Film Profile Research Articles

Investigation of electrothermal properties of indium-tin-oxide thin films

Transparent conductive oxide (TCO) thin films are highly sought-after for their unique characteristics of conducting electricity and transmitting visible light, making them ideal conductive coating materials for electronic devices. We carried out a comprehensive analysis of the deposition, optical, electrical, and structural properties of ITO and Ag/ITO thin films on glass substrates in this study. The weight ratio of the deposited metals was 1:10, 2:10, and 4:10[Formula: see text]wt.% (Sn:In) for ITO films and 1:1:10[Formula: see text]wt.% (Ag:Sn:In) for Ag–ITO film. The films were annealed at 300°C using a program controller furnace. We employed infrared cameras to analyze the surface temperature profiles of these thin films under external voltage supply. We also investigated the resistivity behavior of both ITO and Ag–ITO films, analyzing them with regard to Mott’s variable range hopping (VRH) model and the fluctuation-induced tunneling model. Scanning electron microscope images revealed that adding Ag increased the grain size of ITO thin films. The average grain size for ITO thin film was determined as 186[Formula: see text]nm, while it was found to be 270[Formula: see text]nm for Ag–ITO thin film. Furthermore, incorporating Ag into the ITO thin film resulted in a reduction of 21.5% in transmittance over the complete visible range of the electromagnetic spectrum when compared to the ITO thin film without Ag as measured by ultra-visible spectrophotometer. The figure of merit was obtained as [Formula: see text] for ITO and [Formula: see text] for Ag–ITO thin films. However, the resistance of the ITO thin film was calculated to be 9.58[Formula: see text]k[Formula: see text], while that of the Ag–ITO film was found to be 6.99[Formula: see text]k[Formula: see text]. The ITO thin film that included Ag exhibited a lower electrical resistivity due to the larger grain size caused by doped Ag atoms in the structure, leading to less electron scattering at the grain boundaries and a resulting decrease in resistivity as determined by four-point probe system. Thermal imaging camera measurements revealed that the surface temperature of the ITO thin film decreased with the addition of Ag under high voltage application, but not under low voltage. When a voltage of 350[Formula: see text]V and 250[Formula: see text]V was applied to the thin films, the ITO film exhibited a surface temperature of 73.9°C and 50.4°C, whereas under identical conditions, the Ag–ITO film showed a surface temperature of 62°C and 44.1°C, respectively. Furthermore, both films exhibited exponentially increasing surface temperature behavior under a certain voltage, suggesting that they have potential for transparent heaters and high-voltage/low-current applications.

Angular distribution of species in pulsed electron beam deposition of BaxSr1-xTiO3

The angular thickness and composition profiles of thin films obtained by irradiating a BaxSr1-xTiO3 (x = 0.2) target with a pulsed electron beam were investigated by Rutherford backscattering spectrometry for argon and oxygen background gases at a pressure of about 10-2 mbar. A “semi-sphere” holder was used, resulting in a fixed target to substrate distance of about 40 mm. The film thickness profiles have forward shaped peaks, with measurable thickness up to 80-90° for major axis and 25° for minor axis, and presents similar trend for both argon and oxygen background gas. The analysis of the congruent transfer of the elements from the target as a function of the angle showed that the film composition is not uniform over this wide angular range and differs with respect of the ablated target depending on the element used and on background gas.

Experimental Study on Gas-Liquid Two-Phase Stratified Flow at High Pressure in a Horizontal Pipe

This study investigates wave-stratified flow in a horizontal pipe at high pressure, and flow characteristics are obtained, such as flow pattern map, liquid film thickness, and pressure drop. Compared with a flow pattern map of a gas-liquid two-phase flow carried out at atmosphere, stratified flow zone is depressed with increasing system pressure and the critical gas superficial velocity decreases for smooth-wave-stratified flow transition, while the critical liquid superficial velocity increases for stratified-intermittent transition. On one hand, the compressed air results in an increase in momentum transfer between gas and liquid phases, which accounts for the smaller gas superficial velocity that is encountered in both smooth-wave and stratified-annular flow transition at higher pressure. One the other hand, it slows down the liquid below the crest, and it makes the interface wave crest unstable and split for the vortex shedding behind the wave crest, which accounts for flow regime transition in gas-liquid two-phase flows in pipelines. As a result, stratified-intermittent flow transition is depressed and delayed. The pressure influence on the liquid film profile is analyzed, and relationships between film thickness and dimensionless numbers are studied, such as liquid Weber number and gas Weber number. Friction factors on different interfaces at high pressure are studied, and new empirical formulas are deduced.

DEVELOPMENT OF A DISCRIMINATORY METHOD FOR DETERMINATION OF IN VITRO DISSOLUTION OF CILNIDIPINE

Objectives: This study involves the development of a discriminatory method to differentiate the in vitro dissolution of cilnidipine’s mouth-dispersing film from that of a commercial tablet. Methods: The mouth-dispersing film was initially developed using a reported established method. A discriminatory dissolution method was developed to assess the in vitro dissolution of the mouth-dispersing film and compare the same with that of the commercial tablet. Results: The study findings indicated the method employed was able to differentiate the dissolution of the fast-dissolving film from the commercial tablet. About 98.52±0.60% of the drug was found to be released from the oral film in 40 min whereas the tablet took nearly 5 h for 92.06±0.49% of the drug to get released. Conclusion: These results demonstrate that the dissolution media identified was able to create the necessary sink condition that would be able to differentiate the dissolution profile of the mouth-dispersing film from the conventional tablet. The ultrasound spectrophotometric method employed was found to be simple rapid and sensitive enough to estimate the drug release from diverse pharmaceutical dosage forms.

Synthesis of Silicon and Germanium Oxide Nanostructures via Photonic Curing; a Facile Approach to Scale Up Fabrication.

Silicon and Germanium oxide (SiOx and GeOx) nanostructures are promising materials for energy storage applications due to their potentially high energy density, large lithiation capacity (~10X carbon), low toxicity, low cost, and high thermal stability. This work reports a unique approach to achieving controlled synthesis of SiOx and GeOx nanostructures via photonic curing. Unlike conventional methods like rapid thermal annealing, quenching during pulsed photonic curing occurs rapidly (sub-millisecond), allowing the trapping of metastable states to form unique phases and nanostructures. We explored the possible underlying mechanism of photonic curing by incorporating laws of photophysics, photochemistry, and simulated temperature profile of thin film. The results show that photonic curing of spray coated 0.1 M molarity Si and Ge Acetyl Acetate precursor solution, at total fluence 80 J cm-2 can yield GeOx and SiOx nanostructures. The as-synthesized nanostructures are ester functionalized due to photoinitiated chemical reactions in thin film during photonic curing. Results also showed that nanoparticle size changes from ~48 nm to ~11 nm if overall fluence is increased by increasing the number of pulses. These results are an important contribution towards large-scale synthesis of the Ge and Si oxide nanostructured materials which is necessary for next-generation energy storage devices.

Modeling and Simulation of Elastohydrodynamic Lubrication in Spur Gears

An analysis using computational modeling by finite elements of the phenomenon of elastohydrodynamic lubrication (EHL) was carried out for a transmission system of pinion gear in a crankcase with partial filling lubrication. The analysis utilized tribological studies describing the contact behavior characteristics of solid surfaces with the lubrication film caused by dragging and splashing. Furthermore, the characteristics of the Reynolds-Hertz model for this type of phenomena are described, as well as the equations of elastic deformation and elastic displacements along with the geometry of the non-concordant bodies in contact. This was done by modeling the Lagrangian-Eulerian type for non-Newtonian fluid, implementing multiphysics coupling methods. The pressure profile of the lubricant films, the temperature reached by the lubricant, and the von Mises stress at the contact were obtained, showing a good approximation with the related results, indicating a range of 30 MPa to 900 MPa of pressure in the lubricant film and von Mises stress ranging from 30 MPa to 100 MPa in the contact area of the gear tooth.

Synthesis and characterization of macrodiols and non-segmented poly(ester-urethanes) (PEUs) derived from α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH): effect of initiator, degree of polymerization, and diisocyanate.

Nine different macrodiols derived from α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH) were prepared by ring-opening polymerization of ε-caprolactone (CL) using three linear aliphatic diols (HO-(CH2) n -OH, where n = 4, 8, and 12) as initiators and catalyzed by ammonium decamolybdate (NH4)8[Mo10O34]. The crystallization temperature (T c) and crystallinity (x i) were relatively high for HOPCLOH species with a long aliphatic chain [-(CH2)12-] in the oligoester. Also, HOPCLOH was the precursor of twenty-seven different poly(ester-urethanes) (PEUs) with various degrees of polymerization (DP) of HOPCLOH and three types of diisocyanates such as 1,6-hexamethylene diisocyanate (HDI), methylene diphenyl diisocyanate (MDI), and 4,4'-methylenebis (cyclohexyl isocyanate) (HMDI). HOPCLOH exhibited the melting temperature (T m) and crystallinity (x i) with a proportional dependency to the degree of polymerization (DP). PEUs showed significant thermal and mechanical properties, which had a direct correlation in terms of the type of DP and diisocyanate. PEUs derived from HDI versus MDI or HMDI exhibited an apparent effect where aliphatic diisocyanate (HDI) induced a significant x i with respect to aromatic and cyclic diisocyanate (MDI or HMDI). The profile of PEUs films according to mechanical properties is mainly a plastic behavior. The chemical nature and properties of HOPCLOH and PEUs were characterized by NMR, FT-IR, GPC, MALDI-TOF, DSC, and mechanical properties.

Thermal Runaway in Thin Film PV: temperature profile modeling

Thermal runaway is a well known phenomena in degradation analysis of the CdS/CdTe thin film solar cells. The thin thickness of such devices can be deteriorated by the temperature fluctuations after a long enough time. We modeled the temperature profile of thin film devices considering the uniform and nonuniform distribution for temperature of the glass substrate and current flowing through TCO layer. In addition, the temperature profile of a hot spot at the edge of the device has been formulated and compared with the real data and fitting functions represented in a few literature. All the above modeling was based on the heat transfer equation considering the importance of thermal resistances. The convection and conduction resistances were introduced in the considered Biot number optimized for PV applications. The modeling presented in this paper can be extended to other solar cell structures or large scale modules. The current study suggests that the thickness and temperature dependencies of the thermal conductivity, convection and conduction resistance might be taken into account and be optimized in thermal runaway issues of thin film devices. The hot spot modeling suggests that the current flowing across the TCO layer can assist the thermal runaway and deformation of neighboring area.

(Invited) Gallium Nitride for Vertical Power Devices: Improving Morphology and Unintentional Impurities for Better Devices

While GaN has been researched for many years as a material for light emitting diodes, lasers, high electron mobility transistors, and other devices, further improvements to material purity are still needed to realize the full potential of this material for vertical device applications. To achieve high quality, high purity GaN for power devices, our research employs ammonia-assisted molecular beam epitaxy (NH3-MBE) and plasma-assisted molecular beam epitaxy (PA-MBE). Past studies of fast growth rates (more than 1 μm/hr) and ultra-low impurity incorporation revealed that both PAMBE and NH3-MBE can achieve low net doping levels, and NH3-MBE as low as 1x1015 cm-3.1 However, This work also indicated that impurity incorporation increased with increasing growth rate.Recent research efforts have focused on further improvements to morphology and unintentional dopants in NH3-MBE-grown homoepitaxial layers with fast growth rates. By optimizing growth conditions for faster growth rates and using indium as a surfactant, devices with drift layers up to 10 μm thick were grown. These layers exhibited smooth surface morphology as seen in AFM scans with RMS surface roughness as low as 0.21 nm for a 2x2 μm2 scan area.2 Adding the In surfactant also led to reduced incorporation of unintentional Si impurities in UID films as shown by SIMS depth profiles for GaN films grown with and without In. The extremely low impurity levels were further confirmed by CV measurements which indicated that the net doping density in the UID GaN layers decreased from 2x1016 cm-3 to 5x1015 cm-3 with the addition of the In surfactant.2 Based on these UID levels and the theoretical critical electric field of GaN (3 MV/cm), drift layers up to 29.5 μm and 7.4 μm can be depleted with a triangular electric field profile for net donor concentrations of 5x1015 cm-3 and 2x1016 cm-3, respectively. Devices with the same net concentrations with drift regions 3 μm thick can hold voltages of 854 V and 717 V, respectively.Based on the previously described studies of low-impurity GaN at different growth rates, we developed vertical p-n GaN power devices grown by NH3 MBE.3 These p-n diodes contained a 0.25 µm n+ region, 4 µm n- region with 3x1015 cm-3 unintentional carriers, 0.4 µm p+ region and 10nm p++ capping layer to improve the ohmic anode contact. The circular diodes were fabricated with Pd/Pt anode contacts and Ti/Au cathode contacts. Device diameters were between 80 and 100 µm. The devices featured a 15 µm field plate made from Ti/Au contacts on top of an Al2O3/Si3N4 dielectric stack.The diodes exhibited outstanding forward J-V behavior with a low specific on-resistance (Ron,sp) of 0.28 mΩ-cm2 and a minimum ideality factor of 1.36, which are among the best achieved among similar homoepitaxial GaN p-n diodes.3-5 The best diodes also exhibited a breakdown voltage of > 1 kV (equipment limit 1 kV). The reverse-voltage properties indicate that punch-through was achieved with a peak electric field (EC) >2.6 MV/cm, as confirmed by Silvaco simulations (Fig. 7). The combination of >1 kV breakdown voltage and on-resistance of 0.28 mΩ-cm2 represents one of the best performances of the p-n GaN diodes, achieved with a significantly thinner drift layer compared to comparable MOCVD GaN p-n diodes with drift layers more than 8 µm. Work is ongoing to develop NH3-MBE p-n diodes with indium surfactant-assisted drift layer growth which shows promise to further improve the surface morphology, reduce leakage, and enhance breakdown performance of the vertical devices.

Fine-line formation of cobalt thin films via cyclic etching using two-step process

Co thin films were etched via cyclic etching using a two-step process of Cl2 plasma and Ar sputtering. In the first step, the Co surface was chlorinated by exposing the Co film to Cl2 plasma to form a CoCl2 layer, and the chlorinated Co film was removed via Ar sputtering in the second step. The saturation point of chlorination in the first step provided a 2 nm-thick CoCl2 layer. In the second step, the dc bias voltage and Ar sputtering time were varied to optimize the removal of the CoCl2 layer. A close relationship between the thickness of the CoCl2 layer and the sputtering conditions was revealed, which was responsible for the etch profiles of the Co films. Finally, 300 nm patterns of the Co films were successfully etched via cyclic etching without redeposition on the sidewall.

Effect of capillary arrays on the profile of multi-layer micro-capillary films

Abstract Multi-layer micro-capillary films (MCFs) have broad application prospects in the micro-fluid field. These films consist of two-dimensional arrays of hollow microcapillaries. The arrangements of hollow microcapillary arrays in extrusion die strongly influence the shape and size of multi-layer MCFs. However, most of the studies focus on a single-layer film. In this study, the models of multi-layer MCF extrusion die with hollow capillary arrays from one layer to four layers have been modeled. Numerical simulations show that when the hollow capillary arrays in different layers are aligned, the aspect ratio of the capillary is smaller and the flow resistance is small, so this kind of multi-layer MCF is suitable for micro-reactor and melt pump. When the hollow capillary arrays in different layers are non-aligned, the aspect ratio of the capillary is relatively larger and the specific surface is bigger, so this kind of multi-layer MCF has a high capability of heat exchange and is suitable for micro heat exchangers.

Optimal boundary control of a model thin-film fiber coating model

This paper considers the control of fluid on a solid vertical fiber, where the fiber radius is larger than the film thickness. The fluid dynamics is governed by a fourth-order partial differential equation (PDE) that models this flow regime. Fiber coating is affected by the Rayleigh–Plateau instability that leads to breakup into moving droplets. In this work, we show that control of the film profile can be achieved by dynamically altering the input flux to the fluid system that appears as a boundary condition of the PDE. We use the optimal control methodology to compute the control function. This method entails solving a minimization of a given cost function over a time horizon. We formally derive the optimal control conditions, and numerically verify that subject to the domain length constraint, the thin film equation can be controlled to generate a desired film profile with a single point of actuation. Specifically, we show that the system can be driven to both constant film profiles and traveling waves of certain speeds.

Structure of aluminum films for creating tunnel junctions.

A series of studies of the structure of aluminum films deposited on single-crystalsilicon substrates in different temperature conditions. The roughness and grain size of films of nuclei 20 nm thick, deposited at elevated temperatures, and also dusted on top of the seed layer at room temperature to a thickness of 150 nm. The film profile was measured in an electron microscope. It was found that films on the hot sublayer turn out to be smoother, more rigid (less loose) and allow one to expect the creation of superconductor–insulator–superconductor and superconductor–insulator–normal metal transitions, respectively, with a higher current density and lower capacitance.

Leadership Policy and Empowerment of Human Resources in Production Houses in Jakarta

The purpose of this research is to determine leadership policies in empowering employees and the demands of the world of the creative industry on production houses engaged in television, film, advertising production, and company profiles. Research method with a qualitative approach that describes the phenomenon of events at production house locations. Collection techniques were obtained through field observations, in-depth interviews with key respondents who understand the problem, documentation studies in the form of existing archives and scenario notes, and focus group discussions on the data obtained, discussed together with the existing crew. The research results show that production house leaders want a policy to empower their human resources, so they can meet company needs and customer demands, but are often constrained by work demands, production deadlines, and employee working hours, as well as technology and other factors. Leader policies in implementing production house management to improve the company through empowering Human Resources. Policies that have been implemented include employee protection, strengthening employee systems, and support and maintenance.

Experimental study on hydro- thermal behavior of journal bearing oil film profile in a slow speed diesel engine

Utilizing universal journal bearing test rig, the performance of a heavy-loaded main journal bearing has been investigated based on tracing operational behavior of oil film temperature and pressure profiles. Test trials were conducted observing the loading program of slow speed diesel engine. Examining the effect of different oil grades, it turned out that oil grade of higher viscosity index enhances journal bearing performance and maintains oil film temperature profile stability at both maximum speeds and heavy loads. Further, medium viscosity grade oil reduces fuel consumption and costs from power production for all operational conditions. Regarding the impact of heavy loads on shaft power performance with medium viscosity oil grade, the differences between optimal and heavy loads get lower as the shaft speed increases. Those were 22 %, 9.7 % and 2.1 % corresponding to the shaft speeds of 43 rpm, 90 rpm and 104 rpm respectively. Additionally, the lower the value of the maximum oil film pressure Pmax difference between optimal and heavy load, the higher the ability of the lubricant to promote performance and provide enhanced operating condition stability. Yet, at part load operating conditions entailing running journal shaft at slow speeds during ship maneuverability, it cannot be considered as the best selection due to the heavy loads often applied in such critical operating conditions. Finally, the test-trial based experimental outcomes can provide useful guidance regarding the proper selection of a lubricant for enhanced performance, cost saving and prolonged journal bearing working life.

Analysis of Liquid Film Evaporation in Porous Particles: Toward Optimal Wick Parameters for Heat Transfer in Heat Pipes

Abstract Evaporation of working fluids inside capillary wicks determines the heat transfer capability of heat pipes. However, the relationship between wick parameters and evaporative heat transfer remains unclear. To establish a correlation between wick parameters of sintered porous particles and evaporation characteristics, a boundary condition model was developed, incorporating wick parameters such as particle radius (R), particle distance (d), apparent contact angle (θa), and initial liquid height (H). In the absence of a significant size effect, the profile of the liquid–vapor interface was determined using the boundary model by numerically solving the augmented Young–Laplace equation. Ammonia was used as an example to investigate evaporation characteristics. The curvature radius of the intrinsic meniscus (Re) was found to serve as a bridging factor between these wick parameters and evaporation characteristics. When Re exceeded 40.3 μm, a limitation in evaporative heat transfer within the thin film region was observed. The relationship between R, d, θa, and H was quantitatively described based on this evaporative heat transfer limit. Furthermore, a nondimensional analysis of the governing equation for the evaporating liquid film profile was conducted, yielding an influencing factor (λ) that governed the thin film profile. The proposed model and its outcomes could offer valuable theoretical insights for the structural design of sintered porous particles, the optimization of surface modification levels, and the determination of the appropriate working fluid charging ratio during the manufacturing process of heat pipes.

Heat and mass transfer of Ag–H2O nano-thin film flowing over a porous medium: A modified Buongiorno’s model

Due to their numerous applications, such as fibre and wire coating, polymer preparation, etc., thin films have recently come into focus in the analysis of heat and mass transport. As a result, the current article’s main objective is to investigate how heat and mass are transferred when an Ag−H2O(sliver–water) thin film flows past a stretching sheet that is subject to thermal and velocity slips. The research takes into account other variables including porosity, thermal radiation, thermophoresis, and Brownian motion, among others, to ensure that the outcomes are consistent with real-world conditions. Along with these parameters, the impact of the nanoparticle volume fraction is also analysed by incorporating the modified model of the existing Buongiorno model. The resulting mathematical model is transformed into ordinary differential equations with the help of appropriate similarity transformation. The system of equations thus obtained is solved by employing the RKF-45 technique and the outcomes are expressed in terms of graphs and tables. The major outcomes indicate that the increase in the mixed convection parameter causes enhancement in the temperature profile while a reduction in the velocity profile. The thermophoresis is found to increase both the temperature and concentration profiles of the thin film. Whereas, the greater values of the volume fraction of the nanoparticles enhance the temperature and diminishes the velocity.

Reactive plasma sputtering deposition of polycrystalline GaN thin films on silicon substrates at room temperature

We report on the successful growth of polycrystalline GaN thin films on Si (100) substrates at room temperature (without intentional heating) using radiofrequency reactive magnetron sputtering. We use Ar and N2 as the main sputtering and N-atom precursor gas sources, respectively, and a gallium cathode as the Ga-atom source. We focus here on studying the effect of working pressure, as it is found to be the parameter that plays the most influential role on the crystalline quality of the thin films in the investigated range (20–95 mTorr). The morphology, microstructure, and composition profile of the GaN thin films are analyzed using a set of ex situ solid-state characterization techniques. This study reveals that for process pressures below 50 mTorr, the resulting films possess an amorphous nature, while for process pressures above that they become polycrystalline. Most of the crystalline films are found to be nanostructured with grain sizes typically ranging from 10 to 30 nm in size. The highest growth rate of ∼ 2.9 Å/s is obtained for the deposition carried out at 50 mTorr. At this pressure, the films exhibit the best crystallinity with a dominant wurtzite hexagonal structure. The elemental distribution of Ga and N throughout the growth profile is uniform with a sharp interface at the substrate, demonstrating one of the interests in working at low temperatures to avoid melt-back etching, a destructive reaction between gallium and silicon, that usually takes place at high temperatures.

Chemical mechanism of oxidative etching of ruthenium: Insights into continuous versus self-limiting conditions

Ruthenium (Ru) has emerged as a promising material for microelectronic applications that require precise modification and patterning of thin films at the nanoscale. However, the susceptibility of Ru to oxidative etching has raised challenges in achieving the desired profile of Ru thin films. In this study, we investigated the mechanisms and conditions required for oxidative etching of Ru using density functional theory (DFT) calculations. Our calculations examined the thermodynamics and kinetics of several pathways toward the formation of gaseous RuO4, including oxidations of bulk Ru and RuO2, from both surfaces of which surface reactions were considered. Our findings suggest that etching reactions under O3 exposure are more favored on a Ru surface than on RuO2. Experimental results obtained from etching of Ru using O3 further support our computational predictions, indicating that oxide formation leads to a reduction in the etching rate and that quasi-self-limiting etching conditions can be achieved towards oxidative ALE of Ru. Our study may contribute to the fundamental understanding of Ru surface phenomena and provides insights into the development of effective ALE techniques for Ru.

Combined electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy analysis of the passive films formed on 5083 aluminium alloy

A combined electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) approach showed that the corrosion behaviour of 5083 Al alloy was controlled by Mg dissolution at the Mg-rich intermetallic coarse particles (IMCs) that were defects of the passive film. It was thus shown that microstructures with high amount of Mg-rich IMCs were less resistant to corrosion. EIS experimental data were well superimposed with fitted ones calculated using a model proposed in the literature for pure magnesium. The model allowed to plot the resistivity profiles of the passive films, which highlighted their double-layer structure evidenced by XPS.