• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.543-543
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• 2013

Thin-film transistors (TFTs) based on oxide semiconductors have been regarded as promising alternatives for conventional amorphous and polycrystalline silicon TFTs. Oxide TFTs have several advantages, such as low temperature processing, transparency and high field-effect mobility. Lots of oxide semiconductors for example ZnO, SnO2, In2O3, InZnO, ZnSnO, and InGaZnO etc. have been researched. Particularly, zinc-tin oxide (ZTO) is suitable for channel layer of oxide TFTs having a high mobility that Sn in ZTO can improve the carrier transport by overlapping orbital. However, some issues related to the ZTO TFT electrical performance still remain to be resolved, such as obtaining good electrical contact between source/drain (S/D) electrodes and active channel layer. In this study, the bottom-gate type ZTO TFTs with staggered structure were prepared. Thin films of ZTO (40 nm thick) were deposited by DC magnetron sputtering and performed at room temperature in an Ar atmosphere with an oxygen partial pressure of 10%. After annealing the thin films of ZTO at $400^{\circ}C$ or an hour, Cu, Mo, ITO and Ti electrodes were used for the S/D electrodes. Cu, Mo, ITO and Ti (200 nm thick) were also deposited by DC magnetron sputtering at room temperature. The channel layer and S/D electrodes were defined using a lift-off process which resulted in a fixed width W of 100 ${\mu}m$ and channel length L varied from 10 to 50 ${\mu}m$. The TFT source/drain series resistance, the intrinsic mobility (${\mu}i$), and intrinsic threshold voltage (Vi) were extracted by transmission line method (TLM) using a series of TFTs with different channel lengths. And the performances of ZTO TFTs were measured by using HP 4145B semiconductor analyzer. The results showed that the Cu S/D electrodes had a high intrinsic field effect mobility and a low effective contact resistance compared to other electrodes such as Mo, ITO and Ti.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.453-453
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• 2013

유기 태양전지는 저비용으로 제작이 가능하고 제작이 용이한 장점을 가지고 있으므로 많은 그룹에서 관심을 가지고 있다. 정공 수송층으로 사용되는 PEDOT:PSS는 많이 사용되지만 강한 산성 특성 때문에 ITO 전극에 식각이 되므로 문제가 있다. 그러므로 산화물 반도체 $WO_3$, $MoO_3$, 그리고 $V_2O_3$ 등이 태양전지에 많이 만들어지고 있다. 특히 copper oxide는 높은 광흡수율을 가지고 있으므로 태양전지에 사용하는 데 많은 기대되는 물질이다. Copper oxide 박막은 열증착 법, 스프레이 필로시스, 전기화학 증착, 화학증착법, 그리고 솔-젤법 등 다양한 증착 방법이 있다. 넓은 면적의 소자를 제작할 경우 솔-젤 방법은 기존의 증착법에 비해 낮은 비용으로 제작, 높은 성장율, 그리고 높은 기계적 탄력성의 장점이 있다. 솔-젤법으로 만든 copper oxide는 P3HT의 HOMO (high occupied molecular orbital)와 비슷한 위치에 접하고 있으므로 정공수송층으로 적합하다. 본 연구에서 제작된 태양전지의 구조는 ITO/P3HT:PCBM/CuxO로 구성되어 있다. ITO가 $10{\Omega}$/sq의비저항을 가지고 있었고 UV 처리를 하였다. 그 위에 P3HT:PCBM (1:0.8 weight)를 스핀 코팅하였다. 마지막으로 0.1 M $Cu_xO$용액은 Cu (II) acetate monohydrate를 소스로 2-methoxyethanol ($C_3H_8O_2$)의 용제와 안정제로 monoethanolamine ($C_2H_7NO$)을 섞어서 만들었다. 그리고 P3HT:PCBM 위에 스핀 코팅하였고 열증착 방법으로 전극인 Ag 을 증착하여 최종 소자를 만들었다. Cu(II) acetate의 소스로 제작된 박막의 투과율 측정을 통해 에너지 밴드갭을 구할 수 있었다. Copper oxide 박막은 다결정구조 이므로 다중 밴드갭으로 구성되어지는 것을 알 수 있었다. 최종적으로 만들어진 소자를 열처리를 통해 소자 특성을 조사했더니 250도에서 가장 좋은 결과를 얻을 수 있었다.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.99-102
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• 2010

Large-scaled area and aligned copper oxide nanowires have been synthesized by a vapor-phase approach to the facial synthesis of copper oxide nanowires supported on the surface of a copper gasket. The effects of annealing temperature and time were investigated. Long and aligned nanowires can only formed within a narrow temperature range from 400 to $500^{\circ}C$ for 4 hrs. Annealing copper gasket in static air produces large-area, uniform, but not well vertically aligned nanowires along the copper gasket surface. The surface of copper gasket is converted into bicrystal CuO nanowires was observed after the copper gasket is annealed under static air condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.620-623
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• 2001

The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid state phase synthesis for production of high temperature superconductor materials are discussed. Oxide superconductors with general formula $ReBa_2$$Cu_3$$O_{7-x}$ (Re= Y, Yb, Sm, Nd) have been made with using barium oxide initial powder instead of traditional barium carbonate. X-ray powder diffraction showed a single phase orthorhombic perovskite structure was produced in all reactions. Phenomena observed during the grinding of the reactant mixture are presented. Mechano-chemical activation - as a pretreatment of the reactant mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

• Tribology and Lubricants
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• v.12 no.3
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• pp.48-54
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• 1996

Examined in this paper, is the effect of B$_{4}$C addition on the frictional characteristics of Cu-Sn based sintered friction materials. For the specimens 1wt%, 2wt% and 4wt% of B$_{4}$C were added into the reference material. A pin-on-disk type friction tester was used to,measure the friction torque with respect to the surface temperature and sliding distance. Wear mechanism of each specimen is analyzed in the view point of the oxide film formation. The specimen containing 4wt% of B$_{4}$C showed stable friction and low wear since the oxide film was sustained up to higher surface temperature ranges.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.102-103
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• 2013

As an important p-type semiconductor metal oxide with a narrow band gap (1.2 - 2.6eV), copper oxide (Cu2O) has been studied because of its various applications as material for heterogeneous catalysts, gas sensors, optical switch, lithium-ion electrode materials, field emission devices, solar cells. The fundamental properties of oxide-semiconductor can be greatly affected by the surface morphology, size, geometry and spatial orientation.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.142-150
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• 2001

Due to naturally formed copper oxides, the adhesion strength between copper and epoxy resin is often very poor. To improve the adhesion strength between copper and epoxy resin, Cu-based leadframe sheets were oxidized in a brown-oxide forming solution. Then the effect of brown-oxide formation on the adhesion strength of leadframe to epoxy molding compound (EMC) was studied using pull-out specimens. After the pull-out test, fracture surfaces were analyzed using SEM, AES and EDS to determine failure path. The results showed that the failure path lay over inside the CuO and inside the EMC irrespective of the pull strength.

• Journal of Powder Materials
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• v.25 no.1
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• pp.30-35
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• 2018

The friction characteristics of Al-Fe alloy powders are investigated in order to develop an eco-friendly friction material to replace Cu fiber, a constituent of brake-pad friction materials. Irregularly shaped Al-Fe alloy powders, prepared by gas atomization, are more uniformly dispersed than conventional Cu fiber on the brake pad matrix. The wear rate of the friction material using Al-8Fe alloy powder is lower than that of the Cu fiber material. The change in friction coefficient according to the friction lap times is 7.2% for the Cu fiber, but within 3.8% for the Al-Fe alloy material, which also shows excellent judder characteristics. The Al-Fe alloy powders are uniformly distributed in the brake pad matrix and oxide films of Al and Fe are homogeneously formed at the friction interface between the disc and pad, thus exhibiting excellent friction and lubrication characteristics. The brake pad containing Al-Fe powders avoids contamination by Cu dust, which is generated during braking, by replacing the Cu fiber while maintaining the friction and lubrication performance.

• Journal of Powder Materials
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• v.10 no.5
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• pp.337-343
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• 2003

Nanostructured Cu-$Al_2O_3$ composite powders were synthesized by thermochemical process. The synthesis procedures are 1) preparation of precursor powder by spray drying of solution made from water-soluble copper and aluminum nitrates, 2) air heat treatments to evaporate volatile components in the precursor powder and synthesis of nano-structured CuO + $Al_2O_3$, and 3) CuO reduction by hydrogen into pure Cu. The suggested procedures stimulated the formation of the gamma-$Al_2O_3$, and different alumina formation behaviors appeared with various heat treating temperatures. The mean particle size of the final Cu/$Al_2O_3$ composite powders produced was 20 nm, and the electrical conductivity and hardness in the hot-extruded bulk were competitive with Cu/$Al_2O_3$ composite by the conventional internal oxidation process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1272-1275
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• 2010

The Cu powder was prepared in distilled water. It has a wide range of size distribution. The submicron-sized particles in the Cu powder were removed by using continuous type centrifugal separator. The average particle size after classification was approximately 50nm. The XRD analysis showed that pure Cu phase and oxide phase ($Cu_2O$)weremixedinthepowderpreparedbythismethod.