• 센서학회지
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• 제7권3호
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• pp.218-224
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• 1998

ZnO 분말과 $Al_{2}O_{3}$ 분말을 1 : 1의 mole 비로 ball milling 시킨 후, 압착하여 펠렛을 제작하였다. 소성시 분위기를 진공으로 유지하기 위하여 각각 $3{\times}10^{-5}$ Torr의 진공도로 석영관에 봉입한 다음 $900^{\circ}C{\sim}1200^{\circ}C$로 소성하였다. 실험결과, $900^{\circ}C{\sim}1100^{\circ}C$까지는 ZnO, $Al_{2}O_{3}$ 및 $ZnAl_{2}O_{4}$의 혼합구조를 보이다가 $1200^{\circ}C$에서 (311), (220)면등의 주된 피크를 갖는 다결정으로 성장하여 $ZnAl_{2}O_{4}$ 삼원화합물의 구조가 확인되었고, 전자현미경촬영에 의해 화합물의 결정화된 입자들이 관찰되었다. 광흡수측정에 의해 에너지 밴드갭은 약 4.53 eV로 계산되었으며, PL 스펙트럼은 소결온도의 상승에 따라 단파장영역으로 이동하여, $1200^{\circ}C$에서 430nm부근에서 발광피크를 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.458.2-458.2
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• 2014

We have demonstrated that simple brush-painted Ti-doped $In_2O_3$(TIO) films can be used as a cost effective transparent anodes for organic solar cells (OSCs). We examined the RTA effects on the electrical, optical, and structural properties of the brush painted TIO electrodes. By the direct brushing of TIO nanoparticle ink and rapid thermal annealing (RTA), we can simply obtain TIO electrodes with a low sheet resistance of 28.25 Ohm/square and a high optical transmittance of 85.48% under atmospheric ambient conditions. Furthermore, improvements in the connectivity of the TIO nano-particles in the top region during the RTA process play an important role in reducing the resistivity of the brush-painted TIO anode. In particular, the brush painted TIO films showed a much higher mobility ($33.4cm^2/V-s$) than that of previously reported solution-process transparent oxide films ($1{\sim}5cm^2/V-s$) due to the effects of the Ti dopant with higher Lewis acid strength (3.06) and the reduced contact resistance of TIO nanoparticles. The OSCs fabricated on the brush-painted TIO films exhibited cell-performance with an open circuit voltage (Voc) of 0.61 V, shot circuit current (Jsc) of $7.90mA/cm^2$, fill factor (FF) of 61%, and power conversion efficiency (PCE) of 2.94%. This indicates that brush-painted TIO film is a promising cost-effective transparent electrode for printing-based OSCs with its simple process and high performance.

• 한국진공학회지
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• 제12권2호
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• pp.112-117
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• 2003

MgO 박막은 PDP(plasma display panels)분야에서 널리 사용되어 왔다. 본 연구에서는, 기존에 사용되고 있는 e-beam evaporation, reactive magnetron sputtering법과 arc deposition법으로 MgO 보호막을 증착하여 구조적 · 광학적 특성을 비교하였다. 반응 가스인 산소 가스의 유입량을 변화시켜 Mg metal target을 이용하여 vacuum arc deposition equipment 의해 유리 기판 위에 증착하였다. Ellipsometer를 이용하여 치밀도를 측정하고, MgO보호막의 마모율(erosion rate)를 측정하기 위해 가속 실험 방법을 도입, Ar+ 이온빔에 의한 erosion test를 시행하여 내마모성을 알아보았다. 또한, XPS와 UV test를 사용하여 MgO보호막의 광투과도에 미치는 수분의 영향을 조사한 결과, arc evaporation 법이 광투과도 90%이상을 유지하여 수분의 영향에 둔감한 것을 알 수 있었다. 한편, XRD와 AFM을 이용하여 MgO 박막의 구조와 표면 형상에 대해 조사하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.153-153
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• 2010

Recently, to develop GaN-based light-emitting diodes (LEDs) with better performances, various approaches have been suggested by many research groups. In particular, using the patterned sapphire substrate technique has shown the improvement in both internal quantum efficiency and light extraction properties of GaN-based LEDs. In this paper, we discuss the influences of the direction of the hexagonal-structure arrays of lens-shaped patterns (HSAPs) formed on sapphire substrates on the crystal, optical, and electrical properties of InGaN/GaN multi-quantum-well (MQW) LEDs. The basic direction of the HSAPs is normal (HSAPN) with respect to the primary flat zone of a c-plane sapphire substrate. Another HSAP tilted by 30o (HSAP30) from the HSAPN structure was used to investigate the effects of the pattern direction. The full width at half maximums (FWHMs) of the double-crystal x-ray diffraction (DCXRD) spectrum for the (0002) and (1-102) planes of the HSAPN are 320.4 and 381.6 arcsecs., respectively, which are relatively narrower compared to those of the HSP30. The photoluminescence intensity for the HSAPN structure was ~1.2 times stronger than that for the HSAP30. From the electroluminescence (EL) measurements, the intensity for both structures are almost similar. In addition, the effects of the area of the individual lens pattern consisting of the hexagonal-structure arrays are discussed using the concept of the planar area fraction (PAF) defined as the following equation; PAF = [1-(patterns area/total unit areas)] For the relatively small PAF region up to 0.494, the influences of the HSAP direction on the LED characteristics were significant. However, the direction effects of the HSAP became small with increasing the PAF.

• 한국재료학회지
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• 제18권10호
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• pp.521-528
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• 2008

We present the structural, optical, and electrical properties of amorphous silicon suboxide (a-$SiO_x$) films grown on indium tin oxide glass substrates with a radio frequency magnetron technique from a polycrystalline silicon oxide target using ambient Ar. For different substrate-target distances (d = 8 cm and 10 cm), the deposition temperature effects were systematically studied. For d = 8cm, oxygen content in a-$SiO_x$ decreased with dissociation of oxygen onto the silicon oxide matrix; temperature increased due to enlargement of kinetic energy. For d = 10 cm, however, the oxygen content had a minimum between $150^{\circ}\;and\;200^{\circ}$. Using simple optical measurements, we can predict a preferred orientation of liquid crystal molecules on a-$SiO_x$ thin film. At higher oxygen content (x > 1.6), liquid crystal molecules on an inorganic liquid crystal alignment layer of a-$SiO_x$ showed homogeneous alignment; however, in the lower case (x < 1.6), liquid crystals showed homeotropic alignment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.187-187
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• 2011

Nowadays, the issue of solar cell durability in local weather and environment is a crucial issue. Above all, surface corrosion on solar cell multilayers is a major factor that determines the durability of commercial solar cells; corrosive chemical interactions between air, humidity and chemical species and solar cell multilayers can unfavorably affect the durability. Here, we study microscopic and spectroscopic surface techniques to investigate the corrosive interaction on the antireflective layers of solar cell multilayers under various conditions such as acid, base, constant temperature and humidity. Surface morphology and adhesion force were characterized with atomic force microscopy before and after chemical treatment. Chemical composition, and transmittance factors were studied with X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy, respectively. Based on these studies, we suggest the dominant factors in the corrosive chemical processes, and their influences on the structural, compositional, and optical properties of the antireflective layers.

• Corrosion Science and Technology
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• 제7권3호
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• pp.152-157
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• 2008

New wrought magnesium alloys have increasingly been developed in recent years for the automotive industry due to their high potential as structural materials for low density and high strength/weight ratio demands. However, their poor mechanical properties and low corrosion resistance have led to a search for new kinds of magnesium alloys with better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behaviour of new magnesium alloys: Mg-Zn-Ag (ZQ), Mg-Zn-Mn-Si (ZSM) and Mg-Zn-Mn-Si-Ca (ZSMX). These ZQ6X, ZSM6X1, and ZSM651+YCa alloys were prepared using hot extrusion. AC, DC polarization and immersion tests were carried out on the extruded rods. Microstructure was examined using optical and electron microscopy (SEM) and EDS. The addition of silver decreased the corrosion resistance. The additions of silicon and calcium also affected the corrosion behaviour. These results can be explained by the effects of alloying elements on the microstructure of Mg-Zn alloys such as grain size and precipitates caused by the change in precipitation and recrystallisation behaviour.

• 한국세라믹학회지
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• 제48권4호
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• pp.316-322
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• 2011

Tin oxide thin films were deposited by rf reactive sputtering and annealed at $400^{\circ}C$ for 1 h in vacuum. To minimize the influence such as reduction, oxidation, and doping on tin oxide thin films during annealing, a vacuum ambient annealing was adopted. The structural, optical, and electrical properties of tin oxide thin films were characterized by X-ray diffraction, atomic force microscope, UV-Vis spectrometer, and Hall effect measurements. After vacuum annealing, the grain size of all thin films was slightly increased and the roughness ($R_a$) was improved, however irregular and coalesced shapes were observed from the most of the films. These irregular and coalesced crystal shapes and the possible elimination of intrinsic defects might have caused a decrease in both carrier concentration and mobility, which degrades electrical conductivity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.51-53
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• 2005

$Zn_{1-x}Cd_xO$ thin films were grown on (0001) sapphire substrates by pulsed laser deposition. The energy bandgap of $Zn_{1-x}Cd_xO$ films decreases withincreasing Cd content. An increase of Cd content also leads to the emission broadening and degraded crystallinity. The absorption edge and ultraviolet emission peak shift to lower energy from 3.357 eV to 3.295 eV and 3.338 eV to 3.157 eV, respectively, with increasing Cd content from 0.3% to 3%. The Stokes' shift between the absorption and emission indicates the increase of localization of exciton with Cd content.

• 한국세라믹학회지
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• 제54권5호
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• pp.422-428
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• 2017

Single-phase yellow phosphor, $CaGd_{2-x}ZrSc(AlO_4)_3:xCe^{3+}$ ($CGZSA:Ce^{3+}$), possessing cubic symmetry with varied $Ce^{3+}$ concentrations, was synthesized using the solid-state reaction method. The samples were characterized using X-ray diffraction (XRD), excitation spectra, emission spectra, thermal quenching, and decay curves. The cubic phase of $CGZSA:Ce^{3+}$ phosphor was confirmed via XRD analysis. The photoluminescence spectra of $CGZSA:Ce^{3+}$ phosphor demonstrated that the phosphor could be excited at the wavelength of 440 nm; a broad yellow emission band was centered at 541 nm. These results indicate that the phosphors are adequately excited by blue light and have the potential to function as yellow-emitting phosphors for applications in white light-emitting diodes.