Topography Of Films Research Articles

Dispersion of Few-Layer Black Phosphorus in Binary Polymer Blend and Block Copolymer Matrices

Exfoliated black phosphorus (bP) embedded into a polymer is preserved from oxidation, is stable to air, light, and humidity, and can be further processed into devices without degrading its properties. Most of the examples of exfoliated bP/polymer composites involve a single polymer matrix. Herein, we report the preparation of biphasic polystyrene/poly(methyl methacrylate) (50/50 wt.%) composites containing few-layer black phosphorus (fl-bP) (0.6–1 wt.%) produced by sonicated-assisted liquid-phase exfoliation. Micro-Raman spectroscopy confirmed the integrity of fl-bP, while scanning electron microscopy evidenced the influence of fl-bP into the coalescence of polymeric phases. Furthermore, the topography of thin films analyzed by atomic force microscopy confirmed the effect of fl-bP into the PS dewetting, and the selective PS etching of thin films revealed the presence of fl-bP flakes. Finally, a block copolymer/fl-bP composite (1.2 wt.%) was prepared via in situ reversible addition–fragmentation chain transfer (RAFT) polymerization by sonication-assisted exfoliation of bP into styrene. For this sample, 31P solid-state NMR and Raman spectroscopy confirmed an excellent preservation of bP structure.

Facile fabrication of silk fibroin/graphene oxide composite films and real‐time morphological observation in stretching

AbstractLayer‐structured regenerated silk fibroin (SF)/graphene oxide (GO) composite films were fabricated by a facile solution casting method. Fourier transform infrared spectroscopy, X‐ray diffraction, and thermal gravity analysis confirmed the successful incorporation and uniform dispersion of graphene oxides in the SF matrix. To visualize GO's effect on the morphological evolution, atomic force microscopic images were recorded in real‐time during the composite elongation to establish a correlation between microscopic structural characters and macroscopic mechanical properties. The result showed that the incorporation of graphene oxide into the SF matrix resulted in chain conformational transition, film surface flattening, and mechanical reinforcement. Surface roughness dramatically decreased from 65 to 10 nm, while tensile modulus increased substantially from 8.61 to 22.37 MPa by adding well‐dispersed graphene oxide up to 1 wt% into the SF matrix. Through the real‐time AFM observation under the horizontal stretching mode, the surface topography of original SF films varied from tori‐spherical aggregations to rod‐like ones resulting from GO's incorporation. In the meantime, SF's hydrophobicity was also increased, as manifested by contact angle increase from 30.81° to 45.09°.

Self-stopping slurry for planarizing extremely high surface film topography in nanoscale semiconductor devices

Self-stopping slurry for planarizing extremely high surface film topography in nanoscale semiconductor devices

Structure and Oligonucleotide Binding Efficiency of Differently Prepared Click Chemistry-Type DNA Microarray Slides Based on 3-Azidopropyltrimethoxysilane.

The structural characterization of glass slides surface-modified with 3-azidopropyltrimethoxysilane and used for anchoring nucleic acids, resulting in the so-called DNA microarrays, is presented. Depending on the silanization conditions, the slides were found to show different oligonucleotide binding efficiency, thus, an attempt was made to correlate this efficiency with the structural characteristics of the silane layers. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray reflectometry (XRR) measurements provided information on the surface topography, chemical composition and thickness of the silane films, respectively. The surface for which the best oligonucleotides binding efficiency is observed, has been found to consist of a densely-packed silane layer, decorated with a high-number of additional clusters that are believed to host exposed azide groups.

Effects of thickness on the wettability and electrical properties of Sn thin films

Sn films of four thicknesses, 50, 200, 500, and 1000 nm, were deposited on Si (111) substrates by a thermal evaporation technique, and the effects of thickness on the structural, surface morphology, electrical, and wettability properties were investigated. X-ray diffraction studies revealed the coexistence of predominantly β-Sn (metallic phase) and small concentration of α-Sn (semiconducting phase) in all samples except the 1000 nm thickness sample which is entirely β-Sn. The crystallite size and surface roughness enhance with thickness, and the 1000 nm film shows secondary nucleation growth which lowers the average crystallite size and the surface roughness of the sample. The 50 nm film shows semiconducting electrical properties while all other samples are metallic. The wettability studies found that Sn films are hydrophobic with a maximum water contact angle of 128° for the 1000 nm sample. It is concluded that the thickness critically determines the phase formation, surface topography, electrical properties, and hydrophobic properties of Sn films.

Corrosion behavior of titanium modified by direct laser interference lithography

This paper reports on the corrosion behavior of Titanium Grade 2 when subjected to non-contact laser functionalization. Direct Laser Interference Lithography (DLIL) was used to create periodic topography with two different surface patterns on pre-modified titanium. Corrosion resistance was measured in physiological saline at 37 °C. Electrochemical Impedance Spectroscopy data (EIS) and potentiodynamic polarization curves were correlated with the characteristics of the passive films through analysis of the topography, chemical composition, and thickness of oxides formed on the titanium after surface modifications. The corrosion tests showed that laser-textured surfaces have a beneficial impact on titanium corrosion resistance in a physiological saline solution 0.9% NaCl. Moreover, the passive layer on DLIL-modified samples is more stable and less susceptible to growth in the corrosive environment. The results highlight the local interaction of DLIL treatment of the titanium surface after it had been shot-peened and acid-etched. The improved corrosion resistance in DLIL samples derives mainly from changes in the surface topography, chemical composition, and thickness of oxide films obtained after laser processing.

The influence of corrosion on diamond-like carbon topography and friction at the nanoscale

The influence of corrosion upon the nanoscale topography and friction response of a hydrogenated amorphous carbon film (a-C:H) was investigated. Electrochemical atomic force microscopy was used to characterise topographical changes to the coating at two oxidative potentials. Corrosion of the coating at 1.5 V (corrosion rate 0.5 nm h−1) resulted in no changes to the nanoscale topography; whereas corrosion at 2.5 V (corrosion rate 26.4 nm h−1) caused the root mean square roughness of the a-C:H film topography to decrease, but the local fine-scale irregularity or ‘jaggedness’ of the surface to increase. X-ray photoelectron spectroscopy revealed that corrosion at both potentials oxidised the a-C:H surface to form alcohol, carbonyl and carboxyl groups. Lateral force microscopy and adhesion force measurements showed that both the friction force and surface adhesion of the coating increased upon corrosion. The outcome was attributed to the surface oxidation that had occurred at both oxidative potentials, resulting in several potential mechanisms including increased attractive intermolecular interactions and capillary forces. The highest friction coefficient was observed for the a-C:H film corroded at 2.5 V, and identified as a consequence of the jagged surface topography promoting an interlocking friction mechanism.

Effect of Annealing Temperature on Microstructure and Resistivity of TiC Thin Films

Titanium carbide (TiC) thin films were prepared by non-reactive simultaneous double magnetron sputtering. After deposition, all samples were annealed at different temperatures under high-vacuum conditions. This paper mainly discusses the influence of deposition methods and annealing temperatures on microstructure, surface topography, bonding states and electrical resistivity of TiC films. XRD (X-ray diffraction) results show that TiC thin films can still form crystals without annealing, and the crystallinity of thin films is improved after annealing. The estimated grain size of the TiC films varies from 8.5 nm to 14.7 nm with annealing temperature. It can be seen from SEM (scanning electron microscope) images that surfaces of the films are composed of irregular particles, and when the temperature reaches to 800 °C, the shape of the particles becomes spherical. Growth rate of film is about 30.8 nm/min. Oxygen-related peaks were observed in XPS (X-ray photoelectron spectroscopy) spectra, which is due to the absorption of oxygen atoms on the surface of the film when exposed to air. Raman spectra confirm the formation of TiC crystals and amorphous states of carbon. Resistivity of TiC films decreases monotonically from 666.73 to 86.01 μΩ·cm with the increase in annealing temperature. In brief, the TiC thin films prepared in this study show good crystallinity, thermal stability and low resistivity, which can meet the requirements of metal gate applications.

MWCNTs/PEDOT: PSS Composite as Guiding Layer on Screen-Printed Carbon Electrode for Linear Range Lactate Detection

The emerging field of nanomaterials could be utilized in biosensors for addressing challenging applications due to its abundant strategic properties. Herein, a composite of multi-walled carbon nanotubes (MWCNTs) and poly (3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) was synthesized, and used as guiding layer on screen printed carbon electrode (SPCE) for lactate detection. Lactate plays a substantial role in health care applications. Fundamental characteristics of the composite modified SPCE were studied using FE-SEM, EDS, and Raman spectroscopy and sensor performance was analyzed by electrochemical methods. AFM was used to thoroughly study the screen-printed carbon electrode and as-deposited MWCNT/PEDOT:PSS composite film topography. Various parameters were optimized to achieve the best performance of lactate sensor. The developed sensor provided a wide linear range response (R2 = 0.97) from 1 mM to 10 mM for buffer samples with 35.224 μA mM−1 sensitivity. The proposed sensor was applied for to detect lactate in cancer (MCF-7) cells media. A calculated LOD 4.0 ± 5 μM (S/N) was achieved and the results showed a linear response up to 7 mM. As a result, the advanced approach could be applied for the detection of a range of metabolites using respective enzymes. This approach could open on-line lactate detection in organ-on-a-chip applications.

Relationship between structure, surface topography and tribo-mechanical behavior of Ti-N thin films elaborated at different N2 flow rates

Titanium nitride films were deposited by reactive magnetron sputtering on Si (100) wafers, glass and Ti6Al4V substrates. The film deposition was carried out in a gas mixture of Ar and N2. The nitrogen content was varied between 0 and 30 % of the total gas mixture. This variation led to the formation of different films with different microstructures. The microstructure of the Ti-N coatings presented nanocomposites with a low tendency to surface oxidation. From a pure Ti to tetragonal Ti2N and cubic Ti-N microstructures, the films showed a (111) TiN plane growth that led to an increase in the lattice strain and a decrease in the grain size when increasing the nitrogen flow rate. The water-film contact angle measurements showed that the surface hydrophobicity increased with the increase of nitrogen content in the film. Mechanical properties were measured and a strong dependence between microstructure and hardness was found. The Ti-N deposited under 20 % of N2 exhibited the highest hardness, the best adhesion and wear resistance, and the lowest friction coefficient with the presence of (111) fiber texture.

The investigation of corrosion behavior of ZrO2–Al2O3-inhibitor/AA2024 nanocomposite thin film using sol-gel and AHP-TOPSIS method

Nowadays, the sol-gel thin films doped with corrosion inhibitor have suggested enhancing corrosion resistance of materials. In the present work, ZrO2 and ZrO2–Al2O3 thin films with benzotriazole (BTA) and cerium nitrate inhibitors were applied on the aluminum alloy substrate by using dip-coating process, and heat treated at 150 °C for 2 h with heating rate of 1 °C/min. Then, the crystalline phase, chemical composition, the microstructure and topography of thin films were evaluated by grazing incidence x-ray diffraction, energy dispersive spectroscopy, field emission scanning electron microscopy, and atomic force microscopy, and the average thickness of thin films was measured by ellipsometry technique. In addition, electrochemical impedance spectroscopy, and potentiodynamic polarization investigations were used to study the corrosion protection properties of thin films. Eventually, the experimental results related to the three independent coating conditions (sample A, B, D) were investigated by analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS). Results indicate the formation of composite thin films without microcracks comparison to the single-component coating, and electrochemical impedance tests after 4 day immersion in the corrosive environment illustrates an improvement of corrosion resistance of sample C (with the first and outside layer of ZrO2 and two middle layers of ZrO2, Al2O3 and BTA) more than 5 times compare to the bare AA2024 aluminum alloy. Additionally a decrease in the corrosion current density from 3.1 μA/cm2 for the uncoated aluminum to 0.2 μA/cm2, which was observed for sample C. Moreover, the data evaluation was studied by AHP and TOPSIS methods, which was presented the best thin films conditions for the sample B (Four layers of ZrO2 – Al2O3- BTA thin films on the AA2024 alloy) which was in good agreement with the experimental results.

Effect of silane/amine-based dopants on polymer-metal interaction of sub-surface silver nanoparticulate films

The optical and morphological properties of the vacuum-evaporated silver (Ag) nanoparticulate films on softened polyvinyl alcohol (PVA) modified with the 3-mercaptopropyl trimethoxysilane (MPTMS) and 3-aminopropyl trimethoxysilane (APTMS) dopants are reported. The topography of the particulate films is characterized by the field-emission scanning electron microscopy. The optical spectra broadening, red-shift, and the increase in the intensity values of the plasmonic resonance peak with the nature of dopant have a strong dependence on the particle size, shape, and inter-particle separation. The conducted experimental optical studies are supported by Finite Difference Time-Domain (FDTD) simulation results. Quantitative analysis of the Fourier-Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy studies confirm the surface modification of Ag nanoparticulate films on doped PVA substrates. The amount of polymer-metal interaction caused by the strongly interacting silane groups of the dopants and their influence on the morphology and optical properties are discussed.

Radiation crosslinking of linear polyethyleneimine‐based nanoparticles grafted to poly(glycidyl methacrylate) via trimethylolpropane triacrylate as potential electronic packaging material

AbstractLinear polyethyleneimine (L‐PEI)‐based nanoparticles were synthesized via hydrolysis of poly‐2‐methyl‐2‐oxazoline (PMeOx), which was prepared by cationic ring‐opening polymerization of the oxazoline five‐membered ring. Herein, a kinetic study of the ring‐opening polymerization reaction is discussed. The nuclear magnetic resonance spectrum of PMeOx verified the presence of repeating units and terminal groups in the polymer's structure. Molar ratios of PEI and PMeOx were characterized using size exclusion chromatography with low‐polydispersity polymer chains as the controlled polymerization reaction. PEI and PMeOx exhibited narrow particle size distribution with hydrodynamic radii of 89 and 67 nm, respectively, as determined via dynamic light scattering analysis. In addition, atomic forces and scanning electron microscopy were used to investigate the topography of the PEI thin films. Poly(glycidyl methacrylate) P(GMA) was grafted onto a PEI chain in the presence of trimethylolpropane triacrylate (TMPTA) as the crosslinking agent to synthesize the P(GMA–PEI–TMPTA) tripolymer via free radical polymerization using gamma irradiation. The thermal characterization of the P(GMA–PEI–TMPTA) tripolymer was conducted using thermogravimetric analysis and differential scanning calorimeter. Generally, the thermal stability of the P(GMA–PEI–TMPTA) tripolymer was improved at low‐glycidyl methacrylate concentrations. The prepared tripolymer could be used as effective packaging materials for electronics industries.

Time-Resolved Morphology and Kinetic Studies of Pulsed Laser Deposition-Grown Pt Layers on Sapphire at Different Growth Temperatures by in Situ Grazing Incidence Small-Angle X-ray Scattering.

Optimizing and monitoring the growth conditions of Pt films, often used as bottom electrodes in multiferroic material systems, represents a highly relevant issue that is of importance for controlling the crystalline quality and performance of ferroelectric oxides such as, e.g. LuFeO3. We performed a time-resolved monitoring of the growth and morphology of Pt films during pulsed laser deposition (PLD) in dependence on the grown film effective thickness and on the growth temperature Tg using in situ grazing incidence small-angle X-ray scattering (GISAXS). Through real-time analysis and modeling of GISAXS patterns, we could fully characterize the influence of Tg on the morphology and on the growth kinetics of the Pt layers. Consequently, critical and characteristic effective thicknesses for the transitions nucleation phase (I)/coalescence phase (II) and coalescence phase (II)/coarsening phase (III) could be determined. In combination with complementary microscopic imaging and chemical mapping via combined SEM/EDXS, we demonstrate the occurrence of a morphological progression in the Pt PLD-grown Pt films, changing from grains at room temperature to a 3D-island morphology at 300 °C, further to a hole-free structure at 500 °C, and finally to a channel structure for 700 and 900 °C. The film topography, as characterized by atomic force microscopy (AFM), favors the PLD growth of Pt layers at temperatures beyond 700 °C where the film is homogeneous, continuous, and hole-free with a flat and smooth surface. The double dependency of the percolation transition on the film effective thickness and on the growth temperature has been established by measuring the electrical conductivity.

The influence of substrate temperature on the near-infrared absorption and carrier mobility of lead phthalocyanine phototransistors

To improve their near-infrared photosensitive properties, lead phthalocyanine (PbPc) phototransistors were fabricated at different substrate temperatures (Ts) of 60, 100, 140 and 180 °C in this paper. The crystal structure, absorption spectra and surface topography of PbPc films were tested. And the photosensitive properties of the devices were measured, the results showed that the photoresponsivity (R), maximum photo/dark current ratio (Pmax) and specific detectivity (D⁎) of the devices first increase and then decrease with Ts increasing and the optimum performances for R, Pmax and D⁎ are acquired at Ts = 100 °C. The relations among substrate temperature, film properties and device performance were studied, which indicated that the phase structure, crystallinity, interconnection of grains, carrier mobility and near-infrared absorption of the PbPc films can be altered via substrate heating, and thus giving rise to the changes in device performance. In addition, a mathematic model that semi-quantitatively describes the relationships of photocurrent versus photoabsorption coefficient and carrier mobility was established.

Probing axial metal distribution on biopolymer-based layer-by-layer films for antimicrobial use

This study presents the axial molar composition of polysaccharide-based polyelectrolyte multilayer (PEM) films loaded with silver ions for antimicrobial applications. Individual polymers (chitosan, hyaluronan or alginate) and silver composition were determined using X-Ray Photoelectron Spectroscopy coupled with C60+ cluster ion sputtering technique, while the influence of silver loading on film topography was assessed using Atomic Force Microscopy. Despite the use of the layer-by-layer approach for film assembly, these PEM films present a non-stratified, nanoblend-like, polymer composition, with a nearly uniform metal distribution over the axial direction. Results also show surface antimicrobial activity towards Staphylococcus aureus bacteria and Candida albicans fungi over 20 h for hyaluronan/chitosan PEM, which is associated with its higher silver loading capacity. The interplay of bulk film composition and surface properties may provide valuable insights for engineering advanced materials with controlled spatio-temporal behavior.

The effect of density and surface topography on the coefficient of friction of polytetrafluoroethylene films

AbstractPolytetrafluoroethylene (PTFE) film is observed to increase surface roughness during annealing. Longer annealing times leads to greater surface roughness. The coefficient of friction of PTFE film is affected by the shape of microscale sized particles on the film surface. In this study, we investigate the coefficient of friction of PTFE films using a coarse-grained molecular dynamics model based on experimental observations. We observe how the variation in PTFE chain length and film density affect the topography of PTFE films. We also investigate how these properties of PTFE, and the indenter radius affect the coefficient of friction observed during surface scratch. We find that short PTFE chain lengths create a dense film with greater particle spacing, but longer chains form a mesh structure which reduces the density and creates overlapping portions of particles in the film. We develop a convolutional neural network to classify PTFE film surface and predict the coefficient of friction of a modeled film based solely on the equilibrated film topography. The accuracy of the network was seen to increase when the density and images of internal fiber orientation were added as input features. These results indicate that the coefficient of friction of PTFE films in part is governed by the internal structure of the film.

Bipolar resistive switching properties of titanium dioxide thin films deposited by different techniques

A comparative study of bipolar resistive switching in thin films of titanium dioxide, fabricated by different techniques, was carried out by analysis of current-voltage characteristics (I-V). For this purpose metal-insulator-metal (MIM) structures were formed with 60-nm-thick titanium dioxide layer deposited by atomic layer deposition (ALD) or RF magnetron sputtering. Based on the analysis of resistance switching characteristics, it was found that the deposition technique of titanium dioxide thin films influences the reproducibility of high-resistance state (HRS) at cycling measurements, the on-resistance (low resistance state)/off-resistance (HRS) ratio, the average values of SET [switching the resistance from a HRS to a low resistance state (LRS)] and RESET [switching the resistance from LRS to HRS] voltages and the number of resistive switching cycles. The results of study of the thin film topography performed by atomic force microscopy (AFM) suggest that the difference in resistive switching parameters could be caused by structural properties of titanium dioxide layers deposited by different techniques.

Thermal History Induced Surface Restructuring of La0.6Sr0.4CoO3-δ thin-Film Solid Oxide Electrodes and Its Significance for the Catalytic Activity and Stability

Thin-films deposited by Pulsed Laser Deposition (PLD) have enabled the fabrication of cathodes for solid oxide cells (SOC) to possess various microstructures, crystalline states and surface chemistry. These films are often subjected to various processing and thermal treatments which influence the chemical activity and stability of the films. Here, we investigate how the catalytic activity and stability is affected by the thermally induced surface restructuring in complex transition metal oxides, in particular, La0.6Sr0.4CoO3-δ (LSC) thin films grown by PLD.(1) To this end, the influence of substrate temperature during PLD as well as post-annealing treatments on the film microstructure and surface chemistry were studied. In comparison to high-temperature grown films, the post-annealed low-temperature grown films showed 2-fold lower degradation rate in the long-term electrochemical tests at 500 °C. The differences in the electrochemical stability were found to be related to the initial microstructure and morphology of the films (Fig 1). The post-annealed low-temperature grown film showed localised Sr-segregation into protruding particles, leaving the remaining surface with catalytically active stoichiometry. On the other hand, the high-temperature grown films showed a fully covered surface with Sr-rich particles, which continued to thicken with time. Here we emphasise the importance of processing and thermal history in the elemental surface distribution, especially for the stability of LSC64 electrodes and propose that it should be considered as among the main pillars in the design of the active surface.Fig. 1 Top-view (a,d,g) and cross-section view (b,e,h) SEM micrographs and corresponding AFM images (c,f,i) showing the topography of LSC64 films deposited by the PLD: (a−c) LT-grown film, (d−f) postannealed LT-grown film, and (g−i) HT-grown film. (https://pubs.acs.org/doi/10.1021/acsami.0c08308) Reprinted with the permission of the American Chemical Society. Further permissions related to the material excerpted should be directed to the ACS.(1) Celikbilek, O.; Cavallaro, A.; Kerherve, G.; Fearn, S.; Chaix-Pluchery, O.; Aguadero, A.; Kilner, J. A.; Skinner, S. J.. ACS Appl. Mater. Interfaces 2020, 12, 34388−34401. Figure 1

Изучение поверхности пленок хитозана и его солей с органическими кислотами методом атомно-силовой микроскопии

The results of the study of the morphology and surface topography of chitosan films of the salt (S-) and basic (B-) chemical form by atomic force microscopy are presented. The films were cast from polymer solutions in acetic, lactic, citric and succinic acid. NaOH and triethanolamine were used for the salt → chitosan base reaction. Surface tomograms were obtained; the main morphological characteristics and roughness parameters of the film samples were estimated. It was found that the morphology, the degree of order, root-mean-square roughness and the height of the surface roughness were determined by the polymer chemical form, the nature of the acid used and the reagent of the polymer-like conversion reaction. The surface of the S-form chitosan films is characterized by fibrillar structural ordering (also dendritic for chitosan succinate), and that of the B-form is globular. The smallest size of surface supramolecular elements was observed for the S-form chitosan films, while the greatest roughness was for the B-form ones. Changing the reagent of the chitosan S → B reaction did not affect the morphological characteristics of the films; however, it affected the microrelief roughness. A more uniform basic chitosan film is formed in an organic base environment. It was suggested that the formation of fibrillar supramolecular structures was due to the unfolding and straightening of macrochains because of the repulsion of the same charged monomer units, while the globular ones were formed due to the folding and densification of macrocoils after neutralizing the total charge of the macrochain.