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The effects of working pressure on the physical properties of amorphous InGaZnO x (a-IGZO) films fabricated using inductively coupled plasma-enhanced reactive sputtering deposition were studied, while also assessing the plasma employed during film deposition. With decreasing working pressure, the ion saturation current corresponding to the plasma density increased along with the film deposition rate, because of the greater number of ions incident on the IGZO target. The physical properties of the resulting a-IGZO films were examined to determine the effect of ion energy while varying the working pressure. With decreasing working pressure, the film densities estimated from X-ray reflection data were found to increase. In addition, the concentrations of excess oxygen and hydrogen species incorporated into the a-IGZO films, which can potentially lead to structural and electrical instability, decreased. These results indicate the feasibility of enhancing the electrical properties of a-IGZO films.

We present here an analysis of the discharge characteristics near the liquid surface in the plasma jet operated at a He gas flow rate of 1.5–10 slm. The plasma diameter on the liquid surface increases with an increase in He gas flow rate, which results in an increase in the total amount of charge particles transferred from the plasma to the liquid. We also analyzed the gas flow patterns using a Schlieren gas flow imaging system. The diameter of the laminar flow and the gas flow distance along the liquid surface increase with an increase in He gas flow rate, which well explains the increase in the plasma diameter on the liquid surface. Our experiments clearly demonstrate that high gas flow rate realizes the large reaction area between the water molecule and the plasma in the plasma jet system.

We present here the analysis of the characteristics of a dielectric-barrier-discharge (DBD) plasma jet in open air using the optical emission spectroscopy (OES). The OES on oxygen emission is useful to estimate the presence of reactive excited O atoms. The O emission intensity is much higher near the quartz-tube outlet and abruptly decreases with distance from the quartz tube. Our experiments also show that the DBD plasma jet is quite sensitive to He gas flow rate ( $R_{{\rm He\mbox{-}gas~flow}})$ : increasing $R_{{\rm He\mbox{-}gas~flow}}$ induces weak pulse discharge, resulting in decreasing O emission intensity.

Cyclic transport of dust particles (dust hour glass) in a capacitively coupled radio frequency discharge with horizon- tal electrodes is demonstrated. Dust transport toward the upper electrode is initiated by varying the electrical asymmetry of the discharge. A shaped upper electrode guides dust particles to move toward the center of the discharge. Subsequently, the dust drops through the plasma bulk spontaneously, this way returning to the starting location.

A chemical interaction between an atmospheric pressure plasma jet and liquid media is of great interest for biomedical applications. In this paper, the visualization method and typical results of the 2-D distribution of oxidizing substances generated by the plasma jet were reported using the gel visualization reagent. The plasma jet generator consists of a glass tube and two electrodes. As a result, the distribution of oxidizing substances was able to be visualized around the contact point between the plasma jet and the reagent in atmospheric air. The interesting distribution patterns depending on the supplied gas were visually obtained by the reagent. In addition, its relative concentration distribution was also obtained by an absorbance measurement.