Films Of Various Thicknesses Research Articles

Thin Ni/Al Metal Films Characterization Using a High-Frequency Electromagnetic Field

The paper presents methods of obtaining and studying new materials - thin metal films of the Ni/Al system. The technique and main parameters of the resistive method of thermal evaporation of the alloy using a vacuum universal station are briefly presented. Samples of thin films of various thicknesses were obtained. The thickness of the material was determined both using a scanning electron microscope and a developed eddy-current gage system operating under a hardware-software complex. In the course of the research, the limit the film thickness gauging capabilities of the developed gage system was established (400 nm). The ability of the gage system to detect differences in the thickness of the same film was shown using the developed method. Also, the possibility of determining the thickness of an undoubtedly unknown thin film by an eddy-current transducer signal amplitude has been demonstrated.

Superminiature Eddy Current Probe for Measuring the Electrical Conductivity of Copper Thin Films

The article considers the possibility of applying the eddy current method of non-destructive testing for measuring the electrical conductivity of new material - thin metal films. Copper films of various thickness obtained by physical vapour deposition were used as the measurement object. The deposition method and the hardware and software complex for measuring the electrical conductivity of the film were briefly described. A calibration curve that makes it possible to restore the values of the electrical conductivity of the material by the signal value of the eddy current probe was presented. The test results of films with different characteristics were given, and the distribution of the electrical conductivity of the films depending on the batch was shown. Based on different values of the electrical conductivity in a batch, the difference in deposition quality of various films was found.

Investigation and optimization of polarization properties of self-assembled carbon nanotube films

Super-aligned carbon nanotubes (CNTs) film has strong anisotropy to light propagation. In order to better integrate the self-assembled CNTs into microelectromechanical system (MEMS) for polarization applications, some inherent impacts on polarization properties of CNT film were investigated. We described the polarization effects of the film thickness variation in detail, giving an optimum thickness range which is around 700–800 nm. The amorphous carbon content of CNT film was reduced by oxidation process where the transmittance increased by almost 4 folds. The alignment of CNT arrangement was optimized from 0.41 (Chebyshev orientation parameter) to 0.54 by manipulating the C2H4 flow rate from 54 to 80 sccm. More specifically, a sample possessing a degree of polarization up to 99% and transmittance over 45% was obtained through proper regulations. The validated optimization makes the aligned CNT films more feasible and valuable for the integration of the CNT polarimeters with MEMS technology.

Determination of surface film thickness of heavy fuel oil using hyperspectral imaging and deep neural networks

ABSTRACT The determination of surface oil film thickness is essential to safeguard the coastal water quality in major cities globally, particularly during the incidents of oil spills. The spilled oil film is typically very thin of the order of millimeters or less and thus the thickness quantification is very challenging. This study develops a laboratory approach for the thickness estimation using hyperspectral imaging combined with Deep Neural Networks for the image data analysis. Pool experiments were conducted in stagnant seawater with floating oil films of various thicknesses. Hyperspectral imaging was performed, and the images were augmented via a pixel extraction method. The data were then analyzed using two developed models of Dense Artificial Neural Network (DANN) and Convolutional Neural Network (CNN) to predict the thickness of the surface oil film. The results showed that both models managed to produce reasonably accurate predictions with a relatively high coefficient of determination of 0.87 and 0.95, respectively. Comparatively, the CNN model had overall better results by making use of the spatial information of surrounding pixels.

Effects of Various Drying Times on the Properties of 3D Printed Orodispersible Films.

Orodispersible films are an innovative dosage form. Their main advantages are the application comfort and the possibility of personalization. This work aimed to evaluate the influence of different drying times on the properties of orodispersible films of various thicknesses, prepared in two different semisolid extrusion 3D printing setups. In the first experiment, drying times were dependent on the overall print time of each batch. In the second setup, the drying time was set equal according to the longest one. The evaluated parameters were films’ weight uniformity, thickness, moisture content, surface pH, disintegration time, hardness, and tensile strength. Upon statistical comparison, significant differences in the moisture content were found, subsequently affecting the disintegration time. Moreover, statistically significant differences in films’ mechanical properties (hardness, tensile strength) were also described, proving that moisture content simultaneously affects film plasticity and related properties. In conclusion, a mutual comparison of the manufactured orodispersible films showed that the drying time affects their physical and mechanical properties. The in-process drying setup was proved to be sufficient while allowing quicker manufacturing.

Effect of thickness and reaction media on properties of ZnO thin films by SILAR

Zinc oxide (ZnO) is one of the most promising metal oxide semiconductor materials, particularly for optical and gas sensing applications. The influence of thickness and solvent on various features of ZnO thin films deposited at ambient temperature and barometric pressure by the sequential ionic layer adsorption and reaction method (SILAR) was carefully studied in this work. Ethanol and distilled water (DW) were alternatively used as a solvent for preparation of ZnO precursor solution. Superficial morphology, crystallite structure, optical and electrical characteristics of the thin films of various thickness are examined applying X-ray diffraction (XRD) system, scanning electron microscopy, the atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Hall effect measurement analysis and UV response study. XRD analysis confirmed that thin films fabricated using ethanol or DW precursor solvents are hexagonal wurtzite ZnO with a preferred growth orientation (002). Furthermore, it was found that thin films made using ethanol are as highly crystalline as thin films made using DW. ZnO thin films prepared using aqueous solutions possess high optical band gaps. However, films prepared with ethanol solvent have low resistivity (10–2 Ω cm) and high electron mobility (750 cm2/Vs). The ethanol solvent-based SILAR method opens opportunities to synthase high quality ZnO thin films for various potential applications.

Broadband point-spread function engineering via a freeform diffractive microlens array.

We utilized inverse design to engineer the point-spread function (PSF) of a low-f-number, freeform diffractive microlens in an array, so as to enable extended depth of focus (DOF). Each square microlens of side 69 µm and focal length 40 µm (in a polymer film, n∼1.47) generated a square PSF of side ∼10 µm that was achromatic over the visible band (450 to 750 nm), and also exhibited an extended DOF of ∼ ± 2 µm. The microlens has a geometric f/# (focal length divided by aperture size) of 0.58 in the polymer material (0.39 in air). Since each microlens is a square, the microlens array (MLA) can achieve 100% fill factor. By placing this microlens array (MLA) directly on a high-resolution print, we demonstrated integral imaging with applications in physical security. The extended DOF preserves the optical effects even with expected film-thickness variations, thereby increasing robustness in practical applications. Since these multi-level diffractive MLAs are fabricated using UV-nanoimprint lithography, they have the potential for low-cost large volume manufacturing.

A volume plasmon blueshift in thin silicon films embedded within Be/Si periodic multilayer mirrors.

Microstructural properties of the beryllium (Be) and silicon (Si) in periodic multilayer mirrors Be/Si with the variation of film thickness were comprehensively determined by Raman scattering. For the thinner films, the structure of Be evolved in the amorphous phase, and it was transformed into the polycrystalline phase for thicker films. The Si films in the periodic structure were condensed into the amorphous phase. The small fraction of nanocrystalline Si particles was distributed within the amorphous phase. A shake-up satellite peak of Si 2s photoelectrons was observed in X-ray photoelectron spectroscopy which suggested the excitation of a plasmon in Si films embedded within Be/Si periodic multilayers. The energy of plasmons was sensitive to the film thickness of Si in the periods which directly corresponds to the particle size. The binding energy of the satellite peak of Si 2s photoelectrons was blueshifted (higher energy) with a decrease in the particle size. This was explained by size dependent quantum confinement of particles.

Atomic-level thick TiO2–CoTiO3 multilayer p-n junction with extended built-in electric field as efficient photoanode

Formation of p-n junction was an effective method to improve the photocatalytic performance due to its built-in electric field. However, the electric field was distributed only on the interface between two semiconductors, which was insufficient in comparison to the entire material. In this work, a multilayer TiO 2 –CoTiO 3 p-n junction was designed and fabricated by atomic layer deposition. The charge transport and photoelectrochemical properties of multilayer TiO 2 –CoTiO 3 films of various thicknesses are thoroughly investigated. The PL and electrochemical tests demonstrate that TiO 2 –CoTiO 3 exhibits enhanced charge separation and transport. Additionally, the extra visible light response was achieved by introduction of CoTiO 3 . Also, theoretical calculations indicate that the electrons prefer to immigrate from TiO 2 to CoTiO 3 in a multilayer TiO 2 –CoTiO 3 structure. Benefited from the boosted light absorption and charge transfer, the multilayer TiO 2 –CoTiO 3 composite film exhibits a significantly increased photocurrent, much higher than pure TiO 2 and a single TiO 2 –CoO p-n junction. This multilayer p-n junction structure opens a rational and novel way for nanostructure construction in the energy conversion region.

Structural and gas-sensitive characteristics of thin semiconductor PdO films of various thicknesses during ozone detection

PdO films were obtained by thermal deposition of palladium metal with a thickness of 30 and 90 nm, followed by its oxidation in air at different temperatures. PdO oxide films are characterized by transmission electron microscopy (TEM) and reflection high-energy electron diffraction (RHEED). Data on the semiconductor properties and gas sensitivity to different concentrations of ozone in the air are obtained. The optimal temperature conditions for the oxidation of the films are established, which ensure their uniform phase composition and the absence of electrical noise during the detection of gases. The mechanism of the electrical noise appearance in ultrathin films associated with their fragmentation during oxidative annealing is proposed and justified. The possibility of detecting ozone impurities in the air below the maximum permissible concentration (MPC) by PdO semiconductor films is shown. Keywords: palladium oxide thin films, phase composition, electrical noise, gas sensor properties.

Electron microscopy of the microstructure of antimony thin films of variable thickness

Thin Sb films with a thickness gradient deposited in vacuum were investigated by transmission electron microscopy. Microstructures in films with increasing thickness change from amorphous islands of increasing density and size to labyrinthine and continuous films with texturing, which also changes with increasing thickness. Based on the analysis of the patterns of bend extinction contours, a strong internal bending of the crystal lattice, up to 120 deg/μm, and the dependence of the crystallographic orientations in the structures of the film on the thickness were revealed. Keywords: Antimony, thin films, TEM, crystallography, extinction bend contours.

Analysis and Evaluation of Paint Film Thickness Variation due to Solvent Volatilization Based on Drying Rate Curves

During the drying process of paints, the solvent contained in the paint volatilizes and the film thickness decreases. Since this property is highly dependent on the drying temperature and can affect the quality of the paint, appropriate temperature conditions and film thickness control are required. In this study, a model based on mass transfer theory was developed to calculate the paint film thickness at an arbitrary elapsed time. As a validation test, wet film thickness was measured by a non-contact film thickness gauge and compared with the analytical results. As a result, accurate paint film thickness prediction was achieved by setting appropriate parameters for different drying conditions.

Impact of surface morphology and thickness of tin selenide thin films on their optical properties

Thin tin selenide (SnSe) films were synthesized on polyamide sheets via the two-stage adsorption/diffusion method. The surface morphology and chemical composition of the hereby obtained thin film were characterized by energy-dispersive spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and X-ray photoemission spectroscopy techniques. The X-ray diffraction analysis showed that the obtained films are chemically close to tin selenide with three orthorhombic phases. A systematic investigation was carried out to understand the factors of the next stage process, the influence of conditions on the structure, the surface morphology of SnSe thin films, and their thickness. It was found that the concentration of tin(II) precursor solution, its pH value, and temperature led to the creation of films of various thickness and surfaces with different features. The SnSe films consisted of nanoscale ∼40 nm size grains, which in turn were combined into agglomerates of up to 100 nm to 3 µm. The stoichiometric ratios of tin and selenium in SnSe films were also dependent on the next-stage conditions of the synthesis process. The thickness of the SnSe films and the size of the crystallites of which they are composed have a decisive influence on the optical properties of these layers and the band gap of which varied in the range of 1.75–1.24 eV.

Microstrip Array Ring FETs with 2D p-Ga2O3 Channels Grown by MOCVD

Gallium oxide (Ga2O3) thin films of various thicknesses were grown on sapphire (0001) substrates by metal organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa), high purity deionized water, and silane (SiH4) as gallium, oxygen, and silicon precursors, respectively. N2 was used as carrier gas. Hall measurements revealed that films grown with a lower VI/III ratio had a dominant p-type conduction with room temperature mobilities up to 7 cm2/Vs and carrier concentrations up to ~1020 cm−3 for thinner layers. High resolution transmission electron microscopy suggested that the layers were mainly κ phase. Microstrip field-effect transistors (FETs) were fabricated using 2D p-type Ga2O3:Si, channels. They achieved a maximum drain current of 2.19 mA and an on/off ratio as high as ~108. A phenomenological model for the p-type conduction was also presented. As the first demonstration of a p-type Ga2O3, this work represents a significant advance which is state of the art, which would allow the fabrication of p-n junction based devices which could be smaller/thinner and bring both cost (more devices/wafer and less growth time) and operating speed (due to miniaturization) advantages. Moreover, the first scaling down to 2D device channels opens the prospect of faster devices and improved heat evacuation.

Structural morphology and electrical transitions of V[formula omitted]O[formula omitted] thin films grown on SiO[formula omitted]/Si by high power impulse magnetron sputtering

The study presents the synthesis of V2O3 films on thermally oxidized Si(001) substrates by reactive high power impulse magnetron sputtering. The effect of film thickness and oxygen variation were explored at fixed discharge parameters. X-ray diffraction (XRD), grazing incidence-XRD and pole scans reveal the films to be textured. The results show that for a critical thickness up to ∼ 5 nm, highly strained V2O3 films are obtained, and with increased thickness the film exhibit increased surface roughness and the formation of a granular structure arising from strain relaxation in the films. With increasing thickness the films exhibit a variation in the lattice parameters affecting their electrical characteristic i.e. metal-insulator transition (MIT). Subject to variation in O2 flow setting we observe the MIT magnitude and transition temperatures to be strongly dependent on the film stoichiometry and lattice parameters which can be fine tuned by mapping the O2 flow settings. The most dominant transition out of the studied structures was observed for those having film thickness of ∼ 36 nm with an O2 flow setting ranging from 0.8 to 0.95 sccm and displaying a low c/a lattice ratio. The MIT observed for these structures displayed a change in resistance of up to ∼ 4 decades with a total change in resistance of ∼ 7 decades.

Normal-state transport in superconducting NbN films on r-cut sapphire

High-quality thin NbN films are very crucial for realizing quantum devices. Here, we investigated electrical transport and noise properties of a series of thin NbN films of various thicknesses grown on r-cut sapphire substrate using a DC magnetron sputtering technique. The films exhibit non-uniform thickness dependences for superconducting transition temperature (Te ) and normal-state resistivity. Morphological characterization of NbN samples of various thicknesses reveals uniform structure in thin films and granular structure in thick films. By measuring transport and noise properties in a normal state, we observe that the granular structure of NbN films does not have a strong effect on resistivity and does not cause an additional source of current noise.

Providing a Specified Level of Electromagnetic Shielding with Nickel Thin Films Formed by DC Magnetron Sputtering

Nickel films of 4–250 nm thickness were produced by DC magnetron sputtering onto glass and silicon substrates. The electrical properties of the films were investigated by the four-probe method and the surface morphology of the films was studied by atomic force microscopy. To measure the shielding effectiveness, a portable closed stand based on horn antennas was used. A theoretical assessment of the shielding effectiveness of nickel films of various thickness under electromagnetic radiation of a range of frequencies was carried out using two different approximations. The results demonstrate the shielding effectiveness of up to 35 dB of the nickel thin films in the frequency range of 2–18 GHz.

Wettability and thermal performance of Ga62.5In21.5Sn16 liquid metal alloy on W-coated Cu substrates with varying film thickness

The Ga62.5In21.5Sn16 liquid metal alloy (LMA) has been considered as a promising thermal interface material for electronics cooling. In this work, the Cu substrates were deposited with tungsten (W) films or copper (Cu) films of various thicknesses to form different morphology and composition. The surface morphology and wettability of the filmed Cu substrates were investigated by the scanning electron microscope and drop shape analyzer, respectively. Thermal performances of the Ga62.5In21.5Sn16 sandwiched between filmed Cu substrates were studied using the laser flash analyzer. It was observed that the rough Cu substrate becomes smooth after being deposited with metal film. A decrease in surface roughness leads to the decrease in the contact angle of Ga62.5In21.5Sn16 droplet on filmed Cu substrate and the thermal resistance of Ga62.5In21.5Sn16 sandwiched between filmed Cu substrates. The wettability and thermal performance are strongly dependent on the surface composition. Thermal performance of the Ga62.5In21.5Sn16 sandwiched between the W-coated Cu substrates initially varies dramatically with W film thickness, and then changes slowly beyond a critical film thickness of ∼60 nm. This trend originates from the changing of surface composition arising from the thickening of W films.

Modeling and analysis of transient lubrication characteristic of the helicopter main transmission spiral bevel gears in point contacts

An engineering calculation model is introduced for point-contact elastohydrodynamic lubrication analysis of spiral bevel gears. This model can analyze transient lubrication characteristics of spiral bevel gears. The influence of the angle between the lubricant entrainment and the minor axis of the contact ellipse is included in this model. The contact parameters of the spiral bevel gear are calculated, which will change with time during the meshing process. The variation of lubricant film thickness during the meshing process of spiral bevel gears is unraveled. Due to the influence of entrainment velocity, the oil film thickness at the out mesh side is smaller than that at the enter mesh side under the same contact force. It is evident that the higher the pressure is, the larger the contact area will be. Meanwhile, the thickness of the oil film is reduced, and the oil film distribution in the contact area is relatively uniform. Taking helicopter main transmission spiral bevel gears as an example, this study finally calculates the distribution characteristics of the oil film thickness of the spiral bevel gear, and solves the lubrication performance of the spiral bevel gear under different working conditions.

Ion tracks in ultrathin polymer films: The role of the substrate

Surface damage produced by single MeV-GeV heavy ions impacting ultrathin polymer films has been shown to be weaker than those observed under bulk (thick film) conditions. The decrease in damage efficiency has been attributed to the suppression of long-range effects arising from excited atoms lying deeply in the solid. This raises the possibility that the substrate of the films itself is relevant to the radiation effects seen at the top surface. Here, the role of the substrate on cratering induced by individual 1.1 GeV Au ions in ultrathin poly(methyl methacrylate) (PMMA) layers is investigated. Materials of different thermal and electrical properties (Si, SiO2, and Au) are used as substrates to deposit PMMA thin films of various thicknesses from ∼1 to ∼300 nm. We show that in films thinner than ∼40 nm craters are modulated by the underlying substrate to a degree that depends on the transport properties of the medium. Crater size in ultrathin films deposited on the insulating SiO2 is larger than in similar films deposited on the conducting Au layer. This is consistent with an inefficient coupling of the electronic excitation energy to the atomic cores in metals. On the other hand, the damage on films deposited on SiO2 is not very different from the Si substrate with a native oxide layer, suggesting, in addition, poor energy transmission across the film/substrate interface. The experimental observations are also compared to calculations from an analytical model based on energy addition and transport from the excited ion track, which describe only partially the results.