Surface Topography Of Films Research Articles

Cellulose Nanocrystals and Corn Zein Oxygen and Water Vapor Barrier Biocomposite Films.

Cellulose nanocrystals (CNC) are well-suited to the preparation of biocomposite films and packaging material due to its abundance, renewability, biodegradability, and favorable film-forming capacity. In this study, different CNC and corn zein (CZ) composite films were prepared by adding CZ to the CNC suspension prior to drying, in order to change internal structure of resulting films. Films were developed to examine their performance as an alternative water vapor and oxygen-barrier for flexible packaging industry. Water vapor permeability (WVP) and oxygen transmission rate (OTR) of the biocomposite films decreased significantly in a specific ratio between CNC and CZ combined with 1,2,3,4-butane tetracarboxylic acid (BTCA), a nontoxic cross linker. In addition to the improved barrier properties, the incorporation of CZ benefitted the flexibility and thermal stability of the CNC/CZ composite films. The toughness increased by 358%, and Young’s modulus decreased by 32% compared with the pristine CNC film. The maximum degradation temperature increased by 26 °C, compared with that of CNC film. These results can be attributed to the incorporation of a hydrophobic protein into the matrix creating hydrophobic interactions among the biocomposite components. SEM and AFM analysis indicated that CZ could significantly affect the CNC arrangement, and the film surface topography, due to the mechanical bundling and physical adsorption effect of CZ to CNC. The presented results indicate that CNC/CZ biocomposite films may find applications in packaging, and in multi-functionalization materials.

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.

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.

Digital holographic microscopy for real-time observation of surface-relief grating formation on azobenzene-containing films

Light-induced surface structuring of azobenzene-containing films allows for creation of complex surface relief patterns with varying heights, patterns which would be difficult to create using conventional lithography tools. In order to realize the full potential of these patternable surfaces, understanding their formation dynamics and response to different types of light fields is crucial. In the present work we introduce digital holographic microscopy (DHM) for real time, in-situ observation of surface-relief grating (SRG) formation on azobenzene-containing films. This instrument allows us to measure the surface topography of films while illuminating them with two individually controlled laser beams for creating periodically varying patterns. By utilizing the information of the grating formation dynamics, we combine multiple grating patterns to create pixels with wide gamut structural colors as well as blazed grating structures on the film surface. As long as the material behaviour is linear, any Fourier optical surface can be created utilizing this multiple patterning approach. The DHM instrument presented here has the potential for creating complex 3D surface reliefs with nanometric precision.

The tuning of electrical performance of Au/(CuO:La)/n-Si photodiode with La doping

In this study, CuO thin films are grown by spin coating method as a function of La doping on n-Si substrates. The morphological properties of thin films have been analyzed by AFM images, and it has been observed that the roughness of thin films have been decreased with increasing La dopant concentration. The surface topography and chemical composition of thin films have been studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. Then, the electrical characteristics of the fabricated heterostructures have been measured and analyzed under dark and illumination condition. All diodes show rectification behavior and sensitivity to light. It has been observed that the series resistance and ideality factor values, which are among the basic parameters of the diodes, have been improved by La content. Detailed examination of the photoelectrical properties of photodetectors has revealed that the photoresponsivity and detectivity of Au/(CuO:La)/n-Si have been significantly enhanced compared to the photodetector without La doped CuO. Results indicated that all structural and electrical parameters strongly depended on lanthanum concentration.

Hierarchical architecture of a superhydrophobic Cd-Si co-doped TiO2 thin film

Superhydrophobic coatings have various applications in the industries for successful control and removal of droplets from the surface. Hierarchical structures are promising to achieve a superhydrophobic surface. We fabricated a Cd-Si co-doped TiO2 hierarchical coating on the surface of a glass slide, exhibiting superhydrophobic properties. Cd-Si co-doped TiO2 thin films were prepared by a sol-gel dip-coating method. The morphology, the dominant TiO2 phase, and the crystal structure of the thin films were studied by the concentration of the Si dopant and the calcination temperature. Accordingly, the optical bandgap, surface chemical ligands, and surface topography of thin films also investigated. The lowest bandgap energy (3.23 ± 0.004 eV) was obtained for the sample with 5 wt% Cd and 20 wt% Si. Moreover, by increasing the calcination temperature of a sample with 5% Cd and 10% Si, the water contact angle was increased from 112.2° ± 6° to 168.5° ± 7°, due to the synergy effect of surface ligands and hierarchical structure.

Physicochemical and biological characteristics of chitosan/κ-carrageenan thin layer-by-layer films for surface modification of nitinol

Thin films based on the natural polysaccharides κ-carrageenan (Carr) and chitosan (Chit) were formed by layer-by-layer deposition technique. Surface topography and mechanical characteristics (Young's modulus, adhesion strength) of the polymer films with different number of layers were determined using various modes of atomic force microscopy (AFM). Polymer films were used to deposit on the surface of nitinol (NiTi) plates. The creation of polysaccharide coatings on nitinol led to a change in surface properties, such as hydrophilicity and root mean square roughness. in vitro cytotoxicity assay for nitinol plates with and without polymer coating by the MG-63 osteoblast-like cell line was conducted and was shown that all the studied samples are not toxic. A decrease in cytotoxicity for samples with a polymer film consisting of 4 layers of chitosan and carrageenan was shown as compared to an uncoated nitinol plates.

Microstructure, Hardness, Adhesion and Corrosion Properties of Ti and TiN Films on Stainless Steel 316L

Ti-based coating has been used for biomaterials to improve biocompatibility, mechanical and corrosion properties. Each coating shows unique performance depending on a variety of factors such as coating microstructure and properties as well as in-service conditions. In this study, the microstructure, surface topography, hardness, adhesion and corrosion properties of Ti and TiN films on stainless steel 316L coated by cathodic arc physical vapor deposition process (PVD) were studied. The results showed that the surface roughness of 316L increased after being coated with Ti and TiN film as evidenced by the numerous particles and voids observed on the surface of both films. The hardness of 316L coated with Ti and TiN was increased by approximately 50% and 85%, respectively. Ti and TiN coated samples showed good adhesion strength with the first critical load (LC1) of approximately 10N and 15N, respectively. However, the types of film failure for Ti and TiN were found to be different. Partial delamination with a high degree of plastic deformation was observed for Ti coating, whereas surface cracks were found for TiN coating. This finding is likely attributable to the difference in flow resistance and the amount of particles and voids observed. All samples showed a stable passive region during 7 days of immersion in Ringer’s solution. Ti film showed better corrosion resistance than TiN, which may have been caused by the effect of more voids on TiN surfaces formed by PVD coating.

Oxidative Ageing and Structural Characterization of Naturally Weathered Low Density Polyethylene Films

Natural weathering was performed in a Saharan region to characterize its effect on low-density polyethylene (LDPE) films used for greenhouse coverings. The morphological changes, followed by differential scanning calorimetry (DSC), showed that the damages caused by the oxidation of tie molecules increased the lamellae thickness, its distribution and the crystallinity. Wide-angles X-ray diffraction (WAXD) was used to follow both the structural and morphological changes of the film. The WAXD crystallinity increase had the same trend as that determined by DSC. Field emission scanning electron microscopy (FESEM) of the films surfaces and cross-sections showed that the degradability increased with exposure time. Atomic force microscopy (AFM) analysis was used to evaluate changes in the surface morphology and roughness. Ageing caused a change of the surface topography of the LDPE films as observed by the increase of surface roughness which is indicated by the increase of the roughness parameters. Simultaneously the peaks-spacing $$\bar {d}$$ decreased.

Synthesis of Mesoporous SBA-16 and SBA-16/ZnO₂ Nano-Composite Thin Film for Anti-Biofilm Application.

SBA-16 is a mesoporous nanostructure with high surface area and cubic symmetry which make them an ideal carrier to carry different nanoparticles. Zinc peroxide (ZnO₂) is a novel nanoparticle that inhibits the growth of microorganisms due to its antiseptic property. Thin film of SBA-16 and SBA-16/ZnO₂ was deposited on glass slide by spin coating method. Anti-biofilm property of the thin films was examined against E. coli and S. aureus bacteria. Structural property was found out by wide angle X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and High Resolution Transmission Electron Microscope (HRTEM). Fourier Transform Infrared Spectrophotometer (FTIR) was used to confirmation the presence of ZnO₂ in Nano-composite and AFM utilized for surface topography of thin films. Fluorescent microscope image clearly revealed that SBA-16/ZnO₂ nanocomposite thin film significantly inhibit the biofilm formation against both E. coli (gram negative bacteria) as well as S. aureus (gram positive bacteria) in comparision to SBA-16. The antimicrobial behavior of ZnO nanoparticle is due to formation of H₂O₂ as reactive oxygen species (ROS) to which the bacterial cells are permeable. H₂O₂ is a powerful oxidizing agents that oxidized the mycobacterial elements like DNA and proteins which results into the toxicity of the bacteria cell.

An out of the box vision over oxidative chemical vapor deposition of PEDOT involving sublimed iron trichloride

Oxidative chemical vapor deposition (oCVD) is an efficient technique to produce highly conductive films of Poly (3,4-ethylenedioxythiophene) (PEDOT). Despite numerous studies on the oCVD of PEDOT films, there is limited information on the stability of the sublimation of solid oxidants and on their impact on the polymerization reactions. In this work, we use an in situ Quartz Crystal Microbalance to monitor film formation over time. Through a series of deposition experiments between 20 °C and 100 °C and for FeCl3/EDOT molar gas ratios between 17.3 and 75.3, we analyze in detail the correlations between process parameters and film morphology, composition, surface topography and electrical conductivity on 10 cm silicon wafers. By using multiple substrates at different positions into the reactor, we demonstrate that the formation of PEDOT occurs uniformly through purely surface reactions, following step growth polymerization principles. These results pave the way towards highly conductive oCVD PEDOT films processed from convenient solid oxidants.

Study of humidity sensing properties and ion beam induced modifications in SnO2-TiO2 nanocomposite thin films

Swift heavy ion beam induced dense electronic excitation in the nanocomposite thin film is a unique way to introduce various modifications such as track formation, atomic transport and phase transformation. Therefore, this work based on the modification in the properties of Titanium dioxide and Tin oxide nanocomposite thin films prepared by RF sputtering deposition technique in the mol% 50:50 on ITO coated glass and silicon substrates. The prepared nanocomposite thin films annealed at 500 °C and irradiated with SHI of 150 MeV Fe11+ ion beam with varied ion fluences ranging from 5 × 1012to 5 × 1013 ions.cm−2. The SRIM simulation was confirmed the electronic energy loss (Se) as 1.038 × 102 eV/nm, nuclear energy loss (Sn) as 1.33 × 10−1 eV/nm and the projectile depth of the iron ion inside the thin films was founded to be 17.18 um. Structural analyses of pristine and irradiated thin films were analyzed by X-ray diffraction technique. Changes observed in the peak intensity were confirmed by the significant variations in crystallite size, which was calculated by the Debye Scherrer equation. The crystallite size of all samples was found to be improved from 59 nm to 141 nm. The influence of ion irradiation on surface topography of nanocomposite thin films was analyzed by Atomic Force Microscopy (AFM). The sectional analysis of AFM images reveals that the grain size depends on the ion irradiation fluences. The grain size was increased from 52 nm to 129 nm. The optical properties were studied using UV–Visible spectroscopy and Photoluminescence (PL) spectroscopy. Tauc's method was used to calculate the optical energy band gap of the samples. The direct band gap was decreased as ion fluence increases may be due to creation of metastable energy states in between the valance and conduction band. The recombination and separation of photo generated charge carriers were studied by the photoluminescence spectroscopy. Rutherford Backscattering Spectrometry (RBS) was performed on all samples to ensure depth profiling, elemental composition and absence of impurities in titanium dioxide and tin oxide nanocomposite thin films. The response time, recovery time, repeatability and ageing effect after (one, two and three) weeks of nanocomposite thin films were obtained during humidity sensing measurements.

Synthesis and Characterization of Hydrogenated Diamond-Like Carbon (HDLC) Nanocomposite Films with Metal (Ag, Cu) Nanoparticles.

In this work, the synthesis and characterization of hydrogenated diamond-like carbon (HDLC) nanocomposite thin films with embedded metallic Ag and Cu nanoparticles (NPs) are studied. These nanocomposite films were deposited using a hybrid technique with independent control over the carbon and metal sources. The metallic nanoparticles were directly deposited from the gas phase, avoiding surface diffusion of metal species on the deposition surface. The structural features, surface topography and optical properties of pure and nanocomposite HDLC films are studied and the effect of metal introduction into the carbon matrix is discussed. The interactions between the carbon ion beam and the NPs are considered and it is demonstrated that the nanocomposite HDLC:metal films, especially for Cu NPs, can retain the transparency level of the pure HDLC, by limiting the interactions between metal and carbon during deposition.

Effect of Etchant Concentration on the Optical Properties and Surface Topography of MoO3 Selective Solar Absorber Thin Films

ABSTRACTA novel technique providing a cost effective sustainable wet chemical etching method of synthesizing black Moly thin films rapidly has been presented. A top- down method for fabricating MoO3 has been investigated to understand the effect of chemical etchant concentration on the structural, morphological and optical properties of the thin films on Mo substrates. The XRD patterns demonstrated the formation of Tugarinovite MoO2 films on Mo substrate after annealing at 500°C in a vacuum. In this work, we developed nanostructured MoO3 on Mo substrate solar absorber, with a high solar absorptance of over 89%. These results suggest that solar absorbers made from refractory metal oxide nanostructures can be used for solar thermal applications.

The impact of DCSBD plasma discharge on polypropylene

The diffuse coplanar surface barrier plasma discharge (DCSBD) still belongs to specific methods of modifying (activating) the surface of polymeric materials. The present work deals with surface treatment of polypropylene foils by plasma discharge, investigation and subsequent identification of changes caused by mentioned discharge. The modified surface was examined by measuring the wetting angle. Film surface morphology and topography was investigated by scanning electron microscope (SEM) and atomic force microscopy (AFM), respectively. Subsequently, it was examined whether the modification of polypropylene by DCSBD plasma discharge only affects the surface of the investigated material or also changes structural properties in studied material, based on the obtained data from DMA analysis.

An effect of Zn content doping on opto-third order nonlinear characteristics of nanostructured CdS thin films fabricated through spray pyrolysis for optoelectronics

Abstract The facile and cost-effective fabrication of cadmium sulphide (CdS) thin films with diverse contents of Zn was carried out on substrates of glass which maintained at 300 °C temperature. The grown CdS films are observed to belong monophasic hexagonal system at all Zn contents through structural and vibrational inspections. The values of crystallites size were determined in range of 16–31 nm. The Zn existence and its homogeneity were confirmed by EDX and e-mapping. SEM study displayed the modification in surface topography of CdS films by Zn content. Ultra violet-visible-near infrared spectroscopy study revealed that the grown films are of good optical transparency. The indices of refraction values were estimated and shows the variation in range of 1–2.8 owing to Zn. The PL study propose the applications of grown films in green LEDs as the emission peak has been observed at 513 ± 17 nm. Third-order-nonlinear optics (TONLO) constraints were determined through off and on orifice Z-scan data. The order of the values of TONLO index of refraction and susceptibility was noted of 10−8 cm2/W and 10−5 esu, orders correspondingly and found to be enhanced with Zn doping in CdS. Enhancement in optical limiting behaviour of CdS was also noticed when doped with Zn.

Effect of wavelengths on the structure, morphology and optoelectronic properties of cadmium sulfide thin films by laser assisted chemical bath deposition

Laser assisted chemical bath deposition (LACBD) is an interesting technique to synthesize semiconductor thin films. The effects of three laser wavelengths (445, 457 and 532 nm) on the structure, composition, morphology and optoelectronic properties of cadmium sulfide (CdS) thin films by LACBD are presented. Structural analysis of the thin films confirmed their polycrystalline nature. The surface composition specifics and chemical states of Cd and S were studied by X-ray photoelectron spectra. The topography and roughness of the films were explored by atomic force microscopy. The films exhibited high transmittance in visible region with 2.5 eV bandgap. All the samples showed photocurrent response under irradiation for white light as well as selected wavelengths of visible light emitting diodes from which the electrical properties were evaluated. The results showed that the laser irradiation by various wavelengths was effective in modification of surface topography and optoelectronic properties of the polycrystalline CdS thin films.

On the adhesion and wear resistance of DLC films deposited on nitrile butadiene rubber: A Ti-C interlayer

To promote the adhesion strength between diamond-like carbon (DLC) films and nitrile butadiene rubber (NBR) substrates, titanium-doped carbon (Ti-C) films prepared by dual-target magnetron sputtering under varied substrate bias voltages were used as an interlayer on the rough NBR. The surface topography and structure of Ti-C films were investigated by atomic force microscopy (AFM) and Raman spectra. Raman analysis indicates that the increase of substrate bias voltage leads to an increase of the number or the size of sp2 clusters in the Ti-C interlayer. The adhesion strength and tribological properties of DLC films coated on NBR substrate were scrutinized by a scratch tester and a ball-on-disk tribometer, respectively. It was found that DLC film with a Ti-C interlayer at a certain bias voltage exhibited superior wear resistance with a low coefficient of friction (CoF) during the sliding of 6000 laps. No clear damages in the coatings were observed from the wear tracks. Besides, the scratch test also revealed a reliable adhesion when the interlayer was prepared at −150 V, as confirmed by a scratch crack width of ~50 μm as compared to that of the pure DLC film increasing to ~ 120 μm. Therefore, a Ti-C interlayer could significantly enhance the adhesion and wear resistance of DLC thin films deposited on NBR.

Power spectral density-based fractal analysis of annealing effect in low cost solution-processed Al-doped ZnO thin films

Thin films of aluminium-doped zinc oxide (Al:ZnO) have been deposited using the sol-gel spin coating method and annealed at 300 °C, 400 °C, and 500 °C. The structural phase purity of the annealed films has been confirmed by the glancing angle x-ray diffraction patterns. The average microcrystalline size and residual microcrystalline stress have been calculated from it. It is observed that the average microcrystalline size increases and the residual microcrystalline compressive stress first increases and then decreases with increasing annealing temperature from 300 °C to 500 °C. The conventional surface roughness calculations and the power spectral density (PSD)-based fractal computations of the AFM micrographs have been carried out. The values of the power-law exponent demonstrate the underlying mechanism of the films’ residual surface growth. All the annealed films have a combined surface transport mechanism of viscous flow and evaporation-condensation. However, evaporation-condensation becomes dominant at the higher annealing temperatures of 400 °C and 500 °C. The spatial and vertical anisotropy of thin film surface topography has been quantified in a scale-invariant and generalized manner with the help of fractal geometrical analysis. The values of the fractal dimensions and Hurst exponents indicate that the vertical roughness of the films increases and the spatial self-similarity decreases with increasing annealing temperature. It is noteworthy that the Hurst exponent can alone depict the complexity of a thin film surface, whereas in conventional techniques at least three parameters are necessary for this. The fractal dimension increases with increasing average grain size and annealing temperature. Consequently, overall surface complexity increases with increasing annealing temperature. Thus, the fractal analysis can find its application in the predictability and assessment of surface topography. Also, various physical properties of films may be correlated with the fractal parameter of thin film surfaces in future works for micro and nano device fabrications.

Influence of Electron Beam Treatment of Co–Cr Alloy on the Growing Mechanism, Surface Topography, and Mechanical Properties of Deposited TiN/TiO2 Coatings

This study examines the effect of electron beam treatment (EBT) of Co–Cr substrate on the film growth mechanism, mechanical properties, and surface topography of TiN/TiO2 coatings deposited by reactive magnetron sputtering. The obtained results and processes that occurred during the deposition are discussed in the context of crystallographic principles, and special attention is paid to the crystallographic orientation and growth mechanism studied by X-ray diffraction (XRD). The mechanical properties were investigated by means of nanoindentation and wear tests. The surface topography was evaluated using atomic force microscopy (AFM). The results obtained in the present study showed that polycrystalline TiN and anatase TiO2 phases were present in all cases. Electron beam treatment of Co–Cr substrate tended to form a reorientation of the microvolumes from (111) to (200) of TiN, leading to a change in the growth mechanism from three-dimensional (Volmer–Weber) to layer-by-layer (Frank–van der Merwe). It was found that the electron beam treatment process did not significantly affect the thickness of the coatings and the deposition rate. The treatment process led to an increase in surface roughness. The higher surface roughness after the EBT process should be appropriate to support cell growth and adhesion on the surface of the deposited bilayer coating. It was demonstrated that EBT of the substrate caused a decrease in hardness of the deposited coatings from 10 to 5 GPa. The observed decrease in hardness was attributed to the change in the preferred crystallographic orientation and film growth mechanism. The hardness of the bilayer coating after the application of EBT of the Co–Cr substrate was much closer to that of human bones, which means that severe stress shielding effect could not be expected. The evaluated coefficient of friction (COF) exhibited significantly lower values in the case of EBT of the substrate compared to the untreated Co–Cr material.