• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.99-103
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• 2012

Presently, A glass is widely used in telecommunication system, optoelectronic devices and micro electro mechanical systems. Micro drilling of glass using the laser can save processing cost and improve the accuracy. This paper experiments micro drilling using KrF excimer laser on the pyrex glass of $500{\mu}m$ thickness. We have experiment to find out optimum laser machining conditions of micro drilling of glass and ablation depth and influence by processing parameter suc'h pulse repetition rate, energy density and number of pulses. Pulse repetition rate don't influence ablation depth at the micro drilling of pyrex glass. Energy density influence micro drilling of parallelism and maximum thickness that can be drilled. Ablation depth is most influenced by number of pulses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.82-85
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• 2003

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by Micro-lapping process. The sapphire crystalline wafers were characterized by DCXD(Double Crystal X-ray Diffraction). The sample quality of crystalline sapphire wafer at surface has a FWHM(Full Width at Half Maximum) of 250 arcsec. This value at the sapphire wafer surfaces indicated 0.12${\mu}{\textrm}{m}$ sizes. Surfaces of sapphire wafers were mechanically affected by residual stress and surface default. Also Surfaces roughness of sapphire wafers were measured 2.1 by AFM(Atom Force Microscope).

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.717-722
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• 2010

Two derivatives of star shaped compounds based on naphthylamine with symmetric trisubstituted benzene as core, methoxy and ethoxy as end substitutions are synthesized. The synthesized compounds are characterized by UV-visible, FT-IR and NMR spectrometric techniques. The electronic and thermal properties of the compounds are studied using cyclic voltametry (CV) and differential scanning calorimetry (DSC) respectively. The data's obtained have similarity with the arylamines that have been already used in optoelectronic devices. So these compounds are interesting materials for applications in such devices.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.4-5
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• 2004

• Rapid Communication in Photoscience
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• v.2 no.1
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• pp.9-17
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• 2013

Visible light-sensitive $TiO_2$ and ZnO nanostructure materials have attracted great attention as the promising material for solar energy conversion systems such as photocatalysts for water splitting and environmental purification as well as nano-biosensors. Success of their applications relies on how to control their surface state behaviors related to the exciton dynamics and optoelectronic properties. In this paper, we briefly review some recent works on single nanoparticle photoluminescence (PL) technique and its application to observation of their surface state behaviors which are raveled by the conventional ensemble-averaged spectroscopic techniques. This review provides an opportunity to understand the temporal and spatial heterogeneities within an individual nanostructure, allowing for the potential use of single-nanoparticle approaches in studies of their photoenergy conversion and nano-scale optical biosensing.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.230-232
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• 2006

Eutectic Au-20Sn solder has been widely used for optoelectronic packages because of fluxless soldering process and thus are particularly valuable for many applications such as biomedical, photonic, and MEMS devices that can not use any flux. Also when good joint strength, superior resistance to corrosion, whisker-free, and good thermal conductivity are demanded, eutectic Au-20Sn solder can be satisfied with above-mentions best. In this study, we tried to know the interfacial reactions between Au-20Sn solder and Cu substrate with or without ENIG plating layer In the results, Au-Cu-Sn ternary phases were formed at the Au-20Sn/Cu substrate, and Au-Ni-Sn, Au-Ni-Cu-Sn phases were formed at the Au-20Sn/ENIG substrate.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.2
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• pp.119-123
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• 2006

This work presents the fabrication and characteristics of $Bi_2O_3/Si$ heterojunction prepared by rapid thermal oxidation technique without any postdeposition annealing condition. The bismuth trioxide film was deposited onto monocrystalline Si and glass substrates by rapid thermal oxidation of bismuth film with aid of halogen lamp at $500^{\circ}C/\;45$ s in static air. The structural, optical and electrical properties of $Bi_2O_3$ film were investigated and compared with other published results. The structural investigation showed that the grown films are polycrystalline and multiphase (${\alpha}-Bi_2O_3$ and ${\beta}-Bi_2O_3$). Optical properties revealed that these films having direct optical band gap of 2.55 eV at 300 K with high transparency in visible and NIR regions. Dark and illuminated I-V, CV, and spectral responsivity of $Bi_2O_3/Si$ heterojunction were investigated and discussed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.1
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• pp.74-81
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• 2004

We propose a novel scheme to transmit high center frequency RF signals using electroabsorption devices (EADs) as frequency converters at the transmitter and the receiver. In this approach frequency heterodyning is employed for obtaining high center frequency. With the EAD as a detector/mixer at the receiver we demonstrated a smaller conversion loss than that of the conventional modulator/mixer. With EAD as a modulator/mixer at the transmitter and with two heterodyned lasers to generate an optical local oscillator (LO), we demonstrated a large reduction (${\sim}23dB$) in conversion loss, and the transmission is not limited by the optical saturation of the EAD. This transmission scheme has optical single-side-band transmission feature which greatly relieves the fiber dispersion effect.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.298-303
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• 2001

The critical thickness of an epitaxial film on a substrate in electronic or optoelectronic devices is studied on the basis of equilibrium dislocation analysis. Two geometric models, a single dislocation and an array of dislocations in heteroepitaxial system, are considered respectively to calculate the misfit dislocation formation energy. The isotropic linearly elastic stress fields for the models are obtained by means of complex potential method combined with alternating technique, and are used for calculating the formation energies. As a result, the effect of elastic mismatch between film and substrate on critical thickness is presented and $Si_xGe_{1-x}/Si$ epitaxial structure is analyzed to predict the critical thickness with varying germanium concentration.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.73-78
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• 2003

The InP thin films grown by metalorganic chemical vapor deposition (MOCVD) are widely used to optoelectronic devices such as laser diodes, wave-guides and optical modulators. Effects of various parameters controlling film growth rate such as gas-phase reaction rate constant, surface reaction rate constant and mass diffusivity are numerically investigated. Results show that at the upstream region where film growth rate increases with the flow direction, diffusion including thermal diffusion plays an important role. At the downstream region where the growth rate decreases with flow direction, film deposition mechanism is revealed as a mass-transport limited. Mass transport characteristics are also studied using systematic analyses.