Thin Films Of Uniform Thickness Research Articles

The development of low-cost spin coater with wireless IoT control for thin film deposition

A low-cost spin coater with a wireless remote system that can deposit thin films of uniform thickness and quality at a significantly lower cost than traditional methods. The system consists of three main parts, a motorized spindle, a spin-coating head, and a control system connected to the network. The mechanical design on the mechanical part, spin coater system design with ESP32, and implementation of wireless control through visual basic. The network-enabled control system allows for real-time monitoring and adjustment of the deposition process, which can improve efficiency and reproducibility. This low-cost spin coating system represents a promising solution for organizations seeking to access thin film deposition technology at a fraction of the cost of traditional systems. By integrating wireless IoT control into low-cost spin coaters, the impact of this technology on coating uniformity will provide valuable insights for future advancements in this field.

Two-dimensional tungsten disulfide nanosheets and their application in self-powered photodetectors with ultra-high sensitivity and stability

Two-dimensional (2D) tungsten disulfide nanosheets (WS2) could be a promising candidate for high-performance self-powered photodetectors. The present 2D nanosheets were obtained from liquid exfoliation in a mixture of ethanol, methanol, and isopropanol via a direct dispersion and ultrasonication method. Using the spin-coating technique, a thin film of uniform thickness was formed on the SiO2/Si substrate. Energy-dispersive X-ray analysis showed that the S/W ratio in the fabricated WS2 film was around 1.2 to 1.34, indicating certain deficiencies in the S atoms. These S vacancies induce localized states within the bandgap of pristine WS2, resulting in a higher conductivity in the exfoliated sample. The obtained thin film seems to be highly efficient in photoelectric conversion, with a responsivity of ∼0.12 mA/W at 670 nm under zero bias voltage, with an intensity of 5.2 mW/cm2. Instead, at a bias of 2 V, it exhibits a responsivity of 12.74 mA/W and a detectivity of 1.17 × 1010 cm Hz1/2 W−1 at 4.1 mW/cm2. The present 2D nanosheets exhibit high photon absorption in a wide range of spectra from the near-infrared (IR) to near UV spectrum.

Process optimization & reactive extrusion of high-molecular weight Poly(butylene-adipate-co-terephthalate) (PBAT) polymer for film blowing application

The present study demonstrates a novel approach of the process optimization for the synthesis of Poly(butylene-adipate-co-terephthalate) polymer, and its exclusive reactive extrusion for the film blowing application. The polymers have been synthesized under different processing conditions in order to determine the effect of different variables on the kinetics and optimize the system to obtain biopolymers. The catalytic chemistry of tetra-isopropyl titanate (TIPT) and zinc acetate in the optimal dosage resulted in the development of very high molecular weight PBAT, which is very essential for a polymer to have superior mechanical properties. The polymers were characterized using gel permeation chromatography (GPC), FT-IR, and calorimetry (DSC) analysis to investigate their properties. Furthermore, the polymer compounding was conducted using a unique reactive extrusion process which resulted in the compound with physiochemical property retention at the reduced polymer dosage level. This novel extrusion process reduced the polymer consumption in the compounding by up to 25% with intact properties. Mechanical and thermal properties were enhanced using metal complex-based inorganic coupling agents and fluoropolymers during the process. In the blowing, a flexible and thin film of uniform thickness was obtained in the continual run on the machine. The films were tested for mechanical properties which were at par with commercially available bags. With the ever-increasing demand for environmental-friendly products in plastics & polymers and stricter regulations against the use against conventional plastics, these polymer-based bio-films can be extensively used in the packaging and plastic bag applications due to their biodegradability and the superior strength in terms of mechanical properties which are comparable to the one exhibited by conventional polyethylene bags.

Photoresponsive polymers with dangling triptycene units as efficient receptor for fullerene‐C60

AbstractWe report herein a new triptycene derivative (1) with an azo functional group. This molecule has been used as a monomer to yield two linear polymers (TAFPs) that have several triptycene units dangling from the linear polymer chain. TAFPs are soluble in organic solvents and are thermally stable. TAFPs can be cast into thin films. Further, these polymers are fluorescent with emission intensity increasing upon irradiation with ultraviolet light due to photoisomerization of the azo groups present in them. The fluorescence of TAFPs are quenched in the presence of C60, which supports their strong affinity for each other. Since both TAFP1 and TAFP2 form stable thin films of uniform thickness over large area coupled with their interaction with C60, these polymers may find potential applications in the development of optoelectronic devices or as molecular sensors in supramolecular chemistry.

Drop spreading with random viscosity.

We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid’s viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop’s motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop’s effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated viscosity within the precursor film to hinder spreading. A low-order model provides explicit predictions of the variances in spreading rate and drop location, which are validated against simulations.

Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

Structural Characterization and Compositional Dependence of Optical Properties of Ge16Se52Te32−x Sb x (x = 0, 2, 4, 6, 8) Glassy Alloys

Antimony-substituted Ge-Se-Te quaternary chalcogenide glasses have been synthesized using the melt quench technique. The bonding arrangements in the glassy matrices have been studied through infrared spectra in the spectral region from 50 cm−1 to 300 cm−1. The effect of Sb addition on the optical properties has also been studied using ultraviolet–visible–infrared (UV–Vis–IR) spectroscopy on thin films of uniform thickness. The materials possess high refractive index and tunable bandgap with low values of optical loss. They also possess good infrared transparency regions, high refractive index, and low optical bandgap, making them suitable for use in photonic applications.

METHODS FOR PULSED LASER DEPOSITION OF LARGE-AREA FILMS USING MORE THAN ONE TARGET

Several new methods of pulsed laser deposition for fabricating large-area thin films of uniform thickness and composition on a rotating substrate and onto a moving ribbon are proposed. The peculiarities of the methods are the laser deposition of a compound upon a substrate through a diaphragm or the mask placed in immediate proximity of the substrate together with a use of more than one target. The proposed method makes it possible to obtain thin films of uniform thickness on substrates with sizes limited only by the deposition chamber size. Some of the methods are experimentally verified by depositing CuO thin films and the deviation of the film thickness from the average value does not exceed ±3%. Given the advantage of laser deposition, the offered methods should find practical use, in particular, in micro-electronics, optical industry, development of superconducting coated conductors, deposition of thin films of functional materials and other modern technologies.

TiN증착 조건에 따른 박막의 특성에 대한 실험적 연구

PVD방식에 의한 TiN박막의 형성은 DC와 RF sputtering deposition 방식을 적용할 수 있지만, 플라즈마 생성을 위해 주입된 가스의 이온화율이 떨어져 박막성형 속도가 느려지며, 박막과의 접착력을 높이는 것에도 한계성을 가지고 있다. 이를 개선하기 위해 증착과 동시에 이온빔을 조사하는 이온빔 진공증착 IBAD(Ion beam assisted deposition)를 이용 하게 되면, 코팅 전에 소재 표면을 Ion beam으로 조사하기 때문에 표면cleaning의 효과가 크고, 접착력이 높은 박막을 얻을 수 있다. 또한 고 진공과 낮은 온도에서도 균일한 두께의 고순도의 박막을 얻을 수 있는 이점이 있다. 【Formation of TiN films by PVD method and the DC and RF sputtering deposition method can be applied, the injected gas to generate plasma ionization rate of the film forming speed is slow away, anything to increase the adhesion between films limitations have. To improve this, to investigate the deposition and ion beam evaporation simultaneously IBAD(Ion beam assisted deposition) when used, Ion beam surface coating material prior to the survey because the surface cleaning effect of a large, high film adhesion can be obtained. In addition, the high vacuum and low temperature, high purity thin film of uniform thickness in the benefits is.】

Laser deposition of large-area thin films

A new method for fabricating large-area thin films of uniform thickness on a rotating substrate is proposed. Its distinctive features are (i) the presence of a diaphragm, partially transmitting the evaporated material, between the target and substrate and (ii) the translatory motion of the rotating substrate with respect to the target at a certain velocity. The method proposed makes it possible to obtain thin films of uniform thickness on substrates with sizes limited by only the deposition chamber size. The method is experimentally verified by depositing thin CuO films on silicon substrates placed over the radius of a disk 300 mm in diameter. The deviation of the film thickness from the average value does not exceed ±3% throughout the entire radius, which confirms good prospects of this method for microelectronics, optical industry, and other modern technologies.

Super Hydrophilic Thin Film Nitinol Demonstrates Reduced Platelet Adhesion Compared with Commercially Available Endograft Materials

Thin film nitinol (TFN) is a novel material with which to cover stents for the treatment of a wide range of vascular disease processes. This study aimed to show that TFN, if treated to produce a super hydrophilic surface, significantly reduces platelet adhesion, potentially rendering covered stents more resistant to thrombosis compared to commercially available materials. TFN was fabricated using a sputter deposition process to produce a 5-μ thin film of uniform thickness. TFN then underwent a surface treatment process to create a super hydrophilic layer. Platelet adhesion studies compared surface treated TFN (S-TFN) to untreated TFN, polytetrafluoroethylene, Dacron, and bulk nitinol. In vivo swine studies examined the placement of an S-TFN covered stent in a 3.5 mm diameter external iliac artery. Angiography confirmed placement, and repeat angiography was performed at 2 wk followed by post mortem histopathology. S-TFN significantly reduced platelet adhesion without any evidence of aggregation compared with all materials studied (P < 0.05). Furthermore, in vivo swine studies demonstrated complete patency of the S-TFN covered stent at 2 wk. Post mortem histopathology showed rapid endothelialization of the S-TFN without excessive neointimal hyperplasia. These results demonstrate that S-TFN significantly reduces platelet adhesion and aggregation compared with commercially available endograft materials. Furthermore, the hydrophilic surface may confer thromboresistance in vivo, suggesting that S-TFN is a possible superior material for covering stents.

In situ TEM Straining of Nanograined Al Films Strengthened with Al2O3 Nanoparticles

AbstractGrowing interest in nanomaterials has raised many questions regarding the operating mechanisms active during the deformation and failure of nanoscale materials. To address this, a simple, effective in situ TEM straining technique was developed that provides direct detailed observations of the active deformation mechanisms at a length scale relevant to most nanomaterials. The capabilities of this new straining structure are highlighted with initial results in pulsed laser deposited (PLD) Al-Al2O3 thin films of uniform thickness. The Al-Al2O3 system was chosen for investigation, as the grain size can be tailored via deposition and annealing conditions and the active mechanisms in the binary system can be compared to previous studies in PLD Ni and evaporated Al films. PLD Al-Al2O3 free-standing films of various oxide concentrations and different thermal histories were produced and characterized in terms of average grain and particle sizes. Preliminary in situ TEM straining experiments show intergranular failure for films with 5 vol% Al2O3. Further work is in progress to explore and understand the active deformation and failure mechanisms, as well as the dependence of mechanisms on processing routes.

Sol–gel synthesis of Au/TiO 2 thin films for photocatalytic degradation of phenol in sunlight

Thin films of Au/TiO 2 on glass substrates have been prepared by simple sol–gel dip coating method using a sol of colloidal gold doped titanium peroxide (Au/TiO 2 sol). The sol of colloidal gold and titanium peroxide forms a viscous gel after 1–3 h depending on the concentration of both colloidal gold and titania. The sol of particular viscosity range (140–2800 cps) was used to deposit the Au/TiO 2 thin films of uniform thickness on various substrates such as glass slides, glass helix and silica rashig rings. Films deposited on glass plates after drying were transparent, uniform in color as well as thickness. Optical characterization by UV–vis spectrophotometer showed a shift in optical absorption wavelength to visible region may be due to the incorporation of gold nanoparticles into titania structure. The optimum concentration of gold loading was found to be 1–2% (by weight) beyond this the gold particles disturb the gel network resulting the formation of gelatinous precipitate. Thin film photo-catalyst prepared was characterized by various techniques such as UV–vis, TG-DTA, XRD, ICP-OES and TEM. The photo-activity of the thin films was tested in sunlight using phenol as model pollutant. The kinetic study showed that the rate of decomposition of phenol using Au/TiO 2 photo-catalyst was improved by 2–2.3 times than undoped TiO 2.

New Insights into the Generation Mechanism of Quasicrystal by the Surface Reaction Between Ultrafine Particles and Deposited Clusters

On heating Mn-deposited Al particles (Mn–Al specimen) at 300°C, diffraction spots due to a Al86Mn14 quasicrystal appeared, in addition to those due to Al6Mn alloy. On heating a specimen of the Al-deposited Mn particles (Al–Mn specimen), Al50Mn50 alloy was formed. Neither the quasicrystal nor Al6Mn phases appeared. The electron microscope images of the Mn–Al specimen showed the existence of void clusters in the Al particles. This indicates that the alloys and the quasicrystals were produced by the diffusion of Al atoms to the Mn clusters. In the case of the Al–Mn specimen, the surface of Mn particles was covered with an Al thin film of uniform thickness. The surface Al layer changed to Al50Mn50 alloy. These results indicate that the diffusion direction of atoms and diffusion rates are different between Mn–Al and Al–Mn systems.

The phase constancy of electron waves traveling through Boersch's electrostatic phase plate

We draw attention to the observation that an electrostatic phase plate, originally proposed by Boersch in 1947, introduces a uniform phase shift. The device consists of a ring electrode, shielded by earthed electrodes. The phase shift of the electron wave traveling through the interior of the ring is uniform and constant independent of the radius of the ring for a very low applied voltage. This can be shown by considering the Laplace equation, which is satisfied by the electrostatic scalar potential subjected to the boundary conditions. The phase shift, which is proportional to the potential integrated along the optic axis, is constant inside the ring as if there were a thin film of uniform thickness. With such a device in the back focal plane of the objective lens, a phase contrast electron microscope could be constructed. The device could also be used as a constant phase shifter for electron interferometry.

Thin films of uniform thickness by pulsed laser deposition

In order to enhance the utility of pulsed laser deposition, a method to deposit uniform films has been devised. The target and substrate are offset from each other and the substrate is rotated about its axis between laser pulses. We have simulated this process using experimentally determined deposition profiles. Films of uniform thickness to within a few percent across a substrate 5.08 cm in diameter have been fabricated, where we have obtained excellent agreement between theory and experiment.

Development of materials with enhanced optical non-linearity by control of ultrastructure

Copolymers incorporating rigid electroactive moieties and flexible segments have been synthesized in an effort to develop non-linear optical materials which can be processed into optical quality films. A variety of coupling linkages have been employed including ether, ester, amide, imine and azo linkages. Among the most attractive materials examined in this survey are heteroaromatic ladder and tetraazaannulene copolymers which yield optical non-linearities (ratioed to optical loss), χ (3) α of 10 −12−10 −13 esu cm −1 and have desirable auxiliary properties of high laser damage threshold and fast optical switching (t ps for three-ring copolymer). Electron donating and withdrawing groups are conveniently incorporated and these have been observed to influence optical non-linearity. The copolymer approach yields linear optical spectra characterized by sharp band edges thus optimizing the window of transparency. Finally, it is noted that this approach yields excellent control of solubility and solution viscosity necessary for spin casting in the fabrication of thin films of uniform thickness.

Thin Films of Uniform Thickness by Pulsed Laser Deposition

ABSTRACTIn order to enhance the utility of Pulsed Laser Deposition (PLD), a method to deposit uniform films has been devised. This method employs the deposition profile produced by PLD and the discrete nature of the process. We have simulated this process using experimentally determined deposition profiles and have used the results to design a system that produces films of uniform thickness to within a few percent across a substrate of 1 inch diameter and have obtained excellent agreement between theory and experiment.

The Influence of Liquid Film Thickness on Airblast Atomization

The influence of initial liquid film thickness on mean drop size and drop-size distribution was examined using two specially designed airblast atomizers. Both were constructed to produce a flat liquid sheet across the centerline of a two-dimensional air duct with the liquid sheet exposed on both sides to high velocity air. In one case a thin film of uniform thickness was produced by injecting the liquid through a porous plate located just upstream of the atomizing edge. The film thickness, t, was then measured by a needle contact device. In the second design the fuel entered the air stream through a thin slot whose height could be adjusted accurately to vary and control the initial film thickness. Drop sizes were measured by the well-established light-scattering technique. From analysis of the processes involved, and from correlation of the experimental data, it was found that high values of liquid viscosity and liquid flow rate result in thicker films. It was also observed that thinner liquid films produce better atomization, according to the relationship, SMD ∝ t0.38.

Radiochromic plastic films for accurate measurement of radiation absorbed dose and dose distributions

Thin radiochromic dye films are useful for measuring large radiation absorbed doses (10 5–10 8 rads) and for high-resolution imaging of dose patterns produced by penetrating radiation beams passing through non-homogeneous media. Certain types of amino-substituted triarylmethane cyanides dissolved in polymeric solutions can be cast into flexible free-standing thin films of uniform thickness and reproducible response to ultraviolet and ionizing radiation. The increase in optical density versus energy deposited by radiation is linear over a wide range of doses and is for practical purposes independent of dose rate (1–10 14 rad s −1). Upon irradiation of the film, the profile of the radiation field is registered as a permanent colored image of the dose distribution. Unlike most other types of dyed plastic dose meters, the optical density produced by irradiation is in most cases stable for periods of at least one year. Methods have been developed for casting various types of thin radiochromic plastic films and combinations of plastics (cellulose acetate, polyvinyl butyral, polyvinyl acetate, polyvinyl pyrrolidone and polyvinyl chloride) having radiation absorption characteristics corresponding to those of many polymeric systems in industrial radiation processing. The result is that errors due to energy dependence of response of the radiation sensor are effectively reduced, since the spectral sensitivity of the dose meter matches that of the polymer of interest, over a wide range of photon and electron energies (0.01–10 MeV).