Growth Behavior Of Films Research Articles

Nanostructured thin film SrCo0.8Nb0.1Ta0.1O3-δ cathode for low-temperature solid oxide fuel cells

Nanostructured perovskite-type cathodes are considered essential for the realization of high-performance solid oxide fuel cell (SOFC). However, perovskite-type cathode materials demonstrating high electrochemical performance in the low-temperature operating region below 600° are limited. SrCo0.8Nb0.1Ta0.1O3-δ (SCNT) has been identified as a material that exhibits exceptional performance even in the low-temperature region of 500 °C. This paper investigates the growth behavior and electrochemical properties of SCNT thin films for SOFC cathode applications. Pulsed laser deposition (PLD) was employed to fabricate SCNT films under varying chamber pressures: 5 mTorr, 75 mTorr, and 150 mTorr. Systematic analysis through X-ray diffraction and X-ray photoelectron spectroscopy indicates that the structural factors of PLD perovskite oxide nanostructures, such as grain size, porosity, and in-plane connectivity, are intricately influenced by deposition pressure without affecting crystallinity and chemical composition. The findings demonstrate that achieving desired electrochemical properties of the nanostructured PLD perovskite oxide necessitates specific optimal deposition conditions for these structural parameters. Electrochemical assessments revealed an optimal nanostructure achieved with 1200 nm at 75mTorr, demonstrating enhanced power density due to increased active reaction surface area, which significantly reduced resistances in ohmic and polarization. Excessive thickness, however, led to performance decline due to film delamination. Integration of optimized SCNT films into an anodic aluminum oxide supported thin film SOFC exhibited 907 mW/cm2 of peak power density at 550 °C.

Ultrathin Metal Films with Low Resistivity via Atomic Layer Deposition: Process Pressure Effect on Initial Growth Behavior of Ru Films

Ultrathin Metal Films with Low Resistivity via Atomic Layer Deposition: Process Pressure Effect on Initial Growth Behavior of Ru Films

Investigating the growth behavior of titanium dioxide film prepared with direct current pulsed–magnetron sputtering technology

The direct current pulsed magnetron sputtering technology is employed to deposit TiO2 film onto the glass and Si(100) substrates. After annealing treatment, TiO2 film displays anatase (001) preferential orientation. The growth behavior of deposited and annealed TiO2 films is investigated. The results show that in the original stage, TiO2 film growth behavior is in Volmer–Weber mode, which is dominated by the diffusion effect. Considering the rivalry between TiO2 crystal nuclei, both crystallographic orientation and diffusion effects jointly dominate the film growth behavior in the rest stage. More importantly, the annealing treatment resulted in the coalescence of TiO2 crystal nuclei, as well as the growth of TiO2 crystal nuclei. Most importantly, after coalescence and growth of TiO2 nuclei, the anatase [001] crystal orientation of TiO2 grains remains the same as the normal direction of TiO2 film. Finally, after annealing treatment, TiO2 films comprise anatase (001) preferential orientation.

Grain engineering of solution-processed Sb2S3 thin film by tuning precursor fabrication environments

Antimony sulfide (Sb2S3) has garnered significant attention recently due to its remarkable photovoltaic properties and low toxicity. However, the conventional physical vapor deposition approach faces challenges in achieving high-quality films due to Sb2S3 having a quasi-one-dimensional nanoribbon structure. In contrast, solution-processed Sb2S3 thin films have shown improved photovoltaic behavior, offering a low-cost and scalable fabrication method. Nonetheless, the sensitivity of the solution process to the chemical composition of the precursor poses a challenge, often requiring noble gas protection to prevent exposure to toxic solvents or moisture-sensitive chemicals. Despite this, the impact of precursor fabrication conditions on film growth behavior remains unexplored. In our study, we investigate how different processing atmospheres of precursors, namely nitrogen (N2) and air, affect grain growth and the associated optical and electronic performance of Sb2S3 thin films. Our findings reveal that the presence of oxygen in the precursor can hinder grain growth by obstructing surface integration sites, resulting in undesired (hk0) orientation and even the formation of Sb2O3 on the surface of the Sb2S3 films, despite identical post-deposition conditions. This research sheds light on how the ambient conditions during precursor preparation can influence grain engineering, thereby providing valuable insights for controlling the grain size and producing high-quality Sb2S3 absorber films.

Surface diffusion effects on the system and the film properties of a Ziff–Gulari–Barshad type growth model

Surface diffusion stands as a fundamental process influencing the dynamics and thermodynamics of surface reactions, playing a pivotal role in the behavior of heterogeneous catalysis and thin film growth. To enhance our understanding, we extend the Ziff-Gulari-Barshad (ZGB) growth model by incorporating the diffusion of reactants involved in film formation. Initially, in the realm of heterogeneous catalysis, we compare our findings with an extended ZGB model that accounts for reactant diffusion. We analyze the shift in phase transition positions, induced by diffusion, in comparison to the original ZGB model. Subsequently, we integrate the film growth aspect. Across all examined cases, diffusion fails to adequately preserve the dynamic features of the extended ZGB model, resulting in poisonous states. Our conclusion underscores the dual impact of diffusion: firstly, it diminishes the film growth rate relative to the diffusionless scenario, and secondly, its effective influence on the final film height is evident only when considering hops in different layers. This assertion is validated through computations where diffusion with hops in different layers is either permitted or prohibited.

Hardness Distribution and Growth Behavior of Micro-Arc Oxide Ceramic Film with Positive and Negative Pulse Coordination.

Micro-arc oxidation (MAO) is a promising technology for enhancing the wear resistance of engine cylinders by growing a high hardness alumina ceramic film on the surface of light aluminum engine cylinders. However, the positive and negative pulse coordination, voltage characteristic signal, hardness distribution characteristics of the ceramic film, and their internal mechanism during the growth process are still unclear. This paper investigates the synergistic effect mechanism of cathodic and anodic current on the growth behaviour of alumina, dynamic voltage signal, and hardness distribution of micro-arc oxidation film. Ceramic film samples were fabricated under various conditions, including current densities of 10, 12, 14, and 16 A/dm2, and current density ratios of cathode and anode of 1.1, 1.2, and 1.3, respectively. Based on the observed characteristics of the process voltage curve and the spark signal changes, the growth of the ceramic film can be divided into five stages. The influence of positive and negative current density parameters on the segmented growth process of the ceramic film is mainly reflected in the transition time, voltage variation rate, and the voltage value of different growth stages. Enhancing the cathode pulse effect or increasing the current density level can effectively shorten the transition time and accelerate the voltage drop rate. The microhardness of the ceramic film cross-section presents a discontinuous soft-hard-soft regional distribution. Multiple thermal cycles lead to a gradient differentiation of the Al2O3 crystal phase transition ratio along the thickness direction of the layer. The layer grown on the outer surface of the initial substrate exhibits the highest hardness, with a small gradient change in hardness, forming a high hardness zone approximately 20-30 μm wide. This high hardness zone extends to both sides, with hardness decreasing rapidly.

Impact of alternating precursor supply and gas flow on the LPCVD growth behavior of polycrystalline 3C-SiC thin films on Si

In this paper, we will provide information on the growth mechanism of 3C-SiC using alternating supply deposition (ASD). SiH4 and C3H8 were introduced successively in a low-pressure chemical vapor deposition (LPCVD) system at 1000 °C, forming a stoichiometric polycrystalline 3C-SiC thin film on Si substrates. We demonstrate the influence of different gas flow rates on thin film properties. In detail, altering the flow rates of the precursors and the carrier gas resulted in changes of the growth rate, the surface roughness, the crystal growth mechanisms as well as the crystal quality. Hydrogen inhibition and passivation are proposed to be the main effects influencing the growth behavior of ASD thin films. Applying ASD to grow 3C-SiC thin films with precursors from low to high flow rates resulted in a transition of different growth mechanisms influencing the surface roughness and grain size. Furthermore, we could prove that ASD is a cyclic step-by-step carbon-assisted redistribution of a prior deposited silicon film. This is shown by contact angle measurements of three differently terminated surfaces during the specific phases of one ASD cycle. High resolution transmission electron microscopy (HRTEM) analysis showed a continuous and homogenous thin film and confirmed the absence of silicon- or carbon-rich layers. ASD enables 3C-SiC thin films with customized properties for tailored micro electromechanical system (MEMS) applications.

Research on the growth behavior of scanning microarc oxide film

Research on the growth behavior of scanning microarc oxide film

Self-Assembly of Organic Semiconductors on Strained Graphene under Strain-Induced Pseudo-Electric Fields.

Graphene is used as a growth template for van der Waals epitaxy of organic semiconductor (OSC) thin films. During the synthesis and transfer of chemical-vapor-deposited graphene on a target substrate, local inhomogeneities in the graphene-in particular, a nonuniform strain field in the graphene template-can easily form, causing poor morphology and crystallinity of the OSC thin films. Moreover, a strain field in graphene introduces a pseudo-electric field in the graphene. Here, the study investigates how the strain and strain-induced pseudo-electric field of a graphene template affect the self-assembly of π-conjugated organic molecules on it. Periodically strained graphene templates are fabricated by transferring graphene onto an array of nanospheres and then analyzed the growth and nucleation behavior of C60 thin films on the strained graphene templates. Both experiments and a numerical simulation demonstrated that strained graphene reduced the desorption energy between the graphene and the C60 molecules and thereby suppressed both nucleation and growth of the C60. A mechanism is proposed in which the strain-induced pseudo-electric field in graphene modulates the binding energy of organic molecules on the graphene.

Physics based optical modeling of iron disulfide thin films

In this work, physics based optical modeling is carried out using iron disulfide thin films deposited by using a plasma-assisted, radio frequency-powered technique. Iron disulfide is a transition metal dichalcogenide material, exhibiting a variety of unique and excellent characteristics. Various characterization techniques are employed to examine the growth rate, film thickness, and behavior of as-grown iron disulfide thin films. Furthermore, the physics based optical modeling was performed using a combination of experimental techniques and computer modeling approaches. The analyzed thin films exhibit a bandgap of around 1.16 eV. The theoretically calculated values of absorbance, transmission, and reflectance show a good match with the experimental measurements. Moreover, a physics based optical model is developed based on the experimental data and is used to calculate the external quantum efficiency and the optically generated current density of the iron disulfide films to provide insight into its use as an absorber layer.

Atomic layer deposition and application of group III nitrides semiconductor and their alloys

Group III nitride semiconductors, such as GaN, AlN, and InN, are an important class of compound semiconductor material, and have attracted much attention, because of their unique physicochemical properties. These semiconductors possess excellent characteristics, such as wide direct bandgap, high breakdown field strength, high electron mobility, and good stability, and thus are called third-generation semiconductors. Their alloy materials can adjust their bandgaps by changing the type or proportion of group III elements, covering a wide wavelength range from near-ultraviolet to infrared, thereby achieving wavelength selectivity in optoelectronic devices. Atomic layer deposition (ALD) is a unique technique that produces high-quality group III nitride films at low temperatures. The ALD has become an important method of preparing group III nitrides and their alloys. The alloy composition can be easily controlled by adjusting the ALD cycle ratio. This review highlights recent work on the growth and application of group III nitride semiconductors and their alloys by using ALD. The work is summarized according to similarities so as to make it easier to understand the progress and focus of related research. Firstly, this review summarizes binary nitrides with a focus on their mechanism and application. In the section on mechanism investigation, the review categorizes and summarizes the effects of ALD precursor material, substrate, temperature, ALD type, and other conditions on film quality. This demonstrates the effects of different conditions on film growth behavior and quality. The section on application exploration primarily introduces the use of group III nitride films in various devices through ALD, analyzes the enhancing effects of group III nitrides on these devices, and explores the underlying mechanisms. Additionally, this section discusses the growth of group III nitride alloys through ALD, summarizing different deposition methods and conditions. Regarding the ALD growth of group III nitride semiconductors, there is more research on the ALD growth of AlN and GaN, and less research on InN and its alloys. Additionally, there is less research on the ALD growth of GaN for applications, as it is still in the exploratory stage, while there is more research on the ALD growth of AlN for applications. Finally, this review points out the prospects and challenges of ALD in preparation of group III nitride semiconductors and their alloys.

Influences of deposition conditions on atomic layer deposition films for enhanced performance in perovskite solar cells

Atomic layer deposition (ALD) is a key technology for fabricating functional layers in perovskite solar cells, as it can deposit pinhole-free films with atomic-level thickness and tunable composition on high-aspect-ratio surfaces. Various deposition conditions have significant effects on the growth, physical, and chemical properties of ALD films, which, in turn, critically influences the performance of associated devices. Here, we review the reaction mechanisms underlying ALD and summarize how variables, such as precursors, deposition temperatures, and substrates, impinge upon the quality of ALD films and the related devices. We emphasize the role of substrate in determining the nucleation and growth behavior of ALD films, which has been overlooked in previous reviews. Finally, we highlight the potential application of ALD in efficient perovskite solar cells in terms of carrier transport, encapsulated, and buffer layers, especially for tandem cells.

Sputter-grown two-dimensional α-MoO3 thin films: Microstructure dependence on growth conditions

Van der Waals epitaxy is an emerging technology for transferring freestanding films grown at high temperatures onto arbitrary substrates using two-dimensional epitaxial layers. This study investigates the microstructure and growth of α-MoO3 thin films prepared via sputtering. Under a narrow deposition temperature range, epitaxial α-MoO3 thin films were successfully grown on SrTiO3 substrates. The films were characterized by a flat surface morphology, corresponding to (0k0) planes, without undergoing reaction with the substrates. To examine the growth behavior and surface morphological variation of the α-MoO3 thin films under various process parameters, we modified the Ar:O2 ratio, working pressure, sputtering power, and crystal structure of the substrates. Transmittance electron microscopy confirmed the epitaxial growth of the α-MoO3 thin films on (001)-oriented SrTiO3 substrates with a two-dimensional layer structure. Finally, we demonstrate the morphological evolution of the α-MoO3 thin films etched in heated water as a function of soaking time. The etching results suggest that the α-MoO3 thin films are promising sacrificial layers for the transfer of large-scale epitaxial thin films onto flexible substrates. External control of the strain states of transferred freestanding thin films by bending or stretching provides new perspectives for the design of flexible or wearable electronic devices.

Growth behavior and mechanism of atomic layer deposition of Ru for replacing Cu-interconnects

The growth behavior and nucleation mechanism of Ru films on various substrates using Ru(EtCp)2 as the precursor and O2 as the reactant were studied systematically. The results show that the Ru films grow rapidly on TiN substrates with almost no incubation time. Different of the segregation and combustion mechanism reported in the previous literature, we established the adsorption and combustion mechanism of ALD-Ru on TiN substrates. SEM and XPS confirmed that the grown Ru films were polycrystalline (average grain size of 16.53 nm, negligible impurities). The Ru films annealed at 600 °C showed significantly low resistivity of 9.73 μΩ•cm, which is one of the lowest resistivities reported in the literature so far. Suppressing electron scattering at grain boundaries is crucial factor to preparing Ru films with low resistivity. The work uses a simple plasma-free technique to construct high-quality Ru films with extremely low resistivity and low impurities, making them one of the ideal candidates for replacing Cu in future ultrafine-pitch interconnects. Furthermore, the work is significant for understanding the growth behaviors and nucleation mechanisms of Ru films on different substrates.

Effect of asphaltenes on growth behavior of methane hydrate film at the oil-water interface

Investigation of the effect of asphaltenes, the natural surfactant in crude oil, on the methane hydrate formation is crucial for flow assurance in deep-water oil and gas field. However, most of recent studies on hydrate growth mainly focused on the impact of artificial and commercial surfactants. Limited attention has been given to the effect of the important natural surfactants presented in crude oil on hydrate film growth, such as asphaltenes. In this study, the influences of dissolved asphaltenes on the properties of oil-water interface and the growth of methane hydrate film were investigated. The morphology of methane hydrate film on the water droplet in the oil phase with different asphaltene concentrations was in-situ visualized in a visual autoclave equipped with microscopic imaging, and the lateral growth rate of the methane hydrate film was measured. The results showed that the addition of asphaltenes could increase the hydrophobicity of the methane hydrate film, inhibit the growth of hydrate, and change the morphology of the hydrate film. The growth rate of the hydrate film was negatively correlated with the asphaltene concentration (0–200 ppm), but stabilized above 200 ppm. In addition, this inhibition effect on the lateral growth rate was negatively correlated with temperature.

Towards modeling of ZrO2 atomic layer deposition at reactor scale based on experimental kinetic approximation

In this study, the growth kinetics of ZrO2 via the atomic layer deposition (ALD) using a mixed alkylamido-cyclopentadienyl zirconium precursor are proposed based on experimental data to evaluate the film growth behavior using reactor-scale simulation. In the ALD process, the hydroxyl concentration on the targeted surface govern the saturated growth per cycle values. However, we found that the bulkiness of remaining ligands on adsorbed species hinders the adsorption of Cp-Zr molecules.Considering this phenomenon, we proposed a kinetic model by calculating the energetic terms to quantify the “steric hindrance effect” of the first elementary surface reaction of CpZr(N(CH3)2)3 precursor (Cp-Zr), which enables the film growth prediction with the reactor-scale computational fluid dynamic (CFD) model.According to the experimental ALD process, the film growth was found to be influenced by the steric hindrance factor, especially at the temperature range from 150 °C to 250 °C, but the hindrance effect decreases with increasing temperature and disappears at 300 °C. The effective activation energy of the adsorption of Cp-Zr molecules on Si substrate was estimated to be 0.175 eV. Further understanding of the kinetic of ZrO2 deposition in this study is estimated to contribute to the optimization of the high-k metal oxides ALD deposition processes.

Achieving ultra-high corrosion-resistant Mg-Zn-Sc alloys by forming Sc-assisted protective corrosion product film

The weak corrosion resistance of magnesium and its alloys greatly limited the industrial application. Though functional self-healing coatings have been proposed as countermeasures, repeated damages on coatings under practical installation and complex external environments could require self-adaptive corrosion protection against multiple abrasions. In this study, an ultra-high corrosion-resistant Mg-1Zn-1Sc (wt.%) alloy with a corrosion rate of 0.087 mm/y has been designed and prepared, which has fine grains and uniform structure of a nano-scale ScZn phase with low potential. A unique and dense corrosion product film with a three-layered structure was found and studied on Mg-1Zn-1Sc alloy, providing excellent corrosion protection. In addition, the formation and protection mechanisms of the three-layered corrosion product film on Mg-1Zn-1Sc alloy have been discussed and proposed. The growth behavior of protective corrosion product film could be driven by the synergy of Sc and Zn elements. Furthermore, with the increase of Sc content, the strength, plasticity, and corrosion resistance of Mg-1Zn-xSc (x = 0, 0.2, 0.6, 1.0, in wt.%) alloys increased simultaneously. The high corrosion resistance and moderate mechanical performance qualify Mg-1Zn-1Sc alloy as a promising candidate for diverse industrial applications.

Nucleation and Layer Closure Behavior of Iridium Films Grown Using Atomic Layer Deposition.

Understanding the initial growth process during atomic layer deposition (ALD) is essential for various applications employing ultrathin films. This study investigated the initial growth of ALD Ir films using tricarbonyl-(1,2,3-η)-1,2,3-tri(tert-butyl)-cyclopropenyl-iridium and O2. Isolated Ir nanoparticles were formed on the oxide surfaces during the initial growth stage, and their density and size were significantly influenced by the growth temperature and substrate surface, which strongly affected the precursor adsorption and surface diffusion of the adatoms. Higher-density and smaller nanoparticles were formed at high temperatures and on the Al2O3 surface, forming a continuous Ir film with a smaller thickness, resulting in a very smooth surface. These findings suggest that the initial growth behavior of the Ir films affects their surface roughness and continuity and that a comprehensive understanding of this behavior is necessary for the formation of continuous ultrathin metal films.

Time-Dependent Passivation Performance of Plasma Sprayed FeCrMoCBY Amorphous Coating

The relationship between passive film growth behavior and passivation time for plasma-sprayed Fe48Cr15Mo14C15B6Y2 amorphous coating in borate buffer solution has been thoroughly studied. The morphological characteristic and structural feature of as-spayed amorphous coating were estimated by scanning electron spectroscopy (SEM), X-ray diffraction (XRD) and transmission electron spectroscopy (TEM). The influence of passivation time on the film evolution properties was measured by electrochemical impedance spectra (EIS), Mott–Schottky curves, atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The results revealed that both corrosion resistance and self-repairing capacity of passive film greatly increased with time based on high electric field assumption. Reductions in donor density and flat band potential were accountable for a lower conductivity of passive film. An increment in Cr2O3 oxide as the inner barrier layer derived from the dehydration reaction of Cr(OH)3 contributed to the gradually densified structure of passive film. The extracted passive film thickness d increment with passivation time t conformed to the logarithm law on the basis of effective capacitance hypothesis: d=0.43lnt+52.06−2.18 (nm). Passivation mechanism within 600 s was ascribed to the adsorption of mechanical mixtures between metal ions and electrolytes, possibly leading to mechanical stress and rupture of passive film in the later growth procedure. The cation vacancy condensation process at the interface of coating/film was propitious in stabilizing the growth rate of passive film.

Disordered Phase-Assisted Growth of Organic Semiconductor Crystals on Self-Assembled Monolayer Templates.

Achieving high mobility and bias stability is a challenging obstacle in the advancement of organic thin-film transistors (OTFTs). To this end, the fabrication of high-quality organic semiconductor (OSC) thin films is critical for OTFTs. Self-assembled monolayers (SAMs) have been used as growth templates for high-crystalline OSC thin films. Despite significant research progress in the growth of OSC on SAMs, a detailed understanding of the growth mechanism of the OSC thin films on a SAM template is lacking, which has limited its use. In this study, the effects of the structure (thickness and molecular packing) of SAM on the nucleation and growth behavior of the OSC thin films were investigated. We found that disordered SAM molecules assisted in the surface diffusion of the OSC molecules and resulted in a small nucleation density and large grain size of the OSC thin films. Moreover, a thick SAM with disordered SAM molecules on the top was found to be beneficial for the high mobility and bias stability of the OTFTs.