the visible range was measured to be > 70%. A water contact angle (WCA) of ~0° was observed for TiO2 thin-film, post-annealed at 400 °C and 500 °C. However, WCA of 40.3° was observed for post-annealed at 600 °C. The photocatalytic dye-degradation using post-annealed thin-film was investigated indicating a steady improvement in the dye-degradation percentage (from 24.3 to 29.4%) with the increase of post-annealing temperature. The demonstrated TiO2 thin-films deposited by wire-bar coating technique showed promises for the manufacturing of large-area cost-effective self-cleaning window glass.

Fabrication and characterization of Zn doped CuO nanofiber using newly designed nanofiber generator for the photodegradation of methylene blue from textile effluent

Abstract High aspect ratio, Zn doped copper oxide (Zn-CuO) nanofibers have been fabricated employing a newly designed electrospun coating unit using copper acetate, sodium hydroxide and polyethylene glycol in aqueous state. The prepared Zn doped copper oxide (Zn-CuO) nanofibers were sintered at 400 °C, 500 °C and 600 °C separately and characterized using X-ray diffraction XRD, Fourier transformation infrared spectroscopy FT-IR, scanning electron microscopy SEM, energy dispersive spectroscopy EDS. The average crystallite size was in the range of 28 nm to 30 nm. Optical properties of Zn-CuO nanofibers were analyzed using UV-DRS studies which showed a blue shift in the absorption band. An increase in band gap with the increase in postannealing temperature was observed due to the blue shift in absorption edge of CuO causing enhanced photodegradation. The catalytic properties of the CuO nanofibers were tested using methylene blue in aqueous medium. The influences of parameters responsible for high photodegradation were optimized and the rate of the photodegradation process was calculated using photodegradation kinetics. The reusability test was conducted to find the stability of the fabricated Zn-CuO nanofibers.

Tuning of Magnetic and Optical Properties of Co0.8Zn0.2Fe2O4 Spinel Ferrite Thin Films Based on Post Annealing Temperature

This paper is dedicated to deposit zinc substituted cobalt ferrite (Co0.8Zn0.2Fe2O4) thin films on glass substrate using electron beam deposition technique. The effect of post annealing temperature on structural, magnetic, and optical properties of thin films has been investigated. Thin films have been characterized using x-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), vibrating sample magnetometer (VSM), UV-VIS spectroscopy, and spectroscopic ellipsometry (SE) analysis. The as-deposited thin films are amorphous in nature. After deposition, these thin films post annealed at different temperature ranges from 200 to 500 ∘C to enhance the crystallinity of films. The film post annealed at 200 ∘C is also amorphous in nature. As the post annealing temperature increases, the thin films become more crystalline. X-ray diffractometer and Raman analysis confirm the formation of cubical inverse spinel structure of thin films. The saturation magnetization of the thin films decreases with the annealing temperature due to the sites occupancy of cations between tetrahedral and octahedral. The reduction in coercivity is correlated with the anisotropy constant, but the anisotropy value is still high which is suitable to form stable magnetic storage memories. The band gap energy are decreased which is mainly attributed due to increase in grain size of the film. It is noted that the band gap energy of these thin films are higher than that of bulk material, so these may be suggested for use in wide band gap applications.

In situ analysis of post-annealing effect on Sn-doped indium oxide films

Oxygen post-annealing effects on tin (Sn) doped indium oxide (ITO) film are investigated with various analytical tools as a function of temperature, including in situ XRD, ambient pressure XPS (AP-XPS), and Hall measurement. As the annealing temperature increases up to 200 °C under the oxygen pressure of 100 mTorr, the in situ XRD shows the evidence of crystallization of the film while the AP-XPS reveals the formation of oxygen vacancy and Sn4+ states on surface. In addition, the mobility of ITO thin film is increased as the post-annealing temperature increases, supporting the results of both in situ XRD and AP-XPS. The results of angle-resolved XPS reveal that the degree of Sn segregation changes little after post-annealing procedure.

Blue luminescence from Ba0.05Zn0.95O nanostructure

Blue luminescence has been realized from ternary alloy compound of Ba0.05Zn0.95O nanostructure. Ba0.05Zn0.95O nanostructure was synthesized by sol–gel spin coating method on a glass substrate. The deposited samples were characterized by X-ray diffractometer (XRD), UV–visible spectrophotometer, field emission scanning electron microscopy (FESEM) and photoluminescence (PL). XRD pattern of Ba0.05Zn0.95O nanostructure film reveals polycrystalline nature with hexagonal wurtzite structure. FESEM-EDAX analysis shows that Ba was successfully incorporated into ZnO with uniform granular nanostructure having average grain size of 30 nm. Analysis of transmission, band gap and thickness have been carried out to investigate effect of post annealing temperature. All the deposited samples exhibit more than 95 % transparency in the visible region. It was observed that the average transmission of the deposited films gradually increase with increasing annealing temperature. Thickness of the synthesized samples were found to be decrease with an increase in post annealing temperature. Optical band gap energy was found to be increased from 3.182 to 3.28 eV with increasing annealing temperature. The dominant peak at 467 nm corresponding to the intense blue emission in the visible range was observed in the PL spectra.

Post-annealing effects on the physical and optical waveguiding properties of RF sputtered ZnO thin films

ZnO thin films were deposited at room temperature onto glass substrate by RF sputtering technique. Effects of the post-annealing at 300–500°C on the structural, morphological, optical and waveguiding properties were investigated using different characterization techniques. X-ray diffraction (XRD) analyses have shown that all thin films have a hexagonal wurtzite structure with higher c-axis preferred orientation (002), better crystallinity and larger crystallite size as post-annealing temperature increases. Fourier transform infrared (FTIR) spectra of annealed samples confirmed that the ZnO stretching vibration bond was found to be stable at 419 cm−1. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images have revealed that film morphology and surface roughness were influenced by heat treatment temperatures. The UV-Vis-NIR spectrophotometry characterisations have indicated that all the films were highly transparent with average transmittance exceeding 81% within the visible region, and the bandgap energy of the as-deposited film was increased with increasing of the annealing temperature.The obtained results from m-lines spectroscopy (MLS) measurements at 632.8 nm wavelength have demonstrated that all ZnO thin film optical waveguides were single mode and the ordinary and extraordinary refractive index values of the film annealed at 500°C were very close to the corresponding ZnO single-crystal values.

후열처리에 따른 스퍼터된 ZnO:Al 박막의 전기적, 광학적 특성

RF magnetron sputtering 법을 이용하여 증착된 ZnO:Al 박막을 열처리하여 열처리 전 후 ZnO:Al 박막의 전기적, 광학적 특성을 연구하였다. 열처리 온도에 따라 ZnO:Al 박막의 특성이 많이 영향 받음을 확인하였다. 열처리 온도가 증가함에 따라 ZnO:Al 박막의 결정성과 가시광선 영역(400~800 nm)에서 투과도는 감소함을 보였다. 반면, 박막의 비저항은 <TEX>$400^{\circ}C$</TEX>로 열처리 온도가 증가함에 따라 급격히 증가하였다. 이는 박막 표면에 <TEX>$O_2$</TEX> 또는 <TEX>$N_2$</TEX>가 흡착하여 캐리어 농도 감소에 의한 것으로 판단된다. ZnO:Al thin films deposited by RF magnetron sputtering were post-annealed and the electrical and optical properties of ZnO:Al thin films were investigated before and after anneling. We confirmed that the ZnO:Al thin film was affected by post-annealing temperature. As post-annealing temperature increases, crystallinity and transmittance in visible area (400~800 nm) of ZnO:Al thin films decreased. While sheet resistance of thin films increased sharply with increasing to <TEX>$400^{\circ}C$</TEX>. This result is due to reduce of carrier concentration caused by absorption of <TEX>$O_2$</TEX> or <TEX>$N_2$</TEX> at surface of thin film.

SrAlxOy:Eu2+, Dy3+ (x = 4) nanostructures: Structure and morphology transformations and long-lasting phosphorescence properties

Long-lasting phosphor SrAlxOy:Eu2+, Dy3+ (x = 4) nanostructures were synthesized through a facile but efficient combustion technique followed by a post-annealing reaction at different temperatures. During the synthesis process, triethanolamine (TEA) can not only be used as an organic fuel, but also can control the morphology of nanostructured combustion products. With an increase in post-annealing temperature, their morphology transforms from nanosheets into semi-curled nanobelts due to the crystal growth and the edge curl effect, and moreover, the products with various crystallographic structures can be obtained, whose transition presents the following rule: amorphous → hexagonal β-SrAl2O4 (1000 °C) → monoclinic SrAl4O7 (1100 °C) → orthorhombic Sr4Al14O25 (1300 °C). Excess Al facilitates the stabilization of the β-SrAl2O4 high-temperature phase at room-temperature. Due to the difference of Eu2+ surroundings in various crystallographic structures, their excitation and emission spectra exhibit some discrepancy in peak position and intensity. Surface and boundary defects, originating from small size and poor crystallinity, can both increase trap densities and depth levels; while Sr vacancies (VSr), donated by the deficiency of Sr2+ ions in β-SrAl2O4 and Sr4Al14O25, mainly increase the concentration of relatively shallow traps. Thus, β-SrAl2O4 shows a relatively small afterglow decay constant compared to SrAl4O7. Moreover, the afterglow decay constant of Sr4Al14O25 is initially much smaller than those of β-SrAl2O4 and SrAl4O7, then increases gradually, and finally exceeds them. Additionally, the maximum value of initial brightness and effective afterglow time emerges in the SrAl4O7 and Sr4Al14O25 composite phosphor annealed at 1200 °C.

Highly transparent solution processed In-Ga-Zn oxide thin films and thin film transistors

Highly transparent In-Ga-Zn oxide (IGZO) thin films were fabricated by spin coating using acetate- and chlorate-based precursors, and thin film transistors (TFTs) were further fabricated employing these IGZO films as the active channel layer. The impact of the post-annealing temperature on the physical properties of IGZO films and performance of IGZO TFTs were investigated. Compared to the nitrate-based IGZO precursor, the chlorate-based precursor increases the phase change temperature of IGZO thin films. The IGZO films changed from amorphous to nanocrystalline phase in an annealing temperature range of 600–700 °C. The transparency is more than 90% in the visible region for IGZO films annealed with temperatures higher than 600 °C. With the increase of post-annealing temperature, the carrier concentration of IGZO film decreases, while the sheet resistance increases firstly and then saturates. The bottom-gate TFT with IGZO channel annealed at 600 °C in oxygen showed the best performance, which was operated in n-type enhancement mode with a field effect mobility of 1.30 cm2/V s, a threshold voltage of 10 V, and a drain current on/off ratio of 2.5 × 104.

POST-ANNEALING EFFECTS ON THE STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF ITO FILMS STUDIED BY SPECTROSCOPIC ELLIPSOMETRY

ITO thin films were coated on unheated glass and Si -wafer (100) substrates by ion-assisted evaporation. The effects of post annealing, in vacuum at 250°C and 350°C for 1 h, on the structural, optical and electrical properties were studied. The structure was characterized by X-ray diffraction (XRD). The surface morphology of the films was investigated by atomic force microscopy (AFM). The optical properties were evaluated by spectrophotometer and spectroscopic ellipsometry (SE). The resistivity was measured by the four-point probes method. It was found that the increase of post-annealing temperature would improve the film crystallinity and electrical properties. The preferred orientation of ITO thin film after annealing is (222). The resistivity of the as-deposited film is found to be 5.52 × 10-4 Ωcm and decreases to 2.11 × 10-4 Ωcm after annealing at 350°C. The AFM image reveals that the surface roughness decreases with increasing annealing temperature. The uniqueness test based on SE analysis data has been applied for ITO modeling. This modeling indicates that the film microstructure consists of three layers including the higher-index ITO layer, the effective medium approximation (EMA) layer to represent a slightly lower optical index, and the surface roughness layer on top. The EMA thickness and its relative composition decrease with increasing annealing temperature. The extinction coefficient in the IR region increases whereas the refractive index decreases with increasing annealing temperature.

Formation and photoluminescence characteristics of Er-related nanostructures on Si(0 0 1) substrate covered with an ultrathin SiO 2 film

Er-related nanostructures self-assembled on the Si(0 0 1) covered with an ultrathin SiO 2 layer have been studied by scanning tunneling microscopy and photoluminescence (PL), compared with Er-related nanostructures formed on clean Si(0 0 1). The post-annealing temperature of 560 °C–660 °C can lead to the formation of Er silicate nanobunches, with an ultrahigh density of 1 × 10 12–1 × 10 13 cm −2. The Er silicide nanowires are obtained at the post-annealing temperature above 700 °C. Er-related nanostructures will change from the amorphous nanobunches to the crystalline nanowires with the increase of post-annealing temperature due to the SiO desorption. The PL band shape and intensity depend strongly upon the preparation conditions and a wide band is exhibited from 1.3 μm to 1.6 μm due to defect related luminescence (D bands) and Er 3+ ion. A dominant peak at 0.80 eV is observed for the nanobunches. We have distinguished the Er 3+ line from the D1 line, which have the same energy region around 0.80 eV, and it is shown that our samples have effective optically-active Er 3+ ions.

MICROSTRUCTURE AND FERROELECTRIC PROPERTIES OF Bi3TiTaO9 THIN FILMS BY METALORGANIC DECOMPOSITION METHOD

ABSTRACT Bismuth titanium tantalum—Bi3TiTaO9 (BTT) thin films with different thickness from 100 nm to 400 nm were successfully fabricated on Pt/Ti/SiO2/Si(100) substrates using modified metalorganic decomposition (MOD) technique at different annealing temperatures. The microstructure of BTT thin films was affected by the film thickness and process temperature. Definite c-axis orientation growth of BTT thin films was found for Pt/Ti/SiO2/Si(100) substrate. The c-orientation ratio and grain size increased with the increase of post annealing temperature. The grain size in BTT thin films annealed at 750°C and 800°C was about 90∼ 100 nm and 150∼ 180 nm, respectively. The higher the process temperature, the higher the c-axis orientation of BTT thin film was. The growth of BTT thin film was affected by the microstructure of the lower layer and the effect of substrate. BTT thin films annealed at 800°C was found to have much improved remanent polarization (Pr) than that at 650°C and 750°C. The Pr and Ec values were measured to be 2 μ C/cm2 and 100 kV/cm, respectively. The critical grain size existed in BTT thin films, and BTT films showed well-defined ferroelectric properties with grain size larger than 100 nm.

Luminescence Characteristics of Red Light Emitting (YVO4:Eu Thin-Film Phosphors Deposited on Si Substrate Using Pulsed Laser Deposition

Europium doped yttrium vanadate (YVO 4 :Eu) phosphor thin films were grown using a pulsed laser deposition (PLD) technique on silicon substrate. The structural characterization carried out on a series of YVO 4 :Eu films at post annealing temperature in the range of 550 °C-1150 °C indicating that films were preferentially (200) oriented at post annealing temperature above 950 °C. Photoluminescence of thin film increased with the increase of post annealing temperature and ambient oxygen pressure though the thin film has the powder-like surface morphology at oxygen pressure above 200 mTorr. Photoluminescence decay from 5 D 1 level of Eu 3 + show the great concentration dependency, which can be used as a good parameter to control the composition of YVO 4 :Eu thin film.

Preparation and characterization of Ba 2TiSi 2O 8 ferroelectric films produced by sol–gel method

Fresnoite (Ba 2TiSi 2O 8, BTS) thin films were grown on polished Si(100) substrates by sol–gel method. The films were characterized using Fourier transform infrared spectroscopy (FTIR), Raman scattering spectroscopy, X-ray diffraction (XRD) and atom force microscopy (AFM). The results reveal that the crystallinity of fresnoite thin films increases and their structures become more compact as post-annealing temperature increases. Combined with XRD data, the strong FTIR peaks and Raman bands assigned to Ti–O and Si–O vibration indicate the formation of fresnoite phase in the films at a temperature of 750 °C. Besides, the AFM observation showed the films have a smooth surface, fine grains and dense structure.

Temperature dependence of composition ratio of Bi 2Sr 2CaCu 2O 8+ δ film by PLD method

We have prepared Bi 2Sr 2CaCu 2O 8+ δ (Bi-2212) thin films by a pulse laser deposition (PLD) method followed by post-annealing. The thin films were grown on MgO substrates at 400–630 °C and 100 mTorr oxygen. They were about 200 nm thick. The crystalline structure of thin films deposited at lower temperature (∼470 °C) was amorphous. The films deposited at higher temperature (∼550 °C) began to crystallize ( c-axis oriented) but it turned out that Bi decreased with an increase temperature. After deposition, post-annealing were performed at 860–880 °C in a tubular furnace with mixed gas (Ar:O 2 = 93:7, 1 atm, 0.2 l/min flow) for 3 h. Bi did not decrease with the increase of post-annealing temperature up to 870 °C. The critical temperature of film was 78 K, and the root-mean-square (RMS) roughness in 10 μm square was less than 10 nm.