Structure Of Films Research Articles

Ferroelectric behavior arising from polar topologies in epitaxially strained SrTiO3-δ ultrathin films

In this work, we show that epitaxially strained SrTiO3-δ thin films, grown by ion-beam sputtering onto (001)Nb:SrTiO3 substrates, exhibit a ferroelectric behavior. At the atomic-scale, through high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, it was possible to identify the presence of polar nanoregions with a non-trivial polar topological structures in the SrTiO3-δ film, which are induced through oxygen vacancies. To further confirm the presence of strained regions with a polar structure, Raman spectroscopy and high-resolution X-ray diffraction were employed and it was possible to confirm the presence of a tetragonal structure in the SrTiO3-δ film, with a tetragonality ratio (c/a) of 1.005. Scanning probe microscopy and macroscopic polarization-electric field hysteresis loops show ferroelectric behavior with maximum polarization of ∼1.5 μC/cm2, remnant polarization of ∼0.4 μC/cm2 and coercive field of ∼0.3 MV/cm. This work opens a window for exploring novel polar topological effects in sub-10 nm thin film materials for non-volatile memory application.

Effects ofAs8structure formation on the surface morphology and internal microstructure of GaAs thin films.

Gallium arsenide (GaAs) materials have the advantages of high electron mobility, electron saturation drift rate, and other irreplaceable semiconducting properties. They play an important role in the electronics, solar and other fields. However, during GaAs film sedimentary growth, As atoms can undergo segregation to formAs8clusters because of the influence of external factors, which affect the surface morphology and internal structure of these films. In this study, a series of investigations on the deposition and growth of GaAs crystal films were performed. Additionally, the deposition and growth of GaAs thin films were simulated using molecular dynamics. The influence of As8clusters on the surface morphology and internal structure of GaAs films at different incidence angles, velocities and substrate temperatures was studied by using 'defect analysis technology' and 'diamond structure identification' in open source software, along with surface roughness and radial distribution function. Results show that with increasing incident angle, the number ofAs8clusters decreases and film density increases. Increasing incident velocity increases the irregular movement ofAs8clusters in air, and their deposition on the film surface affects the morphology of the film, and the surface roughness increases first and then decreases. Additionally, we investigated the effect of different substrate temperatures on the film surface. Results show that at a substrate temperature of 1173 K, the number ofAs8clusters in the film decreases or the As8clusters disappear, heterogeneous nucleation occurs in the film, and the crystallization rate increases. Although the dislocation line associated with nucleation may affect the mechanical and optical properties of the film, it considerably reduces the annealing effort after the deposition and growth.

Structure, magnetic and magnetocaloric properties of the Mn5Ge3 thin film grown on Si(111)

Structure, magnetic and magnetocaloric properties of the Mn5Ge3 thin film grown on Si(111)

Atomic level mechanism of disorder-order transformation kinetics at nanoscale in FePt based systems

L10 ordered FePt is one of the most promising materials for spintronic and recording media applications. In the present work, the mechanism of L10 phase transformation in FePt based films with varying initial structures is examined at the nanoscale to understand the ordering process using synchrotron based GIXRD, MOKE, VSM, and techniques with sub nanometer depth selectivity like XRR and SIMS. Precisely controlled compositions of the films are deposited using magnetron sputtering. Rapid thermal annealing is used for post-deposition processing. It is evaluated experimentally that for a shorter annealing time of 70 s at 400 °C, besides volume diffusion, short circuit diffusion paths along the intercrystallite region owing to the presence of nanostructured grains play a dominant role in alloying behavior. A study of the L10 ordering process reveals the crucial role of film structure in controlling the transformation kinetics, texturing of nanograins, and magnetic coercivity. Diffusion studies disclose that type B diffusion kinetics is activated for the annealing time during which L10 transformation occurs in the films.

Controlling the formation of ionic complex vesicles through double-tailed surfactants.

Liposomes are often used in cosmetics since they are naturally derived and have excellent texture enhancing capabilities. However, when preparing them by using phospholipids with unsaturated acyl groups, they easily suffer from oxidative degradation. Accordingly, hydrogenated phospholipids are preferred, however, it is difficult to prepare stable liposomes due to its high gel-liquid crystalline phase transition temperature. On the other hand, although dialkyl dimethyl ammonium type cationic surfactants are widely known to form vesicles, they have rarely been used for skincare products except for water-in-oil type emulsion creams stabilized by organically modified clay minerals. We decided to overcome all of the problems above through ionic complex vesicles formed by double-tailed cationic and anionic surfactants. Distearyl dimethyl ammonium chloride (DSAC) and sodium dilauramidoglutamide lysine (DLGL) were selected as cationic and anionic surfactants, respectively. Differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SWAXS) measurements were performed to confirm the DSAC/DLGL/water ternary phase diagram. Newly developed ionic complex vesicle formation was confirmed by cryogenic transmission electron microscopy (cryo-TEM). The adsorbed cosmetic film structure on the skin invivo was evaluated through the polarized infrared external reflection (PIR-ER). Finally, a cosmetic lotion formula was developed and the vesicle size was determined by dynamic light scattering (DLS). DSC and SWAXS data indicated that stable vesicles could be obtained at a molar ratio of DLGL to DSAC = 6:4. At this molar ratio, multi lamellar vesicles with diameters less than 100 nm were observed through cryo-TEM. PIR-ER data revealed that the developed vesicles formed a highly perpendicular orientation to the human skin surface. We have succeeded in formulating a cosmetic lotion containing developed vesicles with a mean diameter of 63.2 nm, which was stable over 1 month at 0, 37, and 50°C. Our newly developed vesicles can be easily obtained through a coagulation process. Also, the adsorbed film structure supported by PIR-ER experiments implies that the developed lotion has an excellent texture that is the same as cosmetic lotions containing liposomes. Therefore, it's possible that this ionic complex vesicle could take the place of liposomes.

Crystallization of Y3Fe5O12 thin films on silicon photonic waveguides using CO2 laser annealing

We report the local crystallization of Y3Fe5O12 (YIG) thin films grown on Si substrates, and SOI waveguides by CO2 laser annealing (LA). The effect of laser power and oxygen pressure on the crystal structure of YIG films was systematically studied. Laser power dominated the YIG film crystallinity, while oxygen partial pressure during LA strongly influenced the crystal grain size and magnetic anisotropy. Fully crystallized YIG thin films with pure garnet phases were fabricated by LA. The refractive index n and extinction coefficient k were comparable to thin films fabricated by rapid thermal annealing (RTA). Propagation loss measured at 1550 nm wavelength on YIG/SOI waveguides and YIG/SiN ring resonators were comparable to RTA annealed films, promising device development for silicon photonics.

Polysaccharide‐Modified SnO2 for Highly Efficient Perovskite Solar Cells

Tin oxide (SnO2) has been demonstrated as a promising electron transport material for perovskite solar cells (PSCs) due to its low‐temperature process and high charge extraction ability. However, the key to improving the internal performance of PSCs toward unity lies in the ability of enhancing bulk SnO2 quality and reducing the energy level mismatch between SnO2 and perovskite layer. Herein, a facile and effective strategy to simultaneously functionalize SnO2 structure by sodium alginate (SA) polysaccharide compound is reported. The investigations reveal that SA leads to the formation of nanosynapse structure of SnO2 films, which allows the aligned energy levels and suppressed charge recombination, significantly enhancing carrier extraction and transport. Consequently, CsMAFAPb(IxBr1−x)3 and CsPbI2Br solar cells achieve a remarkable power conversion efficiency of 24.11% and 16.90%, respectively, based on SnO2‐SA electron transport layers (ETLs). This work offers a facile and effective way to fabricate high‐performance SnO2 ETL in PSCs.

Structural, linear/non-linear optical, and optoelectrical properties of PVB/Bi2WO6 nanocomposite for industrial applications

Nanocomposite films composed of polyvinyl butyral (PVB) and Bi2WO6 were produced through solution casting. The goal of this investigation was to examine the effects of different Bi2WO6 concentrations (0%, 2%, and 4% wt.) on the linear/non-linear optical and optoelectrical properties, as well as the structure and dispersion of films of PVB/Bi2WO6 nanocomposite. The direct band gap Eg1 value falls from 5.1 eV to 3.83 eV with the progressive increase in Bi2WO6 content from 0% to 4% wt., while indirect band gap Eg2 decreased from 4.1 eV to 2.89 eV. Conversely, the PVB + 4% Bi2WO6 nanocomposite increased Urbach’s energy (EU) from 1.00 eV for pure PVB to 1.97 eV. Moreover, our research has documented the impact of different concentrations of Bi2WO6 on a range of optical properties, including the refractive index ( n), extinction coefficient ( k), and other pertinent parameters. Utilizing the real and imaginary components of the dielectric constants εr and εi, an investigation was carried out into the dielectrics’ behavior and the optoelectrical parameters’ calculation. Furthermore, investigations were performed on the linear optical susceptibility, the non-linear refractive index, and the third-order non-linear optical susceptibility concerning the concentrations of Bi2WO6. In addition, the results indicated that varying Bi2WO6 concentrations substantially affect the oscillator strength, average oscillator wavelength, and optical conductivity. The nanocomposite films of PVB/Bi2WO6 concentrations exhibited favorable associations between their optoelectrical and non-linear/linear optical parameters, rendering them viable candidates for implementation in flexible electronic devices and radiation shielding.

Development of Bio-Photoelectrochemical Hybrids for Solar Energy Conversion

Recent advancements in solar energy conversion have identified bio-photoelectrochemical hybrids as one of the most promising sustainable techniques. This study integrates BiVO4 and TiO2 semiconductors with photoautotrophic microorganisms (e.g., Algae) to enhance solar energy conversion. Thin films of these materials were prepared and characterized, revealing a relatively smooth surface for BiVO4 while structures for TiO2 thin films deposited as nanorods. Optical properties showed band gaps of ≤ 3.1 and 2.4 eV for TiO2 and BiVO4, respectively. The point of zero charge of materials was investigated, indicating that naturally occurring biofilm formation might not be favorable for as-prepared materials. To overcome this challenge, we aimed to use polyelectrolytes to enhance attachment of cells on the surface of semiconductor and in this regards we determined the biocompatibility of using this approach. Photoelectrochemical (PEC) measurements were conducted to evaluate solar energy conversion efficiency. This study offers insights into optimizing biosystem attachment, biofilm stability, and PEC performance of coupled semiconductors with photoautotrophic microorganisms as one photoelectrode in PEC cell, advancing sustainable solar energy conversion technologies.

Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

Atomically Resolved Phase Coexistence in VO2 Thin Films.

Concurrent structural and electronic transformations in VO2 thin films are of 2-fold importance: enabling fine-tuning of the emergent electrical properties in functional devices, yet creating an intricate interfacial domain structure of transitional phases. Despite the importance of understanding the structure of VO2 thin films, a detailed real-space atomic structure analysis in which the oxygen atomic columns are also resolved is lacking. Moreover, intermediate atomic structures have remained elusive due to the lack of robust atomically resolved quantitative analysis. Here, we directly resolve both V and O atomic columns and discover the presence of intermediate monoclinic (M2) phase nanolayers (less than 2 nm thick) in epitaxially grown VO2 films on a TiO2 (001) substrate, where the dominant part of VO2 undergoes a transition from the tetragonal (rutile) phase to the monoclinic M1 phase. Strain analysis suggests that the presence of the M2 phase is related to local strain gradients near the TiO2/VO2 interface. We unfold the crucial role of imaging the spatial configurations of the oxygen anions (in addition to V cations) by utilizing atomic-resolution electron microscopy. Our approach can be used to unravel the structural transitions in a wide range of correlated oxides, offering substantial implications for, e.g., optoelectronics and ferroelectrics.

Nanoscale Phase and Orientation Mapping in Multiphase Polycrystalline Hafnium Zirconium Oxide Thin Films Using 4D-STEM and Automated Diffraction Indexing.

Ferroelectric hafnium zirconium oxide (HZO) holds promise for nextgeneration memory and transistors due to its superior scalability and seamless integration with complementary metal-oxide-semiconductor processing. A major challenge in developing this emerging ferroelectric material is the metastable nature of the non-centrosymmetric polar phase responsible for ferroelectricity, resulting in a coexistence of both polar and non-polar phases with uneven grain sizes and random orientations. Due to the structural similarity between the multiple phases and the nanoscale dimensions of the thin film devices, accurate measurement of phase-specific information remains challenging. Here, the application of 4D scanning transmission electron microscopy is demonstrated with automated electron diffraction pattern indexing to analyze multiphase polycrystalline HZO thin films, enabling the characterization of crystallographic phase and orientation across large working areas on the order of hundreds of nanometers. This approach offers a powerful characterization framework to produce a quantitative and statistically robust analysis of the intricate structure of HZO films by uncovering phase composition, polarization axis alignment, and unique phase distribution within the HZO film. This study introduces a novel approach for analyzing ferroelectric HZO, facilitating reliable characterization of process-structure-property relationships imperative to accelerating the growth optimization, performance, and successful implementation of ferroelectric HZO in devices.

Influence of HiPIMS Pulse Widths on the Structure and Properties of Copper Films.

High-power pulse magnetron sputtering is a new type of magnetron sputtering technology that has advantages such as high peak power density and a high ionization rate compared to DC magnetron sputtering. In this paper, we report the effects of different pulse widths on the current waveform and plasma spectrum of target material sputtering, as well as the structure and properties of Cu films prepared under the same sputtering voltage and duty cycle. Extending the pulse width can make the sputtering enter the self-sputtering (SS) stage and improve the ion quantity of sputtered particles. The Cu film prepared by HiPIMS with long pulse width has higher bond strength and lower electrical resistivity compared to the Cu film prepared by short pulse width. In terms of microstructure, the Cu film prepared by HiPIMS with the long pulse width has a larger grain size and lower micro-surface roughness. When the pulse width is bigger than 200 μs, the microstructure of the Cu film changes from granular to branched. This transformation reduces the interface on the Cu film, further reducing the resistivity of the Cu film. Compared to short pulses, long pulse width HiPIMS can obtain higher quality Cu films. This result provides a new process approach for preparing high-quality Cu films using HiPIMS technology.

Effects of Curing Defects in Adhesive Layers on Carbon Fiber-Quartz Fiber Bonded Joint Performance.

Due to their mechanical load-bearing and functional wave transmission, adhesively bonded joints of carbon fiber-quartz fiber composites have been widely used in the new generation of stealth aviation equipment. However, the curing defects, caused by deviations between the process environment and the setting parameters, directly affect the service performance of the joint during the curing cycle. Therefore, the thermophysical parameter evolution of adhesive films was analyzed via dynamic DSC (differential scanning calorimeter), isothermal DSC and TGA (thermal gravimetric analyzer) tests. The various prefabricating defects within the adhesive layer were used to systematically simulate the impacts of void defects on the tensile properties, and orthogonal tests were designed to clarify the effects of the curing process parameters on the joints' bonding performance. The results demonstrate that the J-116 B adhesive film starts to cure at a temperature of 160 °C and gradually forms a three-dimensional mesh-bearing structure. Furthermore, a bonding interface between the J-116 B adhesive film and the components to be connected is generated. When the curing temperature exceeds 200 °C, both the adhesive film and the resin matrix thermally degrade the molecular structure. The adhesive strength weakens with an increasing defect area ratio and number, remaining more sensitive to triangle, edge and penetration defects. By affecting the molecular structure of the adhesive film, the curing temperature has a significant impact on the bonding properties; when the curing degree is ensured, the curing pressure directly impacts the adhesive's performance by influencing the morphology, number and distribution of voids. Conversely, the heating rate and heat preservation time have minimal effects on the bonding performance.

Cold plasma treatment: An innovative approach to reduce the moisture and the water reabsorption in iron ore concentrate

Wet beneficiation is a primary process employed by mining companies for iron ore concentration. The moisture content in the ore is a result of this beneficiation process, in addition to inherent moisture within the mineral composition. The moisture content of iron ore is a crucial parameter that requires effective control to ensure safe handling and transportation operations. Surface plasma treatment of iron ore has been investigated as a method to enhance the hydrophobicity of ore particles, thereby reducing residual moisture and water reabsorption by the particles. The samples underwent treatment using argon plasma and cold hexamethyldisiloxane (HMDSO) plasma, leading to the formation of a thin, silicon-rich surface layer. The treatments were applied to both polished ore samples and fine powder samples. The plasma treatment resulted in a reduction in moisture content and water absorption. The reabsorption of water decreased to approximately 35% of the pretreatment values. Contact angle measurements demonstrated that all HMDSO-treated samples exhibited hydrophobic behavior, with contact angles ranging from 110° to 120°, while the untreated samples exhibited angles close to 0°. Furthermore, atomic force microscopy (AFM) topographic imaging revealed a granular structure in the thin films.

Wear-resistant and adherent nanodiamond composite thin film for durable and sustainable silicon carbide mechanical seals

In response to environmental concerns, there is a growing demand for durable and sustainable mechanical seals, particularly in high-risk industries like chemical, petroleum, and nuclear sectors. This work proposes augmenting the durability and sustainability of silicon carbide (SiC) ceramic seals with the application of a nanodiamond composite (NDC) film through coaxial arc plasma deposition (CAPD) in a vacuum atmosphere. The NDC coating, with a smooth surface roughness of Ra = 60 nm as substrate, demonstrated a thickness of 1.1 μm at a deposition rate of 2.6 μm/h. NDC film has demonstrated exceptional mechanical and tribological characteristics, such as a hardness (H) of 48.5 GPa, Young's modulus (E) of 496.7 GPa, plasticity index (H/E) of 0.098, and fracture toughness of H3/E2 = 0.46 GPa, respectively. These NDC films showcased commendable adhesion strength (>60 N), negligible wear, and low friction (≤0.18) during dry sliding against a SiC counter material. Raman analysis has confirmed the nanocomposite structure of NDC film, emphasizing the role of highly energetic carbon ions in enhancing film adhesion by forming SiC intermetallic compounds at the interface through the diffusion of silicon atoms from the substrate into the films. The abundance of grain boundaries and rehybridization of carbon sp3 to sp2 bonding is perceived to improve tribological performance. CAPD excels in synthesizing long-life eco-friendly NDC coatings for durable and sustainable mechanical seals, featuring smooth surfaces, superior adhesion, outstanding hardness, and wear resistance, making them high potential candidates for various tribological applications.

Effect of Picosecond Laser Irradiation on the Properties of Nanostructured Zinc Oxide Thin Films

In this article, a picosecond laser source was employed to irradiate the nanostructured ZnO thin film prepared by the sol-gel method. The impact of laser irradiation on the characteristics of a nanostructured ZnO thin film was investigated. Analysis using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy confirmed a significant influence on the structure of the ZnO thin film. As the duration of laser irradiation (the number of laser pulses) increased, there was a remarkable decrease in both the electronic and photoluminescence intensities of the nanostructured film. Tauc's plot indicates a noticeable change in the optical band gaps of the thin film with the increase in irradiation time. The morphological image suggests that the laser irradiation energy induces both degradation and modification of the film surface, consequently causing changes in the structural, absorption, and photoluminescence properties of nanostructured ZnO. The observed effects are attributed to alterations in the crystal structure and size of the nanostructured ZnO film, as confirmed by XRD. The reduction in photoluminescence intensity observed over the laser irradiation times may be a result of potential degradation in the crystalline structure of the nanostructured ZnO film.

Recognizing online video genres using ensemble deep convolutional learning for digital media service management

It's evident that streaming services increasingly seek to automate the generation of film genres, a factor profoundly shaping a film's structure and target audience. Integrating a hybrid convolutional network into service management emerges as a valuable technique for discerning various video formats. This innovative approach not only categorizes video content but also facilitates personalized recommendations, content filtering, and targeted advertising. Given the tendency of films to blend elements from multiple genres, there is a growing demand for a real-time video classification system integrated with social media networks. Leveraging deep learning, we introduce a novel architecture for identifying and categorizing video film genres. Our approach utilizes an ensemble gated recurrent unit (ensGRU) neural network, effectively analyzing motion, spatial information, and temporal relationships. Additionally,w we present a sophisticated deep neural network incorporating the recommended GRU for video genre classification. The adoption of a dual-model strategy allows the network to capture robust video representations, leading to exceptional performance in multi-class movie classification. Evaluations conducted on well-known datasets, such as the LMTD dataset, consistently demonstrate the high performance of the proposed GRU model. This integrated model effectively extracts and learns features related to motion, spatial location, and temporal dynamics. Furthermore, the effectiveness of the proposed technique is validated using an engine block assembly dataset. Following the implementation of the enhanced architecture, the movie genre categorization system exhibits substantial improvements on the LMTD dataset, outperforming advanced models while requiring less computing power. With an impressive F1 score of 0.9102 and an accuracy rate of 94.4%, the recommended model consistently delivers outstanding results. Comparative evaluations underscore the accuracy and effectiveness of our proposed model in accurately identifying and classifying video genres, effectively extracting contextual information from video descriptors. Additionally, by integrating edge processing capabilities, our system achieves optimal real-time video processing and analysis, further enhancing its performance and relevance in dynamic media environments.

Effect of Boron-doping and annealing on the structure, morphological and optical properties of ZnO films prepared by spray pyrolysis method

Abstract Investigations have been conducted into the structure, morphology, thickness, and optical properties of ZnO thin film upon doping it with Boron from boric acid (H3BO3) at a constant concentration and annealing it at various temperatures (200, 300, and 400 °C). The thin films were formed on glass substrates using the spray pyrolysis process at 250°C, and they were then annealed for two hours in air at various temperatures. It was discovered that the annealing temperature and boron doping had a substantial impact on all properties of the ZnO nanostructure. The polycrystalline hexagonal wurtzite structure is present in both ZnO and BZO thin films. With high optical transmission (≥70%), crystallite diameters of 25.8 to 28.5 nm for ZnO and 15.96 to 24.80 nm for BZO, respectively, and significant absorbance up to 400 nm at the maximum annealing temperature (400 °C) for both films. Moreover, the as-deposited and annealed BZO films had optical band gaps of 3.04 eV and 2.9 eV, respectively, which are less than the ZnO film's 3.23 eV band gap; in general, as the annealing temperature increased it decreased.

Multiple-angle incidence resolution spectrometry (MAIRS): applications in nanoarchitectonics and applied physics

Abstract The cutting-edge thin film studies using the multiple-angle incidence resolution spectrometry (MAIRS) are introduced from the principle to forefront applications in a wide variety of research fields covering semiconductor material with respect to nanoarchitectonics. MAIRS basically reveals quantitatively optical anisotropy in thin films, which is mostly used for quantitative molecular orientation analysis of each chemical group for chemistry purposes. This works powerfully especially when the material has poor crystallinity that cannot be analyzed by X-ray diffraction analysis. As a matter of fact, MAIRS works as a role that compensates for the diffraction techniques, and the combination of MAIRS and the diffraction techniques has already established as the most powerful technique not to miss the molecular aggregation structure in thin films. In this review, in addition, another application for physics purposes is also introduced where phonon in thin films is discriminated from normal infrared absorption bands by using the MAIRS technique.