Advances in Nanomaterials and Processing

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Authors: Jae Hyouk Yoo, Su Cheol Gong, In Jae Baek, Hyun Seong Lim, Sang Baie Shin, Young Chol Chang, Gee Keun Chang, Ho Jung Chang
Abstract: Polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al structure were prepared by spin coating method on the plasma-treated ITO(indium tin oxide)/glass substrates. PVK(N-vinylcabozole) and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)] polymers were used as hole injection and transport materials. As blue light emitting material, PFO-poss(poly(9,9-dioctylfluorence) polymer was used. The dependence of the plasma treatment of ITO films on the optical and electrical properties of the PLEDs was investigated. The sheet resistance of ITO films increased slightly with increasing the plasma intensity from 20W to 300W in RF power. In contrast, the surface roughness was improved as the plasma intensity increased. The maximum current density and luminance were about 20 mA/cm2 and 250 cd/m2 at 9 V for the PLED sample coated on ITO/glass substrate with plasma treatment of 100W for 30s under 40 mtorr O2 pressure. The maximum emission spectrum of the PLEDs was 441 nm showing blue color.
Authors: In Sung Cha, Jin Hyon Lee, Ung Yu Paik, Seon Mi Yoon, Eun Sung Lee, Jae Young Choi
Abstract: The effect of a binary surfactant on the luminance efficiency of a green phosphor was investigated with an emphasis on the chemical control of interactions between the suspension components. The dispersion system of the green phosphor paste was designed by an evaluation of the acid and base properties of the green phosphor and the surface active organic molecules by a non-aqueous titration method. Oleyl amine and 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethylene phosphoric acid (hereafter SAIT7) were added into the green phosphor paste taking into account the ratio between the acid and base sites of the green phosphor particle’s surface. This resulted in a higher maximum solid loading and a further decrease in the viscosity of the green phosphor paste compared to a single addition of SAIT7 and oleyl amine. The green phosphor paste with the binary surfactant exhibited a much improved photoluminescence intensity and homogeneity of the emission properties than a single addition of the dispersant.
Authors: Hyoung June Kim
Abstract: Polycrystalline Si thin film transistors (TFTs) have been fabricated through solid phase crystallization using field-enhanced rapid thermal annealing (FE-RTA) system. The system consists of inline furnace modules for preheating and cooling of the glass substrates and a process module for rapid radiative heating combined with alternating magnetic field induction. The FE-RTA system enables crystallization of amorphous Si at high throughputs without any glass damages. While the typical grain structures of poly-Si by FE-RTA are similar to those of solid phase crystallization, the residual amorphous Si and intragranular defects are reduced.
Authors: Jung Min Kim, Hyun Jung Her, J.H. Yoon, Jae Wan Kim, Y.J. Choi, C.J. Kang, D. Jeon, Yong Sang Kim
Abstract: We investigated the characteristics of pentacene thin films of different materials for gate insulators using atomic force microscope (AFM) and x-ray diffraction (XRD). The pentacene thin films are fabricated by evaporation on different polymer substrates. We used HMDS (Hexa Methyl Di Silazane), PVA (Poly Vinyl Alcohol) and PMMA (Poly Methyl Meth Acrylate) for the polymer substrates, on which pentacene is deposited at various substrate temperatures. The case of pentacene deposited on the PMMA has the largest grain size and least trap concentration. We also fabricated pentacene TFTs with the PMMA gate insulator. Pentacene TFTs with PMMA gate insulator, shows high field-effect mobility (uFET= 0.03 cm2/Vs) and large on/off current ratio (>105) and small threshold voltage (Vth= -6 V).
Authors: Seong Hoon Kim, Han Ki Yoon, Riichi Murakami
Abstract: The thin films of SiO and SiON were deposited individually by the inclination opposite target type DC magnetron sputtering equipment onto the glass substrate. And it was deposited IZO(In2O3 (90wt.%) + ZnO(10wt.%)) on those films. The effects of SiO and SiON were investigated on properties of IZO thin films. AFM images of IZO thin film included SiON film were shown smoother surfaces than that included SiO film. Multi layers of IZO were shown good properties because it have high transmissivity. Resistivity is in inverse proportion to Mobility. If it deposited SiO and SiON, generate layer of change between two layers(SiO or SiON + Substrate). Layer of change influenced resistance because Oxygen content was more than single layer of IZO. In case of using PET substrate, it influenced stronger than Glass substrate for rigid gas permeable and osmosis.
Authors: El Hang Lee, In Joo Chin, Yong Ku Kwon, S.G. Lee, B.H. O, S.G. Park, Kyong Hon Kim
Abstract: We report on the synthesis and fabrication of novel polymer/organic materials for application for what we call optical printed circuit board (O-PCB) for VLSI photonic circuit (VLSI-PIC). We synthesize copolymers containing cross-linkable pendant groups suitable for embossing and novel device fabrication. We also synthesize organic-inorganic hybrid materials of low optical absorption, good adhesion, low dielectric constant, high dielectric strength, high thermal stability, excellent photo-patterning possibility and variability of refractive index. Steps of synthesis and fabrication of these materials are described along with their optical, material, and performance characteristics. O-PCB and VLSI photonic circuit design and fabrication processes are also presented.
Authors: Dong Bok Lee, Dae Ho Yoon
Abstract: About 2-thick, amorphous SiON thin films were deposited by the PECVD method, and heated up to 1000oC in air to study the post-annealing effect on the composition and structure of the SiON film. SiON had a strong SiO2 binding energy with a weak N-binding, so that air-annealing resulted in nitrogen escape from the film. The inwardly transported oxygen from the atmosphere was simply supersaturated inside the annealed, amorphous SiON thin film.
Authors: Jin Kyo Seo, Jeong Hwan Lee, Jong Wan Park
Abstract: The crystal defects in diamonds are diverse. In other words, there are almost no perfect diamonds without impurities or dislocations. Most natural diamonds contain a considerable amount of nitrogen impurity in aggregated forms. CVD diamond films also included many crystal defects. We investigated the distribution of luminescence center of natural type Ia diamonds and CVD diamond films by various photoluminescence excitation source. Photoluminescence (PL) spectroscopy is a useful technique to provide information on defects of diamond with high sensitivity.
Authors: Jae Suk Oh, Sang Il Seok, Ha Kyun Jung
Authors: J.W. Roh, J.S. Yang, S.H. Ok, Deok Ha Woo, Young Tae Byun, Young Min Jhon, Tetsuya Mizumoto, Woo Young Lee, Seok Lee
Abstract: A novel process of wafer bonding between InP and a garnet crystal (Gd3Ga5O12, CeY2Fe5O12) based on O2 plasma surface-activation and low temperature heat treatment is presented. The O2 plasma assisted wafer bonding process was found to be very effective in bonding of InP and Gd3Ga5O12, providing good bonding strength and hydrophilicity as well as no voids in the interface, which is crucial for fabrication of an integrated optical waveguide isolator. The isolation ratio of an integrated optical waveguide isolator fabricated by the O2 plasma assisted wafer bonding process was obtained to be 2.9 dB.

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