Thin Film Layer Research Articles

Molecular Dynamics Analysis of Multi-Factor Influences on Structural Defects in Deposited Mg-Matrix Zn Atom Films.

Mg metal vascular stents not only have good mechanical support properties but also can be entirely absorbed by the human body as a trace element beneficial to the human body, but because Mg metal is quickly dissolved and absorbed in the human body, magnesium metal alone cannot be ideally used as a vascular stent. Since the dense oxide Zn film formed by Zn contact with oxygen in the air has good anti-corrosion performance, the Zn nanolayer film deposited on the Mg matrix vascular scaffold by magnetron sputtering can effectively inhibit the rapid dissolution of Mg metal. However, there are few studies on the molecular dynamic structural defects of Mg-matrix Zn atomic magnetron sputtering, and the atomic level simulation of Mg-matrix Zn thin-film depositions can comprehensively understand the atomic level structural defects in the deposition process of Zn thin films from a theoretical perspective to further guide experimental research. Based on this, this research first studied and analyzed the atomic layer structure defects, surface morphology, surface roughness, atomic density of different deposited layers, radial distribution function, and residual stress of the thin-film deposition layer of 1500 deposited Zn atoms at the initial deposition stage, during and after deposition under Mg-matrix thermal layer 500K and a deposited velocity 5 Å/ps by molecular dynamics. At the same time, the effects of temperature and deposited velocity of the Mg-matrix thermal layer on the surface morphology, roughness, and biaxial stress of the deposited films were studied.

Sensitive and selective determination of upadacitinib using a custom-designed electrochemical sensor based on ZnO nanoparticle-assisted molecularly imprinted polymer.

Upadacitinib (UPA) is a selective and reversible oral Janus kinase (JAK) 1 inhibitor and is of great importance in treating inflammatory bowel disease (Zheng et al., Int Immunopharmacol 126:111229, 2024; Foy et al., JAAD Case Rep 42:20-22, 2023). Although there are limitations to the effectiveness of UPA, it has received positive responses in clinical trials and is approved for the treatment of atopy dermatitis (AD) (Li et al., Int Immunopharmacol 125:111193, 2023). In this study, a nanoparticle-doped molecularly imprinted polymer (MIP)-based electrochemical sensor was developed for sensitive and selective detection of UPA. The developed sensor was designed as a thin film layer using the photopolymerization method on the surface of the prepared nanoparticle-doped polymerization solution glassy carbon electrode (GCE). Various nanoparticles, such as multi-walled carbon nanotube, titanium dioxide, oxide, and zinc oxide (ZnO) nanoparticles, were the most suitable for UPA. Surface characterization of the developed sensor was done by scanning electron microscopy (SEM), and electrochemical characterization was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The quantitative analysis of UPA was performed in 5.0mM [Fe (CN)6]3-/4- solution using the differential pulse voltammetry (DPV) technique. Under optimum conditions, the calibration range was between 0.1 and 1pM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.005pM and 0.017pM, respectively. The sensor's accuracy was proven by performing a recovery study in serum. The sensor's selectivity was also evaluated using common interfering substances such as KNO3, CaCl2, Na2SO4, uric acid, ascorbic acid, dopamine, and paracetamol. According to the results obtained, the performance of the designed sensor was found to be quite sensitive and selective in determining UPA. The developed UPA-ZnO/3-APBA@MIP-GCE sensor showed high sensitivity and selectivity towards UPA. In addition, the selectivity, the most important feature of the MIP-based sensor, was confirmed by imprinting factor (IF) calculations using tofacitinib (TOF) and ruxolitinib (RUX). The sensor's unique selectivity is demonstrated by its successful performance even in the presence of UPA impurities.

Investigation of the impact of environmental conditions on the mechanical properties of thin-film copper wafers

Thin-film copper offers excellent film texture for multilevel interconnections in integrated circuit fabrication due to its superior resistance to electromigration and high electrical conductivity. To perform a chemical mechanical planarization process during semiconductor fabrication of copper, it is necessary to have a thorough understanding of the nanomechanical properties of thin-film copper. In this study, thin-film copper and reacted passivation layers on silicon substrate wafers are investigated for their nanomechanical properties under various environmental conditions. The results of this study indicate that thin-film copper passivation layers have different properties in deionized (DI) water and polishing slurry environments compared to thin-film copper exposed to ambient air. Interestingly, variations in temperature within wet environments do not significantly affect the properties of thin-film copper wafers; but changes in properties are largely driven by chemical processes. The insights gained from this study emphasize the significance of considering both the passivation layers and wet environments in semiconductor fabrication processes, which contributes to the advancement of copper-based interconnect materials and optimization of the chemical mechanical planarization process in semiconductor manufacturing.

Microfluidic Device with an Oxygen Gradient Generator for Investigating Effects of Specific Hypoxia Conditions on Responses of Tumor Cells.

The oxygen level in the tumor microenvironment (TME) plays a critical role in regulating cell fates such as proliferation, migration, apoptosis, and so forth. To better elucidate how hypoxia affects tumor cell behaviors, a series of microfluidic strategies have been utilized to generate an oxygen gradient covering both hypoxia and normoxia conditions. However, in most studies, some chemicals are introduced into microfluidic chips, causing the potential of their poor biocompatibility. The common oxygen gradient with linear variation does not allow the effects of specific oxygen concentrations on tumor cells to be analyzed accurately. In this paper, based on the physical method of gas diffusion, a microfluidic device integrated with an oxygen gradient generator is proposed for investigating effects of different hypoxia levels on responses of tumor cells. This device consists of three layers, i.e., upper layer, thin film layer, and bottom layer. The upper layer is used for introducing the initial gas and generating an oxygen gradient in the form of gas. The bottom layer is used for introducing cells and culture medium. The thin film layer separates the former two layers, allowing the gas to diffuse from the top to the bottom through it. The oxygen gradient in the bottom layer is finally generated in the form of dissolved oxygen. The device is fabricated using microfabrication technology. The effects of structural and working parameters of the device on the oxygen gradient are evaluated by finite element simulation. The oxygen gradient in cell culture channels is characterized by using oxygen-sensitive fluorescence materials. The proliferation and morphology of HeLa cells under specific oxygen levels are compared after culturing for 48 h. The oxygen gradient with a ladder-like distribution demonstrates that this microfluidic device can provide a prospective experimental platform for in vitro cell studies and revelation of the mechanism of tumor metastasis associated with a specific hypoxic microenvironment.

Study of effect of nanomaterial above the add layer on performance parameters of plasmonic structure

In this paper, we explored the effect of adding a nanomaterial layer above the add layer on performance parameter of the considered plasmonic structures (conventional, four and five layer SPR sensors). These structures are stimulated by the COMSOL Multiphysics. We have considered LiNbO3 as an add layer over a thin film of gold. Further, Graphene, Black Phosphorene, Mxene, MoS2 MoSe2, WS2 and WSe2 as nanomaterial are considered over add-layer. First, we optimised the thickness gold and LiNbO3. After that, we calculated reflectance and magnetic field dependent performance parameters, i.e., shift in resonance angle (∆θr), full beam width (FBW), sensitivity (S), detection accuracy (DA), quality factor (Q. F.), figure of merit (FoM), field intensity at different interfaces (metal-sensing medium (M-S), metal-dielectric (M-D), dielectric-sensing medium (D-S), dielectric-nanomaterial (D-N), nanomaterial-sensing medium (N-S), and penetration depth (PD) for the considered plasmonic structures. The minimum ∆θr is obtained for conventional structure i.e. 1.492° and maximum ∆θr is obtained for WS2 as nanomaterial used in five layer SPR sensor i.e., 2.052°. Moreover, FBW is also maximum for five layer SPR sensor with WS2 as nanomaterial i.e., 6.8430°. Moreover, PD has maximum value for conventional SPR sensor i.e., 190.894 nm, 175.94 nm for four layer SPR sensor and less than 175.94 nm for five layer SPR sensor. This comparative study will help to choose add-layer with nanomaterial over add layer and metal thin film layer in a SPR sensor for the detection of analyte or molecules present in the sensing medium.

Structural and phase transformations in Fe-Pd-Ag layered thin films by grain boundary diffusion

The influence of the stacking order and of an additional Ag layer on the formation of ordered phases in thin (< 50 nm) layered Fe/Pd and Fe/Ag/Pd films was investigated at 460 °C. The samples were prepared by magnetron sputtering at room temperature on Si/SiO2 substrate and were post-annealed in vacuum. Composition depth profiling and x-ray diffraction were used to characterize the processes. It has been shown, that the stacking order strongly influences the formation of ordered phases both in Fe/Pd bilayered and Fe/Ag/Pd trilayered films. In bilayered Fe/Pd films for both stacking orders the FePd3 phase appeared and it also showed L12 ordering for one stacking order. Addition of Ag layer between the Fe and Pd layers found to promote the formation of FePd phase which showed L10 ordering or A1 disordered structure depending on stacking order. Based on the analysis of the chemical depth profiles and XRD patterns the transformations were interpreted by grainboundary diffusion mechanisms including grainboundary diffusion induced grainboundary migration and solid state reaction.

Ladybug-inspired hierarchical composite adhesives for enhanced surface adaptability

Abstract Enhanced adhesion on rough surfaces is highly desired for a wide range of applications. On the other hand, surface roughness compatibility and structure stability are two critical but competing factors for biologically-inspired dry adhesives in the real world. Inspired by ladybug, a hierarchical structural composite dry adhesive (denoted as PP-M) with enhanced robustness on surface roughness is developed, which is composed of a thin compliant contact layer (a thin soft polydimethylsiloxane (PDMS) film supported discretely by PDMS micropillars) and a rigid bottom layer magnetorheological elastomers (MREs). The PP-M shows a high pull-off strength of 8.2 N cm−2 on a smooth surface and nano-scale rough surface at a mild preload (2 N cm−2). For micro-scale rough surfaces, the PP-M exhibits better surface adaptability compared to the double-layered adhesive (PDMS on MRE) without micropillar support. The increased compliance of the contact layer also leads to a 2.11 fold superior pull-off strength at a wider range of roughness (Sq &gt; 2.23 μm). Element analysis confirms PP-M’s enhanced adaptability, attributed to deeper indentation and lower contact stress. This hierarchical composite structure in PP-M, characterized by a ‘soft on top and hard on bottom’ stiffness distribution, synergizes the flexible contact layer with the stiff MRE bottom layer, leading to superior adhesive properties. The results provide a new reference for achieving enhanced adhesion on rough surfaces.

Триплетные сверхпроводящие корреляции гибридной меза-структуры с двухслойной ферромагнитной прослойкой

We present results on electron transport in hybrid Josephson mesa-structure Sd/F1F2/S, consisting of epitaxial films of cuprate superconductor YBa2Cu3O7-δ (Sd), bi-layer ferromagnetic interlayer (F1F2), thin film of metallic Nb was deposited on the top of a thin protective Au film layer used as the upper superconducting electrode (S). The long-range triplet component of superconducting correlations arises when strontium ruthenate SrRuO3 F1 and manganiteLa0.7Sr0.3MnO3 with non-collinear magnetizations are used as ferromagnetic material F2. Superconducting current took place up to the thickness d = 52 nm of the F1F2 interlayer. Superconducting current disappeared in the case of a single ferromagnetic interlayer of manganite (La0.7Sr0.3MnO3 or La0.7Ca0.3MnO3) and SrRuO3 with minimized thicknesses, limited by the occurrence of pinholes. The magnetic field properties of mesa-structure are discussed as well, along with the impact of the second harmonic in the superconducting current-phase relation.

New Hybrid Materials Based on N-Doping Copolymers of Thiophene Derivatives for Electrochemical Energy Storage

Over the past decade, electroactive conducting polymers (ECPs) are among the most potential pseudocapacitive materials for the electrodes of microsupercapacitors. ECPs exhibit several advantages, such as good conductivity (up to 103 S cm-1), flexibility, high specific capacitance (values ranging from 300 to 800 F.g-1 depending on synthesis and electrochemical performance conditions), relatively cheap and ease of synthesis [4]. Therefore, the electrochemical deposition of ECPs revealed a new strategy to design a great variety of various polymer morphologies as an innovative pseudocapacitive materials. Based on the different storage mechanism, electrochemical supercapacitors can be divided into three types, namely electrochemical double layer capacitors (EDLCs), pseudosupercapacitors and hybrid supercapacitors in which ECPs and other pseudocapacitive materials such as carbon materials, transition metal oxides, nitride complexes allow to store higher amount of capacitance per gram (faradic reactions) than EDLCs (pure capacitive energy storage reaction).In this work, we have elaborated new n-doped conducting polymers Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] by making electropolymerization on Pt disk electrode and 3 nm alumina coated silicon nanowires in acetonitrile organic electrolyte. The comonomers 3,6-bis(thienyl)pyridazine and (3,6-bis(2-(3-nhexylthienyl))pyridazine) have been successively synthesized. The produced polymeric materials Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] during n-doping process on Pt working electrode in acetonitrile solution of TBAPF6 (0.1 M) expose very low potential value of -2.23 V and -2.19 V at current density of -0.25 mA.cm-2 and -0.06 mA.cm-2, respectively. The elctropolymerization of synthesized comonomer 3,6-bis(thienyl)pyridazine has been done on Al2O3@SiNWs and resulted in thin layer of polymer film with micropores. The experimental results are compared to electropolymerization study of thiophene monomer on Pt disk and Al2O3@SiNWs electrodes to highlight the similarities and electrochemical advancements.

Crystallinity-Driven Formation of Highly Arrayed ZnO Nanorods Via Low-Temperature Chemical Bath Deposition on Transparent Conductive Oxide Substrates

The wide-band gap semiconductor zinc oxide (ZnO) nanostructures have attracted much interest in extensive applications such as gas sensors, photoelectrodes in dye sensitized solar cells and catalysts, etc. Among the various synthesis methods of ZnO nanostructures, chemical bath deposition (CBD) method is a low cost and simple technique to synthesize nanostructures. However, there are still remaining issues on growth of well- arrayed ZnO nanostructures with high uniformity and high crystallinity. In this research, we conducted a comprehensive investigation into various parameters, including seed layers, seed-layer thickness, precursor concentration, and reaction time during CBD process. Three kinds of transparent conductive oxide (TCO) films, specifically AZO, GZO, and ITO films, each with a thickness of 300nm, were individually deposited on glass substrates using radio frequency magnetron sputtering and DC magnetron sputtering. These obtained TCO films served as seed layers for the fabrication of ZnO nanorods in CBD process. The solution was prepared with Zn(NO3)2•6H2O and hexathylenetetramine (HMTA) diluted into deionized water, which was heated to 95 °C during CBD process. As the results: 1) Effect of different seed layers: ZnO nanorods exhibited vertically aligned hexagonal structures with uniform morphology when grown on AZO and GZO thin films. The alignment was found to depend on the crystal growth direction of the underlying TCO seed layers. Higher crystallinity of the seed layer contributed to superior alignment, with the crystal mismatch ratio between ZnO nanorods and GZO/AZO films being significantly lower than that with ITO film. 2) The thickness effect investigation was using AZO films varied from 100nm to 300nm. It was found that the thickness influenced the morphology of ZnO nanorods, correlating with the grain sizes of the seed layer thin films. Increasing film thickness led to larger average grain sizes, contributing to the diameter increase of ZnO nanorods in the CBD process, resulting in the improvement of crystallinity of ZnO nanorods. 3) The precursor ratio between concentration ratio of Zn(NO3)2•6H2O and HMTA was set as 2:0.25, 2:0.5, 2:1 and 2:2 individually for ZnO nanorods growth on AZO film. Increasing HMTA concentration initially led to an increase in diameter and length of ZnO nanorods, followed by a decrease at higher ratio of 2:2. The highest crystallinity of ZnO nanorods was obtained at the optimized ratio at 2:1. 4) The growth reaction time was investigated on ZnO nanorods grown on AZO film with concentration ratio of Zn(NO3)2•6H2O and HMTA at 2:1 with varied reacting time from 1 to 5 hours in CBD process. It was found that the reaction time significantly influenced on the growth and crystallinity of well-aligned ZnO nanorods on the as-deposited AZO seed layer. The crystallinity of ZnO nanorods in (0001) growth orientation was improved when the reaction time was increased from 1 hour to 5 hours during the CBD growth. The highest crystallinity was obtained from the ZnO nanorods grown with 5 hours reaction time. When the growth reaction time was increased, more Zn2+ ions were generated and strongly bonded with oxygen. The formed ZnO could be stacked along the c-axis (0001) growth direction and resulted in the length increasing during the CBD process. All fabricated ZnO nanorods showed a high transmittance of over 70% in the visible region. The ZnO nanorods synthesized on AZO substrates with optimized fabrication conditions will be in high potential for optoelectronic applications.

Modeling Bicarbonate Kinetics on Silver Catalysts for CO2 Electrolysis

Low-temperature CO2 electrolyzers transform captured CO2 into more useful chemicals, such as syngas (CO and H2) for systems with silver or gold catalysts and ethylene and other C2+ products for systems with copper catalysts. At low overpotentials, bicarbonate ions act as proton donors and have been shown to have enhanced activity1, leading to nonlinear Tafel slopes for the hydrogen evolution reaction (HER). We have developed a 1D planar electrode model for CO2 electrolysis, similar to the model developed by Gupta et al.,2 including a thin ionomer layer on top of a silver catalyst layer surface. The model includes buffer chemistry and ion transport in the boundary layer as well as the ionomer thin-film layer. Tafel parameters are fit for both bicarbonate and water as proton donors for HER using the model results to account for mass transport in the boundary layer. A comparison against a bare silver electrode shows that the Donnan potential across the ionomer/electrolyte interface has a significant effect on the ion concentrations at the catalyst layer surface, leading to enhanced HER from bicarbonate at low overpotentials. These results are then compared against Butler-Volmer parameters that are derived from a full microkinetic model. The Tafel kinetic parameters were then used in a 1D full-cell membrane electrode assembly (MEA) model, and we found good agreement with experimental data, illustrating that the ionomer in contact with the catalyst layer surface impacts the underlying kinetics both in planar electrodes and industrially-relevant MEA systems.References D. M. Koshy et al., J. Am. Chem. Soc., 143, 14712–14725 (2021) https://doi.org/10.1021/jacs.1c06212.N. Gupta, M. Gattrell, and B. MacDougall, J. Appl. Electrochem., 36, 161–172 (2006). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was partially supported by a Cooperative Research and Development Agreement (CRADA) between Lawrence Livermore National Laboratory, Stanford University, and TotalEnergies American Services, Inc. (affiliate of TotalEnergies SE) under Agreement No. TC02307 and Laboratory Directed Research and Development (LDRD) funding under project 22-SI-006.LLNL-ABS-857478 Figure 1

Investigation on methane hydrate formation behaviors in deep-sea methane seepage environments

Deep-sea cold seep is a natural phenomenon where methane leaks from the sea floor. Methane can be partially conversed through physical, chemical, and biological processes, but the excess methane that remains uncaptured escapes into the atmosphere and contributes to the greenhouse effect. Physical carbon sequestration via hydrate formation is a fast and high-energy density type of carbon sequestration; however, it has been largely overlooked. This study investigated hydrate formation in authigenic carbonate rocks through deep-sea geological surveys in cold seeps in the South China Sea. Investigations have shown that authigenic carbonate rocks can sequester carbon by blocking the methane plume from the seepage vents. This perspective provides a new physical carbon sequestration mode of carbonate rocks by observing the artificial collection of methane plumes in deep-sea seepage areas. The mode was simplified into two steps including the formation of a thin layer of planar hydrate film on carbonate rocks and a thick layer of hydrate through the stacking of bubbles under the thin film. Salinity, a key distinction between seawater and freshwater, was further investigated for its impact on the carbon sequestration mechanism. Results showed that saline ions in seawater had little impact on the thickening rate of the planar hydrate film but reduced the lateral growth rate of hydrates on the bubble by 60%. This reduction in the lateral growth rate greatly facilitated the three-dimensional growth, increased the hydrate thickness on the bubble, and improved the carbon sequestration efficiency. Hydrate formation on the exposed carbonate rock can effectively impede methane plume migration into upper water and atmosphere, mitigate the greenhouse effect, and present a promising strategy for carbon sequestration in deep-sea methane seepage areas.

Effect of AZO seed layers on the ultraviolet photoresponse of Ag/ZnO NRs Schottky junctions

Al-doped ZnO (AZO) thin films with different layers were prepared by sol-gel method. The SEM, XRD and AFM for three layers thin films demonstrates high crystal quality and low roughness. ZnO nanorods arrays (NRs) with different AZO seed layers were fabricated using hydrothermal process, and the effect of AZO seed layers on the structural, optical, and electrical characteristics was investigated. When there are three AZO seed layers present, ZnO NRs exhibit fewer surface states, smaller interface charge transfer resistance (Rce = 6.1 × 103Ωand Rct = 6.6 × 106Ω), longer carrier lifetimes (τe = 4.0 ms), higher carrier concentration (ND = 4.73 × 1019 cm−3), and narrower depletion region width W = 3.1 nm. Under weak UV light 381 nm (5.68 mW/cm2) at a bias −0.5 V, Ag/ZnO NRs Schottky devices with three AZO seed layers display a comparatively strong responsivity 34.64 mA/W. Appropriate AZO seed layers are favorable for highly efficient ZnO NRs-based photoelectric conversion devices.

Optical constants and thickness gradients for light intensities in glass substrate layers and for complex electric fields in indium tin oxide (ITO) transparent conductor thin film layer, using Bode and Nyquist wavelength-dependent diagrams

Abstract The optical constants of a thin film layer of transparent conductive indium tin oxide (ITO), deposited on a thick glass substrate (G), were obtained for an ITO-G sample using a multilayer matrix method by fitting the regular transmittance and specular reflectance measurements to the collimated equations of the four-flux model, once the optical constants of the glass substrate layer had previously been obtained from a G sample of a single glass substrate layer. The accuracy of the results was validated using a feedback system called the three-extinction matching requirement, that is, obtaining the same extinction coefficients from the optical constants and from the forward and backward collimated differential equations of the four-flux model. To calculate the extinction coefficients of the glass from optical constants, the compression of the wavelength of the incident light in the glass substrate and in the thin ITO film layer was demonstrated, with a thickness less than the wavelength of incident light. The thickness gradients of the forward and backward collimated light intensities, on the glass substrate of the ITOG sample, were compared with those obtained for the single-layer G sample. Then, the thickness gradients for the complex forward and backward electric fields of the ITO thin film layer were obtained and plotted using spectral magnitude and phase Bode plots and new Nyquist plots, i.e. imaginary versus real parts, dependent on wavelength.

Growth rate of AL2O3 Thin Film by Liquid Phase Deposition as an Anti-reflection Coating Layer on Crystalline Silicon for Solar Cell Applications

The fabrication of photovoltaic (PV) device requires that surface reflectance of solar cells has to be minimized to achieve higher photo-conversion efficiency (PCE). Antireflection coating layer is deposited on the surface of a p-type crystalline silicon material to reduce the surface reflections of solar radiation and increase its absorption for efficient solar cell application. In this work, aluminum oxide thin film by liquid phase deposition (LPD-Al2O­3) is synthesized from combined solution of aluminum sulfate octadecahydrate (Al2(SO4)3·18H2­O) and sodium carbonate (NaHCO3) with pH of 3.1. Some samples of p-type (100) crystalline silicon (c-Si) wafers of resistivity 1 – 10 mΩ were immersed inside the growth liquid of LPD-Al2O­3 thin film for 1hr – 2.5 hours. This is followed by annealing the samples at a temperature of 450oC, the deposition rate is faster in the range 1 – 1.5 hours is about 35nm/hr. As the growth time increases, the growth rate of the film decreases and remains nearly constant at about 10 nm/hour at 1 – 2 hours. When the growth time exceeds 2 hours, the film thickness remains unchanged showing that the liquid has lost in growth ability. The weighted average reflection (%) of planar c-Si is reduced from 44.9 % to 29.6 % after deposition of the LPD-Al2O­3 for 2.5 hours growth time, indicating a 34.1 % reduction in reflection within wavelength region of 300–1100 nm. While the root means square (RMS) surface roughness of 36.5 nm was also recorded at the highest growth time of 2.5 hours. This shows the effect of thicker LPD-Al2O­3 thin film layer increases the anti-reflecting coating property of the material.

Growth rate of AL2O3 Thin Film by Liquid Phase Deposition as an Anti-reflection Coating Layer on Crystalline Silicon for Solar Cell Applications

The fabrication of photovoltaic (PV) device requires that surface reflectance of solar cells has to be minimized to achieve higher photo-conversion efficiency (PCE). Antireflection coating layer is deposited on the surface of a p-type crystalline silicon material to reduce the surface reflections of solar radiation and increase its absorption for efficient solar cell application. In this work, aluminum oxide thin film by liquid phase deposition (LPD-Al2O­3) is synthesized from combined solution of aluminum sulfate octadecahydrate (Al2(SO4)3·18H2­O) and sodium carbonate (NaHCO3) with pH of 3.1. Some samples of p-type (100) crystalline silicon (c-Si) wafers of resistivity 1 – 10 mΩ were immersed inside the growth liquid of LPD-Al2O­3 thin film for 1hr – 2.5 hours. This is followed by annealing the samples at a temperature of 450oC, the deposition rate is faster in the range 1 – 1.5 hours is about 35nm/hr. As the growth time increases, the growth rate of the film decreases and remains nearly constant at about 10 nm/hour at 1 – 2 hours. When the growth time exceeds 2 hours, the film thickness remains unchanged showing that the liquid has lost in growth ability. The weighted average reflection (%) of planar c-Si is reduced from 44.9 % to 29.6 % after deposition of the LPD-Al2O­3 for 2.5 hours growth time, indicating a 34.1 % reduction in reflection within wavelength region of 300–1100 nm. While the root means square (RMS) surface roughness of 36.5 nm was also recorded at the highest growth time of 2.5 hours. This shows the effect of thicker LPD-Al2O­3 thin film layer increases the anti-reflecting coating property of the material.

Interfacial behaviour of short-chain fluorocarbon surfactants at the n-hexane/water interface: a molecular dynamics study.

The utilization of long-chain fluorocarbon surfactants is restricted due to environmental regulations, prompting a shift in the focus of research towards short-chain fluorocarbon surfactants. The present study employs molecular dynamics techniques to model the behaviour of potassium perfluorobutylsulfonate (PFBS) at the n-hexane/water interface, aiming to investigate the efficacy of short-chain fluorocarbon surfactants in enhancing oil recovery. The findings suggest that ionized PFBS- has the ability to autonomously migrate to the oil/water interface, forming a layered thin film, with the sulfonic acid group being submerged in water, while the fluorocarbon chain is oriented towards the oil phase. This phenomenon aligns with the fundamental concept of surfactants in reducing interfacial tension between oil and water. The spontaneous dispersion process is supported by changes in the number of water molecules surrounding each PFBS- anion, as is well indicated by the number density distribution within the simulation box. Based on the analysis conducted by IGMH (Independent Gradient Model based on Hirshfeld partition), it was determined that sulfonic acid molecules are capable of forming hydrogen bonds with water molecules, whereas the interaction between fluorocarbon chains and the oil phase is predominantly characterized by weak van der Waals interactions.

Doctor Blade Casting of Thin Films Containing Different Concentrated Endemic Plant Extracts: Determination of Structure and Optical Properties

This study provides a thorough properties of the optical analysis of the thin films which produced from Astragalus tokatensis Fisch., Helichrysum noeanum Boiss. and Stachys huber-morathii R. Bhattacharjee extracts. Methanol extracts of plants were obtained via Soxhlet extractor. The highest extract yield (10.10%) was determined in H. noeanum. Doctor blade coating method is used to make thin film layer on glass substrate. The optical behavior of the deposited films is tested by means of he UV-vis-near IR absorbance and transmittance characterization. It is found that the maximum transmittance spectra reaches nearly to a value of 90 % for A. tokatensis sample. Significantly, all the samples display same optical absorbace spectra behavior. Energy band gaps of the films are presented based on Tauc relation and were found to be in the range between 3.68-3.81 eV. Besides, the analysis of functional groups available in the materials is broadly studied by Fourier transform infrared (FT-IR) spectroscopy. FT-IR measurement also confirms that all produced films have carbohydrate pattern. These findings demonstrate a cost-efficient approach for the production of thin films with plant extraction, and open a new perspective on the potential applications of optoelectronic devices.

Properties Enhancement of Cu2O/TiO2 Heterostructure Film Using Two-step Hydrothermal and Potentiostatic Deposition Method

Two-steps hydrothermal were demonstrated to create a high efficiently interfacial layer of TiO2 thin film. The first hydrothermal was conducted to synthesize a well-aligned and compact structure of TiO2 nanorods on FTO substrate. Etching treatment in an acidic medium of hydrochloric acid (HCl) as a second hydrothermal favors increasing the surface area prior to any deposition to be a heterostructure film. The morphology of nanorods changed while the electrical resistivity decreased, demonstrating that the etching treatment had a substantial effect on the TiO2 thin film properties. Cyclic voltammetry (CV) was conducted prior deposition. The electrodeposition of Cu2O on the TiO2 thin film was fabricated by using copper acetate-based solution with pH value of 12.0 at bath temperature of 60°C. The finding revealed that the pyramidal structure of Cu2O film was deposited uniformly, which is believed that the properties of TiO2 interfacial layer were excellently improved.

Two comparative novel facile synthesis of Prussian blue/polyaniline bilayer films for supercapacitor electrode

A nanocomposite films of Prussian Blue/Polyaniline were prepared on ITO without binder, by two procedures: The first by forming thin multi layers of films of Prussian blue and Polyaniline alternatively, up to seven utilizing “layer by layer” technique. To prepare another film, a thick layer of Prussian Yellow was made under a Polyaniline layer with almost the same load of materials.PB successive layers were fabricated by dipping the ITO in a mixture of (Fe (NO3)3 + K3Fe(CN)6) solution, for a few minutes. next Pani layers were overlayed by electropolymerizing of aniline solution on the ITO/PY electrode. PY instantly was reduced by aniline as soon as dipped in solution, resulting in a nano Prussian Blue film on ITO.Uv-vis and FT-IR spectroscopy were used to characterize the fabricated films. AFM and SEM were utilized to study its morphology. The capacitive behavior of the two types of films was studied utilizing CVs and GCD techniques. The resistance of the electrode/electrolyte interface was studied by EIS. The electrochemical analysis confirmed that the multi-layer by layer thin film has much-improved specific capacitance of 255.6 F/g at 1 A/g current density and superior stability of 96.4 % of its initial value after 500 cycles.