Increasing Substrate Temperature Research Articles

Reaxff MD Analysis of Substrate Material Properties into Oxide Films during Thermal Oxidation Process of Group IV Semiconductor Materials

In a rapidly changing world, the evolution of semiconductors and information processing technology is unstoppable and will continue to be a source of international competitiveness in the future. Semiconductor devices are becoming increasingly miniaturized for higher integration. Therefore, the manufacturing process is becoming more complex and delicate. Oxidation is the first step in semiconductor fabrication, and the formed oxide film serves as a protective film against impurities, thus affecting the accuracy of subsequent microfabrication processes. An experimental oxidation model for Si, a commonly used group IV semiconductor substrate material, has been clarified by B. E. Deal et al. 1. In recent years, device design based on material properties has become mainstream, and Ge is attracting attention as a next-generation semiconductor material. However, the effects of parameters such as atomic species and surface orientation of the substrate material on oxide film quality and oxygen diffusion still need to be investigated. Therefore, a systematic and atomistic understanding of the reaction-diffusion phenomenon of oxygen into the substrate and a better understanding of the oxide film formation process will contribute to the optimization of actual production conditions.In this study, the influence of substrate material properties on oxide film quality and oxygen diffusion during the oxidation process was simulated using the Reactive force-field Molecular Dynamics (ReaxFF MD) method, which can simulate the behavior of atoms by considering dynamics and chemical reactions. The parameter set of the Si/Ge/O/H system developed by Nayir et al.2 was used in this study. In the calculation system, a substrate consisting of single elements of Si or Ge was placed in the lower part of the system, while the upper part of the system was vacuumed and O2 was injected at regular time intervals.The radial distribution function (RDF) analysis between O-O atoms on Si (100) and Ge (100) substrates at 500 K and 1500 K is shown in Figure 1. The RDF is denoted by g(r) and is a quantitative function of the probability of the presence of other atoms at a certain distance from an atom. Figure1. (a) is the RDF for a Si substrate. Large peaks appeared at 1.32 Å and 2.52 Å, indicating a specific strong interaction force between oxygen atoms on the Si substrate. From the snapshot of the calculation system in the graph, oxygen atoms are deposited more on the substrate surface, confirming the same trend as in the model of B.E. Deal et al. Since the calculations were validated by obtaining qualitatively the same trend as the existing oxidation model for the Si substrate, the calculations for Ge were also performed using the same simulator. The RDF results for the Ge substrate are shown in Figure 1. (b) shows that the oxygen atoms are relatively more deeply buried than in the Si substrate since the peaks are located at positions where the distance r between the oxygen atoms is large. The second peak at Ge 500 K in (3) changed from 2.52 Å to 3.72 Å due to the difference in bond length between Si and Ge. In (4), oxygen atoms are present to some extent at any distance, suggesting that oxygen diffusion is more intense on the Ge substrate than on the Si substrate.As the temperature was increased for each substrate material, the peak at 1.32 Å at 500 K became smaller at 1500 K. In (1) and (3), 1.32 Å is the distance between atoms of O2 molecules bonded to the substrate, indicating that the O-O bond is preserved at 500 K. At 1500 K in (2) and (4), the peaks at 2.52 Å and 3.72 Å (O-substrate-O bond) become larger, and the peak at 1.32 Å becomes smaller. This indicates dissociation of O2 at the surface with increasing substrate temperature, and it is more likely to occur on Ge substrates than on Si substrates. Thus, differences in the reactive diffusivity of oxygen for each substrate material were confirmed. The results suggest that the reaction and diffusion of oxygen atoms are slow on Si substrates and that multiple oxygen atoms move in layers, while on Ge substrates, the incident O2 dissociates one after another, and oxygen atoms may diffuse one after another.References B. E. Deal and A. S. Grove, J Appl Phys, 36, 3770–3778 (1965).N. Nayir, A. C. T. Van Duin, and S. Erkoc, Journal of Physical Chemistry C, 123, 1208–1218 (2019). Figure 1

Conventional epitaxy of NiO thin films on muscovite mica and c-Al2O3 substrates

Fiber-textured and epitaxial NiO thin films were deposited on Si(100), c-Al2O3, and muscovite mica(001) substrates using reactive magnetron sputtering at substrate temperatures of 300 °C and 400 °C, to investigate the effect of film thickness and substrate temperature on epitaxial growth of NiO films. The as-deposited films exhibited a face-centered cubic structure with a larger lattice constant, attributed to strain induced during the sputtering process. With an increase in substrate temperature to 400 °C, the d-spacing decreased due to strain release, approaching the NiO bulk value for the thickest film. The NiO film grown on Si(100) displayed fiber texture. On c-plane sapphire, NiO thin films exhibited twin domains and three-fold symmetry, consistent with expected crystallographic orientation relationship for NaCl-structured materials on sapphire:(111)NiO∥(0001)Al2O3and[01¯1]NiO∥[1¯010]Al2O3, [011¯]NiO∥[101¯0]Al2O3. On muscovite mica(001) substrates, the observed epitaxial shows that the mechanism is conventional epitaxy, rather than van der Waals epitaxy, consistent with the epitaxial growth of the non-layered non-van-der-Waals compound NiO. The epitaxial relationship was identified as of (111)NiO∥(001)Mica and [01¯1]NiO∥[010]Mica, [011¯]NiO∥[01¯0]Mica.

Mechanism of heterogeneous substrate stimulating growth for nickel-based single crystal superalloy

Minimizing the deviation of single-crystal (SX) primary orientation can significantly enhance the yield rate, service life, and performance of turbine blades or castings. Substrate stimulating method controls the deviation of <001> orientation within a narrower range by inducing nucleation of specific crystalline planes. In this study, during heterogeneous substrate stimulating growth for DD5 superalloy, the mechanism by which lattice misfit influences the orientation of new crystals were systematically elucidated. The study variables include substrate materials ((001) SX DD5, polycrystal DD5, and polycrystal Cu), orientations ((001), (101), (111)), cooling rates, and temperature. The target oriented grains were increased when the lattice misfit between the substrates of varying materials or orientations and new crystal were minimized. The melt undercooling decreases as the substrate cooling rate decreases, which can only stimulate the nucleation of crystalline planes with lower energy barriers (characterized by minimal lattice misfit). The thermal gradient in the melt decreases and the lattice misfit simultaneously decreases as the substrate temperature increases, these two factors jointly contribute to stimulating grains with lower lattice misfit. The substrate temperature leads to more pronounced variation in the proportion of target grains, than does the substrate cooling rate.

Influence of substrate temperature on plasma-enhanced chemical vapor deposition to improve the surface flashover performance of epoxy resin

Abstract Epoxy resin composites are widely used as insulating and supporting materials in high-voltage power systems due to their excellent mechanical and electrical properties. However, long-term operation under high-voltage direct current induces surface flashover. Plasma enhanced chemical vapor deposition (PECVD) has been shown to effectively improve the surface insulation properties of epoxy resin. However, the influence of substrate temperature on the film composition, stress, morphology, and surface flashover performance remains unclear. This study uses PECVD to treat epoxy resin, enhancing its surface flashover performance. Tetraethoxysilane is used as the precursor to deposit nano-scale SiO x films on the epoxy resin surface. The effects of different substrate temperatures on the surface flashover voltage, physicochemical properties, and mechanical properties of epoxy resin are characterized. The results show that the surface flashover voltage increases and then saturates with increasing substrate temperature, improving by 27.4% at 60 °C compared to untreated samples. The surface roughness of epoxy resin decreases after plasma deposition, while highly oxidized silicon-containing functional groups are introduced. When the substrate temperature increases from 20 °C to 60 °C, the interfacial bonding strength improves by 25.9%. This study provides a simple, efficient, and controllable method to enhance the surface flashover performance of epoxy resin, promoting the application of this technology in engineering practice.

Influence of substrate temperature and Mn/Y co-doping concentration on the morphological, structural and optical properties of CuO nanostructured film deposited by the spray pyrolysis method

In this work, the effect of substrate temperature (ST) during deposition and dopant amount of Mn (1,3,5, and 7 %) and Y(3 %), (Mn/Y), on the physical properties of copper oxide (CuO) the nanostructured film were analyzed using different diagnostic tools. The pure and (Mn, Y) co-doped CuO thin films were deposited by the spray pyrolysis method, which is effective and easy to apply for any substrate. Deposited pure and (Mn,Y) co-doped CuO nanostructured films were investigated by X-ray diffraction (XRD), UV–Vis spectroscopy, and Field emission scanning electron microscopy (FESEM) techniques to analyze the influence of ST and co-doping on the structural, morphological, and optical properties of prepared films. The FESEM is used to visualize nanostructures on the surface of the film. Also, it is observed that the surface morphology of CuO film changes from a spherical-like to a nanocloumnar-like structure with increasing substrate temperature. The XRD diffractograms confirm the monoclinic crystal structure of CuO, in polycrystalline nature for all deposited films. UV–Vis spectra suggest changing the optical absorbance and the band gap of the pure and Mn/Y co-doped CuO nanostructured films. In the first investigation of this study, the better substrate temperature was obtained as 400 °C according to results. In the second part, the effect of Y and Mn doping with different content was analyzed for the CuO film deposited at the chosen ST of 400 °C. There is no observable crystalline structure variation in the XRD pattern, but the size of nanostructure and dislocation density are varied with Mn/Y co-doping. FESEM micrographs confirm the impact of the co-doping concentration on the size, shape, and surface properties of CuO nanostructured film. In addition, the optical band gap increases with Mn doping up to 3 % of Mn content and it was determined as 2.69 eV for the sample 3Mn/Y@CuO nanostructured film. The obtained results suggest that the substrate temperature has an important impact on the physical properties of the spray deposited CuO nanostructured film, and the structural, optical, and surface properties of the CuO nanostructured films may be engineered by Mn/Y doping concentration.

Preparation and Characterization of Nanostructured ITO Thin Films by Spray Pyrolysis Technique: Dependence on Annealing Temperature

Transparent conducting oxides (TCOs) like Indium tin oxide (ITO) have wide attention from all scientists which have low resistance and high visible light transmittance, used as transparent electrodes in many optoelectronic devices such as liquid crystal displays, touch screens, light emitting diodes, and solar cells. In this research, the relationship between the crystallization, optical transmittance, and surface roughness of nanostructured ITO thin films and the change in annealing temperature was investigated. To enhance the efficiency of this material in optoelectronic applications, both the optical transmittance in the visible region and the crystallite size must be increased. These results can be obtained by the heat treatment of the films. Nanostructured ITO thin layer films have been successfully prepared at a substrate temperature equal to (350)℃ by chemical spray pyrolysis (CSP) technique. The physical characterizations of nanostructured ITO thin layer films were investigated at different annealing temperatures (400,450 and 500)℃. The presence of diffraction peaks indicates that the as-deposited and post annealed films are polycrystalline cubic structure and the peak (400) is a preferred growth orientation. For all samples the value of intensity of diffraction peaks increases with increasing substrate temperature. The crystallite size of nanostructured ITO thin films is strongly related to the annealing temperature. The crystallite size estimated from XRD was found to rise with rising annealing temperature. The surface roughness of nanostructured ITO thin layer films increases with rising annealing temperature. High values of transmittance have been measured in the visible region 550 nm equal to (70, 82, 84 and 88)% corresponding to annealing temperature (350,400,450 and 500)℃ respectively.

Enhanced adhesion and wear resistance of DLC films on AZ31 alloy achieved with high bias voltage

Diamond-like carbon (DLC) films exhibiting high adhesion and exceptional wear resistance were successfully applied onto the AZ31 surface without a adhesive layer. The structural features of the film were examined utilizing Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Raman spectroscopy. Mechanical properties were evaluated through Nano-indentation testing, while adhesion was evaluated using a scratch tester. Residual stress was determined by Stoney's equation. The results indicate that utilizing a high substrate bias ranging from −500 to −800 V, results in the presence of multiple craters and dislocations, which contribute to the enhancement of high residual compressive stress and hardness in the DLC film. The heightened compressive stress effectively embeds carbon atoms into the surface of the soft AZ31, creating an interfacial layer that significantly improves adhesion and wear resistance of the film. In contrast, at moderate bias levels with a range from −300 to −500 V, an increase in substrate temperature leads to the expansion and discontinuation of adjacent layers that decreases the mechanical properties, adhesion, and wear resistance of the film. When at low bias levels between 0 and -300 V, the hardness, crack resistance, residual stress, and wear resistance all increase with increasing of bias. Additionally, in this work, the mechanisms of adhesion and wear for the biased film are analyzed.

Epitaxial growth and characterization of copper gallate (CuGa2O4) thin films by pulsed laser deposition

High-quality crystalline copper gallate (CuGa2O4) thin films were grown on c-plane sapphire substrates using the pulsed laser deposition (PLD) technique by optimizing the growth parameters (i.e., temperature, oxygen chamber pressure, and laser energy density). The obtained XRD patterns validated that the preferred orientation of the crystalline CuGa2O4 thin film is along the [111] direction, and the crystallinity of the films improved with increasing substrate temperature while maintaining a constant O2 pressure, as assessed by measuring the full width at half maximum (FWHM) of the prominent (222) plane. Reducing the oxygen pressure leads to the emergence of β-Ga2O3 peaks rather than the CuGa2O4 peaks due to the incomplete oxidation of copper (Cu). Subsequent XRD phi (φ) scans revealed a sixfold rotational symmetry of CuGa2O4 and a 30° epitaxial relationship between the film and the sapphire substrate. X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of Cu1+, Cu2+, and Ga3+ oxidation states in the films. Increasing laser energy density resulted in the complete oxidation of Cu and an increase in the film thickness from 51.8 nm to 183.4 nm. The direct bandgap of CuGa2O4 films was determined to be approximately 4.50 eV by analyzing the UV–Vis absorbance spectra using the Tauc equation. The refractive index was found to be approximately 2.05 ± 0.01 based on the spectroscopic ellipsometry data. While the impact of increasing laser energy density was negligible on the parameters such as crystal structure, rotational symmetry, oxidation states of gallium (Ga), oxygen (O), bandgap, and refractive index of CuGa2O4 thin film, notable alterations in the oxidation state of Cu and film thickness were observed. The surface roughness (Rrms) measured from AFM images showed a strong correlation with the values derived from ellipsometry analysis.

Effect of gamma and ultraviolet irradiation on the optical properties of copper oxide nanostructured thin films by chemical spray pyrolysis

Nanostructured copper oxide thin films were grown by the chemical spray pyrolysis (CSP) technique. Utilizing a homemade spray pyrolysis method, thin films are created. This work investigates the role of gamma ray and ultraviolet ray irradiation on the optical properties of copper oxide thin films(CuO) prepared. In this framework, used different substrate temperatures 300 °C, 350 °C, and 400 °C for the layers were grown on glass for the prepared CuO thin films. UV–visible spectrometer, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction patterns(XRD) measurements were all used to characterize the samples. The UV–visible spectroscopy showed a decrease in the absorbance and the optical band gap of CuO thin films with the increase in the higher substrate temperatures before irradiation. Additionally, surface plasmon resonance peaks (λSPR) were observed at 329 nm. FE-SEM images revealed spherical-like shapes with an average diameter range of 48 nm,56 nm and 62 nm for 300 °C, 350 °C, and 400 °C, respectively. An analysis of X-rays revealed that CuO thin films contained the crystallographic planes of a monoclinic and an orthorhombic crystal system. Also, when samples were exposed to gamma and UVC radiation, the absorbance intensity of CuO thin films increased, but the optical band gap decreased.

Influence of magnetron sputtering process parameters on the morphology of palladium thin films: An empirical study

Abstract The heightened initial energy of deposited atoms during the magnetron sputtering process alters the conventional rules of structure zone transformation for film morphology, posing challenges in fabricating Pd films with specific morphologies. This study aims to elucidate the impacts of substrate temperature and sputtering power on the morphology of Pd films and to determine the magnetron sputtering process parameters for preparing Pd films within a typical structure zone. Pd thin films were fabricated by using magnetron sputtering under varying substrate temperatures and sputtering powers. The morphologies of the films were examined through Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). With increasing substrate temperature, the structure zone of Pd films transitions from Zone T to Zone 2, and subsequently to Zone 3. Given that initial energy enhances the diffusion capability of deposited atoms, the threshold temperature for structural zone transformation of Pd films prepared by magnetron sputtering is lower than the critical value suggested by the Structure Zone Model (SZM). While sputtering power does not critically affect the structure zone of Pd films, it influences grain size and preferred orientation. The substrate temperature is the decisive factor affecting the structural zone of thin films, with the critical temperature for structure zone transformation in magnetron sputtering being lower than that proposed by the Structural Zone Model (SZM). Furthermore, the research has determined the magnetron sputtering process parameters necessary for fabricating Pd thin films with specific structure zones. This study paves the way for subsequent enhancements in the hydrogen sensitivity of palladium thin film sensors through morphology control.

Intricate Evaporation Dynamics in Different Multidroplet Configurations.

We experimentally investigate the evaporation dynamics of an array of sessile droplets arranged in different configurations. Utilizing a customized goniometer, we capture side and top view profiles to monitor the evolution of height, spread, contact angle, and volume of the droplets. Our results reveal that the lifetime of a droplet array surpasses that of an isolated droplet, attributed to the shielding effect induced by neighboring droplets, which elevates the local vapor concentration, thereby reducing the evaporation rate. We found that lifetime increases as droplet separation distance decreases at a fixed configuration and substrate temperature. It is observed that the lifetimes increase with the number of droplets. We observe a decrease in lifetimes, following a power law trend, with increasing substrate temperature, with the shielding effect diminishing at higher substrate temperatures due to natural convective effects. We also observe a generalized behavior for the centrally placed droplet across various separation distances and substrate temperatures. This arises from different droplet configurations and substrate temperatures, which modify the local vapor concentration around the droplets without significantly impacting the contact line dynamics. Additionally, the experimental results are compared with a diffusion-based theoretical model that incorporates the evaporative cooling effect to predict the lifetime of the central droplet within the array. We observe that the theoretical model satisfactorily predicts the lifetime of the droplet at room temperature. However, for high-temperature cases, the model slightly overpredicts the evaporative lifetimes.

Substrate Moisture and Temperature Effects on Limestone Reaction Rate in a Peat-Based Substrate

ABSTRACT Lime reaction rate in a container substrate is influenced by temperature and moisture, which are factors that vary between batches of substrate during manufacturing, storage, and crop production. The effects of temperature and moisture on the duration required to achieve a stable substrate-pH are useful information for substrate companies and growers, as well as a key component when modeling lime reaction over time. The pH of a 70 peat : 30 perlite (by volume) substrate was quantified over time under a range of different storage temperature (1.9 to 33.3°C) and substrate volumetric water content (VWC, 0.168 to 0.568 L of H2O/L of substrate). The lime source was a horticultural dolomitic carbonate limestone screened to the fraction that passed through a 100 US mesh but was retained on a 200 US mesh (0.075–0.15 mm) incorporated at 2.67 g·L−1 of substrate. Experiments provided two data sets for calibration and validation. Lime reaction rate increased with increasing substrate temperature and substrate moisture level. The duration required to reach a target substrate-pH value of 6.0 was used to indicate 90% of maximum pH effect from lime. Duration varied from 4 days with the combined high temperature (20.6 and 33.3 °C) and high VWC (0.468 and 0.568 L H2O/L of substrate) to 53 days with low temperature (1.9 °C) and low VWC (0.168 L H2O/L of substrate) for the calibration data set. At an example low VWC of 0.168 L of H2O/L of substrate, the duration required to reach substrate-pH 6.0 at 1.9, 7.8, 10, 20.6, and 33.3°C was 53, 38, 34, 23, and 17 days, respectively. Similarly, if the temperature was held constant at 33.3°C, reducing VWC from 0.568 L H2O/L to 0.128 L H2O/L would decrease lime reaction rate from 100% to 21%, requiring five times the duration to reach an equilibrium pH. Results can be used to compare the relative effects of moisture and temperature on lime reaction rate for substrate manufacturers and growers.

Oxidation characteristics of copper oxide thin films deposited by direct current sputtering under substrate temperature and post-deposition copper-ion implantation

The oxidation and structural, optical and morphological properties of copper oxide thin films deposited by direct current magnetron sputtering under different substrate temperatures and oxygen (O2) partial pressures, and subsequent 200 keV Cu ion implantation are investigated. The colour of the films progressively changed from yellowish brown to dark brown and oxide phase from Cu2O to Cu4O3 to CuO through mixed phases with increase in oxygen partial pressure from 20 to 90 % of the working pressure and substrate temperature from room temperature (27 °C) to 350 °C. The rate of oxidation and crystallinity of the films substantially increased with increase in substrate temperature. The ion implantation in the room temperature deposited films produced significant crystallization and decrystallization with respect to the ion fluence, and that in 350 °C substrate temperature deposited films instigated Cu-rich phase. The substrate temperature and ion implantation engendered distinctive red shift of the absorption edge and prevalent changes in the interference patterns in the optical spectra of the films. The calculated direct band gap values of the films are in the range of 1.7 to 2.42 eV, which decreased to the range of 1.65 to 2.17 eV on ion implantation. The indirect band gap of the films with predominant Cu4O3 and CuO phases are in the range of 1.23 to 1.49 eV. The refractive index and extinction coefficient of the films at 1100 nm are in the range of 2.1 to 2.5 and 0.03 to 0.12, which increased to the range of 3 to 7 and 0.2 to 0.45, respectively, on ion implantation. The films displayed agglomeration of the particles and directional growth of the agglomerates with respect to O2 partial pressure and substrates temperature, and increase in the size of the particles / agglomerates, and rough surface morphology on ion implantation.

Monomer diffusion tendencies in complex-shaped materials by vapor deposition polymerization

Conformal coatings are crucial for various applications. In this study, we investigate polyurea coatings on complex-shape polytetrafluoroethylene (PTFE) membranes using vapor deposition polymerization. The diffusion mechanism involves monomer adsorption and desorption on PTFE fibers, enhanced by an increased substrate temperature, facilitating monomer diffusion. A system pressure of 100 Pa promoted monomer collisions, forming oligomers with lower desorption rates, aiding polymer thin-film formation. The combination of high substrate temperature for diffusion and gas-phase oligomer formation resulted in uniform polyurea coatings across the PTFE membrane. A non-exhaustion method provided an extensive monomer diffusion, achieving a thorough polyurea deposition throughout the membrane structure.

Thermal response of a sky island lizard to climate change

ABSTRACT Climate change models for lizards assume that changes in its climate envelope (the climatic conditions that define a species’ distribution at a given time) are due to species being unable to withstand temperature increases, but this assumption has not been tested to assess its robustness. Studies on lizards’ preferred temperature in thermal gradients can fill this gap. Our aim is to assess the response to climate change of Liolaemus nigroviridis, a sky island lizard, by (i) assessing its thermal preference in a thermal gradient; and (ii) estimating which localities inhabited by the species would exhibit hours of activity restriction (Hr) implying an increased risk of local extinction. The results of this research and the information obtained from the literature concur on the consequences that climate change will have on the thermal ecology of Liolaemus from specialized habitats; the increase in substrate temperature is indeed a factor determining its presence. We also have information that not all populations of L. nigroviridis will be influenced in the same way; the northern populations will be more affected in terms of thermal restrictions and, in addition, Hr will increase at higher elevations. We propose that this be considered for future management for this species.

INFLUENCE OF SUBSTRATE TEMPERATURE ON THE MICROSTRUCTURE AND PROPERTIES OF CoCrFeNiNbx HIGH ENTROPY ALLOY COATINGS

This work studies the effect of the substrate temperature on the microstructure and properties of CoCrFeNiNbx high entropy alloy (HEA) coatings fabricated by magnetron sputtering. The results indicate that all three CoCrFeNiNbx HEA coatings were composed of a simple FCC solid solution with a columnar structure. As the substrate temperature increased, Nb content in the FCC matrix increased while the grain size first decreased and then increased. Accordingly, CoCrFeNiNbx HEA coatings exhibited an increasing micro-hardness and a decreasing fracture toughness with the increasing substrate temperature. Moreover, CoCrFeNiNbx HEA coating deposited at 200∘ had better corrosion performance, which was due to its better surface quality and denser columnar structure compared to the other two coatings.

Investigation of microstructural and mechanical properties of sputter-deposited Ni3Al films at different substrate temperatures

Ni3Al films were deposited on silicon (100) substrate at different substrate temperatures by DC magnetron sputtering. The evolution of phase, microstructure, surface topography and mechanical properties have been investigated as a function of substrate temperature via XRD, FE-SEM, AFM and nanoindentation respectively. Results revealed that the deposited film possessed the preferred orientation of (111) whereas the crystallite size increased and grain size decreased with increase in the substrate temperature. The results of nanoindentation showed that the hardness of the film increased up to 400 °C after which it abruptly decreased. Maximum hardness of ∼13 GPa was achieved when the film was deposited at the substrate temperature of 400 °C. The surface roughness of the film increases simultaneously with the increase in substrate temperature whereas the static contact angle and mechanical properties declined significantly for the film deposited at the substrate temperature of 600 °C. This study reflects the impact of substrate temperature on the evolution of phase, microstructure and mechanical properties of Ni3Al coatings deposited at different substrate temperatures.

Optoelectronic properties of perovskite thin films derived from lead sulfide via radio frequency magnetron sputtering: effect of the substrate temperature

Methylammonium lead iodide (CH3NH3PbI3; MAPbI3) films were fabricated from sputtered lead sulfide (PbS) films prepared at various substrate temperatures according to the Thornton structural zone model. PbS films were converted to lead iodide (PbI2) and finally to MAPbI3 in a two-step gas-phase reaction. The increase in substrate temperature caused the morphology to change to fibrous interconnected grains, which played an important role in improving the optoelectrical properties of perovskite films. Moreover, enhanced charge transport of MAPbI3 films was observed owing to the fibrous interconnected PbI2 precursor, which was confirmed by a higher absorption coefficient and longer carrier lifetime.

Molecular dynamics simulations and analyzation of Cu deposited on stainless steel substrate surfaces

Copper (Cu) is used in integrated circuits and microdevices and has the potential to replace aluminum alloys due to its low resistivity, strong electromigration properties, and affordability. However, a significant factor that influences the performance of devices at the micro and nano scales is the surface roughness of the deposits. LAMMPS software is employed to simulate the deposition Cu on an ideal state for a stainless-steel substrate. The deposition process and deformation behavior of Cu on the surface and the roughness of the deposition surface are analyzed. Taking the deposition process of Cu atoms as an object, the effects of different atomic numbers, different temperatures, different velocities, and different heights on the surface roughness of the deposits were investigated. The atomic structure composition of the deposition velocity is analyzed, and the radial distribution function is analyzed to reveal the microscopic mechanism of action. The results of the theoretical deposition and analysis show that the surface roughness increases with the number of atoms deposited and decreases with increasing substrate temperature. The surface roughness first decreases and then, after some fluctuation, stays constant at a particular level with increasing velocity. Additionally, as the deposition height increases, the surface roughness reduces. There is a nonlinear relationship between the various components and the deposited surface roughness. The surface quality of deposits can be improved during the deposition process by optimizing the deposition parameters of deposition atoms, substrate temperature, deposition velocity, and deposition height.

Enhanced insights into paired droplet evaporation dynamics on heated substrates: Unveiling the role of convection and diffusion

This study aims to examine the evaporation characteristics of single and multiple droplets on a heated substrate. By utilizing a multi-syringe pump, deionized water droplets were precisely deposited on a copper substrate, ensuring uniformity and accuracy in the experimental setup. The shadowgraph technique was instrumental in determining the droplet contact angle and volume with exceptional clarity and precision. This work numerically predicted the vapor distribution and local evaporation flux across the liquid-air interface. A critical assessment of the role of natural convection at varying substrate temperatures was performed by contrasting diffusion-only cases with those incorporating both diffusion and convection. The findings reveal that the droplet pinning motion remains unchanged across different distances between droplets and various substrate temperatures, indicating that neither vapor accumulation nor substrate temperature significantly influences the behavior of the contact line. Notably, the study identifies a reduction in the evaporation rate of closely positioned paired droplets, related to a shielding effect. However, with increasing substrate temperature, the role of natural convection was found to become more pronounced, effectively reducing the overall evaporation time for both single and paired droplets, thus facilitating a quicker evaporation process.