• Proceedings of the KWS Conference
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• 2002.10a
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• pp.475-480
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• 2002

The reliability of the solder joint is affected by type and extent of the interfacial reaction between solder and substrates. Therefore, understanding of intermetallic compounds produced by soldering in electronic packaging is essential. In-based alloys have been favored bonding devices that demand low soldering temperatures. For photonic and fiber optics packaging, m-based solders have become increasingly attractive as a soldering material candidate due to its ductility. In the present work, the interfacial reactions between indium solder and bare Cu Substrate are investigated. For the identification of intermetallic compounds, both Scanning Electron Microscopy(SEM) and X-Ray Diffraction(XRD) were employed. Experimental results showed that the intermetallic compounds, such as Cu$_{11}$In$_{9}$ was observed for bare Cu substrate. Additionally, the growth rate of these intermetallic compounds was increased with the reaction temperature and time. We found that the growth of the intermetallic compound follows the parabolic law, which indicates that the growth is diffusion-controlled.d.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.122-127
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• 1997

The hexagonal wurtzite structure of CdSe quantum dots are investigated by X-ray diffraction experiment. The absorption peaks due to quantum confinement effect are observed in the linear absorption spectra. Absorption coefficient changes at the lowest transition are measured with pump wavelength at the lowest transition and at the next higher transition from which direct intraband transition is not allowed. The measured larger absorption changes at the lowest transition confirm that the selection rules of intraband transition resulting from quantum confinement effect are satisfied. From the experimental results, therefore, we concluded that the CdSe quantum dots can be described as homogeneous system.

• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.28-32
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• 2008

Hydrogenated microcrystalline silicon(${\mu}c$-Si:H) films were prepared using inductively coupled plasma chemical vapor deposition(ICP-CVD) method, electrical and optical properties of these films were studied as a function of silane concentration. And then, effect of $PH_3\;and\;B_2H_6$ addition on their electrical properties was also investigated for solar cell application. Characterization of these films from X-ray diffraction revealed that the conductive film exists in microcrystalline phase embedded in an amorphous network. At $PH_3/SiH_4$ gas ratio of $0.9{\times}10^{-3}$, dark conductivity has a maximum value of ${\sim}18.5S/cm$ and optical bandgap also a maximum value of ${\sim}2.39eV$. Boron-doped ${\mu}c$-Si:H films, satisfied with p-layer of solar cell, could be obtained at ${\sim}10^{-2}\;of\;B_2H_6/SiH_4$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.124-124
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• 2010

Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. EUVL is one of competitive lithographic technologies for sub-22nm fabrication of nano-scale Si devices that can possibly replace the conventional photolithography used to make today's microcircuits. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics having a completely different configuration compared to those of conventional photolithography. Therefore, new materials and new mask fabrication process are required for high performance EUVL mask fabrication. This study investigated the etching properties of SnO2 (Tin Oxide) as a new absorber material for EUVL binary mask. The EUVL mask structure used for etching is SnO2 (absorber layer) / Ru (capping / etch stop layer) / Mo-Si multilayer (reflective layer) / Si (substrate). Since the Ru etch stop layer should not be etched, infinitely high selectivity of SnO2 layer to Ru ESL is required. To obtain infinitely high etch selectivity and very low LER (line edge roughness) values, etch parameters of gas flow ratio, top electrode power, dc self - bias voltage (Vdc), and etch time were varied in inductively coupled Cl2/Ar plasmas. For certain process window, infinitely high etch selectivity of SnO2 to Ru ESL could be obtained by optimizing the process parameters. Etch characteristics were measured by on scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses. Detailed mechanisms for ultra-high etch selectivity will be discussed.

• Current Optics and Photonics
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• v.1 no.4
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• pp.358-363
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• 2017

In this study, we present a detailed investigation of luminescence properties of a blue light-emitting diode using InGaN/GaN (indium component is 17.43%) multiple quantum wells as the active region grown on patterned sapphire substrate by low-pressure metal-organic chemical vapor deposition (MOCVD). High-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Raman scattering (RS) and photoluminescence (PL) measurements are employed to study the crystal quality, the threading dislocation density, surface morphology, residual strain existing in the active region and optical properties. We conclude that the crystalline quality and surface morphology can be greatly improved, the red-shift of peak wavelength is eliminated and the superior blue light LED can be obtained because the residual strain that existed in the active region can be relaxed when the LED is grown on patterned sapphire substrate (PSS). We discuss the mechanisms of growing on PSS to enhance the superior luminescence properties of blue light LED from the viewpoint of residual strain in the active region.

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.86-91
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• 1998

Multimode planar waveguides have been fabricated by an electric-field assisted ion exchange in soda-lime glass substrates. Measurements of the mode indices have been made and the index profiles modeled on modified Fermi function are explained by a comparative analysis with the concentration profiles obtained using an electron probe X-ray micro analyzer. The analytical measurements showed that no more than 95% of sodium ions were replaced by the cesium ions. We established formulas for guide depth, mobility, and refractive index change, given the applied electric field, the diffusion temperature, and the time. We have verified the linear relations in the formulas not only between guide and root of diffusion time but also between guide depth and the applied electric filed experimentally.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.34.2-34.2
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• 2021

SPT-CL J2106-5844 is the most massive galaxy cluster at z>1 discovered to date. It has been known to be an isolated system with a singular, well-defined halo. However, recent studies provide lines of evidence for its merging state. We strengthen the case with the multi-wavelength observations from ALMA, ACA, ASKAP, ATCA, and Chandra. With the sensitive, high resolution ALMA+ACA observations, we reconstruct the ICM pressure map from the thermal SZ effect. It reveals two main gas components that are associated with the mass clumps inferred from the weak-lensing analysis. Furthermore, the X-ray hardness map supports the bimodal gas distribution. With these multi-wavelength data, we probe the merger phase in SPT-CL J2106-5844.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.30.1-30.1
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• 2020

The ASKAP-EMU survey is a deep wide-field radio continuum survey designed to cover the entire southern sky and a significant fraction of the northern sky up to +30°. Here, we report a discovery of a radio relic in the merging cluster SPT-CL J2023-5535 at z=0.23 from the ASKAP-EMU pilot 300 square degree survey (800-1088 MHz). The deep high-resolution data reveal a ~2 Mpc-scale radio halo elongated in the east-west direction, coincident with the intracluster gas. The radio relic is located at the western edge of this radio halo stretched ~0.5 Mpc in the north-south orientation. The integrated spectral index of the radio relic within the narrow bandwidth is α1088MHz800MHz = -0.76 ± 0.06. Our weak-lensing analysis shows that the system is massive (M200 = 1.04 ± 0.36 × 1015M⊙) and composed of at least three subclusters. We suggest a scenario, wherein the radio features arise from the collision between the eastern and middle subclusters. Furthermore, the direct link between the local AGN and the relic along with the discontinuities in X-ray observation hint us that we are looking at the site of re-acceleration.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.2
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• pp.131-138
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• 2009

The radioprotect effects of fractinated fucoidan, derived from Undaria pinnatifida sporophylls, were examined in lung injured rats treated with partial body irradiation. The right lung of Sprague-Dawley rats, eight separately grouped by including radiation only control group (ROG) and fucoidan+radiation treated group (FRG), were treated with various fraction of Undaria-derived fucoidan every other day by intraperitoneal injection 6 days prior to irradiation and during monitoring at 24 hours, 48 hours, 2 weeks, 4 weeks and 12-weeks post-irradiation of 6 Mev/2 Gy. The rats were euthanized at completion of the treatment. Tissue samples from the injured lung, fixed in formaldehyde using lung perfusion prior to extraction, were H/E stained for histological analysis using optical microscopy. Interstitial congestion (IC), hemorrhage in alveolar sac (HM), number of macrophage (MP) and alveolar wall thickness (AWT) as a measure of early indication of fibrosis were measured. AWTs in 24 hrs post-irradiation rats increased in comparison with $2.49{\pm}0.06{\mu}m$ of control group by $3.67{\pm}0.09{\mu}m$, $3.21{\pm}0.08{\mu}m$ (p=0.013), $2.98{\pm}0.08{\mu}m$ (p=0.00) in ROG, F1-fucoidan+radiation, and F3-fucoidan+radiation group, respectively. AWT of the ROG was further increased by $4.30{\pm}0.13{\mu}m$ in the 12 weeks post-irradiation group, but AWT on average was $2.56{\pm}0.05{\mu}m$ in the FRG. MP in the 24 hrs post-irradiation group markedly increased in comparison with $2.6{\pm}0.34/0.14\;mm^2$ of the control group by $8.0{\pm}1.48/0.14\;mm^2$ in the ROG, but it was only $3.6{\pm}0.48/0.14\;mm^2$ in F3-FRG. MP in the 12 weeks post-irradiation group was $7.2{\pm}1.28/0.14\;mm^2$ in ROG, but it was $2.8{\pm}0.37/0.14\;mm^2$ or $2.4{\pm}0.4/0.14\;mm^2$ (p<0.05) in the FRG. In addition, increased IC and HM in ROG were relatively smaller in FRG of the 24 hr and 12 weeks post-irradiation rats. In conclusion, Undaria pinnatifida sporophylls-derived fucoidan fractions exhibited radioprotectant activity on injured rat lung subjected to X-ray irradiation. However, success was variable according to the fractions and also time of injection post injury.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.147-151
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• 2000

We deposited the ion assisted ${Ta_2}{O_5}$ films and conventional thermal evaporated ${Ta_2}{O_5}$ films by using electron beam gun, and measured the optical properties and mechanical properties of the fabricated films according to the evaporation conditions. In the case of the TazOs films by oxygen ion assisted deposition with the anode voltage of 120 V, and current density of $50~500\muA/cm^2$, the refractive index exhibited 2.15 which was higher than the conventionally deposited film index 1.94 and the tensile stress exhibited $5.0\times10^8 dyne/cm^2$ which was lower than $7.0\times10^8 dyne/cm^2$. This properties coincided with the optical and mechanical properties of the films deposited at the elevated substrate temperature of $230^{\circ}C$. In the case of the argon ion assisted films the tensile stress was decreased but the absorption existed at the short wavelength in the visible spectral region. And all the fabricated films were found to be amorphous by the X-ray diffraction analysis. lysis.