O2 Gas Flow Rate Research Articles

Operando Neutron Imaging of Water Distribution inside Running Anion-Exchange Membrane Fuel Cell

IntroductionAnion-exchange membrane fuel cell (AEMFC) has a potential use of non-precious metal catalysts under an alkaline environment. Furthermore, anion-exchange membranes (AEMs) are expected to be used for water electrolysis. However, the performance of AEMFC is still lower than that of proton-exchange membrane fuel cell (PEMFC). During the power generation, the PEMFC only produces H2O at the cathode, whereas the AEMFC consumes H2O at the cathode and produces twice as much as H2O at the anode. The main factors for the increase in polarization of AEMFC are limitation of H2 diffusion due to liquid water flooding at the anode and lack of H2O as a reactant at the cathode. Therefore, elucidating the water distribution in the AEMFC is essentially important. In this study, we imaged liquid water in an AEMFC during power generation. The data were compared with those of a PEMFC.ExperimentalThe water distribution in the AEMFC was imaged by neutron beams in the directions, perpendicular and parallel to the membrane-electrode assembly (MEA) surface during power generation. Imaging was conducted at the beamline BL-22 of the MLF, J-PARC(2). The cell size was 100×70 mm2, and the active area was 20×20 mm2. Single serpentine flow channels were used for the gas flow channels. The depth and the width of the gas flow channels were both 1 mm. The end plates were made of aluminum to avoid neutron scattering. The thickness of the end plate was10 mm. Both the H2 and O2 gas flow rate was 100 ml/min. Pt/CB was used as a catalyst. For the electrolyte membrane and the binder, QPAF-4(1) was used. The temperature of the cell was 60°C and the humidity was 100% RH.Results and DiscussionFig. 1 shows the water distribution inside the AEMFC parallel to the MEA. In Fig. 1(a), the left side is the anode and the right side is the cathode. In the image, three vertical blue lines are seen. The two outer lines are of a Kapton tape made of silicone. The middle line is of the water on the anode side of the AEMFC. There are blue squares on both side the anode and cathode; the bule squares on the anode side are very clear, whereas those on the cathode side are vague. These blue squares are gas flow channels. The relative thickness of water is represented by the color bar shown on the right in Fig. 1. In the dark area, water hardly existed. As the water increased, the color changed to red. Fig. 1(b) is an enlarged image of the gas flow path and the MEA. In the middle of the image, an MEA (0.55 mm thick) existed with GDLs (anode side 330 µm thick, cathode side 210 µm thick) sandwiching the CCM using a QPAF-4 membrane (30 µm thick). At the cathode, water was hardly imaged, but a small amount of water was observed in the gas flow channels near the outlet, mostly on the wall of flow channel in purple. In the GDL at the cathode, a small amount of water was observed on the CCM. At the anode, water was observed both in the gas flow channel and under the ribs. A larger amount of water was observed in the gas flow channel especially near the outlet, whereas near the inlet, a smaller amount of water was observed in the gas flow channel and under the ribs. In the gas flow channel, a large amount of liquid water was seen on the wall surface of the gas channel of the anode. Therefore, In the gas channel of the AEMFC, the gas path existed on the GDL side. Fig. 2 shows the water distribution inside the AEMFC perpendicular to the MEA. The thickness of liquid water in the gas channel and the entire MEA area at different current densities are calculated. In AEMFC, at low current density, liquid water existed near the outlet of the gas channels. As the current density increases, liquid water was also generated near the ribs and near the inlet of the gas flow channels. In PEMFC (not shown), at low current density, almost no liquid water existed in the gas channel and MEA. As the current density increased, liquid water is generated only near the gas channel outlet. The water distribution trends of PEMFC and AEMFC were significantly different. References Ono et al. J. Mater. Chem. A, 5 (47), 24804-24812 (2017)Shinohara et al., Rev. Sci. Instrum. 91, 043302 (2020). Figure 1

Correlation between the Dimensions and Piezoelectric Properties of ZnO Nanowires Grown by PLI-MOCVD with Different Flow Rates

Zinc oxide nanowires (ZnO NWs) have gained considerable attention in the field of piezoelectricity in the past two decades. However, the impact of growth-process conditions on their dimensions and polarity, as well as the piezoelectric properties, has not been fully explored, specifically when using pulsed-liquid injection metal–organic chemical vapor deposition (PLI-MOCVD). In this study, we investigate the influence of the O2 gas and DEZn solution flow rates on the formation process of ZnO NWs and their related piezoelectric properties. While the length and diameter of ZnO NWs were varied by adjusting the flow-rate conditions through different growth regimes limited either by the O2 gas or DEZn reactants, their polarity was consistently Zn-polar, as revealed by piezoresponse force microscopy. Moreover, the piezoelectric coefficient of ZnO NWs exhibits a strong correlation with their length and diameter. The highest mean piezoelectric coefficient of 3.7 pm/V was measured on the ZnO NW array with the length above 800 nm and the diameter below 65 nm. These results demonstrate the ability of the PLI-MOCVD system to modify the dimensions of ZnO NWs, as well as their piezoelectric properties.

Effect of the Working Pressure and Oxygen Gas Flow Rate on the Fabrication of Single-Phase Ag2O Thin Films

Ag2O thin films have been applied in various devices, such as photodetectors, photocatalysts, and gas sensors, because of their excellent thermal stability, strong electrical properties, and stable structures. However, because various phases of silver oxide exist, the fabrication of single-phase Ag2O thin films using a general deposition system is difficult. In this study, Ag2O thin films were deposited on glass substrates at different working pressures and O2 gas flow rates using a facing-target sputtering (FTS) system. After optimizing the working pressure and O2 gas flow rate, the Ag2O thin films were post-annealed at different temperatures ranging from 100 to 400 °C to improve their crystallographic properties. The X-ray diffraction patterns of the as-fabricated Ag2O thin films indicated the presence of a single phase of Ag2O, and the ultraviolet–visible (UV–vis) spectral analysis indicated transmittance of 65% in the visible light region. The optimum working pressure and O2 gas flow rate were determined to be 4 mTorr and 3.4 sccm, respectively. Finally, the effect of the post-annealing temperature on the thin film was investigated; the Ag2O peak had high intensity at 300 °C, suggesting this as the optimum post-annealing temperature.

Performance Intensification of CO 2 Methanation by Co-Feeding Oxygen Over Various Ru-Based Catalysts

Auto-methanation (AM), which autonomously progresses at room temperature (approximately 25 °C), is an effective reaction for converting CO2 to CH4 and can thus reduce the processing costs. In this study, the AM reaction over various Ru-based catalysts with different support materials positively proceeded by selecting reaction conditions such as the O2 concentration and gas flow rate. The progression of AM was the best over the Ru/CeO2 catalyst, followed by the Ru/ZrO2 and Ru/Al2O3 catalysts. The progression of AM over the Ru/SiO2 catalyst was slow. The rapid progress of AM over the Ru/CeO2 catalyst was attributed to the presence of oxygen defects on the CeO2 support that accelerates the hydrogen–oxygen combustion as well as to the differences in the CO2 and H2O adsorption characteristics between the CeO2 support and other supports. Even when the Ru-based catalyst underwent H2 reduction at low temperature, AM could proceed over each catalyst. The Ru/CeO2 catalyst was advantageous over other catalysts because AM proceeds only when H2 gas is supplied at room temperature without external heating. X-ray photoelectron spectroscopy indicated that the Ru species on the Ru/CeO2 catalyst are in a metallic state owing to H2 reduction at room temperature, which is associated with AM progression. Moreover, AM proceeded via H2 reduction at 75 °C over the Ru/ZrO2 catalyst and at 150 °C over the Ru/Al2O3 catalyst. The progression of methanation through such low-temperature reduction can strengthen the CO2 conversion process.

Effects of substrate temperature and sputtering gas composition on physical properties and photocatalytic activities of WOx thin films deposited via radiofrequency sputtering

Tungsten oxide (WOx) is expected to act as a photocatalytic material under visible light. We have deposited WOx thin films using radiofrequency sputtering and evaluated the photocatalytic activities of the films via degradation of methylene blue solution. The optical absorbance, crystallization, and surface morphology of the WOx thin films were also investigated. The absorption edge of the WOx thin films was shifted to the long-wavelength region when the substrate temperature was high and the O2 gas flow rate was low. Crystallization proceeded when the substrate temperature was high and additional WOx diffraction peaks were appearing with low O2 gas flow during growth. Furthermore, the grain size of the WOx thin films was smaller when the O2 gas flow was high. The photocatalytic activity was higher when the substrate temperature and O2 gas flow rate were low.

Effects of oxygen concentration variation on the structural and optical properties of reactive sputtered WOx thin film

Tungsten oxide (WOx) has been widely investigated due to mainly its optoelectronic properties. This study primarily aimed to examine the influence of oxygen concentration on the structural and optical properties of WOx films. Herein, WOx thin films have been prepared by reactive sputtering method at low power (50 W) while controlling the Ar:O2 gas flow rate to vary oxygen concentration. Energy Dispersive X-ray (EDX) analysis reveals that the oxygen concentration depends on the gas flow rate. Such oxygen concentration changes affect the film’s thickness, confirmed by the field emission scanning electron microscope (FESEM). Atomic force microscopy (AFM) analysis ensures the dependency of surface roughness of the films on the oxygen concentration. The developed films exhibit the amorphous state as validated by X-ray Diffraction (XRD) analysis. The Ultraviolet–Visible (UV–Vis) spectroscopy measurement was also conducted to determine transmittance and absorbance of the film, which further allows realizing necessary optical parameters, such as absorption coefficient, skin depth, energy bandgap, refractive index, extinction coefficient, etc. The oxygen concentration-dependent optical parameters are investigated in the spectral range of UV to near-infrared regions to ensure the use of WOx for optoelectronic device applications. Finally, we considered the optimized WOx film as a potential electron transport layer (ETL) to realize an efficient perovskite solar cell. The optics and optimization of this solar cell were studied by finite-difference time-domain (FDTD) simulations. The investigation allows us to calculate the maximum quantum efficiency (QE) and short-circuit current density (JSC) of ~90% and 22.1 mA/cm2, respectively.

Thermochemical Energy Storage Performance Analysis of (Fe,Co,Mn)Ox Mixed Metal Oxides

Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.

Model Experimental of Photovoltaic-Electrolyzer Fuel Cells as a Small-Scale Power

The purpose of this study is three to study the flow rates of H2 and O2 oxidants based on KOH concentrations at certain voltages, find the value of the best photovoltaic power at a particular test time, and find the value of fuel cells and improve the best photovoltaic-electrolyzer-fuel cell system based on calculations and the best time. The research method begins with studying the components of the PV electrolyzer and fuel cell, continuing experimental testing, and analyzing the research results. The results were obtained from the results obtained at 14.00 WIB. In electrolyzer testing, testing variations of 1 M, 2 M and 3 M molarity. The test results obtained the highest H2 and O2 gas flow rates at concentrations of 3 M, and the best efficiency at 1 M. From these data used for testing photovoltaic-electrolyzer systems -Fuel cell at 14.00 WIB with a concentration of 3 Molar, obtained the highest efficiency value of 1,847% with a power output of 2,184 Watt.

High-Efficient Generation of H2O2 by Aluminum-Graphite Composite through Selective Oxygen Reduction for Degradation of Organic Contaminants.

Hydrogen peroxide (H2O2) is an effective green oxidant, which has been widely applied for environmental remediation. Here, we prepared a novel aluminum-graphite (Al-Gr) composite, which was capable of high-efficient production of H2O2 through selective O2 reduction via a two-electron pathway. We discovered the production of H2O2 at a wide pH range, which could be enhanced by optimizing Al-Gr synthesis conditions. Poly(ethylene glycol) (PEG) addition could promote the formation of a welding interface and porous structure between Al and Gr in the Al-Gr composite, which enhanced the galvanic corrosion of Al0, the selectivity of oxygen reduction via the two-electron pathway, and the mass transfer of O2 in the Al-Gr/O2 system. The formation of Al4C3 could be regulated by sintering temperature and sintering time, which could promote the intergranular corrosion of Al0 and enhance the mass transfer of O2 by reaction with water to generate the porous structure in the Al-Gr composite. The concentration of H2O2 reached 777.5 mg/L at an initial pH of 9.0, an Al-Gr dosage of 8 g/L, and an O2 gas flow rate of 400 mL/min. The possible mechanisms of Al-Gr synthesis and H2O2 production in the Al-Gr/O2 system were proposed. The Al-Gr composite was effective for the in situ production of H2O2, which could be further decomposed into a hydroxyl radical (•OH) by Al0 in the Al-Gr composite. This composite could be used not only to decolorize the Rhodamine B dye but also to degrade various organic contaminants in different water matrices, indicating its environmental significance.

Thermal plasma synthesis and electrochemical properties of high-voltage LiNi0.5Mn1.5O4 nanoparticles

The synthesis of LiNi0.5Mn1.5O4 has been reported to change the crystal structure with the oxygen partial pressure and affect the battery characteristics. LiNi0.5Mn1.5O4 involves the formation of impurities, such as LixNi1−xO, LixMn3−xO4, and Li2CO3, at a high temperature range exceeding 700 °C because oxygen loss occurs during synthesis. LiNi0.5Mn1.5O4 electrochemically contains Mn4+, however, Mn3+ is formed because of oxygen deficiency. The Li–Ni–Mn-oxide causes a disproportionation of Mn3+ in an oxygen-deficient state. The synthesized Li–Ni–Mn-oxide nanoparticles at 10,000 K by induction thermal plasma formed spinel-type LiNi0.5Mn1.5O4 (space group Fd3m) of Mn4+. The crystal structure of the cubic-spinel nanoparticles approached a LiNi0.5Mn1.5O4 single phase as the flow rate of O2 increased from 2.5 to 5 l min−1. The formation of LiNi0.5Mn1.5O4 was shown to be accelerated by increasing the O2 gas flow rate. The measured current–voltage characteristics of LiNi0.5Mn1.5O4 nanoparticles appeared at around 4.7–4.8 V as the reaction peak of Ni2+/Ni3+ and Ni3+/Ni4+. In contrast, the Mn of the Li–Ni–Mn-oxide nanoparticles synthesized in the oxygen-deficient state was less than trivalent, which caused disproportionation of Mn. The measured current-voltage characteristics showed peak of an oxygen desorption at near 4.6 V. This study investigated the factors affecting the crystal structure formation and electrochemical properties of high-voltage LiNi0.5Mn1.5O4 nanoparticles formed in thermal plasma.

Modelling of titanium oxynitride films for decorative coating by using response surface methodology

In this work, titanium oxynitride films were deposited on SS316L and Si-wafer substrates using reactive DC magnetron sputtering. An experimental design and statistical analysis were applied for the thin film coating. The experiment software (Design-Expert Software) was used to design the deposition parameters, including the plasma current density (10-25 mA/cm2) and N2 gas flow rate (20–60 sccm) by maintaining O2 gas flow rate. Response surface methodology based on a central composite design was used to empirically model the influence of the plasma current density (I) and N2 (N) flow rate on the CIE colour system of titanium oxynitride thin films. The model fitting equations for two colour channels (a* and b*) were obtained and represented by a* = –26.65 + 0.67N + 2.92I + 0.02NI – 0.01N2 – 0.12I2 and b* = 4.83 – 1.05N + 1.72I – 0.02NI + 0.02N2 – 0.03I2. In addition, the effects of current density and N2 flow rate on the chemical composition of TiON films were investigated by X-ray photoelectron spectroscopy (XPS). The titanium 2p (Ti2p) spectra indicated that the TiON and TiO2 structures depended on the deposition parameters. Additionally, the increase in N2 flow rate and current density affected the increase of the TiN structure. Cytotoxicity was performed on the Ti sheet and the TiON film on SS316L by assessing the cellular response to L929 fibroblast cells. The result shows that the TiON film on SS316L exhibits good biocompatibility with the L929 fibroblast cells.

Synthesis and photocatalytic property of Zinc Oxide (ZnO) fine particle using flame spray pyrolysis method

Advance oxidation process (AOP) using photocatalysis constitute a promising technology for the treatment of wastewaters containing non-easily removable organic compound. Zinc oxide (ZnO) is one of efficient photocatalyst materials. This research reported synthesis of ZnO fine particle from zinc nitrate hexahydrate using Flame Spray Pyrolysis (FSP) method. In this method, oxygen (O2) gas were used as oxidizer and LPG (liquid petroleum gas) were used as fuel. The effect of O2 gas flow rate during ZnO particle fabrication to the microstructure, optical and photocatalytic properties were systematically discussed. The photocatalytic activity of ZnO was tested for the degradation of amaranth dye with initial concentration of 10 ppm under irradiation of solar simulator. The rate of decrease in amaranth concentration was measured using UV-Visible spectrophotometer. The ZnO synthesized using FSP has a hexagonal crystalline structure. Scanning electron microscope images showed that ZnO has a spherical formed which was the mixture of solid and hollow particles. The optimum condition for amaranth degradation was shown by ZnO produced at a flow rate of 1.5 L/min which able to degrade amaranth dye up to 95,3 % at 75 minutes irradiation.

Nitride etching with hydrofluorocarbons III: Comparison of C4H9F and CH3F for low-k′ nitride spacer etch processes

The performance of low-k nitride spacer etch processes for fin-field effect transistor device fabrication was investigated using C4H9F based and CH3F based plasma gas chemistries. C4H9F showed a larger process window of O2 gas flow rate to obtain infinite etch selectivities of blanket SiN/SiO and SiN/poly-Si than CH3F. The etch selectivity increased in both gases with the reduction of duty cycle in synchronously pulsed plasmas. Low-k spacer formation using a 60-nm gate pitch testsite was demonstrated resulting in the minimized fin recess of 4.7 nm using C4H9F-O2-He plasma at a duty cycle of 30%. This was 2.2 times smaller than that by the CH3F-He plasma. Fifty percent extended etch time resulted in a fin recess of 5.1 nm, suggesting self-limiting behavior using C4H9F-O2-He plasma chemistry. Gap structure analysis on the blanket films suggested that the selective deposition of fluorocarbon, which enhances the selectivity, is driven by plasma assisted deposition in case of the C4H9F-O2-He plasma. These unique characteristics of C4H9F can facilitate innovative plasma etch processes for nitride-based materials patterning in a wide range of applications.

The effect of sputter growth conditions on the charge transport and stability of In-Ga-Zn-O semiconductors

Thin film transistors (TFTs) incorporating high mobility In-Ga-Zn-O (IGZO) semiconductors were fabricated and evaluated. The Ar:O2 gas flow rates were varied during the sputter growth of IGZO layers, which had a substantial influence on the device performance and stability under negative bias stress (NBS) and negative bias illumination stress (NBIS). As the Ar gas flow rate is increased, the TFTs exhibit inferior performance and stability. Thin film analyses indicate that the relative content of oxygen deficient sites in IGZO increases with increasing Ar gas flow rate, which is accompanied with more pronounced device degradation under bias stress. Relatively high oxygen deficiency usually leads to the generation of excess free carriers in oxide semiconductors, which normally results in high field effect mobility. However a counter-intuitive decrease in mobility is observed in this work, which is suggested to originate from the overall decrease in IGZO film density as a result of elevated sputtering pressure at high Ar gas flow rates. It is conjectured that disruptions of conduction paths occur in low density IGZO layers, owing to the lack of overlap between metal 5s orbitals.

Determination of ultra-trace levels of Mo in plants by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS)

In this work a new procedure for the determination of ultra-trace concentrations of Mo in plants is proposed. Microwave-assisted acid digestion of plants were performed without H2O2 in order to minimize contaminations and obtain lower procedure's blank. Solutions with different HNO3 concentrations were evaluated to digest the samples and 7 or 1molL−1 HNO3 solutions led to similar carbon residual contents. Since, analytical blank was a critical issue all samples were microwave-assisted digested using only 5mL of 1molL−1 HNO3. For Mo determinations in plant materials an ICP-MS with tandem configuration (ICP-MS/MS) with an octopole reaction system (ORS3) pressurized with oxygen gas and operating in MS/MS mode was employed to overcome polyatomic interferences caused by K, a major element in plants. Higher sensitivity was achieved for the determination of Mo using the mass-shift dioxide form (MoO2+) obtained with O2 gas flow rate at 0.2mLmin−1. The limit of detection of the analytical procedure was 260pgg−1. Molybdenum was quantified in six certified reference materials: apple leaves (NIST 1515), peach leaves (NIST 1547), trace elements in spinach leaves (NIST 1570), tomato leaves (NIST 1573), wheat flour (NIST 1567a) and rice flour (NIST 1568b) for accuracy assessment. Recoveries for Mo were in the 100.0–109.6% range and analytical results were in agreement with certified values at a 95% confidence levels (t-test). The procedure was applied for determination of Mo in 7 different samples of sugar cane, corn leaves and roots, and rice flour and the concentrations were in the 0.39 to 3.81μgg−1 range.

Discharge and structural characteristics of MgO thin films under various O2 and H2 gas flow rates during MgO deposition when using ion plating method in microdischarge cells

ABSTRACTThis paper has investigated the characteristics of structure and discharge for the MgO thin films grown by the ion plating process by varying the oxygen (O2) and hydrogen (H2) flow rates. The structural characteristics of the MgO film are measured by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The discharge characteristics are examined based on the firing voltage, secondary electron emission, sustain delay, and address delay. By increasing the O2 flow rates during ion plating process, the grain sizes of the MgO thin films are decreased and the firing voltages are decreased, which would be due to the improvement of secondary electron emission characteristics. In addition, as the O2 gas flow rates are increased in the range from 200 to 260 sccm, the sustain delay times are reduced, on the contrary, the address delay times are increased. Whereas, by increasing the H2 flow rates, the grain sizes of the MgO thin films are increased. In particular, the lower firing voltages are measured at a H2 flow rate of 40 sccm, which also would be due to an enhancement of secondary electron emission characteristics. When H2 flow rates are increased from 0 to 40 sccm, the address delay times are greatly reduced. Whereas, when H2 flow rates are beyond 40 sccm, the address delay times are slightly increased. However, the sustain delay times are slightly increased as the H2 flow rates are increased from 0 to 60 sccm. Accordingly, the optimal control of both O2 and H2 flow rates during the MgO film deposition using ion plating method can contribute to enhancing the discharge characteristics in ac plasma display panels (ac-PDPs).

Densities and Surface Reaction Probabilities of Oxygen and Nitrogen Atoms During Sputter Deposition of ZnInON on ZnO

We report densities and surface reaction probabilities of O and N atoms during sputter deposition of ZnInON films on ZnO templates, measured via vacuum ultraviolet absorption spectroscopy. O density is almost constant of 4.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> irrespective of O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas flow rate, whereas N density increases sharply from 2.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas sccm to 7.7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for 0.6 sccm and it increases gradually 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> for 5 sccm. The surface reaction probability β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> of O atoms on ZnInON increases significantly from 0.022 to 0.404 with increasing O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas flow rate from 0 to 5 sccm, whereas β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> of N atoms on ZnInON decreases slightly from 0.018 to 0.006. The stoichiometric chemical compositional ratio of ZnInON films with [Zn]/([Zn] + [In]) = [O]/([O] + [N]) = 94% is obtained at β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> = 0.404 of O atoms. This stoichiometric compositional ZnInON films grow coherently on ZnO templates, while nonstoichiometric films do not. The stoichiometric chemical composition is the key to coherent growth of ZnInON films.

Highly Bendable In-Ga-ZnO Thin Film Transistors by Using a Thermally Stable Organic Dielectric Layer.

Flexible In-Ga-ZnO (IGZO) thin film transistor (TFT) on a polyimide substrate is produced by employing a thermally stable SA7 organic material as the multi-functional barrier and dielectric layers. The IGZO channel layer was sputtered at Ar:O2 gas flow rate of 100:1 sccm and the fabricated TFT exhibited excellent transistor performances with a mobility of 15.67 cm2/Vs, a threshold voltage of 6.4 V and an on/off current ratio of 4.5 × 105. Further, high mechanical stability was achieved by the use of organic/inorganic stacking of dielectric and channel layers. Thus, the IGZO transistor endured unprecedented bending strain up to 3.33% at a bending radius of 1.5 mm with no significant degradation in transistor performances along with a superior reliability up to 1000 cycles.

Ozone production and losses in N2/O2 mixtures in an ozone generator

Nonunique ozone concentrations at the output of an ozone generator under identical external conditions of barrier discharge activation of N2/O2 mixtures but with different prehistories of operating practice and employed gas mixtures are investigated theoretically. An analytical approach is developed to determine the ozone yield with regard for its heterogeneous loss. Plasma-chemical and electron kinetics in the N2/O2-mixtures are calculated numerically. The results of numerical calculations are compared to experimental data obtained by the authors. It is noted that the heterogeneous loss of ozone is the probable reason for the observed variety of behavior of О3 concentrations, depending on prehistory of ozone generator operation, along with the N2 and O2 gas flow rates and the specific active power.

Improving the etching performance of high-aspect-ratio contacts by wafer temperature control: Uniform temperature design and etching rate enhancement

A novel wafer temperature control system using direct expansion cycles is developed to improve etching performance. This system enables rapid temperature control of a wafer with low power consumption. In a previous report, we confirmed that the etching rate and mask selectivity of high-aspect-ratio contact etching could be increased by around 6% and 14%, respectively, by controlling the temperature of the wafer during the etching process. In this study, an advanced wafer temperature control system that realizes not only rapid response but also uniform wafer cooling is developed, and a new etching process that controls O2 gas flow rate as well as wafer temperature during etching is evaluated to decrease the etching rate depression of high-aspect-ratio contact etching. As a result, a rate of wafer temperature change of 1°C/s and uniformity of ±0.7% with a coefficient of performance exceeding 3 is achieved over a wafer with a diameter of 300mm during the etching process. Furthermore, etching rate depression in C4F6/Ar/O2 plasma is decreased from 14.4% to 7.8% for a sample with a diameter of 100nm and aspect ratio of 30.