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Authors: Guang Fei Liu, Lang Liu, Dian Zeng Jia, Xin Hu, Kaibei Yu
Abstract: A new organic photochromic function material containing pyrazolone-ring, 1-phenyl-3-methyl-4-(4-fluobenzal)-pyrazolone-5 thiosemicarbazone (PM4FBP-TSC) was synthesized and characterized by elemental analysis, IR spectrum and 1H NMR spectrum. The photochromic properties and photocolored kinetics of PM4FBP-TSC were studied by Time-dependent UV-vis reflective spectra and fluorescent spectra under irradiation of 365nm light. The structure of PM4FBP-TSC was determined by single crystal X-ray diffraction. Space group Pbca with cell dimensions of a = 18.445(4) Å, b = 11.987(2) Å, c = 19.249(4) Å, V = 4256.1(18) Å3, Z = 8 and R = 0.0521. The crystal structure analysis of photocolored product of PM4FBP-TSC showed that the photochromic phenomenon was due to the photoisomerization from enol form to keto formı and the mechanism of intermolecular proton transfer was applied to interpret the photochromism. The photoisomerization belongs to the first-order reaction by computation, and kinetic reaction constant is k1 = 6.85 × 10-5 s-1.
Authors: Ju Hyun Myung, Nam Ho Kim, Hyoun Woo Kim
Abstract: We have demonstrated the growth of ZnO thin films with c-axis orientation at room temperature on various substrates such as Si(100), SiO2, and sapphire by the r.f. magnetron sputtering method. X-ray diffraction (XRD) and scanning electron microscopy altogether indicated that the larger grain size and the higher crystallinity were attained when the ZnO films were deposited on sapphire substrates, compared to the films on Si or SiO2 substrates. The c-axis lattice constant decreased by thermal annealing for the ZnO films deposited on Si or SiO2 substrates, while increased by the thermal annealing for the ZnO films grown on sapphire substrates.
Authors: Ling He, Yu Hua Wang
Abstract: The phosphors YBO3:Eu with different morphology was successfully realized by mild hydrothermal process with different reaction condition. Highly spherical shape, uniform size and non-agglomeration of YBO3:Eu phosphors particle was obtained at 260°C,which is about 850°C lower than that by solid state reactions. The result of XRD showed that all samples were single phase with vaterite type structure. From IR and NMR spectra, it could be concluded that YBO3 contains mainly BO4 tetrahedra which is in favor for absorption VUV excitation. Monitoring by 598nm emission, the main excitation peak at about 247nm was observed in the excitation spectrum of spherical Y0.95Eu0.05BO3. Correspondingly, under 247nm excitation, the main peak at about 598nm was observed. The photoluminescence intensity (5D0→7F1 transition of Eu3+) of spherical shape of Y0.95Eu0.05BO3 was 1.5 times in comparison with which prepared by solid-state reactions. The best photoluminescence intensity was obtained when the concentration of Eu3+ is at 20 at. %. It indicated that hydrothermal method have a potential in the preparing various particles phosphors for application in displays and lamps.
Authors: S.M. Liu, Shu Lin Gu, Feng Qin, Su Min Zhu, Jian Dong Ye, W. Liu, X. Zhou, R. Zhang, Y. Shi, Y.D. Zheng
Abstract: In this paper we have characterized the performance of a vertical metalorganic chemical vapor deposition (MOCVD) reactor used for deposition of ZnO thin films. The equations of the mathematical model are solved numerically using a control-volume-based finite difference method. A two-dimensional model is put forward to study the dependence of the growth rate on the inlet flow rate and susceptor temperature. The mass-fraction distribution of the reactants has been studied as a function of the position above the substrate, which shows that gas phase pre-reaction in our reactor is well confined. The simulation results are useful for the practical growth of ZnO.
Authors: Letian Zhang, Wenfa Xie, Yong Hou, Aiwu Li, Jie Zheng, Wei Zheng, Yushu Zhang
Abstract: Ge-doped silica glass films were fabricated on Si (100) substrates for core materials of waveguide using flame hydrolysis deposition. Then the films were hydrogen loaded and irradiated to KrF excimer laser. The refractive indices and extinction coefficients of the samples before and after irradiation were determined using M-2000 variable angle incidence spectroscopic ellipsometer (VASE) and obtain the maximum increase about 0.3% at 1550 nm.
Authors: Guo Qiang Li, Wan Qi Jie
Abstract: The optical properties of CdZnTe crystals grown by vertical Bridgman method were investigated in detail by infrared (IR) transmission spectra and photoluminescence (PL) spectra. IR transmission measurements showed that according to the trends of the IR transmission with the wavenumbers, IR transmission spectra could be classified into four types, i.e. descending, ascending, low straight and high straight. Each of them indicated one type of CdZnTe crystals with specified properties. PL measurements revealed that the low-temperature PL spectra consisted of three emissions: the near-band-edge emission (I0) situated at 1.66eV related to the free and bound excitons, the donor-acceptor emission (I1) centered at 1.62eV related to the impurities, and a defect band emission (I2) centered at 1.50eV due to the dislocations. The full width at half maximum (FWHM) of I0 and the PL intensity ratios of I1/I0 and I2/I0 could be used to evaluate the properties of the crystals.
Authors: Byung Soo Kim, Young Bae Kim, Duck Kyun Choi
Abstract: Considering practical application of field aided lateral crystallization process in channel region of thin film transistors, there might be a different crystallization behavior dependent on the shape of channel to be crystallized. In this study, channel array with various aspect ratios was prepared and the Cu field aided lateral crystallization process was carried out at 500ı for 10 hours with applying 30V/200㎛ through common electrodes for the sake of the actual channel area crystallization. Both the fraction of crystallized area and the degree of crystallization increase as the aspect ratio of channel become away from 1.
Authors: Kyu Shik Shin, Joon Shik Park, Kwang Bum Park, Hyo Derk Park, Jeong Rim Kim, Min Chan Kim
Abstract: Design and fabrication of micro mixing cells and detection cells were investigated. Glass micro mixing cells with island structures among channels were fabricated using sand blaster methods. Depth and width of mixing channel were 200 ㎛ and 180 ㎛ and island size was 90 ㎛ by 90 ㎛. Two 45° mirrors surfaces faced on each other in one detection cell which were fabricated by silicon anisotropic etching using 20% TMAH (Tetramethylammonium hydroxide) solution with 20% or 30% IPA (iso propyl alcohol) at 80°C, respectively. Up side glass wafer for mixing cell and down side silicon wafer for detection cell were bonded using anodic bonding method at 350ı, -600 V and 300 N. Synthetic indophenol was injected at inlet and moved to the detection cell through the mixing channel. HeNe laser of 632.8 nm was focused on one side of a 45° mirror, and passed through indophenol solution until the other side of a 45° mirror. The light of 632.8 nm was absorbed in indophenol solution between two 45° mirrors at detection cell. By the Beer-Lambert’s law, indophenol concentration could be calculated from the measured result of the absorbance.
Authors: J.H. Lee, D.H. Oh, G.J. Lee, S.C. Joo, B. Yang, Sung Jin Kim, Chang Joo Kim
Abstract: A diaphragm, the most important part of pressure sensor, was successfully fabricated by an electro-chemical etch-stop (ECES) technique. It was important to control the thickness of the diaphragm precisely. We compared characteristic results of diaphragms by electro-chemical etch-stop with those by time-control etch-stop (TCES). The 4 inch n-Epi/p-substrate with 16±1 ㎛ thickness was utilized because the thickness of the diaphragm fabricated by ECES is controlled by the thickness of Epi.. The etching of silicon wafer was carried out in the solution (25 wt% KOH) at 80°C, using 3 electrode system with potentiostat. Proper voltages were applied to etch p/n-type silicon wafer after determined open circuit potential (OCP) and passivation potential (PP) of n and p-type silicon, respectively. Thickness of diaphragms fabricated by ECES was controlled in the range of 16±1 ㎛ while that by TCES was in the range of 16.1±2 ㎛. The roughness of diaphragm was 52±5 Å. When the pressure of 50 kPa was applied on the pressure sensor using the diaphragm fabricated by ECES, the error rate was improved to ±10 ㎷. In the case of the error rate of pressure sensor using the diaphragm fabricated by TC was in the range of ±25 ㎷ under the same condition.
Authors: B.I. Seo, No Jin Park, Sung Jin Kim, B. Yang, Y.H. Oh, Suk Kyoung Hong
Abstract: Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined by an electron backscatter diffraction (EBSD) technique. Ferroelectric domain characteristics by a piezoresponse force microscope (PFM) were also performed to study the dependence of reliabilities on the grain orientations and distributions.

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