• 한국진공학회지
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• 제12권S1호
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• pp.88-91
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• 2003

Electromagnetic interference shielding and near-infrared cutoff filters for plasma display panel application were designed and fabricated by radio frequency magnetron sputtering. Three types of the filters were prepared: the basic structure of type A consisted of [$TiO_2$ Ti Ag $TiO_2$]; type B, of [$TiO_2$ ITO Ag $TiO_2$]; type C, of [$TiO_2$ ITO Ag ITO $TiO_2$]. Ti and ITO layers deposited on Ag layers were employed as barriers to prevent the oxidation and the diffusion of Ag film into the adjacent oxide layers. Optical, electrical, chemical, and structural properties were investigated, and the result shows that the filters with the ITO barrier layers provided an enhancement in transmittance in the visible owing to a lower absorption of ITO layers than Ti layers. Type C filter showed better optical and electrical performances and smoother surface roughness than Type B and C filters: the average sheet resistance was as low as 1.51 $\Omega\Box$ (where $\square$ stands for a square film), the peak transmittance in the visible was as high as 78.2 %, and the average surface roughness was 1.48 nm.

• Journal of Advanced Marine Engineering and Technology
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• 제40권2호
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• pp.96-101
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• 2016

The thermal management of high-power LED components in an assembly structure is crucial for the stable operation and proper luminous function. This study employs numerical tools to determine the optimum thermal design in LEDs with a heat sink consisting of a crevice-type vapor-chamber heat pipe. The effects of the MCPCB are investigated in terms of the substrate thicknesses on which the LEDs are mounted. Further, different placement configurations in a system module are considered. This study found that for a confined area, a power of 40 W/LED is applicable to a high-power package. Furthermore, the thermal conductivity of dielectric layer materials should ideally be greater than 0.9 W/m.K. The temperature conditions of the vapor chamber in a heat pipe greatly affect the thermal performance of the system. At an offset distance of 9.0 mm and a $2^{\circ}C$ increase in the temperature of the heat pipe, the resulting maximum temperature increase is approximately $1.9^{\circ}C$ for each heat dissipation temperature. Finally, at a thermal conductivity of 0.3 W/m.K, it was found that the total thermal resistance changes dramatically. Above 1.2 W/m.K, the resistance change reduces exponentially.

• 한국재료학회지
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• 제24권3호
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• pp.140-144
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• 2014

The contact mechanism of devices is usually researched at electrode contacts. However, the contact between a dielectric and channel at the MOS structure is more important. The graphene was used as a channel material, and the thin film transistor with MOS structure was prepared to observe the contact mechanism. The graphene was obtained on Cu foil by the thermal decomposition method with $H_2$ and $CH_4$ mixed gases at an ambient annealing temperature of $1000^{\circ}C$ during the deposition for 30 min, and was then transferred onto a $SiO_2/Si$ substrate. The graphene was doped in a nitrogen acidic solution. The chemical properties of graphene were investigated to research the effect of nitric atoms doping. The sheet resistance of graphene decreased after nitrogen acidic doping, and the sheet resistance decreased with an increase in the doping times because of the increment of negative charge carriers. The nitric-atom-doped graphene showed the Ohmic contact at the curve of the drain current and drain voltage, in spite of the Schottky contact of grapnene without doping.

• Journal of Magnetics
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• 제8권1호
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• pp.24-31
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• 2003

The discoveries of antiferromagnetic coupling in Fe/Cr multilayers by Grunberg, the Giant Magneto Resistance by Fert and Grunberg and a large tunneling magnetoresistance at room temperature by Moodera have triggered enormous research on magnetic thin films and magnetoelectronic devices. Large opportunities are especially opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on an external magnetic field can be found. We will briefly address important basic properties of these junctions like thermal, magnetic and dielectric stability and discuss scaling issues down to junction sizes below 0.01 $\mu\textrm{m}$$^2$with respect to single domain behavior, switching properties and edge coupling effects. The second part will give an overview on applications beyond the use of the tunneling elements as storage cells in MRAMs. This concerns mainly field programmable logic circuits, where we demonstrate the clocked operation of a programmed AND gate. The second 'unconventional' feature is the use as sensing elements in DNA or protein biochips, where molecules marked magnetically with commercial beads can be detected via the dipole stray field in a highly sensitive and relatively simple way.

• Current Optics and Photonics
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• 제1권1호
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• pp.7-11
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• 2017

In this study, multilayered graphene was easily transferred to the target substrate in one step using thermal release tape. The transmittance of the transferred graphene according to the number of layers was measured using a spectrophotometer. The sheet resistance was measured using a four-point probe system. Graphene formed using this transfer method showed almost the same electrical and optical properties as that formed using the conventional poly (methyl methacrylate) transfer method. This method is suitable for the mass production of graphene because of the short process time and easy large-area transfer. In addition, multilayered graphene can be transferred on various substrates without wetting problem using the one-step dry transfer method. In this work, this easy transfer method was used for dielectric substrates such as glass, paper and polyethylene terephthalate, and a sheet resistance of ~240 ohm/sq was obtained with three-layer graphene. By fabricating organic solar cells, we verified the feasibility of using this method for optoelectronic devices.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.428-432
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• 2012

Polyamidimide (PAI)-colloidal silica (CS) nanohybrid films were synthesized by an advanced sol-gel process. The synthesized PAI-CS hybrid films have a uniform and stable chemical bonding and there is no interfacial defects observed by TEM. The thermal degradation ratio of PAI-CS (10 wt%) hybrid films is delayed by 100 ℃ compared with pure PAI sample determined by on set temperature range in TGA. The dielectric constant of PAI-CS (10 wt%) hybrid films decreases with increasing CS content up to about 5 wt% but increases at higher CS content, which is not explained simply by effective medium therories (EMT). The duration time of PAI-CS (10 wt%) hybrid coil is 38 sec, which is very longer than that of pure PAI coil sample. The PAI-CS (10 wt%) hybrid film has a higher breakdown voltage resistance than the pure PAI film at surge environment and exhibits superior heat resistance. The PAI-CS (10 wt%) sample shows the advanced and stable thermal emission properties in transformer module compared with the pure PAI sample. This result illustrates that the advanced thermal conductivity and expansion properties of PAI-CS sample in the case of appropriate sol-gel processes brings the stable thermal emission in transformer system. Therefore, new PAI-CS hybrid samples with such stable thermal emission properties are expected to be used as a high functional coating application in ET, IT and electric power products.

• 마이크로전자및패키징학회지
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• 제6권4호
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• pp.1-7
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• 1999

MCM-D 기판에 수동소자를 내장시키는 공정을 개발하였다. MCM-D 기판은 Cu/감광성 BCB를 각각 금속배선 및 절연막 재료로 사용하였고, 금속배선은 Ti/cu를 각각 1000$\AA$/3000$\AA$으로 스퍼터한 후 fountain 방식으로 전기 도금하여 3 um Cu를 형성하였으며, BCB 층에 신뢰성있는 비아형성을 위하여 BCB의 공정특성과 $C_2F_6$를 사용한 플라즈마 cleaning영향을 AES로 분석하였다. 이 실험에서 제작한 MCM-D 기판은 절연막과 금속배선 층이 각각 5개, 4개 층으로 구성되는데 저항은 2번째 절연막 위에 thermal evaporator 방식으로 NiCr을 600$\AA$증착하여 시트저항이 21 $\Omega$/sq가 되게 형성하였고. 인덕터는 coplanar 구조로 3, 4번째 금속배선층에 형성하였으며, 커패시터는 절연막으로 PECVD $Si_3N_4$를 900$\AA$증착한 후 1, 2번째 금속배선층에 형성하여 88nF/$\textrm {cm}^2$의 커패시턴스를 얻었다. 이 공정은 PECVD $Si_3N_4$와 thermal evaporation NiCr 공정을 이용함으로써 기존의 반도체 공정을 이용하여 MCM-D 기판에 수동소자를 안정적으로 내장시킬 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.311-311
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• 2013

The resistance switching memory devices have several advantages to take breakthrough for the limitation of operation speed, retention, and device scale. Especially, the metal-oxide materials such as ZnO are able to fabricate on the flexible and visible transparent plastic substrate. Also, the quantum dots (QDs) embedded in dielectric layer could be improve the ratio between the low and the high resistance becauseof their Coulomb blockade, carrier trap and induced filament path formation. In this study, we irradiated 0.2-MeV-electron beam on the ZnO/QDs/ZnO structure to control the defect and oxygen vacancy of ZnO layer. The metal-oxide QDs embedded in ZnO layer on Pt/glass substrate were fabricated for a memory device and evaluated electrical properties after 0.2-MeV-electron beam irradiations. To formation bottom electrode, the Pt layer (200 nm) was deposited on the glass substrate by direct current sputter. The ZnO layer (100 nm) was deposited by ultra-high vacuum radio frequency sputter at base pressure $1{\times}10^{-10}$ Torr. And then, the metal-oxide QDs on the ZnO layer were created by thermal annealing. Finally, the ZnO layer (100 nm) also was deposited by ultra-high vacuum sputter. Before the formation top electrode, 0.2 MeV liner accelerated electron beams with flux of $1{\times}10^{13}$ and $10^{14}$ electrons/$cm^2$ were irradiated. We will discuss the electrical properties and the physical relationships among the irradiation condition, the dislocation density and mechanism of resistive switching in the hybrid memory device.

• 한국세라믹학회지
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• 제53권2호
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• pp.129-133
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• 2016

$MnO_2$ was added to the $0.95(Na_{0.5}K_{0.5})NbO_3-0.05CaTiO_3$ (NKN-CT) ceramics in order to promote the densification and improve the poling efficiency by increasing the resistance of the specimens. Densification and abnormal grain growth occurred in the $MnO_2$-added NKN-CT ceramics sintered at $1020^{\circ}C$, indicating that $MnO_2$ assisted the liquid-phase sintering of these materials. $Mn^{3+}$ ions were considered to enter the A-site of the matrix, thereby producing the free electrons, which interacted with the holes resulting from the evaporation of alkali ions. This interaction results in an increase in the resistance of the specimens. The increased resistance improved the poling efficiency and, hence, the dielectric and piezoelectric properties of the NKN-CT ceramics. A few of the $Mn^{3+}$ ions that entered the B-site of the NKN-CT matrix led to a slight increase in the mechanical quality factor.