Fabrication of highly stable solution-processed oxide semiconductor thin-film transistors (TFT) was demonstrated using a method with a hydrogen injection and oxidation (HIO) process that allows low-temperature solution processing. The characteristics of TFTs based on the indium gallium zinc oxide (IGZO) semiconductor were evaluated at a maximum processing temperature as low as 300°C. Application of the HIO process improved the TFT performance in terms of the mobility and the threshold voltage (V th ) shift under positive and negative gate bias stress.
The particle-scattering phenomenon caused by charge-up in ion implantation into spherical dielectric powders in a stationary state or in a vibrational state with no neutralizer was studied theoretically and experimentally. The theoretical threshold charging voltage for scattering was obtained from the force balance equation between the Coulomb repulsive force and the attractive van der Waals force and gravity. The estimated charging voltage which starts scattering of powders agrees well with experimental results for positive-ion implantation into powders both in a stationary state and a vibrational state. Scattering took place even at an ion acceleration voltage of about 1 kV for positive-argon-ion implantation. Conversely, no scattering was observed for negative-carbon-ion implantation at an ion acceleration voltage of 20 kV in a stationary state. The negative-ion implantation technique was found to be a non-scattering implantation method for dielectric powders.
We have developed a negative-ion implanter for uniform implantation into each powder surface without particle scattering. It consists of a plasma sputter-type negative-ion source, a mass separator, an acceleration tube, a lens, X–Y deflectors, a 90° deflector, and a Faraday cup with an agitator. The electrostatic 90° deflector bends a horizontal beam to a vertical direction and leads it into the Faraday cup. The agitator is an electromagnetic vibrator at a frequency of 120 Hz, which mixes particles for whole surface treatment and uniform implantation. In this implanter, we obtained no scattering implantation for spherical oxide beads with diameters ranging from 5 to 1000 μm in an agitated state, and also obtained a good uniformity of implanted atoms among beads. For an application of the negative ion implantation into powders, copper ions were implanted into soda-lime glass beads and plates at conditions of 50 and 30 keV, respectively, with 1×1017 ions/cm2. In linear optical properties, both implanted samples show a clear absorption at a photon energy of 2.2 eV due to resonance absorption of copper surface plasmon. In addition, the implanted glass plate shows the large third-order nonlinear susceptibility, χ(3)=1.3×10−7 esu. These results suggest the existence of copper nanometer-sized particles in glass.
The cathodeluminescencs (CL), photoluminescence (PL), and electroluminescence (EL) properties of Ge implanted SiO2 films (SiO2:Ge) were investigated. The SiO2 films on Si substrate were implanted with Ge-negative ions. The implanted Ge atom concentrations in the films were 3 and 6 at. %. Ge nanoparticles were formed in the SiO2 films after annealing. CL, PL and EL were observed at wavelengths around 400 nm from the SiO2:Ge films. CL of GeO2 films were also investigated. The CL intensity from the GeO2 films is obviously lower than that from the SiO2:Ge films with 6 at.% of Ge atomic concentration. Strong EL from large area of the films was not only to be easily seen with naked eye but also to be measured its wavelength. Ooperating voltage was an order of magnitude lower and the emitting area was two orders of larger than those reported previously. These results suggested that annealing of SiO2:Ge films in moderate oxidative atmosphere is suitable method for the strong luminescence due to Ge-related oxygen deficient center (Ge-ODC).
Photocatalytic properties of titanium dioxide layer deposited on silica glass (SG) including silver nanoparticles at a shallow depth were studied from an aspect of utilization of surface plasmon resonance (SPR) by nanoparticles. In order to adjust resonant photon energy of surface plasmon to the activation energies of 3.0 and 3.2 eV depending on crystallinity of TiO2, Ag nanoparticles were formed in SG at a shallow depth by silver negative-ion implantation and post annealing. Then, TiO2 layer was formed on it at temperatures of 200 and 500°C by rf magnetron sputter deposition. Ag nanoparticles were confirmed from optical absorption by the SPR at 3.0-3.1 eV. The deposited TiO2 film at substrate temperature of 200°C was found to have anatase-type nano-crystals from results of XRD and optically measured bandgap. Photocatalytic properties of TiO2 layer deposited on Ag-implanted silica glass at 200°C were evaluated by decolorization of methylene blue solution and compared with that of the TiO2 film deposited on unimplanted SG at the same conditions. As a result, the TiO2 layers deposited on Ag-implanted SG after annealing at 700°C were showed an enhancement in photocatalysis of factor 3.26.
This paper presents the communication protocol between applications and remote databases in enterprise systems. Although the International Standard OSI-RDA has presupposed of the 1 request - 1 response communication protocol for the remote database access, it is not suitable from the view of system resources occupation and communication overhead in the case that the system should handle the large volumes of multimedia data. This paper proposes a server driven communication protocol in order to solve these problems, and compares the traditional method and the proposed method on the followings: (1) the number of communications, (2) the number of the encoding-decoding, and (3) the dynamic steps. According to the quantitative comparison, the proposed method makes the effort of avoiding communication resources occupation and improves 50% of communication overhead in case of only a large communication data. This paper also implies the guideline for suitable number of data segmentations for the remote database access.
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