• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.65-66
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• 1994

This paper describes study on the preparation of ferrite powder for bonded mallets. The specimen which has the basic composition of SrO$.$nF$_2$O$_3$ with n=5.9 is in nonstoichiomatric region. Calcination is performed under N$_2$ atmosphere 1175$^{\circ}C$, 1200$^{\circ}C$, 1225$^{\circ}C$, 1250$^{\circ}C$ and 1275$^{\circ}C$ respectively. Then, Cooling is carried out in the furnace. In order to increase coecivity and obtain uniform grain size, we add to the specimen 0.7wt%CaCO$_3$, 0.3wt % SiO$_2$, 0.5wt%Na$_2$SiO$_3$ and 0.5wr% Al$_2$O$_3$. Also, in order to increase milling effect, carbon coating on sample particles is tried. As the result, single magnetic domain partic1e with Size of 1$\mu\textrm{m}$ in obtained and magnetic properties are improved.

• Solar Energy
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• v.6 no.2
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• pp.70-75
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• 1986

The fabrication procedure and characteristics of $Ta_2O_5/Al/SiO_2/p-Si$ MIS solar cells forming a fine grating pattern of aluminum evaporated on to p-type silicon crystal are discribed. The proper temperature for oxide growing of these cells was found to be about $450^{\circ}C$ for 20 minutes with oxygen flow. The conversion efficiency increased about 3% after $750{\AA}$ thickness of tantalium silica film spin on anti-reflective coating. The best results showed that $V_{oc}=0.545V,\;J_{sc}=34mA$ and F.F = 0.65, which represent that the conversion efficiency is 12%.

• Solar Energy
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• v.19 no.1
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• pp.29-36
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• 1999

ZnO/n-Si junctions were fabricated by spin coating with ZnO precursor produced by the sol-gel process. In order to increase the electrical conductivity of ZnO films, the films were n-doped with Al impurity and subsequently annealed at about $450^{\circ}C$ under reducing environments. The ohmic contacts between n-Si and AI for a bottom electrode were successfully fabricated by doping the rear surface of Si substrate with phosphorous atoms. The front surface of the substrate was also doped with phosphorous atoms for improving the efficiency of the solar cells. Consequently, conversion efficiencies ranging up to about 5.3% were obtained. These efficiencies were found to decrease slowly with time because of the oxide films formed at the ZnO/Si interface upon oxygen penetration through the porous ZnO. Oxygen barrier layers could be necessary in order to prevent the reduction of conversion efficiencies.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.496-496
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• 2011

A very simple and cost-effective method for fabrication of SiOx-incorporated diamond-like carbon (DLC) thin films at a preparation temperature of less than $200^{\circ}C$ was developed. Since DLC coating can be prepared not under vacuum but atmospheric conditions without any carrier gas flow, not only wafers but also powderic substrates can be used for DLC coating. Formation of DLC coating could result in appearance of superhydrophobic behaviors, which was sustained in a wide range of pH (1~14). DLC-coated surfaces selectively interacted with toluene in a toluene/water mixture. These results imply that our preparation method of the DLC coating can be useful in many application fields such as creating self-cleaning surfaces, and water and air purification filters.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.608-616
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• 2015

The migration of silver (Ag) in silicon carbide (SiC) and $^{110m}Ag$ through SiC of irradiated tristructural isotropic (TRISO) fuel has been studied for the past three to four decades. However, there is no satisfactory explanation for the transport mechanism of Ag in SiC. In this work, the diffusion coefficients of Ag measured and/or estimated in previous studies were reviewed, and then pre-exponential factors and activation energies from the previous experiments were evaluated using Arrhenius equation. The activation energy is $247.4kJ{\cdot}mol^{-1}$ from Ag paste experiments between two SiC layers produced using fluidized-bed chemical vapor deposition (FBCVD), $125.3kJ{\cdot}mol^{-1}$ from integral release experiments (annealing of irradiated TRISO fuel), $121.8kJ{\cdot}mol^{-1}$ from fractional Ag release during irradiation of TRISO fuel in high flux reactor (HFR), and $274.8kJ{\cdot}mol^{-1}$ from Ag ion implantation experiments, respectively. The activation energy from ion implantation experiments is greater than that from Ag paste, fractional release and integral release, and the activation energy from Ag paste experiments is approximately two times greater than that from integral release experiments and fractional Ag release during the irradiation of TRISO fuel in HFR. The pre-exponential factors are also very different depending on the experimental methods and estimation. From a comparison of the pre-exponential factors and activation energies, it can be analogized that the diffusion mechanism of Ag using ion implantation experiment is different from other experiments, such as a Ag paste experiment, integral release experiments, and heating experiments after irradiating TRISO fuel in HFR. However, the results of this work do not support the long held assumption that Ag release from FBCVD-SiC, used for the coating layer in TRISO fuel, is dominated by grain boundary diffusion. In order to understand in detail the transport mechanism of Ag through the coating layer, FBCVD-SiC in TRISO fuel, a microstructural change caused by neutron irradiation during operation has to be fully considered.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.190-190
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• 2003

여러원소 (Sb, F 등)를 도핑한 SnO$_2$ 투명전도막은 여러 가지 훌륭한 특성으로 Solar cell, heat mirrors, gas sensors, liquid crystal displays, thick film resistor 등과 같이 넓은 범위에서 응용되고 있다. 본 연구에서는 Sb 도핑된 Tin Oxide films이 Sol-gel dip coating법에 의해 준비되었다. SnO$_2$:Sb 용액은 SnC1$_2$ 와 SbC1$_3$ Power를 알코올에 용해하여 Ethylene glycol 와 Citric acid를 첨가하여 합성하였다. 막의 상형성은 XRD와 SEM(Scanning electron microscope)에 의해서 분석되었으며, 특성분석은 투과율(UV/VIS Spectrophotometer)과 표면전기저항(four point probe)으로 분석되었다. SiO$_2$ barrier이 SnO$_2$:Sb 막의 특성에 미치는 영향을 확인하기 위하여 XPS(X-ray photoelectron spectroscopy) 분석이 적용되었다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.66-74
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• 2004

The sliding wear behavior of $ZrO_2-22wt\%MgO\;(MZ)\;and\;ZrO_2-8wt\%Y_2O_3\;(YZ)$ deposited on a casting aluminum alloy with bond layer (NiCrCoAlY) by plasma spray against an SiC ball was investigated under dry test conditions at room temperature. At all load conditions, the wear mechanisms of the MZ and the YZ coatings were almost the same. The wear mechanisms involved the forming of a smooth film by material transferred on the sliding surface and pullout. The wear rate of the MZ coating was less than that of the YZ coating. With an increase normal load the wear rate of the studied coatings increased. The SEM was used to examine the sliding surfaces and elucidate likely wear mechanisms. The EDX analysis of the worn surface indicated that material transfer was occurred from the SiC ball to the disk. It was suggested that the material transfer played an important role in the wear performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.582-582
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• 2013

Oxide TFT (thin film transistor) active channel layer에 대한 저온 열처리 공정은 투명하고 flexibility을 기반으로하는 display 산업과 AMOLED (active matrix organic light emitting diode) 분야 등 다양한 분야에서 필요로 하는 기술로서 많은 연구가 이루어지고 있다. 과거 active layer는 ALD (atomic layer deposition), CVD (chemical vapor deposition), pulse laser deposition, radio frequency-dc (RF-dc) magnetron sputtering 등과 같은 고가의 진공 장비를 이용하여 증착 되어져 왔으나 현재에는 진공 장비 없이 spin-coating 후 열처리 하는 저가의 공정이 주로 연구되어 지고 있다. Flexible 기판들은 일반적인 OTFT (oxide thin films Transistor)에 적용되는 열처리 온도로 공정 진행시 열에 의한 기판의 손상이 발생한다. Flexible substrate의 열에 의한 기판 손상을 막기 위해 저온 열처리 공정이 연구되고 있지만 기존 열처리와 비교하여 소자의 특성 저하가 동반 되었다. 본 연구에서는 Si 기판위에 SiO2 (100)를 절연층으로 증착하고 그 위에 IZO (indium zinc oxide) solution을 spin-coating 한뒤 $250^{\circ}C$ 이하의 온도에서 열처리하였다. 저온 공정으로 인하여 소자의 특성 저하가 동반 되었으므로 소자의 저하된 특성 복원하고자 post-treatment로 고가의 진공장비가 필요 없고 roll-to roll system 적용이 수월한 remote-type의 APP (atmospheric pressure plasma) 처리를 하였다. Post-treatment로 APP를 이용하여 $250^{\circ}C$ 이하에서 소자에 적용 가능한 on/off ratio를 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.132-135
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• 1999

Recently, the ceramics of high permittivity are applied to DRAM and FRAM. In this study, (B $a_{x}$ S $r_{l-x}$)Ti $O_3$(BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/ $SiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$] for 30 minutes. Each specimen was analyzed structure and electrical characteristics. Thickness of BST ceramics thin films are about 2000($\AA$). Dielectric constant and loss of thin films was little decreased at 1[KHz] ~1[KHz]. Dielectric constant and loss to frequency were 250 and 0.02 in $Ba_{0.7}$S $r_{0.3}$Ti $O_3$. The properly of leakage current as the realation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.202.1-202.1
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• 2013

ZnO nanostructure was fabricated on a Si substrate using two-step growth. The seed layer was grown on the Si substrate by a sol-gel spin-coating. In the first step, ZnO nanorods were grown by a hydrothermal method at $140^{\circ}C$ for 5 min. In the second step, a ZnO thin film was grown on the ZnO nanorods by spin-coating. After growth, these films were annealed at $800^{\circ}C$ for 10 min. Electrical and optical properties of ZnO nanostructures have modified by plasma-assisted molecular beam epitaxy (PA-MBE) regrowth. The carrier concentration and resistivity increased by PA-MBE regrowth. In the photoluminescence, the full width at half maximum and intensity were decreased and increased, respectively, by PA-MBE regrowth.