Furnace Annealing Research Articles

Воздействие ионного облучения (Аr+, E = 15-20 кэВ) на микроструктуру деформированного сплава Ni - 13.9 мас.% W

Using X-ray diffraction analysis, the effect of Ar+ ions with an energy of 15-20 keV (at ion current densities of 100-300 μA/cm2) on the microstructure, the level of internal microstresses and the texture of cold rolled ribbons of alloy Ni-13.9 wt.% W was studied. It was found that short-term irradiation of 80 μm thick ribbons with a fluence of 3.1·1016 cm-2 (for 50 s) at temperatures T ≤ 370°C and T = 630°C leads to a decrease in microstresses in their entire volume, but at the same time the original texture is retained. With an increase in the fluence to 9.7·1017 cm-2 at T = 630°C, the texture also changes from (220) to (200). Changes in microstresses and texture on the irradiated and unirradiated sides of 80-μm-thick ribbons are comparable to each other, despite the fact that the projective range of Ar+ ions with an energy of 15-20 keV in the alloy is only ~7 nm. It is known that annealing in an oven (700°C, 30 min) of such ribbons does not lead to their recrystallization. At 850°C, microstresses are relieved and the texture drastically changed from (220) to (200) both as a result of annealing in a furnace (15 s) and as a result of irradiation with a fluence of 3.2·1016 cm-2 for 17 s, but the effect removal of stresses in the course of furnace annealing is 3 times lower than in the course of irradiation. Thus, the following facts have been established: 1) the occurrence of recrystallization processes in the alloy under study during irradiation at a temperature lower than the temperature of the onset of thermally activated recrystallization and 2) a higher rate of microstresses drop (and to lower values) in the course of irradiation than during furnace annealing. This indicates a significant role of nanoscale radiation-dynamic effects at the cascade-forming irradiation of metastable media.

Magnetic and electrical properties of single-phase multiferroic (1-x)Pb(Zr0.52Ti0.48)O3–xPb(Fe0.5Nb0.5)O3 thin films prepared by sol-gel route

Single-phase multiferroic (1-x)Pb(Zr0.52Ti0.48)O3-xPb(Fe0.5Nb0.5)O3 (0≤x≤0.5) thin films were synthesized by sol-gel route and characterized to understand their structural, electrical, and magnetic properties. The films were thermally treated by conventional furnace (CFA) and rapid thermal annealing (RTA). A pyrochlore-free perovskite phase is stabilized only by RTA in samples with high Fe3+/Nb5+ content. The films displayed excellent dielectric and ferroelectric properties in the whole concentration range, with saturated hysteresis loops and remanent polarization values of ∼15μC/cm2. Films with x>0.3 showed ferromagnetic behavior at room temperature. Consequently, the multiferroic behavior in the films occurs in a different concentration range than that observed in bulk ceramics. The origin of the weak ferromagnetism is discussed.

Microwave and furnace annealing in oxygen ambient for performance enhancement of p-type SnO thin-film transistors

In this study, we investigated the effect of microwave-irradiation annealing (MWA) and thermal furnace annealing (FA) in oxygen ambient on the active channel layer of p-type tin-oxide (SnO) thin-film transistors. At very low source-drain voltage of −0.1 V, the MWA at 1200 W and FA at 300 °C samples have exhibited significant improvement in the electrical characteristics such as subthreshold swing (SS) of 0.93 and 0.485 V dec−1, the I on/I off ratio of 1.65 × 104 and 3.07 × 104, the field-effect mobility (μ FE) of 0.16 and 0.26 cm2 V−1 s and ultra-low off-state current of 1.9 and 2.0 pA respectively. The observed performance enhancement was mainly attributed to the reduction of interface trap density (N t) by tuning the power of MWA and optimizing the temperature in FA. From the result, we observed the optical band gap (E g) increased by 6% in FA, and 12% in MWA, which confirms improved crystallinity and reduction of defect states. Additionally, a low thermal budget microwave anneal process has shown high transmittance of more than 86% in the visible region (380–700 nm). The physical characterization indicates the partial phase transformation of SnO to SnO2 with retaining p-type conductivity in both annealing processes. The results demonstrate that both the annealing process could be highly promising to be used in the complementary logic circuits of new generation flexible/transparent displays.

Carbothermal reduction of mill scales formed on steel billets during continuous casting

A billet is a bar made from crude steel which surface contains scales which are rich in iron oxides. This study presents the carbothermal reduction of the scales formed in steel billets. The process included the reaction of the iron oxides contents with carbon (in ratio 5:1) and annealing in a tubular furnace under argon atmosphere. The occurred reactions are discussed using thermodynamic calculations and thermal analysis which indicate a three-stage reduction process Fe3O4 ➔ FeO ➔ Fe3C ➔α-Fe with intermediate reactions at the interval temperature 960 and 1300 °C. The X-ray diffraction confirms the reduction to α-Fe with minor presence of unreacted C, magnetite and wustite. Mössbauer spectroscopy analysis was performed at room temperature where a typical sextet corresponding to the dominant α-Fe is shown as well as wustite, magnetite and cementite to a lesser extent. The magnetization measurements confirm the ferromagnetic state corresponding to the α-Fe.

Synthesis and magnetic studies of pure and doped NiZn ferrite films using Sol gel method

In this work, the effect of Co and Cu doping on the magnetic properties of Nickel Zinc ferrite films was investigated. Three types of films with composition Ni0.5Zn0.5Fe2O4, Ni0.35Cu0.2Zn0.45Fe2O4 and Ni0.35Co0.2Zn0.45Fe2O4 were prepared using the sol-gel method. These films were annealed at 500, 600, 700 and 800 °C using a rapid thermal annealing furnace. XRD diffraction confirmed the formation of single-phase spinel structure in these films. Magnetic properties such as saturation magnetization (Ms) and coercivity of these films were measured using an alternating gradient magnetometer. The highest values of Ms were obtained for films annealed at 600 °C which are 350, 334 and 261 emu/cm3 for undoped, Co doped and Cu doped films, respectively. The corresponding coercivity values of these films were 102, 509 and 95 Oe. Thus, Co0.2 doping resulted in an increase in the coercivity whereas Cu0.2 doping reduced the coercivity. Grain size distribution was measured using a scanning electron microscope. It was observed that at higher annealing temperatures (above 600 °C), films developed cracks which results in the reduction of the saturation magnetization from such films.

Simulation on surface roughness variation of Au thin films by microwave post annealing

A simulation study was performed in order to interpret the experimental results in the previous report on roughness reduction in Au thin films by microwave post annealing in comparison with an electric furnace. The simulation model of this study is based on one-dimensional capillary driven surface diffusion with incorporation of electromigration force due to microwave irradiation. It was shown that alternating microwave electric field does not cancel the atomic migration completely, because of the capillary driven (thermal) effects simultaneously occurring within the alternation period, but is not adequate to account for the variation of the film profiles and the observed wave number spectra. In this study, capillary model was applied to the furnace annealing, and an anisotropic factor in atomic transport by electromigration was introduced in microwave annealing simulations. We reproduced the profiles and spectra changes observed in the experiments by both annealing methods.

Successive Free-Radical C(sp 2 )–C(sp 2 ) Coupling Reactions to Form Graphene

Successive Free-Radical C(sp ² )–C(sp ² ) Coupling Reactions to Form Graphene

CFD investigation of a vertical annealing furnace for stainless steel and non-ferrous alloys strips – A comparative study on air-staged & MILD combustion

A 3D CFD modelling approach of a vertical high temperature furnace in a bright annealing line for stainless steel is presented in this study. The observed line has a maximum production rate of 4.5 tonnes per hour and an overall thermal input of 1.5 MW which is provided by gas burners. The muffle furnace is an indirect heating system equipped with flameless burners, which can operate at nominal power and in off-design. The burners are arranged in four heating zones, which can be controlled separately. Pure hydrogen is used inside the muffle as protection gas around the metal. The metal strip is modelled as a highly viscous fluid with temperature-dependent properties including the specific heat, thermal conductivity and emissivity. Good accordance with measurements from an industrial line was achieved with several values from furnace thermocouples and the transient heating characteristic of a selected strip dimension, thus, demonstrating the applicability of the CFD model for the present investigations. Further simulations were performed with air-staged combustion for an evaluation of combustion and furnace efficiency as well as the thermal load on the furnace’s components. It was found that the efficiency decreased by about 0.5% using flameless combustion. The results also showed a decreased peak temperature of about 1155 °C and a reduced heat flux of about 23.3 kW/m2 (−5%) on the muffle when Moderate or Intense Low oxygen Dilution (MILD) combustion is applied. The present methodology presents an efficient approach for investigation and optimization of indirect heated muffle type furnaces.

Effects of Microwave and Furnace Annealing for P-Type SnO Thin Film Material in Oxygen Ambient

Transparent conductive oxide (TCO) semiconductors are attracted considerable attention due to a wide range of applications, such as flat panel display (FPD), touch panels, solar cells, and other optoelectronic devices. Owing to the different carrier conduction paths between n-type and P-type TCOs, the n-type TCO used in TFTs usually have high Ion/Ioff current ratio (>107) and high electron mobility (>10 cm²/V·s), P-type TCO TFTs are both lower than that of n-type one. For complementary circuits design and applications, however, both P-type and n-type semiconductor materials are equally important. For SnO thin films, it is important to adjust the ratio of Sn2+ (SnO P-type) and Sn4+ (SnO₂ n-type) in order to modulate the electrical characteristics. In this investigation of post treatment for SnO thin films, both microwave annealing (MWA) and furnace annealing process with 0₂ ambient are studied. The results show that SnO thin films are optimized at 300 °C, 30 minutes furnace annealing, the P-type SnO/SnO₂ thin film shows surface mean roughness 0.168 nm, [Sn2+]/[Sn4+] ratio as 0.838, at least 80% transmittance between 380 nm-700 nm visible light. Withthe results, SnO can be even used to fabricate high performance P-type thin film transistors (TFTs) device for future applications.

Влияние электроимпульсной обработки на структуру и твердость криокатаного алюминия

The influence of the energy of electric pulse treatment (EPT) in the range of integral current densities (Kj) from 0.06 ×105 to 0.29 ×105 A2s / mm4 on the structure and hardness of coarse-grained high-purity Al, isothermally rolled up to a total strain of 90 % at a liquid nitrogen temperature, was studied. It was found that EPT with an energy up to Кj = 0.104 ×105 A2s / mm4 practically did not affect the microhardness obtained in the cryorolled aluminum (45 – 50 HV). An increase in the EPT energy to Кj = 0.121×105 A2s / mm4 led to a rapid drop of the hardness to 30 HV followed by its gradual stabilization near 25 HV at higher Кj values. It was established that an enhanced microhardness of rolled Al resulted from formation of a well developed cellular structure with a crystallite size of about 2 μm, containing less than 10 % of ultrafine grains of about 4 μm in size. The minor hardness changes after EPT with Кj up to 0.104 ×105 A2s / mm4 were related to occurrence of recovery and continuous recrystallization, resulted only in improving the deformation structure without noticeable changes in its type and the crystallite sizes. Therewith the softening caused by a partial decrease in the scalar dislocation density and the microdeformation of the crystal lattice was compensated by increasing the high angle boundaries fraction. At EPT with Кj = 0.121×105 A2s / mm4, the deformation structure was severely replaced by the fine-grain recrystallized one with the grain size of 19 μm, and resulted in the loss of the strenthening effect, caused by rolling. With further increase in the EPT energy, an extensive grain growth was observed, leading to the formation of a non-uniform structure grains and to appropriate material softening, owing to the grain coarsening. It was concluded that the restoration processes that took place during EPT were similar in nature to those that occur during furnace annealing of heavily deformed materials. Therewith, the short time of the thermal exposure on the deformed metal during EPT was compensated by high applied energies.

Multi‐Step Chemical Solution Deposition‐Annealing Process Toward Wake‐Up Free Ferroelectricity in Y:HfO2 Films

AbstractFerroelectricity in HfO2 thin films can be utilized for fast, power‐efficient, and highly scalable non‐volatile memories. However, the required wake‐up process for inducing ferroelectricity/ achieving higher polarization is one of the major hurdles that hinder HfO2‐based thin films from developing reliable electronic devices. The wake‐up effect is believed to originate from i) phase transformation from non‐ferroelectric to ferroelectric, ii) movement of defect entities (mainly oxygen vacancy defects) near the film‐electrode interface, and iii) heterogeneity of the electrode interfaces. In the present study, an experimental strategy is designed to overcome these sources of the wake‐up process. A multi‐step deposition and annealing process is carried out to induce wake‐up‐free ferroelectricity in Yttrium doped HfO2 (Y:HfO2) thin film directly grown on Si‐substrate. Furnace annealing is utilized instead of the standard rapid thermal annealing process to reduce the oxygen deficiencies and stimulate the direct growth of the polar Y:HfO2. The oxygen‐vacancy‐related defects are found to be the dominating source of wake‐up effect in Y‐doped HfO2 films. The step‐wise deposition and annealing in the oxygen atmosphere facilitate direct growth of the polar phase, reduce the oxygen vacancies, and induce wake‐up‐free ferroelectricity in Y:HfO2.

Excellent soft magnetic properties in Co-based amorphous alloys after heat treatment at temperatures near the crystallization onset

The effect of heat treatment of Co-based amorphous microwires at temperatures near the crystallization (Tcr) onset on micromagnetic structure, magnetostriction, and magnetoimpedance (MI) was investigated. As the annealing temperature approaches Tcr, the hysteresis loops abruptly change the shape from almost rectangular to inclined with a small coercivity and remanence magnetization. This behavior is quite unique since even partial crystallization deteriorates soft magnetic properties. The Kerr-microscopy confirmed the formation of a fine circular domain structure and an easy anisotropy direction of a helical type. Both current and furnace annealing with appropriate high temperatures produce similar magnetic transformation. The origin of the formed easy anisotropy is different from that induced by current annealing at temperatures below the Curie temperature and is associated with a change in the magnetostriction constant, which drops from positive to negative values. This could be explained by structural relaxation leading to amorphous phase decomposition at the very initial stage of crystallization. The effect is not specific for the Co-rich alloy composition and was observed in microwires of two compositions: Co71Fe5B11Si10Cr3 and Co66.6Fe4.28B11.51Si14.48Ni1.44Mo1.69 which in the as-prepared state have axial and circumferential anisotropies, respectively. The obtained combination of magnetic anisotropy, magnetostriction and temperature stability leads to useful MI properties, in particular, at Gigahertz frequencies.

Investigation of the effect of annealing on the structural, morphological and optical properties of RF sputtered WO3 nanostructure

In this study, we focused on examining the effect of annealing on the structural, morphological, and optical properties of the tungsten oxide (WO3) nanostructures. WO3 nanostructure deposited on n-type Si substrate using the radio frequency (RF) magnetron sputtering system. The WO3 nanostructure was divided into 6 parts. 5 samples except as-deposited samples were individually annealed at various temperatures ranging from 300 °C to 700 °C (by step 100 °C) in a conventional thermal annealing furnace (CTA) for 1 h. The stoichiometry of the as-deposited WO3 was determined by SEM-EDS and XPS measurements. Structural, morphological, and optic properties of the as-deposited and different annealed temperatures WO3 nanostructures were characterized by XRD, AFM, Uv–Vis and PL measurements. The effects of annealing on material analysis and properties were reported with a comparative study. It has been reported that the annealed WO3 nanostructure can be preferred as an effective material for device applications.

Evaluation of Crystalline Volume Fraction of Laser-Annealed Polysilicon Thin Films Using Raman Spectroscopy and Spectroscopic Ellipsometry.

We investigated the crystallinities of poly silicon (poly Si) annealed via green laser annealing (GLA) with a 532-nm pulsed laser and blue laser annealing (BLA) with 450-nm continuous-wave lasers. Three-dimensional heat transfer simulations were performed to obtain the temperature distributions in an amorphous silicon (a-Si) thin film, and GLA and BLA experiments were conducted based on the thermal simulation results. The crystallinity of annealed poly Si samples was analyzed using Raman spectroscopy and spectroscopic ellipsometry. To evaluate the degree of crystallization for the annealed samples quantitatively, the measured spectra of laser-annealed poly Si were fitted to those of crystalline Si and a-Si, and the crystal volume fraction (fc) of the annealed poly Si sample was determined. Both the Raman spectroscopy and ellipsometry showed consistent results on fc. The fc values were found to reach >85% for optimum laser power of GLA and BLA, showing good crystallinity of the laser-annealed poly Si thin films comparable to thermal furnace annealing.

Phase evolution of Te-hyperdoped Si upon furnace annealing

Si hyperdoped with chalcogens via ion implantation and pulsed laser melting is known to exhibit strong room-temperature sub-bandgap photoresponse. As a thermodynamically metastable system, an impairment of the optoelectronic properties in hyperdoped Si materials occurs upon subsequent high-temperature thermal treatment (>500 °C). The substitutional Te atoms that cause the sub-bandgap absorption are removed from the Si matrix to form Te-related complexes, which are electrically and optically inactive. In this work, we explore the formation of defects in Te-hyperdoped Si layers which leads to the electrical deactivation upon furnace annealing through the analysis of optical and microstructural properties as well as positron annihilation lifetime spectroscopy. Particularly, Te-rich clusters are observed in samples thermally annealed at temperature reaching 950 °C and above. Combined with polarized Raman analysis and transmission electron microscopy, the observed crystalline clusters are suggested to be Si2Te3.

Site disorder and its tailoring in N implanted post-annealed ZnO: Prospects and problems

The particular role of nitrogen in ZnO as a p type dopant remains a debated topic of research till date. In this work, Raman and Photoluminescence (PL) investigations have been carried out on N implanted granular ZnO with subsequent rapid thermal and conventional furnace annealing (at 750 °C) in oxygen and air ambient. Raman results indicate that rapid thermal annealing is efficient to recover irradiation generated disorder keeping doped N at the lattice site. Conventional furnace annealing, on the other hand, promotes outdiffusion of atomic N from lattice position along with vacancy agglomeration to some extent. No matter whether annealed or not, implanted N prefers to accumulate near the stacking fault defects and increases the well known free to bound transition (here ~ 3.314 eV at 10 K) in ZnO. Still, low temperature PL spectra of the samples show convincing evidences of acceptor bound exciton transition energetically just below the same due to dominant donor bound excitons. Shallow donor to shallow acceptor PL emission has also been clearly identified. The possibilities and problems of hole doping in ZnO via N ion implantation have been discussed in the light of previous reports. At the end, some futuristic proposals have been formulated.

Laser induced crystallization of Co\u2013Fe\u2013B films

Local crystallization of ferromagnetic layers is crucial in the successful realization of miniaturized tunneling magnetoresistance (TMR) devices. In the case of Co–Fe–B TMR devices, used most successfully so far in applications and devices, Co–Fe–B layers are initially deposited in an amorphous state and annealed post-deposition to induce crystallization in Co–Fe, thereby increasing the device performance. In this work, first direct proof of locally triggered crystallization of 10 nm thick Co–Fe–B films by laser irradiation is provided by means of X-ray diffraction (XRD) using synchrotron radiation. A comparison with furnace annealing is performed for benchmarking purposes, covering different annealing parameters, including temperature and duration in the case of furnace annealing, as well as laser intensity and scanning speed for the laser annealing. Films of Co–Fe–B with different stoichiometry sandwiched between a Ru and a Ta or MgO layer were systematically assessed by XRD and SQUID magnetometry in order to elucidate the crystallization mechanisms. The transformation of Co–Fe–B films from amorphous to crystalline is revealed by the presence of pronounced CoFe(110) and/or CoFe(200) reflexes in the XRD θ-2θ scans, depending on the capping layer. For a certain window of parameters, comparable crystallization yields are obtained with furnace and laser annealing. Samples with an MgO capping layer required a slightly lower laser intensity to achieve equivalent Co–Fe crystallization yields, highlighting the potential of laser annealing to locally enhance the TMR ratio.

Post-fabrication resonance trimming of Si3N4 photonic circuits via localized thermal annealing of a sputter-deposited SiO2 cladding

We report a resonance trimming technique, applicable to waveguides employing an SiO2 cladding. The SiO2 is deposited by a room temperature sputtering process. Resonance shifts of micro-ring resonators of 4.4 nm were achieved with furnace annealing, whereas a resonance shift of 1.4 nm was achieved using integrated micro-heaters. For our device layout, with 30 μm ring separation, the thermal cross-talk is negligible, and isolated trimming of each micro-ring is achieved. Three, single-channel ring filters on the same substrate were aligned to the same wavelength within a 20 pm precision. The stability of trimmed micro-rings was assessed following extended storage in atmospheric ambient. For a ring shifted by 4.4 nm using furnace annealing, relaxation of 540 pm is observed, while for a ring shifted by 1.4 nm using integrated heaters, the relaxation is 270 pm.

Comparative study on crystallinity of laser-annealed polysilicon thin films for various laser sources

In this study, we compared the crystallinities of polycrystalline silicon thin films annealed using green laser annealing (GLA) with a 532-nm pulsed laser, near-ultraviolet laser annealing (NULA) with a 355-nm pulsed laser, and blue laser diode annealing (BLDA) with 450-nm continuous-wave (CW) lasers. Three-dimensional heat transfer simulations were performed to obtain the temperature distributions in a 100 nm-thick amorphous silicon layer, and optimum laser conditions were determined for each laser annealing. GLA, NULA, and BLDA experiments were conducted based on the thermal simulation results, and the crystallinity of the annealed samples was quantitatively analyzed via spectroscopic ellipsometry. The analysis results indicated that GLA and BLDA resulted in good crystallinity that was comparable to the result of furnace annealing, whereas NULA resulted in a relatively poor crystal quality. The difference in the crystallinities produced by the annealing lasers could be explained using the thermal simulation results. This study provides an insight into the optimum laser annealing conditions for realizing high-quality poly-silicon thin films.

Effect of Joule heating on giant magnetoimpedance effect and magnetic properties of Co-rich microwires

The effect of Joule-heating on hysteresis loops and giant magnetoimpedance effect, GMI; of Co69.2Fe3.6Ni1B12.5Si11Mo1.5C1.2 glass-coated microwire is studied. Joule heating performed at suitable conditions prevents the magnetic hardening observed during conventional furnace annealing of the studied microwires. A remarkable GMI ratio improvement is observed as compared to as-prepared annealed and even stress-annealed microwires. Observed magnetic softening and GMI ratio improvement have been discussed considering magnetic anisotropy induced by Oersted magnetic field during Joule heating and internal stresses relaxation.