Effect Of Thermal Annealing Research Articles

Cu thin film growth on stepped Si substrate: Effects of incident energy and thermal annealing

The existence of defects on the substrate surface is unavoidable and has a significant impact on the determination of surface properties. Among the prevalent types of defects, steps play an important role. In this study, molecular dynamics simulations are employed to explore the growth process of a thin film of Cu on a Si (001) substrate with a step. This research investigates how incident energy and thermal annealing affect the growth mode, surface roughness, film-substrate interface, and dislocation evolution. The results indicate that during the initial stage of the growth, the nucleation phenomenon was observed on terraces. The simulation indicates that the Cu atoms occur in an island growth mode on the stepped substrate. It is found that when the incident energy is increased and thermal annealing is performed, the surface curvature and roughness are reduced. Furthermore, the intermixing thickness at the interface increases due to the variation of the incidence energy. A dislocation analysis revealed that some dislocations disappeared before and after annealing, and a perfect dislocation appeared by increasing the incident energy.

Effect of thermal annealing on the surface plasmon properties of gold and silver nanodisk structures fabricated by electron beam lithography

This study investigates the effect of thermal annealing on the surface plasmon resonance properties of gold and silver nanodisk structures fabricated by electron beam lithography. Despite no significant size change due to a nickel adhesion layer, thermal annealing at 500 °C notably altered surface plasmon resonance properties, especially in gold nanodisks, which showed peak blue-shifts and narrowing, indicating improved crystallinity. We fitted the peak shift by using an electromagnetic field analysis and discussed the changes in the dielectric function. The dielectric function of the simple Drude model was adopted, which was fitted to the values of the Lorentz Drude model in a limited wavelength region. While both silver and gold exhibited increased oscillation strength, only gold nanodisk structures showed a decrease in damping frequency. Increased oscillation strength indicated that these structures should be useful for selective enhancement of the light at specific wavelengths by a very simple heat treatment.

Testing the physical properties stability of Zinc (8-hydroxyquinoline) thin films toward stable photodetection performance: Effect of annealing

In this study, the effect of thermal annealing on the structural and optical properties of thermally evaporated zinc (8-hydroxyquinoline) (ZnQ2) thin films is discussed in detail. Differential scanning calorimetry analysis revealed the thermal stability of the ZnQ2 powder up to 540 K. Fourier transform infrared spectrometer characterizations revealed the stability of the ZnQ2 molecular structure up to 423 K. The annealing effect on the surface morphology of the ZnQ2 films was tracked using the field emission scanning electron microscope (FE-SEM) technique, which revealed grain growth up to 423 K achieving the highest surface smoothness. Moreover, UV–Vis-NIR spectrophotometric measurements were used to examine how annealing affects the optical characteristics of the prepared films. The optical bandgap of ZnQ2 augmented when the annealing temperature increased to 373 K. The dispersion parameters were estimated from the analysis of the complex refractive index following the single oscillator model. The behavior of nonlinear optical susceptibility suggested the validity of utilizing ZnQ2 thin films in IR and UV optical switching applications and UV photodetection applications.

Effects of hydrogen doping on the phase structure and optoelectronic properties of p-type transparent SnO

Hydrogen (H) is a ubiquitous impurity, which can significantly affect the phase structure and the optoelectronic properties of oxide semiconductors. To date, a well-established understanding of the effects of H doping on the properties of p-type transparent SnO is still lacking. Here, we present a comparative study to reveal the role of H in SnO films by magnetron sputtering. We find that in as-grown undoped SnO films, in addition to the tetragonal SnO phase, secondary phases of SnO2 or Sn3O4 are present under certain growth temperatures. In contrast, a small fraction of metallic Sn phase is included in the as-grown H-doped SnO (SnO:H) films, attributed to the partial reduction of SnO by the H2 in the sputtering gas. Effects of post thermal annealing (PTA) on the properties of SnO films are also explored. Results strongly indicate that H doping or PTA facilitates the formation of Sn phase and Sn vacancies related defects, giving rise to the p-type conductivity observed in the undoped or H-doped SnO films. The present study provides a comprehensive understanding of the evolution of phase structures as well as defect properties of SnO films, which is crucial for their future studies and optoelectronic applications.

Thermal Annealing Effect on Hydrothermal Synthesized Li4Ti5O12/TiO2 as Anode Material for Lithium-Ion Batteries

The thermal annealing effect on the morphological, structural and electrochemical properties of hydrothermal synthesized Li4Ti5O12 / TiO2 has been studied. Lithium titanate (Li4Ti5O12) nanopowders are successfully synthesized by hydrothermal method using titanuim tetrabutyl and lithium hydroxide followed by thermal annealing process at different temperatures: 500 °C, 800 °C and 900 °C. The X-ray diffraction (XRD) patterns indicates the appearance of the Li4Ti5O12 phase at a temperature above 800 °C formed after the reaction of the two phases: TiO2 and Li2TiO3 which appear at 500 °C. Though, the prepared electrode by the powder annealed at 800 °C shows an initial capacity of about 173.1 mAh g−1 (0.1 C), which retained at 75.6 mAh g−1 after 100 cycles.

The Effect of Thermal Annealing on Mechanical and Optical Properties of MgAl2O4 Ceramics Fabricated by Spark Plasma Sintering

The Effect of Thermal Annealing on Mechanical and Optical Properties of MgAl2O4 Ceramics Fabricated by Spark Plasma Sintering

Study on the Thermal Stability of Molybdenum Oxide‐Passivated Silicon Solar Cells

Dopant‐free heterojunction (HJ) solar cells are known for their simple process conditions and low parasitic absorption. However, stability issues remain one of the major obstacles for further development of cells with transition metal oxides (TMOs). Therefore, this research demonstrates the mechanism of thermal annealing degradation effects on TMOs/silicon (Si) HJ, namely, the infiltration of oxygen from air and the bidirectional diffusion of oxygen from TMOs, by investigating a typical molybdenum oxide (MoOx)/Si contact. A dense Au interlayer is introduced to block the interdiffusion of oxygen from the MoOx/Si interface and its surrounding environment. As a result, the dense layer slows down the interfacial oxidation of MoOx/Si and the degradation of the MoOx work function, thus improving the stability of the MoOx/Si HJ to 200 °C. The diffusion of oxygen from MoOx to the MoOx/Si interface will be critical to further promote the thermal stability of the devices thereafter, especially for the cells with i‐a‐Si:H layer as the passivation layer. To attain stable dopant‐free cells with MoOx, it is crucial to prevent oxygen diffusion into Si while maintaining a high MoOx work function and a thin SiOx layer at the interface.

Effect of rapid thermal annealing on microstructure, mechanical and tribological properties of amorphous SiC hard coatings

Herein, a-SiC hard coatings were prepared by pulsed DC magnetron sputtering followed by rapid thermal annealing (RTA) at various temperatures. The influence of the RTA temperature on the coatings’ microstructure, mechanical and tribological properties was investigated. The results show that the surface morphology of a-SiC coatings almost unchanged and remains amorphous within 973 K annealing temperature. The content of sp3 first increases and then decreases with increasing annealing temperature, and reaches the maximum value at 773 K. The hardness (H) and elastic modulus (E) of the a-SiC coatings also increase firstly and then decrease due to the variation of sp3 content, while average friction coefficient decreases first and then increases. As the annealing temperature is 823 K, the maximal H, E of 25.02 GPa, 243.63 GPa are obtained. At 773 K annealing temperature, the minimum friction coefficient of 0.107 is realized, a-SiC coating exhibits higher H/E, H3/E2 and tribological properties.

Improvement of mid-wave infrared quantum cascade laser epitaxy by studying the effect of thermal annealing on GaInAs/AlInAs superlattice

GaInAs/AlInAs superlattice play an important role in the epitaxial structure of mid-wave infrared quantum cascade lasers. This paper find the optimal deoxidation temperature point for an InP/Ga0.31In0.69As/Al0.64In0.36As quantum cascade laser (QCL) epitaxial process combining MBE (for active cores) and MOCVD (for waveguide cladding) co-growth, and investigate the effect of thermal annealing on this superlattice. Comprehensive multi-technical analysis including atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) confirmed that slow annealing of the structure at a temperature of 480 °C can be properly optimized. The crystal quality and surface smoothness were confirmed, and the changes in element content of the ternary alloy under thermal reaction were analyzed. These results provide an extremely effective reference value for the QCL secondary epitaxial waveguide layer.

Influence of Pt Ultrathin Interlayers on Magnetic Anisotropy in Ni/NiO Multilayers

Perpendicular magnetic anisotropy at transition metal/oxide interfaces plays a significant role in technological applications such as magnetic storage and spintronics. In this study, we investigate the effects of thermal annealing and Pt ultrathin interlayers on the magnetic anisotropy in Ni/NiO multilayers. Ni/NiO/Pt multilayers were fabricated via radiofrequency magnetron sputtering and natural oxidation. The static magnetic properties of the samples were studied using temperature-dependent SQUID magnetometry. We focus on a sample with a Nickel thickness of 6.7 nm in each multilayer period. This multilayer in Ni/NiO form showed the maximum enhancement of perpendicular magnetic anisotropy after mild thermal annealing in past work. In this work, we study the effects of ultrathin Pt interlayers on the magnetic properties of such a Ni/NiO multilayer before and after annealing. We have observed a further increase in perpendicular magnetic anisotropy, and we study the temperature-dependent magnetic properties of this system, which combines the favorable magnetic properties of Ni/Pt and Ni/NiO multilayers.

Magnetostructural Transformation and Magnetocaloric Properties of (Ni37.5Co12.5Mn35Ti15)100−xBx (x = 0.0 and 0.4) Melt-Spun Ribbons

The effect of B-doping on the martensitic transformation (MT), microstructure, room temperature (RT) crystal structure, and magnetocaloric properties of a typical all-d-metal Ni37.5Co12.5Mn35Ti15 quaternary alloy was studied by synthesizing melt-spun ribbon samples of nominal composition (Ni37.5Co12.5Mn35Ti15)100−xBx with x = 0.0 and 0.4. For B-free samples, SEM images show a grain-oriented microstructure formed by the columnar in shape-elongated grains with their major axis oriented along the thermal gradient during solidification. By contrast, the B-doped samples show smaller grains whose orientation tends to be perpendicular to the contact surface with the copper wheel. For all samples, austenite (AST) and martensite (MST) phases exhibited a cubic B2-type and 5M monoclinic crystal structure, respectively. The martensitic transition temperature (TM) and the Curie temperature of the austenite phase (TCA) were reduced from 295 K to 253 K and 333 K to 276 K, respectively, with the addition of B. The effect of thermal annealing for different times (from 30 min to 4 h) at 1073 K was studied. Thermal annealing increases the martensitic transformation temperature, whereas TCA remains unchanged. The maximum magnetic field-induced entropy changes |ΔST|max for B-doped samples were around 4.5 J kg−1 K−1 and 4.7 J kg−1 K−1 for as-solidified and annealed samples (1073 K–4 h), respectively, compared to that found for the undoped samples (i.e., ΔST = 16 J kg−1 K−1). However, the entropy reduction is accompanied by an increase in the full width at half-maximum of the ΔST(T) curve.

Creation of Room-Temperature Sub-100 nm Antiferromagnetic Skyrmions in an Antiferromagnet IrMn through Interfacial Exchange Coupling.

Antiferromagnetic (AFM) skyrmions are magnetic vortices composed of antiparallell-aligned neighboring spins. In stark contrast to conventional skyrmions based on ferromagnetic order, AFM skyrmions have vanished stray fields, higher response frequencies, and rectified translational motion driven by an external force. Therefore, AFM skyrmions promise highly efficient spintronics devices with high bit mobility and density. Nevertheless, the experimental realization of intrinsic AFM skyrmions remains elusive. Here, we show that AFM skyrmions can be nucleated via interfacial exchange coupling at the surface of a room-temperature AFM material, IrMn, exploiting the particular response from uncompensated moments to the thermal annealing and imprinting effects. Further systematic magnetic characterizations validate the existence of such an AFM order at the IrMn/CoFeB interfaces. Such AFM skyrmions have a typical size of 100 nm, which presents pronounced robustness against field and temperature. Our work opens new pathways for magnetic topological devices based on AFM skyrmions.

Effect of thermal annealing on the optical properties of 3D-printed nanostructured CuO films for flexible photovoltaic solar cells

In this work, the effect of thermal annealing on the optical and structural properties of 3D-printed nanostructured copper oxide films deposited on polyimide substrates is investigated for the first time. It was shown that both as-deposited and annealed at Ta = 160 °C films have mainly monoclinic CuO phase. XRD and Raman results show that these films also contain a small amount of Cu2O phase, and possibly an amorphous CuO as well as a metastable CuO2-like phases. At the same time, films annealed at 300 °C for 10 min are characterized by a pure CuO phase and have the best optical quality. The band gap of the investigated copper oxide films is equal to (1.53–1.64) eV, which is associated with indirect allowed optical transitions. The results obtained paves the way to the development of nanotechnologies for obtaining CuO films by the 3D printing method, suitable for flexible electronics, especially for solar energy.

ANNEALING EFFECT ON UV DETECTION PROPERTIES OF ZnO:Al STRUCTURES

The aim of this study was to develop low-powered, highly selective UV sensor to continuously monitor personalized UV exposure as well as to study annealing effect on UV detection properties of the sensors. ZnO:Al structures were obtained by chemical growth method followed by thermal annealing at 625 °C for 2 h. The studied samples exhibit maximal UV response of 620/488 at 25 °C/50 °C to 370 nm UV radiation before/after annealing, respectively. Thermal annealing of sensor (250 °C for 1 h) led to improvement in fall time from 3860 seconds to 262 seconds at 25 °C and highest responsivity (~48 mA/W) came out for 370 nm wavelength at 75 °C operating temperatures. Consequently, excellent selectivity for 370 nm UV illumination can be ascribed as due to thermal annealing effect which increases the crystallinity, grain size, and roughness of the sensing film. The PL measurements reveals the suppression of structural defects, increase in intensity after annealing and enhanced UV response due to presence of Al content in films. Overall, these structures showed magnificent UV properties, before and especially after additional thermal annealing. UV sensing mechanism of such nanomaterial-based sensor were explained with physio-chemical processes take place on the surface of these structures. The obtained results on annealed ZnO:Al films-based devices is superior to reported performances of other nanostructures, proving new results for UV sensing applications at different operating temperatures in various fields.

Defect-dependent environmental stability of high mobility transparent conducting In-doped CdO

Highly degenerate n-type CdO with high electron mobility is a promising transparent conducting oxide (TCO) for optoelectronic devices utilizing a spectrum in the Vis-NIR range. In particular, it has been shown that doped CdO thin films can show much superior transparency of >80% in the NIR region compared to conventional transparent conducting oxide (e.g., Sn-doped In2O3) thin films with a similar sheet resistance. However, CdO thin films typically experience rapid degradation in their electron mobilities when exposed to environmental conditions with H2O moisture. Here, we studied the effects of thermal annealing on the environmental stability of In-doped CdO (CdO:In) using a combination of different analytical techniques. CdO:In thin films with different In concentration (0%–8.3%) synthesized by magnetron sputtering were subjected to different post-thermal annealing (PTA) and then aged in different environmental conditions with varying relative humidity (RH) in the range of 0%–85%. Our results reveal that the degradation of CdO:In thin films can be primarily attributed to the oxygen vacancy-related defects at the grain boundaries, which can readily react with the OH− in the moisture. The moisture induced degradation can be mitigated by appropriate PTA at high temperatures (>400 °C) where grain boundary defects, primarily associated with Cd vacancies, can be passivated through hydrogen (H), thus enhancing their environmental stability. The present study provides a comprehensive understanding of the instability mechanisms and defect passivation in transparent conducting CdO:In thin films, which can also be relevant for other wide gap oxides.

Enhancing the Properties of Photo-Generated Metallized Nanocomposite Coatings through Thermal Annealing.

In this work, the effect of thermal annealing on silver nanoparticles@polymer (AgNPs@polymer) nanocomposite coatings was investigated. These photo-generated metallized coatings have a spatial distribution of metal nanoparticles, with a depth-wise decrease in their concentration. During annealing, both structural and morphological variations, as well as a spatial reorganization of AgNPs, were observed, both at the surface and in the core of the AgNPs@polymer coating. Owing to their increased mobility, the polymer chains reorganize spontaneously, and, at the same time, a hopping diffusion process, caused by the minimization of the surface energy, promotes the migration and coalescence of the silver nanoparticles towards the surface. The layer of discrete nanoparticles gradually transforms from a weakly percolative assembly to a denser and more networked structure. Consequently, the surface of the coatings becomes significantly more electrically conductive, hydrophobic, and reflective. The general trend is that the thinner the nanohybrid coating, the more pronounced the effect of thermal annealing on its spatial reorganization and properties. These results open up interesting prospects in the field of metallized coating technology and pave the way for integration into a wide variety of devices, e.g., efficient and inexpensive reflectors for energy-saving applications, electrically conductive microdevices, and printed electronic microcircuits.

Effect of rapid thermal annealing on the surface properties of the microlens arrays machined on monocrystalline silicon

Microstructure arrays, such as microlens arrays, play a significant role in optical systems, biomedical imaging, and telecommunications. However, the machining-induced subsurface defects deteriorate their performance and functionality. To address this issue, this study proposes a rapid thermal annealing method to heal the subsurface defects using different temperatures ranging from 200 °C to 1000 °C in a vacuum. Firstly, the ultra-precision diamond sculpturing process is employed to machine the high-quality microlens array on the monocrystalline silicon surface. Then, the effects of the rapid thermal annealing on the microlens array surface, such as surface roughness and subsurface defect, are comprehensively investigated. Experimental results show that the annealing temperature of >600 °C contributes to the decrease in surface roughness and subsurface defect. Furthermore, to reveal the healing mechanism, a molecular dynamics simulation of rapid thermal annealing is performed by controlling the bulk temperature of machined monocrystalline silicon from 500 K to 1300 K. The simulation results show that recrystallization always occurred on the interface between the amorphous layer and monocrystalline silicon substrate and the healing mechanism should be solid phase epitaxy rather than random nucleation. The research findings would contribute to fabricating the defect-free optical lens in the industry.

Effect of thermal annealing on structural, morphological, optical, and photocatalytic activity of Ag3PO4 in the 17α-ethinylestradiol degradation

The improper disposal of pharmaceuticals can disrupt aquatic ecosystems in rivers and lakes, as well as impact human and animal health. Consequently, heterogeneous photocatalysis stands as a promising technology to mitigate or even eradicate these pollutants from aquatic systems. Silver phosphate crystals (Ag3PO4) exhibit exceptional photocatalytic and bactericidal properties. Ag3PO4 crystals were synthesized using the precipitation method, followed by a 6h heat treatment at temperatures of 100, 200, 300, 400, and 500 °C. X-ray diffraction data showcase structures with outstanding crystallinity, which remain stable even under fluctuating temperatures. Scanning electron microscopy images reveal shifts in material morphology as the temperature rises. Diffuse reflectance spectroscopy unveils optical band energy values ranging from 2.33 to 2.41 eV for the materials. Conversely, both Raman and infrared spectra indicate a reduction in bands linked to phosphate groups. Lastly, Ag3PO4 crystals exhibited remarkable performance in the photodegradation of 17α-ethinylestradiol (EE2) during a 280 min test, achieving removal rates of 77.5 %, 71.2 %, 92.4 %, 82.0 %, 41.3 %, and 92.5 % for crystals treated at 25, 100, 200, 300, 400, and 500 °C, respectively. Ag3PO4 crystals treated at 200 and 500 °C demonstrated the highest photocatalytic efficiency, attributed to their enhanced structural and morphological properties.

Effect of cation disorder on basic parameters of ZnFe2O4 nano-particles synthesized by honey mediated solution combustion technique

Nanotechnology contracts by the invention and practice of material using nanoscale dimension. Nanoscale measurement delivers nano-particles a bulky surface area (S) to volume ratio, hence very specific properties. Bulk zinc ferrite (ZnFe2O4) exhibits anti-ferromagnetism, with Néel temperature of 10K, is paramagnetic at room temperature. It displays normal spinel structure with Zn2+ has exclusive tetrahedral - A site preference, whereas Fe3+ ions occupy the octahedral - B site. Cationic disorder induced fractional overturn of the spinel structure, owing to partial immigration of Fe3+ ions from B to A site can prompt ferrimagnetism in nano zinc ferrite. Due to the large ratio of toxic chemicals and extreme environment employed in the chemical and physical production of these ferrites, green methods employing the use of bacteria, plants fungus have been adopted. Present work reports comprehensive study of the synthesis, structural and magnetic investigation of room temperature ferrimagnetism in ZnFe2O4 nanoparticles, prepared by sol gel auto-combustion mode and green synthesis method. Effect of conventional thermal annealing (ann. at 600oC for 3 hours) on magnetic properties is also reported. The structural and magnetic characteristics of as prepared and annealed ZnFe2O4 samples were determined by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). XRD confirms the formation of single-phase nano-crystalline cubic spinel structure of the samples.

Plasma assisted pulsed laser deposition of WO3 films for thermochromism

Tungsten trioxide (WO3) is one of the extensively investigated transition metal oxides. Its excellent chromogenic properties make WO3 promising for a variety of scientific and technological applications. We report a new method for reactively depositing WO3 films by plasma assisted pulsed laser deposition that combines electron cyclotron resonance microwave discharge and pulsed laser ablation. The plasma formed during film deposition was spectroscopically characterized by optical emission measurement, revealing that the plasma contains high density of reactive gaseous oxygen and tungsten species which are essential for efficiently synthesizing WOx precursors and depositing WO3 films. The structure of the deposited films and the effect of post-deposition thermal annealing on the film structure were characterized by X-ray diffraction and Raman spectroscopy. The as-deposited WO3 film appears amorphous in nature. Annealing resulted in the growth of crystalline grains and the improvement in the crystallinity of monoclinic WO3. Optical properties of the prepared WO3 films were studied by measuring ultraviolet–visible–near infrared transmission spectra. With the increase of annealing temperature, the WO3 films show a continuous change in color, decline in transmittance, red shift in absorption edge, and narrowing in band gap, clearly manifesting the thermochromic features of the deposited WO3 films.