Advances in Nanomaterials and Processing

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Authors: Seong Jun Kim, Ji Kyun Kim, Hyeon Seok Lee, Jeong Yeol Kwon, Heon Yong Lee
Abstract: In this paper, we studied the method of electrets electrode which formed to accumulate negative electric charge by corona discharge. The breakdown voltage sample and damaged sample by various corona discharges have made material stabilization and improved characteristics of electric charge storage throughout the annealing process. After the experiment made material stabilization nearly melting point by many kinds of annealing conditions, we did the corona discharge again by the charged high voltage, a discharge electrode gap, and a discharged time. As we compared it with the best condition, we confirmed that characteristics of electric charge storage were improved.
Authors: Jae Yeong Heo, Hyeong Joon Kim
Abstract: Various annealing conditions after film deposition have a great effect on electrical and structural properties of low-k films. In this work, we studied hydrogen atmosphere heat treatment effect on low-k films. After the room temperature deposition of a-SiOC:H low-k films following post-deposition-annealing (PDA) for 30 min. at 450°C in an N2 ambient, final annealing was performed for 30 min. at 400°C in an N2, a forming gas 1 (5% H2 + 95% N2), and a forming gas 2 (10% H2 + 90% N2) ambient. The flat band voltage was shifted toward the ideal value of 0.61V after two forming gas anneals, but it increased k values of the films. It was ascribed that hydrogen effectively substitutes defect sites or structural imperfections of low-k films and makes the film more hydrophilic. The FT-IR, XPS analyses and the contact angle measurement supported our conclusion.
Authors: Su Jin Yoo, O Dae Kwon, Hee Hwan Choe, Jae Hong Jeon, Kang Woong Lee, Jong Hyun Seo, Dae Jin Seong, Jung Hyung Kim, Yong Hyeon Shin
Authors: Beom Seob Kim, Deug Joong Kim
Abstract: The formation, microstructure and electrical property of conductive ceramic composites derived from polymer pyrolysis were investigated. Methylpolysiloxane was mixed with TiH2 as a filler and pyrolyzed in nitrogen, argon and vacuum atmosphere at a temperature of 1600oC for 1 hour after the preheat treatment at 850oC in N2 atmosphere. Depending on the atmosphere conditions, TiN and Ti5Si3 phases were formed by reaction of TiH2 as reactive filler and atmospheric gas or pyrolytic product such as SiO2. Consequently, the microstructures of the ceramic composites with 70 vol.%TiH2 pyrolyzed at 1600oC for 1 hour in vacuum were composed of TiN and Ti5Si3 particles. The density and electrical conductivity of the ceramic composites were 97.3 TD% and 6200 ohm-1⋅cm-1, respectively. These composites pyrolyzed by polymer were considered as superior conductive material with a value of 103 ~ 104 in log scale at room temperature.
Authors: Sung Hoon Kim, Hong Seop Yun, Hyun Kyung Yang, Kwang Duk Kim, Soung Soo Yi, Jung Hyun Jeong, Dong Uk Kim
Abstract: As-grown Sr2SiO4:Eu thin films on Si (100) substrates have been reduced by hydrogen plasma reaction which was carried out by using radio frequency plasma enhanced chemical vapor deposition system. The photoluminescence spectra, the crystal structure and the surface morphologies of the plasma-reduced films were measured and compared with those of the as-grown films. At as-grown state, Eu3+ and Eu2+ ions co-exist so that the photoluminescence spectra of the films reveal several emission bands between 350 and 650 nm. They were due to f-f and f-d transitions within Eu3+ and Eu2+ ions. After the plasma-reduced process, the photoluminescence spectra of the films show a remarkable increase of blue-green emission from the transitions of Eu2+ ions and decrease of red emission from the transitions of Eu2+ ions.
Authors: Gun Hee Kim, Hong Seong Kang, Dong Lim Kim, Hyun Woo Chang, Byung Du Ahn, Sang Yeol Lee
Abstract: Cu-doped ZnO (denoted by ZnO:Cu) films have been prepared by pulsed laser deposition using 3 wt. CuO doped ZnO ceramic target. The carrier concentrations (1011~1018 cm-3) and, electrical resistivity (10-1~105  cm) of deposited Cu-doped ZnO thin films were varied depending on deposition conditions. Variations of electrical properties of Cu-doped ZnO indicate that copper dopants may play an important role in determining their electrical properties, compared with undoped films. To investigate effects of copper dopants on the properties of ZnO thin films, X-Ray diffraction (XRD), photoluminescence (PL), and Hall measurements have been performed and corresponded.
Authors: Yong Hee Han, Seung Hoon Lee, Kun Tae Kim, In Hoon Choi, Sung Moon
Abstract: In recent years, we have reported uncooled microbolometer with amorphous vanadium-tungsten oxide as a thermometric material. The reported tungsten-doped vanadium oxide showed very high TCR over -3.0%/K compared with common vanadium oxide, which generally has the TCR values near -2.0%/K. In this work, we characterized properties of electrical conductivity of amorphous tungsten-doped vanadium oxide by investigating electronic structure between vanadium oxide and tungsten-doped vanadium oxide. Finally, it is concluded that tungsten addition into vanadium give rise to changes of electronic structure when pure vanadium is oxidized and this changes of electronic structure attribute to electrical properties such as high TCR values of vanadium-tungsten oxide.
Authors: Yong Sup Yun, Takanori Yoshida, Norifumi Shimazu, Yasushi Inoue, Nagahiro Saito, Osamu Takai
Abstract: Plasma diagnosis was performed by means of optical emission spectroscopy in the plasma-enhanced chemical vapor deposition process for preparation of hydrocarbon-doped silicon oxide films. The chemical bonding states were characterized by a fourier-transform infrared spectrometer. Based on the results of the diagnosis in organosilane plasma and the chemical bonding states, a reaction model for the formation process of hydrocarbon-doped silicon oxide films was discussed. From the results of optical emission spectroscopy, we found that the oxygen atoms of methoxy groups in TMMOS molecules can be dissociated easily in the plasma and behave as a kind of oxidizing agent. Siloxane bondings in HMDSO, on the other hand, hardly expel oxygen atoms.
Authors: Kyung Hyun Park, Min Soo Ko, Yong Seog Kim
Abstract: Characteristics of MgO layer deposited under hydrogen atmosphere were investigated. Hydrogen gas was introduced during e-beam evaporation coating process of MgO layer and its effects on microstructure, cathode luminescence spectra, discharge voltages and effective yield of secondary electron emission were examined. The results indicated that the hydrogen influences the concentration and energy levels of defects in MgO layer and that affects the luminance efficiency and discharge delays of the panels significantly.
Authors: Kwan Wuk Park, Jin Seok Lee, Hee Jin Lim, Sung Churl Choi
Abstract: Bi-based glass pastes were prepared in the mixed organic solvents (α-terpineol and texanol) with different kinds and concentrations of organic dispersant such as fish oil , phosphate ester and poly methyl methacrylate (PMMA). The rheological stability of glass pastes was characterized by using a rheometer and adsorption behavior of organic additives for the glass powders was carried out by using a thermal gravimetric analyzer (TGA).The Bi-based glass pastes exhibited the most stable rheological behavior at an addition of phosphate ester of 0.5 in mass %, due to the steric repulsive force acting on the surface of glass powers with adsorbing the organic additives. This study allowed significant delay of the sedimentation time and suppressed generation of micropores during practical forming process by a screen printing method.

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