Optimum Annealing Conditions Research Articles

Magnetic Properties of Nanocrystalline Microwires

We have studied magnetic properties of Finemet-type and Hitperm-type microwires. In the case of the Finemet-type we observed that GMI effect and magnetic softness of microwires can be considerably improved by annealing. A considerable GMI effect has been observed in annealed FeCuNbSiB microwires exhibiting nanocrystalline structure. From the dependence of magnetic properties and GMI effect on the annealing temperature we identified optimal annealing conditions.

Effect of annealing and surfactant on photoluminescence of ZnS:O2− nanoparticles

Abstract ZnS:O2− (ZSO) nanoparticles were synthesized using a low temperature solid-state reaction method. The effects of annealing conditions and the content of the surfactant polyethylene glycol (PEG) on photoluminescence (PL) properties of the ZSO nanoparticles were studied. It was found that annealing and adding PEG during the synthesis did not change the crystal structure of ZSO nanoparticles, and their average crystallite size increased with increasing annealing time and temperature, but decreased with increasing PEG content. The emission intensity of ZSO nanoparticles was found to be enhanced after annealing or using PEG during the synthesis. Optimal annealing conditions both in air and vacuum and the optimal content of PEG were obtained for achieving maximum emission intensity from the ZSO nanoparticles.

Effects of Laser Annealing Parameters on Optical and Electrical Properties of ITO/Metallic Glass Alloy Bi-layer Films.

AgAlMg (AAM) films with three different atomic percentage compositions are prepared, namely, Ag12Al62Mg26 (denoted as A1AM), Ag22Al46Mg32 (denoted as A2AM), and Ag36Al25Mg39 (denoted as A3AM). In addition, the AAM films are deposited with four different thicknesses, i.e., 3, 6, 9, and 12 nm. The indium-tin oxide thickness is assigned a constant value of 30 nm in every case. The results show that the optical transmittance of the AAM/IAAM films improves (i.e., increases) with a reducing AAM film thickness, while the electrical resistivity improves (i.e., reduces) with an increasing film thickness. It is shown that the IA2AM film with an AMM thickness of 9 nm yields the optimal compromise between the optical transmittance and the electrical resistivity. The as-deposited IAAM films are found to have optical transmittance and electric resistivity values of 65 % and 90 Ω/□, respectively. The IA2AM films are annealed using a near-infrared laser at different pulse energies with a wavelength of 1064 nm and repetition rates ranging from 100 ~ 400 kHz. For both films, the optical and electrical properties are enhanced as the pulse energy increases to a certain critical value due to a transition from an amorphous microstructure to a crystalline structure. Given a repetition rate of 400 kHz and a pulse energy of 1.03 μJ, the optical transmittance and sheet resistance of the IAAM film are found to be 80 % and 15 Ω/□, respectively. The corresponding value of the Haacke figure of merit changed from 0.15 × 10−3 to 7.16 × 10−3 Ω−1 due to the optimal laser annealing conditions.

Fabrication of undoped ZnO thin film via photosensitive sol–gel method and its applications for an electron transport layer of organic solar cells

We have investigated ZnO thin films prepared via photochemical reaction as the electron transport layer (ETL) of inverted organic solar cells (OSCs). Morphological and electrical properties of the ZnO thin films prepared by the photosensitive ZnO sol were studied according to the annealing temperature and their effects on the performance of the inverted poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) OSCs was characterized. It was found that the optimal annealing temperature of the ZnO thin films was 330°C, and that devices with the ZnO ETL annealed at this temperature exhibited the largest short-circuit current density (Jsc) of 9.39mA/cm2, as well as the highest power conversion efficiency (PCE) of 2.31%, which can be attributed to enhanced electron transport and interfacial properties. Devices containing ZnO films formed at optimal annealing condition exhibited an open circuit voltage (Voc) of 0.60V and a fill factor (FF) of 41.0%. However, further increase of the annealing temperature led to degradation of the device performance, despite further improvements in electrical properties. We have found that marked increase in the surface roughness of the ZnO films occurred at temperatures above 350°C which could be detrimental to the OSCs characteristics due to a high contact resistance and a large leakage current.

The annealing influence on the microstructure and performance of Au@Ni core-shell bimetal as the cathode of low-temperature solid oxide fuel cells

Core-shell nanoparticles of Au@Ni bimetal with the composition of Au:Ni = 85:15 was developed successfully by facile co-reduction and annealing synthesis route. The forming mechanism of the nano core-shell was proposed. The annealing conditions based on the morphology, microstructure and evolution of the core-shell structures were analyzed and revealed by scanning electron microscope in detail. The core-shell structures were well kept after the uniform films of Au85Ni15 were annealed on top of the GDC (Ce0.9Gd0.1O1.95) electrolyte. The complex impedance of the symmetrical half cells of Au@Ni/GDC/Au@Ni was performed at 500 °C. Under the optimal annealing conditions, the area specific resistance for the cathode on top of GDC was 0.25 Ω cm2 at 500 °C. And the power density of the anode supported cell Au@Ni/GDC/-NiO with the optimal profile was 153, 292, 464, 590, and 835 m Wcm−2 at 450, 475, 500, 525, 550 °C, respectively.

High temperature magnetic permeability of Si-rich Finemet-type nanocrystalline (Fe1−Co )74.5Nb2Si17.5B5Cu1 alloys

Structure and magnetic properties of as-quenched and annealed (Fe 0.9 Co 0.1 ) 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy were mainly investigated by x-ray diffraction and by measuring the temperature dependence of initial permeability ( μ i – T curves) from room temperature up to 700 °C. The as-quenched sample exhibits a lower onset primary crystallization temperature ( T X 1 0 = 475 ° C ) and a larger crystallized interval temperature ( Δ T X = T X 2 0 − T X 1 0 = 201 ° C ) for precipitating the single soft magnetic crystal phase. The Curie temperature of amorphous phase T c a m for as-quenched sample and the Curie temperature of crystalline phase T c c r y for annealed sample were detected to be about 400 °C and 670 °C respectively, which are both higher than that of Fe 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy. So promising high temperature soft magnetic properties are expected. Annealing temperature ( T a ) exerts a significant effect on room- and high-temperature μ i . When T a is at 600 °C (optimum annealing condition), although, the room temperature permeability of nanocrystalline (Fe 0.9 Co 0.1 ) 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy was not as high as that of nanocrystalline Fe 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy, an improved high temperature magnetic softness was observed. The values of μ i for the 600 °C-annealed sample is larger than that of Fe 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy when temperature increases from 520 °C to 670 °C. The origin for the evolution of initial permeability at elevated temperatures was also analyzed. • Adding 10% Co into Si-rich Fe 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy decreases T X 1 0 and enlarges Δ T X . • Adding 10% Co into Si-rich Fe 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy enhances both T c a m and T c c r y . • (Fe 0.9 Co 0.1 ) 74.5 Nb 2 Si 17.5 B 5 Cu 1 alloy exhibits good high temperature magnetic softness.

Fabrication and characterization of ferroelectric-gate thin-film transistors with an amorphous oxide semiconductor, amorphous In–Ga–Zn–O

We fabricated and characterized ferroelectric-gate thin-film transistors (FeTFTs) with an amorphous In–Ga–Zn–O (a-IGZO) channel and an oxide ferroelectric (Bi,La)4Ti3O12 (BLT) gate insulator, and examined the fabrication conditions beforehand for realizing ferroelectric hysteresis in their drain current versus gate voltage (ID–VG) characteristics. First, the optimal annealing conditions for BLT-thin-film formation by the sol–gel method were considered in terms of chemical phenomena and crystallization mechanism. As a result, the leakage current density of the film was decreased by more than two orders of magnitude. Second, sputtering deposition conditions and postdeposition annealing temperatures of a-IGZO thin films were investigated to prepare the a-IGZO channel with good electrical properties. A small charge-injection-type hysteresis width of 0.2 V was obsereved in ID–VG characteristics of a-IGZO/SiO2 TFTs. Finally, a-IGZO/BLT FeTFTs were fabricated using the above results, and the ferroelectric hysteresis with a width of 0.4 V was observed.

Temperature-dependent Dy diffusion processes in Nd–Fe–B permanent magnets

Nd–Fe–B permanent magnets have been coated with 0.6wt.% dysprosium and annealed at various temperatures to study the impact of the temperature-dependent Dy diffusion processes on both the magnetic properties and the microstructure. When optimum annealing conditions are applied the Dy processed magnets with initial coercivity of ∼1100kAm−1 yield coercivity increases which can exceed 400kAm−1 without a significant reduction of the remanent magnetic polarization. The improved stability against opposing magnetic fields can be observed up to a depth of ∼3mm along the diffusion direction, restricting the application of the Dy diffusion process to either thin magnets or magnets with tailored coercivity gradients. While in the proximity of the Dy-coated surface, each grain has a Dy-enriched shell with a Dy content of ∼6at.%; the Dy concentration decreases exponentially to ∼1.8at.% after a diffusion depth of 400μm and to ∼1at.% after a diffusion depth of 1500μm, as was found with wavelength dispersive X-ray spectroscopy and scanning transmission electron microscopy–energy dispersive X-ray spectroscopy, respectively. In the vicinity of the Dy-coated surface, the mechanism of the Dy-shell formation is attributed to the melting/solidification of a heavy-rare-earth-rich intermediate phase during high-temperature annealing. This is based on the observation that a constant Dy concentration over the width of the shells was found. Also an epitaxial relation between the Dy-poor core and the Dy-rich shell was observed by electron backscattered diffraction, which is supported by results obtained with Kerr microscopy.

Study on the CIGS Thin Film Formation by Modified Spray Process

The highly uniform polycrystalline CuIn0.7Ga0.3Se2 (CIGS) thin films for solar cell application were successfully synthesized on the glass substrates using a modified spray process and a continuous flow micro-reactor (CFM) process at low temperature. The as-deposited thin films prepared by each method were annealed under vacuum condition without additional selenization. In order to study the influence of annealing temperature on the properties of the CIGS films, annealing temperature were varied from 200°C to 400°C. The annealing temperature exerted an effect on the properties of the prepared thin films. Based on the XRD measurements, the optimum annealing condition to synthesize the CIGS thin films was 200°C. The crystalline structure of the film annealed at 200°C was in good agreement with the tetragonal structure in the reference. CuIn0.7Ga0.3Se2 thin films were also deposited by a solution-based CFM method and were then thermally treated under the same conditions as the spray. They were compared with the properties of the films deposited by the spray in order to figure out which deposition method is more effective for the synthesis of the CIGS thin films. XRD, SEM, UV-vis, and XPS were employed to study the influence of annealing temperature on the physical properties of the films.

Crystal Growth and Effects of Annealing on Optical and Electrical Properties of Mid-Infrared Single Crystal LiInS2

Single crystal LiInS2 (LIS) is a promising candidate for mid-infrared (MIR) frequency conversion to obtain MIR laser output. Large-sized LIS crystals with a diameter of 16 mm and a length of 50 mm were grown by the modified Bridgman method. The as-grown LIS crystals were annealed in different atmospheres, and the effects of annealing on the electrical and optical properties were studied in detail. The visible-near-infrared and MIR transmission spectra of the crystals were studied before and after annealing in different atmospheres. The experimental results indicate that the optimal annealing conditions for a grown crystal are to use an atmosphere of LIS vapor at 700 °C for 160 h. The electrical properties were investigated before and after annealing in the LIS vapor atmosphere. After proper postgrowth annealing, the quality of the crystal was significantly improved, which resulted in an increase in the damage threshold from 0.9 to 1.2 J/cm2.

Optimization of long-range order in solvent vapor annealed poly(styrene)-block-poly(lactide) thin films for nanolithography.

Detailed experiments designed to optimize and understand the solvent vapor annealing of cylinder-forming poly(styrene)-block-poly(lactide) thin films for nanolithographic applications are reported. By combining climate-controlled solvent vapor annealing (including in situ probes of solvent concentration) with comparative small-angle X-ray scattering studies of solvent-swollen bulk polymers of identical composition, it is concluded that a narrow window of optimal solvent concentration occurs just on the ordered side of the order-disorder transition. In this window, the lateral correlation length of the hexagonally close-packed ordering, the defect density, and the cylinder orientation are simultaneously optimized, resulting in single-crystal-like ordering over 10 μm scales. The influences of polymer synthesis method, composition, molar mass, solvent vapor pressure, evaporation rate, and film thickness have all been assessed, confirming the generality of this behavior. Analogies to thermal annealing of elemental solids, in combination with an understanding of the effects of process parameters on annealing conditions, enable qualitative understanding of many of the key results and underscore the likely generality of the main conclusions. Pattern transfer via a Damascene-type approach verified the applicability for high-fidelity nanolithography, yielding large-area metal nanodot arrays with center-to-center spacing of 38 nm (diameter 19 nm). Finally, the predictive power of our findings was demonstrated by using small-angle X-ray scattering to predict optimal solvent annealing conditions for poly(styrene)-block-poly(lactide) films of low molar mass (18 kg mol(-1)). High-quality templates with cylinder center-to-center spacing of only 18 nm (diameter of 10 nm) were obtained. These comprehensive results have clear and important implications for optimization of pattern transfer templates and significantly advance the understanding of self-assembly in block copolymer thin films.

Annealing time dependent structural, morphological, optical and electrical properties of RF sputtered p-type transparent conducting SnO2/Al/SnO2 thin films

Transparent p-type conducting SnO2/Al/SnO2 multilayer films were fabricated on quartz substrates by radio frequency (RF) sputtering using SnO2 and Al targets. The deposited films were annealed at a fix temperature of 500 °C for different time durations (1–8 h). The effect of annealing time on the structural, morphological, optical and electrical performances of SnO2/Al/SnO2 multilayer films was studied. X-ray diffraction (XRD) results show that all the p-type conducting films possess polycrystalline SnO2 with tetragonal rutile structure. Hall-effect results indicate that 500 °C for 1 h is the optimum annealing condition for p-type SnO2/Al/SnO2 multilayer films, resulting in a hole concentration of 1.14×1018 cm–3 and a low resistivity of 1.38 Ω·cm, respectively. The optical transmittance of the p-type SnO2/Al/SnO2 multilayer films is above 80% within annealing time range of 1–8 h, showing maximum for the films annealed for 1 h.

Effect of n-dodecylthiol and thermal annealing on the performance of P3HT/PC70BM polymer photovoltaic cells

In this research, n-dodecylthiol was added to poly(3-hexylthiophene)/[6,6]-phenyl-C71-butyric acid methyl ester (P3HT/PC70BM) polymer solar cells to improve the crystallinity of P3HT and enhance the phase separation of P3HT/PC70BM. UV–Vis and external quantum efficiency results showed enhancement in P3HT self-organisation ability which led to improved crystallinity and intensified phase separation of P3HT/PC70BM in the cast films. Atomic force microscopic analysis showed that adding n-dodecylthiol to P3HT/PC70BM resulted in an increase in surface roughness which provided more space for P3HT crystallites to form. X-ray diffraction and differential scanning calorimetry analysis showed a higher crystallinity in the heat-treated samples containing up to 2% of n-dodecylthiol by volume, which resulted in a nearly 33% increase in device efficiency at the optimum annealing conditions of 150°C for 30 min. The cell performance deteriorated abruptly at temperatures higher than 150°C.

Formation of Ta/Ti/Al/Mo/Au ohmic contacts to an AlGaN/AlN/GaN heterostructure grown on a silicon substrate

The features of the formation of Ta/Ti/Al/Mo/Au ohmic contacts to a Al0.26Ga0.74N/AlN/GaN heterostructure grown on semi-insulating Si(111) substrates are studied. The dependences of the contact resistance on the Al (90, 120, 150, 180 nm) and Ti (15, 30 nm) layer thickness and optimal temperature-time annealing conditions are determined for each studied metallization scheme. It is shown that the minimum achievable contact resistance monotonically increases from 0.43 to 0.58 Ω mm as the Al layer thickness increases from 90 to 180 nm at unchanged Ta, Ti, Mo, Au layer thicknesses. A change in the Ti layer thickness from 15 to 30 nm has no significant effect on the minimum contact resistance. The least contact resistance of 0.4 Ω mm is achieved for Ta/Ti/Al/Mo/Au layers with thicknesses of 10/15/90/40/25 nm, respectively. The optimal annealing temperature for this metallization variant is 825°C at a process duration of 30 s. The grown ohmic contacts have smooth contact-area edges and flat morphology of their surface.

PHASE EVOLUTION IN BiFeO3 NANOPARTICLES PREPARED BY GLYCINE-ASSISTED COMBUSTION METHOD

We report here the evolution of phase purity in BiFeO3 (BFO) nanoparticles prepared by a novel glycine-assisted combustion method. The study of phase evolution with temperature, in nanoparticles of BFO is carried out using X-ray diffraction (XRD) and thermogravimetry (TG) coupled with differential scanning calorimetry (DSC). Optimum annealing conditions for the synthesis of single-phase BiFeO3 nanoparticles are obtained. The morphology and average grain size of the nanoparticles are determined using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively. In situ microanalysis revealed that there are no significant deviations in the stoichiometry of the prepared compound. The magnetic behavior of BFO nanoparticles at 300 K has been studied using a vibrating sample magnetometer (VSM). A weak hysteresis loop observed is suggestive of the presence of partially destructed antiferromagnetic arrangement of moments in the material. Low temperature magnetization measurements reveal the presence of spin glass–like transition in the nanoparticles of BFO. A well-developed ferroelectric hysteresis loop has been observed at room temperature at a maximum applied field of 45 kV/cm. The nanoparticles of BFO in the present study are found to possess both magnetic and ferroelectric order at room temperature.

Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications

In this work, a picosecond diode pumped solid state laser and a nanosecond Nd:YAG laser have been used for the annealing and the partial nano-crystallization of an amorphous silicon layer. These experiments were conducted as an alternative/complementary to plasma-enhanced chemical vapor deposition method for fabrication of micromorph tandem solar cell. The laser experimental work was combined with simulations of the annealing process, in terms of temperature distribution evolution, in order to predetermine the optimum annealing conditions. The annealed material was studied, as a function of several annealing parameters (wavelength, pulse duration, fluence), as far as it concerns its structural properties, by X-ray diffraction, SEM, and micro-Raman techniques.

The Effect of Annealing Conditions and Alloying Elements on the Microstructure Stability and Mechanical Properties of Mg-Zn-Cesheets

In this work, four Mg-Zn-Ce sheets were processed on an industrial scale by “Helholtz-ZentrumGreesthacht” company. To study the effect of alloying elements and annealing conditions on the rolled sheets, these sheets were annealed at different conditions. Mechanical properties of these rolled and annealed sheets were determined in rolling and transverse directions. Optical microscopy was used to investigate microstructure evolution and stability as well as grain size after annealing. Annealing at 450°C, 1 hr for A and D sheets provides microstructure stability of these sheets. Whereas, annealing B and C sheets for one hour at 400 and 350°C, respectively, provide the optimum annealing conditions. In the studied alloys, the highest zinc (Zn) presence alloyed with magnesium significantly increases the grain size and the amount of precipitates. Whereas, the highest cerium (Ce) presence alloyed with magnesium, refines the grain size during the recrystallization process.

Effect of Intercritical Annealing Temperature and Holding Time on Microstructure and Mechanical Properties of Dual Phase Low Carbon Steel

Dual phase steels are an important advanced high strength steel, which have been widely used in the automotive industry for vehicle components requiring light weight and safety. In this study, the formation of dual phase structure with various volume fraction of martensite in a low carbon steel SS400 during intercritical annealing were investigated. It was found that intercritical annealing temperature and holding time affected the microstructure and mechanical properties of dual phase low carbon steel. The specimens were heated at intercritical annealing temperature of 750°C, 775°C, 800°C and 825°C, for holding periods of 6-18 minutes, followed by water quenching in order to get a dual phase ferrite and martensite. After quenching, it was obtained the optimal annealing conditions at 800°C with a holding periods of 10 minutes. In this condition, the tensile strength was increased up to 621 N/mm2 or 39.24% higher than the initial condition, while the elongation decreased up to 13.8%. The hardness of specimens increased from 127.7 to 235.83 HVN or up to 84.67% higher than the initial condition. Meanwhile the volume fraction of martensite was 24.08%. The higher the temperature of the heating value of grain growth rate constant (K) increases. In addition, at the optimal poin, the value of K (grain growth rate constant) and n (Avramis exponent) were 0.263 and 0.318, respectively, with activation energy (Q) of 3.98 J/mol.

Improved electron collection in fullerene via caesium iodide or carbonate by means of annealing in inverted organic solar cells

Inverted organic photovoltaic cells (IOPVCs), based on the planar heterojunction C60 /CuPc, were grown using MoO3 as anode buffer layer and CsI or Cs2 CO3 as cathode buffer layer (CBL), the cathode being an ITO coated glass. Work functions, Φ f , of treated cathode were estimated using the cyclic voltammetry method. It is shown that Φ f of ITO covered with a Cs compounds is decreased. This decrease is amplified by the annealing. It is shown that the thermal deposition under vacuum of the CBL induces a partial decomposition of the caesium compounds. In parallel, the formation of a compound with the In of ITO is put in evidence. This reaction is amplified by annealing, which allows obtaining IOPVCs with improved efficiency. The optimum annealing conditions is 150 °C for 5 min.

Optimization of Annealing Conditions for ZnO-based Thin Films Grown Using MOCVD

ABSTRACTIn this work, effects of thermal annealing on the structural and optical properties of ZnO thin films grown on p-Si and GaN substrates using metalorganic chemical vapor deposition (MOCVD) are investigated. Annealing at 600 °C results in optimum crystal and optical qualities of the ZnO thin films on both substrates. Smaller lattice mismatch between grown ZnO epitaxial layer on GaN substrates results in better film morphology as compared to p-Si substrates. Higher annealing temperature along with a slower thermal ramp provides better crystal quality of ZnO thin films on both substrates. Annealing ZnO thin films at 700 °C with a slower thermal ramp results in better crystal quality as is evident from a 56% reduction in the full-width at half maximum (FWHM) of the (002) peak compared to the as-grown films. The optical quality also enhances with a slower annealing rate. The determination of the optimum annealing conditions for different substrates has important implications in fabricating optimized and efficient ZnO based electronics.