Effects Of Thin Film Thickness Research Articles

Effect of thin film thickness of ferrofluid on inclined bioconvective flow

This research examines the effect of variable thin film thickness on the bioconvective ferrofluid flow through a rotating sloped surface when a magnetic field (dipole) is present. Similarity transformation is used to standardize the current model's governing equations. By using a finite element method, the normalized nonlinear differential equations are numerically solved. Variable thickness of ferrofluid thin film and bioconvective parameters (bioconvective Lewis number, bioconvective Peclet number, and micro-organism concentration difference) yield the following results: velocity profiles (radial, tangential, and axial), gravity flow (drainage velocity and induced velocity), temperature profile, concentration profile and microorganism profile. In addition, this investigation examines the density of moving microorganisms as well as local heat and mass transport. The temperature, concentration, radial, axial, drainage, induced, and motile microbe velocity are all improved with increasing film thickness. Variable thickness increases local heat transfer whereas increasing Brownian motion and thermophoresis parameters decreases it. This study could be helpful for self-sterilizing applications and biomedical engineering.

Liquid Shear Exfoliation of MoS2: Preparation, Characterization, and NO2-Sensing Properties.

2D materials possess great potential to serve as gas-sensing materials due to their large, specific surface areas and strong surface activities. Among this family, transition metal chalcogenide materials exhibit different properties and are promising candidates for a wide range of applications, including sensors, photodetectors, energy conversion, and energy storage. Herein, a high-shear mixing method has been used to produce multilayered MoS2 nanosheet dispersions. MoS2 thin films were manufactured by vacuum-assisted filtration. The structural morphology of MoS2 was studied using ς-potential, UV-visible, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The spectroscopic and microscopic analyses confirm the formation of a high-crystalline MoS2 thin film with good inter-sheet connectivity and relative thickness uniformity. The thickness of the MoS2 layer is measured to be approximately 250 nm, with a nanosheet size of 120 nm ± 40 nm and a number of layers between 6 and 9 layers. Moreover, the electrical characteristics clearly showed that the MoS2 thin film exhibits good conductivity and a linear I-V curve response, indicating good ohmic contact between the MoS2 film and the electrodes. As an example of applicability, we fabricated chemiresistive sensor devices with a MoS2 film as a sensing layer. The performance of the MoS2-chemiresistive sensor for NO2 was assessed by being exposed to different concentrations of NO2 (1 ppm to 10 ppm). This sensor shows a sensibility to low concentrations of 1 ppm, with a response time of 114 s and a recovery time of 420 s. The effect of thin-film thickness and operating temperatures on sensor response was studied. The results show that thinner film exhibits a higher response to NO2; the response decreases as the working temperature increases.

Effect of MAX phase chromium aluminum carbide thin film thickness on Q-switched Erbium-doped fiber lasers

In recent years, chromium aluminum carbide (Cr2AlC) has gained attention because of its good performance in terms of high-temperature resistance, transparency and conductivity. Therefore, it has been widely used in solar cells, photonics and electronics. Although some related characteristics are investigated in pulse lasers, the effect of thin film thickness in generating laser pulses have not been reported. Therefore, the effect of thin film thickness on the performance of Q-switched erbium-doped fiber laser (EDFL) is explored in this work. Two films of different thicknesses were applied to generate Q-switched laser pulses. The thickness of the films were about 45 µm and 16 µm and they were prepared by a casting method with polyvinyl alcohol (PVA). The effects of two different film thicknesses on laser performance were investigated separately. The results show that the film thickness affects the modulation depth, saturation intensity and insertion loss of SA, which in turn effects the Q-switched laser pulses.

Effect of Thin Film Thickness on the Electronic Properties of Wurtzite Structure (ZnO and GaN): A Density Functional Theory Study

By using first-principle density-functional theory (DFT) calculations supplemented with symmetry analysis, we investigated the effect of thin-film thickness on the electronic properties of non-polar ( ZnO-wz and GaN-wz. We find that the electronic band structures of thin-film non-polar ( surface with layer variations from two until ten bilayers show the Rashba spin splitting. Importantly, we revealed that this splitting is found to be strongly anisotropic observed in the valence band maximum (VBM) around the Γ point. We clarified the origin of the anisotropic spin splitting in the electronic band structures by considering the point-group symmetry (PGS) of the present system. We found that the changes of the PGS from C6v (for polar [0001] direction) to Cs (for non-polar ( direction) are responsible for inducing the anisotropic of the spin splitting. To further confirm the anisotropic splitting, we calculated the Rashba spin splitting parameters for different directions of the k-path. We found that these parameters are different in magnitude for a different direction of the k-path indicating the anisotropic spin splitting quantitatively, which is consistent well with symmetry analysis. Finally, we conclude that the observed Rashba spin splitting in the wurtzite surface structure is promising for spintronics applications.

Characterization of surface physico-chemistry and morphology of plasma-sized carbon fiber

Carbon fiber (CF) surfaces were prepared in order to enhance their cohesion in polymer matrixes for composite applications. Among innovative methods allowing the modification of CF surface, plasma technologies, and more specifically on plasma polymerization is known as an eco-process that allows to size, i.e. to coat the CF strands with organic polymer materials. Depending on plasma parameters and chosen organic precursors, the thin film surface physico-chemistry can be tuned to enhance the plasma-processed CF surface properties. The chemical composition, as well as the effect of thin film thickness, were linked to wettability and surface free energy of the coated CFs. Among the different plasma polymers, plasma-poly(acetylene) is characterized with higher deposition rate and was the most efficient for improving the wettability of CF surface. Surface chemistry and thickness appear to be the key parameter of controlling the CF surface wettability.

Evolution of the Electronic Properties of ZrX2 (X = S, Se, or Te) Thin Films under Varying Thickness

Probing the effects of thin-film thickness on transition metal dichalcogenides offer novel insights into their electronic properties and tunability, which leads to a new avenue of research and appl...

Effects of Thin-Film Thickness on Sensing Properties of SnO₂-Based Gas Sensors for the Detection of H₂S Gas at ppm Levels.

SnO₂ thin-film gas sensors were easily created using the ion sputtering technique. The as-deposited SnO₂ thin films consist of a tetragonal SnO₂ phase and densely packed nanosized grains with diameters of approximately 20-80 nm, which are separated by microcracks. The as-deposited SnO₂ thin film is well crystallized, with a dense columnar nanostructure grown directly onto the alumina material and the Pt electrodes. The grain size and thickness of SnO₂ thin films are easily controlled by varying the sputtering time of the ion coater. The responses of the SnO₂ thin-film sensors decrease as the SnO₂ film thickness is increased, indicating that a negative association exists between the sensor response and the SnO₂ film thickness due to gas diffusion from the surface. The SnO₂ thin-film sensor, which was created by ion sputtering for 10 min, shows an excellent sensor response (Ra/Rg where Ra is the electric resistance under air and Rg is the electric resistance under the test gas) for detecting 1 ppm H₂S at 350°C.

Study the effect of thin film thickness on the optical features of (IR5 laser dye/CdSe nanoparticles) samples

The linear optical features such as (transmittance T, absorbance A, the effective length 𝐿𝑒𝑓𝑓, absorption coefficient 𝛼 and refractive index 𝑛 ) for the thin films samples of (3x10-3 mol/l of (IR5) laser dye, 0.02 gm of (CdS) nanoparticles and 0.04 gm of pp polymer) had been studied at different values of film thickness in one time and at different number of Yb:GdVO4 laser pulses. The non-linear optical features in terms of transmittance difference Δ𝑇𝑝−𝑣, non-linear refractive index 𝑛2, non–linear phase shift Δ𝛷𝑜 non-linear absorption coefficient 𝛽 and minimum normalized transmittance 𝑇(𝑍) have been computed in relation to obtained normalized transmittance data from setup of Z-scan with open and closed apertures, calculated for (3x10-3 mol/l of (IR5) laser dye, 0.02 gm of (CdSe) nanoparticles and 0.04 gm of (pp) polymer) thin films at different values of film thickness at in one time and at different Yb:GdVO4 laser pulses. Thick films causes in deleting the non-linear effects generated by different layers. The (CdSe) nanoparticles leads to an absorption shifting of the wavelengths to lengthier wavelengths of red shift. So, this can be used in selecting the nanoparticles and medium with applicable exciting wavelengths. The film thickness and the laser pulses have the main effects in consolidating the Non-linear optical features.

The effect of thin film thickness on thermal nonlinear optical properties and surface morphology of Cu nanostructure thin films

This study aims to Investigate the effect of thin film thickness on thermal nonlinear optical properties and Surface morphology of Cu Nanostructure Thin Films. Samples are deposited by Thermal Evaporation (TE) and Pulsed Laser Deposition (PLD) Methods. The Morphology of the samples are studied by Field Emission Scanning Electron Microscope (FESEM) images, both samples deposited by PLD and TE showed surface with island nanoparticles. To study the nonlinear optical characteristics of the samples, Z-scan technique was employed. Both TE and PLD samples showed nonlinear absorption and nonlinear refraction. As the thickness of the layers increased, the sign of the nonlinear refraction index changed and the nonlinear absorption coefficient increased.

Thickness dependence of structural, optical and morphological properties of sol-gel derived TiO2 thin film

In this research, Titanium dioxide (TiO2) thin films with different thicknesses were deposited on glass substrate by the sol - gel technique. Formation of TiO2 thin films was confirmed by EDAX spectra. The effect of thin film thickness on the structural, optical and morphological properties of the thin films was respectively analyzed by x-ray diffraction (XRD), UV–vis spectroscopy and atomic force microscopy (AFM). XRD measurements reveal the amorphous structure of the thin films before thermal treatment, while the thin films have crystalline phases after annealing at 600 °C. The XRD patterns also showed the dominant anatase phase in thin films structure. Moreover, peaks that belong to the Brookite phase appear as the thin film thickness increases. Brookite is the rare phase which is hardly gained and is suitable for photo catalytic applications. Crystalline transformation from anatse to anatas- brookite is attributed to grain size increase as increase of thin film thickness. Increase of grain size as a result of thin film thickness increase affect on the structural, optical and morphological properties. In addition, the weight fraction of brookite, grain size, lattice parameter and dislocation density were computed. The direct allowed band gap of TiO2 thin films with thickness of 50 nm to 150 nm was found to reduce in the range of 3.788 eV to 3.687 eV. The extinction coefficient, refractive index, susceptibility and porosity of the thin films were measured at the wavelength of 550 nm. Root mean square (RMS) roughness of the thin films increases as the thin film thickness increases.

Effect of Thickness on the Structure and Magnetic Properties of FePd Films Grown on Glass Substrate

FePd alloy films with different thicknesses have been prepared by DC magnetron sputtering on glass. The effect of thin film thickness on the structural and magnetic properties was investigated by X-ray diffraction (XRD), energy dispersive spectroscope (EDS), and physical property measurement system. The results indicate that the ordering process in the thin FePd alloy film occurs in the thicker ones. In-plane coercivity value first increases rapidly as thickness increases from d= 22.5 to d= 67.5 nm, and then the value decreases with further increasing film thickness. A peak value of coercivity 3.2×79.6 kA/m appears at d= 67.5 nm.

Effect of thickness on the dielectric properties of bismuth magnesium niobium thin films deposited by rf magnetron sputtering

The Bi1.5MgNb1.5O7 (BMN) thin films with cubic pyrochlore structure were prepared on Au-coated Si (001) substrates by rf magnetron sputtering. Effects of thin film thickness on the structure and dielectric properties of BMN thin films were investigated. As the thickness increases, the permittivity increases, the dielectric loss and leakage current decreases, and the tunability has an obvious improvement. The 300nm thick BMN thin films annealed at 750°C exhibit dielectric constant of 93, low dielectric loss of 0.00224 at 1MHz, and maximum tunability of 33.01% at the bias field of 1.25MV/cm. The relationship of leakage current and thickness was also studied and a possible explanation was proposed. The excellent dielectric properties make BMN thin films promising for potential tunable capacitor applications.

Numerical Analysis of the Effect of Thin-Film Thickness and Material in Field Mapping of Eddy-Current Probes Using Photoinductive Technique

Numerical Analysis of the Effect of Thin-Film Thickness and Material in Field Mapping of Eddy-Current Probes Using Photoinductive Technique

EFFECTS OF THIN FILM THICKNESS ON EMITTANCE, REFLECTANCE AND TRANSMITTANCE OF NANO SCALE MULTILAYERS

Knowledge of the radiative properties of multilayer consisting of silicon and related materials, such as silicon dioxide (SiO2), silicon nitride (Si3N4) and gold (Au) with different thicknesses is required for many microsystem applications. This paper describes the study of the effects of thin film thickness on radiative properties of nano scale multilayer. The results showed that silicon dioxide and silicon nitride coating act as anti reflector and these coatings reduce reflectance toward bare silicon. If thickness of non metal coating increases, reflectance of multilayer decreases and transmittance increases. Gold thin film coating increases reflectance. The reflectance of multilayer coated with gold increases by increasing the thickness of coating. This study will benefit and enhance the value of nano coating technology in the semiconductor industries, particularly in the development of micro electromechanical and nano electromechanical devices.

Thermal conductivity measurement of submicrometer-scale silicon dioxide films by an extended micro-Raman method

The micro-Raman method is a noncontact and nondestructive method for thin film thermal conductivity measurements. To apply the micro-Raman method, however, the thickness of the film must be at least tens of micrometers. An analytical heat transfer model is presented in this work to extend the micro-Raman measurement method to measure the thermal conductivity of thin films with submicrometer- or nanometer-scale thickness. The model describes the heat transfer process in the thin film and substrate considering the effects of thin film thickness, interface thermal resistance, thermal conductivity of the thin film and substrate. From this heat transfer model, an analytical expression for the thermal conductivity of the thin film is derived. Experiments were successfully performed to measure the thermal conductivity of 200, 300 and 500 nm thickness silicon dioxide films using the extended micro-Raman measurement method, with results confirming the accuracy and validity of the extended model.

Thickness dependence of magnetic domain formation in La 0.6Sr 0.4MnO 3 epitaxial thin films studied by XMCD–PEEM

We have used photoelectron emission microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD) to study the effect of thin film thickness on the magnetic domain formation in La 0.6Sr 0.4MnO 3 samples that were epitaxially grown on stepped SrTiO 3 (0 0 1) substrates. The magnetic image exhibited a stripe structure elongated along the step direction, irrespective of film thickness, suggesting that uniaxial magnetic anisotropy induced by step-and-terrace structures plays an important role in the magnetic domain formation. Additional domains evolved gradually with increasing film thickness. In these domains, the direction of magnetization differed from the step direction due to biaxial magneto-crystalline anisotropy. The evolution of additional magnetic domains with increasing film thickness implies that a competition exists between the two anisotropies in LSMO films.

The effects of thin-film thickness on the formaton of metallic patterns by direct nanoimprint

Abstract This paper proposes an alternative manufacturing process, the direct nanoimprint method, which is different from nanoimprint lithography (NIL) and can be employed in the fabrication of metallic thin-film nano-structures. A 3D molecular dynamics (MD) simulation is utilized to simulate the imprint process and to investigate the effects of the thickness of the thin film on the formation of metallic patterns. In the MD simulation model, the metallic thin film and mold, made of gold and nickel, respectively, are formed in face central cubical (FCC) single crystal. Simulation results show that during the imprint process, by varying the thickness of thin films, the substrate effect appears to have a great impact on the formation of metallic patterns. Finally, an experimental investigation is performed as comparison. It has been found that the effects of thin-film thickness on the formation of metallic patterns correspond very well both in simulation and experimental results.

Vertical Type Organic Transistor Using C60 and its Application for OLET

We have fabricated static induction transistor of vertical type using C60 with high carrier mobility as n-type organic semiconductor material to improve the characteristics of organic transistor. The effects of thin film thickness and the rate of deposition on the current-voltage and on-off ratio of transistor were investigated. And, we also studied the surface morphology of C60 layer under various deposition rate with AFM. The vertical type organic transistor using C60 exhibited low operation voltage compared to the case of F16CuPc. Additionally, the light emitting transistor using the vertical type transistor and P3HT as a light emitting polymer was investigated.

Mechanical properties and interface toughness of FeCo thin films on Ti–6Al–4V

Magnetostrictive materials such as FeCo are attractive for applications as embedded thin-film sensors for detecting strains or cracks in structural components. For these applications, FeCo thin films must possess good adhesion and adequate mechanical strength such that the embedded sensors would have adequate durability, and not degrade the structural integrity of the underlying components. In this paper, we investigate the effects of thin-film thickness and the surface condition of the substrate on the mechanical properties and interface toughness of FeCo thin films deposited to a Ti–6Al–4V substrate. The Young's modulus, hardness, and yield strength of FeCo thin films were measured by nanoindentation. Furthermore, the interface toughness of FeCo/Ti–6Al–4V was determined by cross-section nanoindentation on the edge and by brale indentation on the face of the thin films. The results indicate that the interface toughness exhibit spatial variations as well as dependence on layer thickness and the surface condition of the substrate. The experimental results are combined with a theoretical analysis to predict the debonding strength of the thin films and to assess the propensity of thin-film cracking versus interface debonding. The theoretical predictions are evaluated against experimental data of the debonding strength of FeCo thin films and notch fatigue strength of Ti–6Al–4V.

Effect of intermetallic compound formation on electrical properties of Cu/Sn interface during thermal treatment

Cu6Sn5 and Cu3Sn intermetallic compounds are commonly found in the Sn-Cu bimetallic system. Due to the distinct resistivity of these two compounds, the electrical properties of Cu/Sn interfaces, e.g., solder joints on Cu metallization, may be impacted by the formation of Cu-Sn compounds. In this study, the kinetics of Sn-Cu compound formation was investigated by in-situ resistivity measurement, x-ray diffraction, and scanning electron microscopy (SEM). The interfacial reaction of the Cu-Sn bimetallic thin film specimen was monitored by the resistivity change of the specimen during thermal treatment. The activation energy of formation of Cu-Sn compounds was determined to be 0.97±0.07 eV. It is proposed that the Cu6Sn5 compound first forms at Sn/Cu interfaces and then reacts with Cu, forming the Cu3Sn compound at elevated temperatures during the thermal ramping process. The effect of thin film thickness on the sequential formation of Sn-Cu compounds is also discussed.