• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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• pp.294-297
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• 2016

Titanium oxide ($TiO_2$) thin films were fabricated by unbalanced magnetron (UBM) sputtering. The fabricated $TiO_2$ films were treated by oxygen plasma under various RF powers. We investigated the characteristics of oxygen plasma treatment on the surface, structural, and physical properties of $TiO_2$ films prepared at various plasma treatment RF powers. UBM sputtered $TiO_2$ films exhibited higher contact angle value, smooth surface, and amorphous structure. However, the rms surface roughness $TiO_2$ films were rough, and the contact angle value was decreased with the increase of the plasma treatment RF power Also, the hardness value of $TiO_2$ film as physical properties was slightly increased with the increase of the plasma treatment RF power. In the results, the performance of $TiO_2$ films for self cleaning critically depended on the with the plasma treatment RF power.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.511-515
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• 2006

The dispersion hardened $Cu-TiB_2$ composites are a promising candidate for applications as electrical contact materials. The $Cu-TiB_2$ composites for electrical contact materials can reduce material cost and resource consumption caused by wear, due to their good mechanical and electrical properties. In this study, we investigated the wear phenomenon for $Cu-TiB_2$ composites fabricated with hot extrusion, by varying particle sizes and volume fractions of $TiB_2$. The wear tests were performed under the dry sliding condition with a fixed total sliding distance of 40 m. The contact loads at a constant speed of 3.5 Hz were 20, 40, 60, and 80 N. The friction coefficients and wear losses were measured during wear tests. Worn surfaces and wear debris after wear tests were investigated using the scanning electron microscope and the optical microscope. The microstructures of interface between Cu matrix and $TiB_2$ particle before and after wear tests were studied by the transmission electron microscope.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.25-26
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• 2008

Electrical properties of Pt/Ti/Au/Pt contacts to n-GaAs were characterized as the V/III ratio of GaAs grown by metalorganic chemical vapor deposition were 25, 50, and 100, respectively. The samples have been annealed during 30sec at 350 and $450^{\circ}C$ in rapid thermal annealing, and those specific contact resistance investigated by using transmission line method. According to experimental results, the specific contact resistance between p-metal and GaAs was decreased as the V/III ratio was lower. These results indicate that Si doping concentration of GaAs increased as the vacancy of V-series of GaAs was high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.561-565
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• 2007

Because of a good wear resistance and a stable contact resistance, Ag-CdO is widely used as electrical contact material. But, the Cd-oxide mainly exists as a coarse particle and adversely affected to environment. As a reason, $Ag-SnO_2$ alloy has been developed. The Sn-oxide maintains stable and fine particle even at high temperature. In order to investigate the effect of Misch metal (Mm) additional that affects the formation of the oxide and the formation of fine matrix Ag, we studied the microstructures and properties of Ag-Sn-In(-Mm) material fabricated by rapid solidification process. The experimental procedure were melting using high frequency induction, melt spinning, and internal oxidation. The Mm addition makes Ag matrix more fine than no Mm addition. The reason is that the addition of Misch metal decreased a latent heat of fusion of alloy, as a result the rapid solidification effect of alloy is increased. The maximum hardness shows at 0.3 wt%Mm. after that the hardness is decreased until 0.4 wt% Mm, but still larger than no Mm addition alloy. At 0.5 wt% Mm alloy, the precipitation of Misch metal causes a decrease of hardness than no Mm addition alloy.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.99-102
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• 2015

Thin film transistors (TFTs) with amorphous 2 wt% silicon-doped zinc tin oxide (a-2SZTO) channel layer were fabricated using an RF magnetron sputtering system, and the effect of post-annealing treatment time on the structural and electrical properties of a-2SZTO systems was investigated. It is well known that Si can effectively reduce the generation of oxygen vacancies. However, it is interesting to note that prolonged annealing could have a bad effect on the roughness of a-2SZTO systems, since the roughness of a-2SZTO thin films increases in proportion to the thermal annealing treatment time. Thermal annealing can control the electrical characteristics of amorphous oxide semiconductor (AOS) TFTs. It was observed herein that prolonged annealing treatment can cause bumpy roughness, which led to increase of the contact resistance between the electrode and channel. Thus, it was confirmed that deterioration of the electrical characteristics could occur due to prolonged annealing. The longer annealing time also decreased the field effect mobility. The a-2SZTO TFTs annealed at 500℃ for 2 hours displayed the mobility of 2.17 cm²/Vs. As the electrical characteristics of a-2SZTO annealed at a fixed temperature for long periods were deteriorated, careful optimization of the annealing conditions for a-2SZTO, in terms of time, should be carried out to achieve better performance.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.53.2-53.2
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• 2010

In this study, we focused on our specialized electrode process for Si back-contact crystalline solar cell. It is different from other well-known back-contact cell process for thermal aspect and specialized process. In general, aluminum makes ohmic contact to the Si wafer and acts as a back surface reflector. And, silver is used for low series resistance metal grid lines. Aluminum was sputtered onto back side of wafer. Next, silver is directly patterned on the wafer by screen printing. The sputtered aluminum was removed by wet etching process after rear silver electrode was formed. In this process, the silver paste must have good printability, electrical property and adhesion strength, before and after the aluminum etching process. Silver paste also needs low temperature firing characteristics to reduce the thermal budget. So it was seriously collected by the products of several company of regarding low temperature firing (below $250^{\circ}C$) and aluminum etching endurance. First of all, silver pastes for etching selectivity were selected to evaluate as low temperature firing condition, electrical properties and adhesive strength. Using the nano- and micron-sized silver paste, so called hybrid type, made low temperature firing. So we could minimize the thermal budget in metallization process. Also the adhesion property greatly depended on the composition of paste, especially added resin and inorganic additives. In this paper, we will show that the metallization process of back-contact solar cell was realized as optimized nano-paste characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.18-20
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• 2010

The mechanism for suppression of Ag agglomeration in Ag-Mg alloy ohmic contact to p-GaN is investigated. The Ag-Mg alloy ohmic contact shows low contact resistivity of $6.3\;{\times}\;10^{-5}\;{\Omega}cm^2$, high reflectance of 85.5% at 460 nm wavelength after annealing at $400^{\circ}C$ and better thermal stability than Ag contact The formation of Ga vacancies increase the net hole concentration, lowering the contact resistivity. Moreover, the oxidation of Mg atoms in Ag film increase the work function of Ag-Mg alloy contact and prevents Ag oxidation. The inhibition of oxygen diffusion by Mg oxide suppresses the Ag agglomeration, leading to enhance light reflectance and thermal stability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.5
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• pp.389-395
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• 2005

The etching technology of the high aspect ratio contact(HARC) is necessary at the critical contact processes of semiconductor devices. Etching the $SiO_{2}$ contact hole with the sub-micron design rule in manufacturing VLSI devices, the unexpected phenomenon of 'profile tilting' or 'bottom distortion' is often observed. This makes a short circuit between neighboring contact holes, which causes to drop seriously the device yield. As the aspect ratio of contact holes increases, the high C/F ratio gases, $C_{4}F_{6}$, $C_{4}F_{8}$ and $C_{5}F_{8}$, become widely used in order to minimize the mask layer loss during the etching process. These gases provide abundant fluorocarbon polymer as well as high selectivity to the mask layer, and the polymer with high sticking yield accumulates at the top-wall of the contact hole. During the etch process, many electrons are accumulated around the asymmetric hole mouth to distort the electric field, and this distorts the ion trajectory arriving at the hole bottom. These ions with the distorted trajectory induce the deformation of the hole bottom, which is called 'profile tilting' or 'bottom distortion'. To prevent this phenomenon, three methods are suggested here. 1) Using lower C/F ratio gases, $CF_{4}$ or $C_{3}F_{8}$, the amount of the Polymer at the hole mouth is reduced to minimize the asymmetry of the hole top. 2) The number of the neighboring holes with equal distance is maximized to get the more symmetry of the oxygen distribution around the hole. 3) The dual frequency plasma source is used to release the excessive charge build-up at the hole mouth. From the suggested methods, we have obtained the nearly circular hole bottom, which Implies that the ion trajectory Incident on the hole bottom is symmetry.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.92-96
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• 2019

In the presence of ${\mu}-tip$ embedded in a slot-die head for stripe coatings, there arises the capillary flow that limits an increase of the stripe density, which is required for the potential applications in organic light-emitting diode displays. With an attempt to suppress it, we have employed a computational fluid dynamics software and performed simulations by varying the ${\mu}-tip$ length and the contact angles of the head lip and ${\mu}-tip$. We have first demonstrated that such a capillary flow phenomenon (a spread of solution along the head lip) observed experimentally can be reproduced by the computational fluid dynamics software. Through simulations, we have found that stronger capillary flow is observed in the hydrophilic head lip with a smaller contact angle and it is suppressed effectively as the contact angle increases. When the contact angle of the head lip increases from $16^{\circ}$ to $130^{\circ}$, the distance a solution can reach decreases sharply from $256{\mu}m$ to $44{\mu}m$. With increasing contact angle of the ${\mu}-tip$, however, the solution flow along the ${\mu}-tip$ is disturbed and thus the capillary flow phenomenon becomes more severe. If the ${\mu}-tip$ is long, the capillary flow also appears strong due to an increase of flow resistance (electronic-hydraulic analogy). It can be suppressed by reducing the ${\mu}-tip$ length, but not as effectively as reducing the contact angle of the head lip.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.412-416
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• 2016

The electrical properties of Au/n-type Ge Schottky contacts with different contact areas were investigated using current-voltage (I-V) measurements. Analyses of the reverse bias current characteristics showed that the Poole-Frenkel effect became strong with decreasing contact area. The contribution of the perimeter current density to the total current density was found to increase with increasing reverse bias voltage. Fitting of the forward bias I-V characteristics by considering various transport models revealed that the tunneling current is dominant in the low forward bias region. The contributions of both the thermionic emission (TE) and the generation-recombination (GR) currents to the total current were similar regardless of the contact area, indicating that these currents mainly flow through the bulk region. In contrast, the contribution of the tunneling current to the total current increased with decreasing contact area. The largest $E_{00}$ value (related to tunneling probability) for the smallest contact area was associated with higher tunneling effect.