Precursor Cat-CVD a-Si films for the formation of high-quality poly-Si films on glass substrates by flash lamp annealing

Amorphous Si (a-Si) films with lower hydrogen contents show better adhesion to glass during flash lamp annealing (FLA). The 2.0 µm-thick a-Si films deposited by plasma-enhanced chemical vapor deposition (PECVD), containing 10% hydrogen, start to peel off even at a lamp irradiance lower than that required for crystallization, whereas a-Si films deposited by catalytic CVD (Cat-CVD) partially adhere even after crystallization. Dehydrogenated Cat-CVD a-Si films show much better adhesion to glass, and are converted to polycrystalline Si (poly-Si) without serious peeling, but are accompanied by the generation of crack-like structures. These facts demonstrate the superiority of as-deposited Cat-CVD a-Si films as a precursor material for micrometer-thick poly-Si formed by FLA.     

Effect of electro-chemical properties of sodium salts of various anions on their diffusional parameters in symmetrical cellulose acetate membranes

A relation was obtained between electro-chemical properties of sodium salts (NaCl, NaBr, and Na₂SO₄), and the thermodynamic property of permeability in symmetrical cellulose acetate membranes, the distribution coefficient K and the kinetic property, the overall diffusion coefficients D. K and D were obtained by the method we proposed using measured unsteady- and steady-state dialysis data. The K values increase with the increase of water content and are in the range of 10⁻² for sodium halides and 10⁻³ for Na₂SO₄. D is found to increase with the increase of the solute concentration, and the extrapolated values of D to zero concentration D⁽⁰⁾ are obtained as 0.015–0.03 μm²/s and increase with the increase of water content in the membrane. D can be divided into the concentration independent diffusion coefficients in the dense part of the membrane D_d and in the porous D_p, applying a two-part (perfect or dense and imperfect or porous) model of the membrane. Contrary to D_d, D_p increases with the increase of W_w and can be correlated as D_p,c = _d exp (γ × W_w). It is shown that the averaged D_d, _D increases with the increase of the quantity of the ionic mobility u of the solutes at infinite dilution divided by valence, and that the parameter γ increases with the increase of the ionic mobility u. The value of K increases slightly with the increase of water content and decreases with the increase of the Flory—Huggins parameter χ. The Flory—Huggins parameter χ is calculated from the measured values of distribution coefficients and data obtained from the literature. And it was found that the gradient of linear decrease of χ (λ_cation) depends on equivalent ionic conductivity of anion of salt, λ_an.     

The Crystal Quality and Surface Wettability of Various Tellurium-Based Chalcopyrite Layers Grown by the Closed Space Sublimation

AgGaTe₂, AgAlTe₂, CuGaTe₂, and Ag(Ga,Al)Te₂ layers were deposited by the close spaced sublimation method. The surface morphology and crystal quality of these Te-based chalcopyrite layers were systematically evaluated. Controlling the stoichiometry of these layers grown by the closed space sublimation was very difficult because Te preferentially detached from the source materials during the sublimation process and then Te vapor leaked out from the reactor. To solve this problem, the gap between the lid and reactor boat was minimized, and the vapor was encapsulated. As a result, the crystal quality of the AgGaTe₂ and AgAlTe₂ was improved. However, the controlling stoichiometry of CuGaTe₂ remained difficult even after the Te vapor leakage was minimized. This behavior was attributed to the large vapor pressure difference between Cu and Te. The surface morphology of the grown AgGaTe₂ and CuGaTe₂ layers exhibited scattered grain structure, while that of AgAlTe₂ possessed a continuous film structure. These different surface structures contributed to differing wettability between the chalcopyrite materials and substrates. It was found that AgAlTe₂ exhibited a high wettability against a sapphire substrate, which promoted continuous film formation.     

A novel low‐power gate driver architecture for large 8 K 120 Hz liquid crystal display employing IGZO technology

A novel low‐power gate driver architecture was developed for large 8 K 120 Hz liquid crystal display panel. For this application, not only high‐speed driving but also low power consumption is required. We employed a high mobility In‐Ga‐Zn‐O, dual V_GL level driving method, and gate driver circuit driven by DC supply. The simulation results show that our proposals meet 8 K 120 Hz driving requirements. Also, we have fabricated a prototype panel and confirmed both high‐speed driving and low power consumption.     

Catalytic graphitization of a phenolic resin carbon by nickel (~100 μm): Selective gasification of three resultant components as studied by SEM

A phenolic resin carbon containing nickel particles, ~100 μm diam., was graphitized to 2773K for 1 h. This treatment created within the specimen three structural components known as graphitic (G), turbostratic (T_s) and matrix (A). The graphitized carbon was oxidized by carbon dioxide, HNO₃-H₂SO₄ mixed acid and Simon's reagent and topographical changes were monitored by SEM. The CO₂ gasified preferentially the T_s-component to produce fissures mainly at the interface with the A- andG-component. The mixed acid reacted preferentially with the G- andT_s-components, the Simon's reagent reacting significantly only with the G-component. The mineral matter of metallurgical coke can act as a graphitization catalyst similar to nickel particles. Hence, the development of structural components within the metallurgical coke followed by gasification by carbon dioxide may cause weakening of the coke at the interfaces of components.     

Synthesis of ultrafine nano-polycrystalline cubic boron nitride by direct transformation under ultrahigh pressure

Using a turbostratic pyrolytic boron nitride as a starting material, we synthesized a variety of ultrahard polycrystalline cubic boron nitride (PcBN) as a function of the heating duration changing from 1 to 60?min under a constant temperature and pressure conditions (1950?°C and 25?GPa) using a multi-anvil apparatus. When the heating duration was less than 13?min, ultrafine nano-polycrystalline cBN (U-NPcBN) with the mean grain size of <50?nm was produced. Among these U-NPcBNs those synthesized with 11–13?min were found to have a uniform texture composed purely of cBN (i.e. with no wurzite BN residue) and a Knoop hardness of >53?GPa, which is 20% higher than that of the hardest conventional binderless PcBN in practical use. Furthermore, the PcBNs synthesized with 18–20?min showed a unique nanocrystalline texture composed of relatively coarse grains dispersed in a fine grained matrix and even higher Knoop hardness (54.5–55.2?GPa).     

Bayesian event detection for sport games with hidden Markov model

Event detection can be defined as the problem of detecting when a target event has occurred, from a given data sequence. Such an event detection problem can be found in many fields in science and engineering, such as signal processing, pattern recognition, and image processing. In recent years, many data sequences used in these fields, especially in video data analysis, tend to be high dimensional. In this paper, we propose a novel event detection method for high-dimensional data sequences in soccer video analysis. The proposed method assumes a Bayesian hidden Markov model with hyperparameter learning in addition to the parameter leaning. This is in an attempt to reduce undesired influences from ineffective components within the high-dimensional data. Implemention is performed by Markov Chain Monte Carlo. The proposed method was tested against an event detection problem with sequences of 40-dimensional feature values extracted from real professional soccer games. The algorithm appears functional.     

Energy-efficient manufacturing on machine tools by machining process improvement

This paper aims to provide information on process improvement for energy-efficient manufacturing. A machine tool has the highest rate of energy consumption among plant equipment. There are effective ways to reduce energy consumption of machine tools such as reducing required energy, shutting down the power to standby equipment, and shortening the cycle time. This paper introduces several approaches for process improvement such as optimizing the cutting conditions and the inclination angle of the tool in 5-axis machining. Minimizing the use of fluid and using control functions are also shown to be effective.