• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.213-213
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• 2010

We investigated the RF sputtering conditions for the deposition of AZO (Al doped ZnO) transparent conducting film on PET using the roll to roll vacuum coater. AZO thin films, sputtered at the various RF powers and working pressures, were studied for their structural, electrical and optical properties.. From the X-Ray diffraction patterns, we calculated the lattice stress using the Bragg equation. The compressive stress tends to decrease with the increase in film thickness. AZO thin film with the thickness of 152nm (1400W, 0.4Pa) exhibit the resistivity of $3.92*10-3{\Omega}/cm$ and the transmittance of 96.9% at 550nm.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.279-285
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• 2021

Recently, cesium tellurium iodine (Cs₂TeI₆) has emerged as an inorganic halide perovskite material with potential application in optoelectronic devices due to its high absorption coefficient, suitable bandgap and because it consists of nontoxic and earth-abundant elements. However, studies on its fabrication process as well as photoresponse characteristics are limited. In this study, a simple and effective method is introduced for the synthesis of Cs₂TeI₆ thin films by a two-step dry process. A Cs₂TeI₆-based lateral photosensor was fabricated, and its photoresponse characteristics were explored under laser illuminations of four different wavelengths in the visible range: 405, 450, 520, and 655 nm. The initial photosensing results suggest potential application and can lead to more promising studies of Cs₂TeI₆ film in optoelectronics.

• Korean Journal of Metals and Materials
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• v.48 no.5
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• pp.387-393
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• 2010

High-strength aluminum alloy sheets with high magnesium contents were fabricated by a strip caster equipped with an asymmetric nozzle, which has been proven to be effective for reducing surface defects and internal segregation. 4 mm thick as-cast sheets consisting of fine dendrites and minor $Al_{8}Mg_{5}$ segregation were hot-rolled successfully to 1 mm sheets and subsequently annealed at various temperatures. The sheet revealed the tensile strength and elongation of 306 MPa and 34%, respectively, when it was rolled at 250${^{\circ}C}$ and subsequently annealed at 475${^{\circ}C}$, which exhibits the feasibility of the practical application for autobodies. The observed mechanical properties were explained on the basis of the microstructural characteristics of the alloy sheets.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.88-88
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• 2008

In this study, effect of thickness on structural, electrical and optical properties of B doped ZnO:Ga (GZOB) films was investigated. GZOB films were deposited on glass substrates by DC magnetron sputtering. The thickness range of films were from 100 nm to 600 nm to identified as increasing thickness, stress between substrate and GZOB film. The average transmittance of the films was over 80 % until 500 nm. Then a resistivity of $9.16\times10^{-4}\Omega$-cm was obtained. We presented that a GZOB film of 400 nm was optimization to obtain a high transmittance and conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.138-138
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• 2008

In this study, effect of thickness on structural, electrical and optical properties of B doped ZnO:Al (AZOB) films was investigated. AZOB films were deposited on PC substrates by DC magnetron sputtering. The thickness range of films were from 300 nm to 800 nm to identified as increasing thickness, stress between substrate and AZOB film. The. average transmittance of the films was over 80 % until 500 nm. Then a resistivity of $1.58\times10^{-3}\Omega$-cm was obtained. We presented that a AZOB film of 500 nm was optimization to obtain a high transmittance and conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.144-144
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• 2007

Effects of power ratio on the electrical and optical properties of Au based Ga-, B- codoped ZnO(GZOB) thin films were investigated. GZOB thin films on Au based PC flexible substrate were deposited at various power in the range from 50 to 125 W by DC magnetron sputtering. Au layer was fabricated to achieve good electrical conductivity. The presence of additional boron impurity leads to improve structural defects. Thus, the c-axis orientation along (002) plane was enhanced with the increasing of power ratio and the surface morphology of the films showed a homogeneous and nano-sized microstructure. GZOB films grown at 125W were investigated a low resistivity value of $1{\times}10^{-3}{\Omega}cm$ and a visible transmission of 80% with a thickness of 300nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.444-445
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• 2007

IZO/Al multilayer anode films for flexible top emitting organic light emitting diodes (TOLEDs) were grown on PEN (polyethylen-enaphthelate) substrate using twin target sputter (TTS) system. To investigate electrical and optical properties of IZO/Al multilayer films, 4-point probe method and UV/Vis spectrometer were used, respectively. From a IZO/Al multilayer films with 100nm-thick Al, sheet resistance of $1.4{\Omega}/{\square}$ and reflectance of above 62% at a range of 500~550nm wavelength could be obtained, In addition, structural and surface properties of IZO/Al multilayer films were analyzed by XRD (X-ray diffraction) and FESEM (field emission scanning electron microscopy) and AES (auger electron spectroscope), respectively. Moreover, flexibility of IZO/Al multilayer anode films were examined by bending test method.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.268-272
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• 2011

Due to their novel properties, GaN based semiconductors and their nanostructures are promising components in a wide range of nanoscale device applications. In this work, the gallium nitride is deposited on c-axis oriented sapphire and porous SWCNT substrates by molecular beam epitaxy using a novel single source precursor of $Me_2Ga(N_3)NH_2C(CH_3)_3$ with ammonia as an additional source of nitrogen. The advantage of using a single molecular precursor is possible deposition at low substrate temperature with good crystal quality. The deposition is carried out in a substrate temperature range of 600-750$^{\circ}C$. The microstructural, structural, and optical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and photoluminescence. The results show that substrate oriented columnar-like morphology is obtained on the sapphire substrate while sword-like GaN nanorods are obtained on porous SWCNT substrates with rough facets. The crystallinity and surface morphology of the deposited GaN were influenced significantly by deposition temperature and the nature of the substrate used. The growth mechanism of GaN on sapphire as well as porous SWCNT substrates is discussed briefly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.290-291
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• 2006

We prepared the multilayer with Al doped ZnO (AZO)/Ag/AZO structure. The multilayer were deposited with various thickness of Ag layer on glass substrates at room temperature by using facing targets sputtering (FTS) method. To investigate the electrical, optical and structural properties, we used Hall Effect measurement system, four-point probes. UV-VIS spectrometer with a wavelength of 300 - 100nm, X-ray Diffractometer(XRD) and scanning electron microscopy (SEM). We obtained multilayer thin film with the low resistivity $5,9{\times}10^{-5}{\Omega}cm$ and the average transmittance of 86% m the visible range (400 - 800nm).

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.234-238
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• 2009

In the excitation spectra of $YNbO_4$ : $Eu^{3+}$, the charge transfer (CT) band around 270 nm due to $[NbO_4]^{3-}$$-Eu^{3+}$ interaction and sharp excitation peaks by f-f transition of $Eu^{3+}$ strongly appeared simultaneously. CT band depended on the structural properties of powders, showing the red-shift with increasing the crystallinity, while the f-f transition peaks were independent of the crystallinity. For $YNb_{1-x}Ta_xO_4$ : $Eu^{3+}$ (x = 0.05.0.2), $[TaO_4]^{3-}$. configuration was locally constructed, leading to the blue-shift in CT band and the decrease in the red emission intensity with increasing the Ta content.