Naofumi Yoshida

Nonequilibrium atmospheric pressure plasma with ultrahigh electron density and high performance for glass surface cleaning

We produced a nonequilibrium atmospheric pressure plasma by applying an alternative current between two electrodes. The gas temperature and electron density were evaluated using optical emission spectroscopy. It was found that the plasma had gas temperatures from 1800to2150K and ultrahigh electron densities in the order of 1016cm−3. A remarkably high oxygen radical concentration of 1.6×1015cm−3 was obtained at a 1% O2∕Ar gas flow rate of 15slm (standard liters per minute). Contact angles below 10° were obtained in the process of glass cleaning with a plasma exposure time of 23ms.

Measurement of Hydrogen Radical Density and Its Impact on Reduction of Copper Oxide in Atmospheric-Pressure Remote Plasma Using H2 and Ar Mixture Gases

A 60 Hz alternating current excited atmospheric-pressure plasma with an ultrahigh electron density of over 1016 cm-3 employing H2/Ar [ p(H2)/p(H2+Ar) 1–3%] gases was used to reduce copper oxides on copper. The remote plasma reduced CuO and Cu2O at room temperature. The ground-state hydrogen (H) radical density in the atmospheric-pressure plasma was measured by vacuum ultraviolet absorption spectroscopy using a micro hollow cathode lamp. The ratio of reduction of amount of CuO flux to the H radical flux was determined from the measured H radical density and gas temperature.

Low temperature cured poly-siloxane passivation for highly reliable a-InGaZnO thin-film transistors

Low temperature processable passivation materials are necessary to fabricate highly reliable amorphous InGaZnO (a-IGZO) thin-film transistors (TFT) on organic substrates for flexible device applications. We investigated 3 types of poly-siloxane (Poly-SX) passivation layers fabricated by a solution process and cured at low temperatures (180u2009°C) for a-IGZO TFTs. This passivation layer greatly improves the stability of the a-IGZO device even after being subjected to positive (PBS) and negative bias stress (NBS). The field effect mobility (μ) of MePhQ504010 passivated on the TFT reached 8.34u2009cm2/Vs and had a small threshold voltage shift of 0.9u2009V after PBS, −0.8u2009V after NBS without the hump phenomenon. Furthermore, we analyzed the hydrogen and hydroxide states in the a-IGZO layer by secondary ion mass spectrometry and X-ray photoelectron spectroscopy to determine the cause of excellent electrical properties despite the curing performed at a low temperature. These results show the potential of the solution processed Poly-SX passivation layer for flexible devices.Low temperature processable passivation materials are necessary to fabricate highly reliable amorphous InGaZnO (a-IGZO) thin-film transistors (TFT) on organic substrates for flexible device applications. We investigated 3 types of poly-siloxane (Poly-SX) passivation layers fabricated by a solution process and cured at low temperatures (180u2009°C) for a-IGZO TFTs. This passivation layer greatly improves the stability of the a-IGZO device even after being subjected to positive (PBS) and negative bias stress (NBS). The field effect mobility (μ) of MePhQ504010 passivated on the TFT reached 8.34u2009cm2/Vs and had a small threshold voltage shift of 0.9u2009V after PBS, −0.8u2009V after NBS without the hump phenomenon. Furthermore, we analyzed the hydrogen and hydroxide states in the a-IGZO layer by secondary ion mass spectrometry and X-ray photoelectron spectroscopy to determine the cause of excellent electrical properties despite the curing performed at a low temperature. These results show the potential of the solution pro...