• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.12
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• pp.1044-1048
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• 2007

With development of electronic products the demands for miniaturization and weight-lightening have increased until a recent date. Accordingly, The effort to substitute glass substrates was widely made. However, polymer substrates have weak point that substrates were damaged at high temperature. In this paper, we deposited transparent conductive film at low temperature. And we inserted Au thin film between oxide to compensate for deteriorated electrical characteristics. Ga-doped ZnO(GZO) multilayer coatings were deposited on glass substrate by DC sputtering. The optimization of deposition conditions of both AZO and Au layers were performed to obtain better electrical and optical characteristics in advance. We presumed that the properties of multilayer were affected by the deposition process of both GZO and Au layers. The best multilayer coating exhibited the resistivity of $2.72{\times}10^{-3}\;{\Omega}-cm$ and transmittance of 77 %. From these results, we can confirm a possibility of the application as transparent conductive electrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.390-390
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• 2010

We fabricate Schottky diodes with the contact between a sol-gel derived ZnO layer and Au that guarantees the expected Schottky contact due to the high work function. The formed single metal Schottky barrier shows characteristics comparable to the barrier formed by alloys. Au is deposited by thermal evaporation on a ZnO thin film that is optimally formed under sol-gel process conditions of a 1-mol zinc acetate concentration and a 3000-rpm coating speed. Possible defects. which can provide deleterious current paths. are minimized by patterning the deposited Au. The I-V curve verifies the formation of a Schottky contact. Measurements showed that the Schottky barrier height and leakage current at -5 V were 0.6 eV and $1{\times}10^{-12}A$. respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.243-243
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• 2009

Bi2O3 doped ZnO nanostructures structure were successfully synthesized by a thermal evaporatiion process and their structural characteristics were investigated. It is demonstrated that the growth condition such as the areal density, pretreatment of the substrates and growth temperature have great influence on the morphology and the alignment of the nanorods arrays. The density of Bi2O3 doped ZnO nanostructures is controlled by the gold (Au) nanoparticle density deposited on the silicon substrates. Relatively homogenous size and shape were observed by introducing gold(Au) seed-layer as nucleation centers on the substrates prior to the VLS reaction. The samples were characterized by X-ray diffraction, scanning electron microscopy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.594-598
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• 2011

We have investigated the sensing properties of ethanol gas sensor with pure ZnO and Ga-doped ZnO nanowires on Au coated (0001) sapphire substrates grown by hot walled pulsed laser deposition. Randomly aligned ZnO nanowires arrays were grown on a Au-electrode patterned under ambient conditions. ZnO nanowires have various sizes and shapes with a different substrate position inside a furnace. The average of length and diameter of the ZnO nanowires were $8\;{\mu}m$ and 100 nm respectively, and confirmed by field emission scanning electron microscopy. Sensitivity chanege characterization of the gas sensor was found that measured sensitivities of the ethanol gas sensors were 83.3% and 68.3% at $300^{\circ}C$ respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.15-23
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• 2002

In this study, metal/ZnO contacts were thermally annealed at different temperatures (as-dep., 400$^{\circ}C$, 600$^{\circ}C$, 800$^{\circ}C$, 1000$^{\circ}C$) for the investigation of electrical properties, and surface and interface characteristics. The analysis of the element composition and the chemical bonding state of the surface was made by the XPS(X-ray photoelectron spectroscopy). An attempt was made to establish the electrical property-microstructure relationship for the (Ti, Au)/ZnO. The Ti/ZnO contact exhibits an ohmic characteristics with a relatively high contact resistance of 4.74${\times}$10$\^$-1/ $\Omega$$\textrm{cm}^2$ after an annealing at 400$^{\circ}C$. The contact showed a schottky characteristics when the samples were annealed at higher temperature than 400$^{\circ}C$. The transition from the ohmic to schottky characteristics was contributed from the formation of the oxide layers as was confirmed by the peaks for O-O and Ti-O bondings in XPS analysis. For the Au/ZnO contact the lowest contact resistance was obtained from the as-deposited sample. The resistance was slowly increased with annealing temperature up to 600$^{\circ}C$. The ohmic characteristics were maintained eden fort 600$^{\circ}C$ annealing. The XPS analysis showed that the Au-O intensity was dramatically decreased with temperature above 600$^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.426-426
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• 2011

최근 들어 금속물질을 나노미터 단위로 구성할 수 있는 기술이 진보하면서, 금속 나노입자에 의해 발생되는 표면 플라즈몬에 대해서도 다양한 분야의 관심이 집중되고 있다. 유전체 물질을 기지상으로 하는 금속:유전체 나노복합체에서 금속 나노입자는 자유전자들의 집단 진동인 국소표면 플라즈몬 공진(Localized Surface Plasmon Resonance, LSPR)현상에 의해 국부전기장을 증대 시키고, 가시광 및 적외선 영역에서 특성 광흡수 거동을 보인다. 이와 같은 광학적 특성은 금속 나노입자들의 크기, 형태, 그리고 나노입자들의 주변을 구성하는 기지상 물질의 종류에 의해 조절된다. 금속:유전체 나노복합체에 나타나는 이러한 특성은 단순장식코팅 뿐만 아니라 광의 효율적 운용과 광을 매개로 한 기능발현을 필요로 하는 디스플레이, 광학 스위칭 소재 및 태양전지의 효율 향상을 위한 광흡수층 등 매우 다양한 응용이 가능하다. 본 연구에서는 다양한 굴절률을 갖는 재료들 중, 저굴절률을 갖는 SiO2와 고굴절률을 갖는 ZnS-SiO2를 기지상 재료로 선택하여 교번증착 스퍼터링법으로 Ag와 Au입자를 형성시켰다. Ag를 금속나노입자로 갖고, SiO2와 ZnS-SiO2를 기지상으로 하는 금속:유전체 나노복합체에서는 금속나노입자 형성에 따른 뚜렷한 표면 플라즈몬 공진 광흡수 피크가 관찰된 반면 Au나노입자는 기지상에 따라 각기 다른 광흡수 특성을 나타냈는데, SiO2기지상에서 명확한 광흡수 피크를 형성했던 경우와는 달리 ZnS-SiO2기지상에서는 특정파장에서의 흡수피크로 규정되기 어려운 넓은 파장범위에 걸친 완만한 광흡수 피크를 나타냈다. TEM 분석을 통해, ZnS-SiO2 기지상 내의 Au입자는 각각 독립되어 있는 Island형태가 아닌 유전체 기지상과 대칭적으로 혼합된 네트워크 형태의 Bruggeman 기하구조를 구성하고 있음을 확인하였고, 이는 Au입자가 형성되고 성장할 때 Au와 S의 높은 결합에너지로 인해 상당한 젖음 특성을 갖고 성장하였기 때문으로 판단됐다. 따라서 나노복합체를 구성하는 물질간의 광학적 특성뿐만 아니라 기지상 내에서의 금속입자의 성장거동에 대한 연구가 수반되었을 때, 금속:유전체 나노복합체의 표면 플라즈몬 공진 광흡수 특성을 보다 정확하게 제어할 수 있다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.425-427
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• 2008

• Economic and Environmental Geology
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• v.27 no.6
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• pp.549-556
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• 1994

Geochemical studies on gold-bearing quartz veins and wallrocks from the Okgye mine were carried out in order to investigate the primary dispersion patterns of gold and associated elements and to quantify the dispersion width of elements with distance from the gold-bearing quartz veins. Gold-bearing quartz veins occur in basaltic trachyandesite of unknown age. Enrichment of $k_2O$, MnO, Au, As, Rb, Sb, Pb, Zn, Cu, Ag and Cd, and depletion of $Na_2O$ and Sr are found in altered wallrocks. The ratio of $k_2O(k_2O+Na_2O)$, alteration index for trace elements, and Rb/Sr in altered wallrocks are increased, whereas Sr/CaO ratio is decreased with approach to the gold-bearing quartz veins. The widths of primary dispersion range from 17 cm to 155 cm. The relative dispersion width increases in order Au=Cu=Zn=Ag=Cd$k_2O$=Rb and Ba< $Na_2O$ $Na_2O$, As, Sb, Sr, Pb, Au, Cu, Zn, Ag and Cd, and a quadratic function for $k_2O$, MnO, Rb and Ba.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.101-105
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• 2010

We fabricated FEDs(Filed emission devices) based on ZnO nanowires. The ZnO nanowires were synthesized on Au thin films by hydrothermal method at the temperature of 90[$^{\circ}C$] on hot plate. In order to form tips of the ZnO nanowire, SDS(Sodium Dodecyl Sulfate) was mixed in O.05-0.3[wt%] solution as capping material. After 2 hour growth, we obtained nanowires of chain form The high-purity nanowires showed sharp tip geometry with a wurtzite structure. The field emission properties of the ZnO nanowires were investigated in high vacuum chamber. The turn-on field for the ZnO nanowires was found to be about 4.1[V/${\mu}m$] at a current density of 0.1[${\mu}A/cm^2$].

• Korean Journal of Materials Research
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• v.19 no.8
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• pp.417-420
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• 2009

This study develops a highly transparent ohmic contact using phosphorus doped ZnO with current spreading for p-GaN to increase the optical output power of nitride-based light-emitting diodes (LEDs). The phosphorus doped ZnO transparent ohmic contact layer was prepared by radio frequency magnetron sputtering with post-deposition annealing. The transmittance of the phosphorus doped ZnO exceeds 90% in the region of 440 nm to 500 nm. The specific contact resistance of the phosphorus doped ZnO on p-GaN was determined to be $7.82{\times}10^{-3}{\Omega}{\cdot}cm^2$ after annealing at $700^{\circ}C$. GaN LED chips with dimensions of $300\times300{\mu}m$ fabricated with the phosphorus doped ZnO transparent ohmic contact were developed and produced a 2.7 V increase in forward voltage under a nominal forward current of 20 mA compared to GaN LED with Ni/Au Ohmic contact. However, the output power increased by 25% at the injection current of 20 mA compared to GaN LED with the Ni/Au contact scheme.