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송풍근(Pung-Keun Song) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.2
Transparent Conductive Oxide (TCO), especially Indium Tin Oxide (ITO) films are almost prepared by DC magnetron sputtering because of the advantage of obtaining homogeneous large area coatings with high reproducibility. The purpose of this report is describe a detailed investigation of key factors dominating electrical and structural properties of sputtered ITO films. It was confirmed that crystallinity and electrical properties of ITO films were strongly depend on the sputtering pressure and kinetic energy of sputtered particles which are expected to have a close relation with the transport processes between target and substrate. And also, nodule formation on the ITO target was suppressed by both CaCO₃ addition and decreasing micro-pore in the target. On the other hand, we focused on the characteristics of amorphous TCO film to use as transparent electrode for various applications. To realize high thermoelectric performance, it was tried to control both high electrical conductivity and low thermal conductivity for the amorphous IZO:Sn films.
Chang Weon Song,Mi Young You,Damin Lee,Hyoung Seok Mun,Seohan Kim,Pung Keun Song 한국표면공학회 2020 한국표면공학회지 Vol.53 No.5
The change of the deposition behavior of diamond through a pretreatment process of the base metal prior to diamond deposition using HFCVD was investigated. To improve the specific surface area of the base material, sanding was performed using sandblasting first, and chemical etching treatment was performed to further improve the uniform specific surface area. Chemical etching was performed by immersing the base material in HCl solutions with various etching time. Thereafter, seeding was performed by immersing the sanded and etched base material in a diamond seeding solution. Diamond deposition according to all pretreatment conditions was performed under the same conditions. Methane was used as the carbon source and hydrogen was used as the reaction gas. The most optimal conditions were found by analyzing the improvement of the specific surface area and uniformity, and the optimal diamond seeding solution concentration and immersion time were also obtained for the diamond particle seeding method. As a result, the sandblasted base material was immersed in 20% HCl for 60 minutes at 100 °C and chemically etched, and then immersed in a diamond seeding solution of 5 g/L and seeded using ultrasonic waves for 30 minutes. It was possible to obtain optimized economical diamond film growth rates.
High Temperature Durability Amorphous ITO
Tae Dong Jung,Pung Keun Song 한국표면공학회 2012 한국표면공학회지 Vol.45 No.6
Yb-doped ITO (ITO:Yb) films were deposited on unheated non-alkali glass substrates by magnetron cosputtering using two cathodes (DC, RF) equipped with the ITO and Yb₂O₃ target, respectively. The composition of the ITO:Yb films was controlled by adjusting the RF powers from 0 W to 480 W in 120 W steps with the DC power fixed at 70 W. The ITO:Yb films had a higher crystallization temperature (200℃) than that of the ITO films (170℃), which was attributed to both larger ionic radius of Yb<SUP>3+</SUP> and higher bond enthalpy of Yb₂O₃, compared to ITO. This amorphous ITO:Yb film post-annealed at 170℃ showed a resistivity of 5.52 × 10<SUP>?4</SUP> Ωcm, indicating that a introduction of Yb increased resistivity of the ITO film. However, these amorphous ITO:Yb films showed a high etching rate, fine pattering property, and a very smooth surface morphology above the crystallization temperature of the amorphous ITO films (about 170℃). The transmittance of all films was >80% in the visible region.
AZ91 마그네슘 합금의 플라즈마 전해산화 피막 형성 및 물성에 미치는 0.1 M NaOH + 0.05 M NaF 용액 중 Na₂SiO₃ 농도의 영향
권두영(Duyoung Kwon),송풍근(Pung-Keun Song),문성모(Sungmo Moon) 한국표면공학회 2020 한국표면공학회지 Vol.53 No.2
Effects of Na₂SiO₃ concentration added into 0.1 M NaOH + 0.05 M NaF solution on the formation behavior and properties of PEO films on AZ91 Mg alloy were investigated under 1200 Hz of alternating current (AC) by voltage-time curves, in-situ observation of arc generation behavior and measurements of film thickness, surface roughness and micro vickers hardness. In the absence of Na₂SiO₃ in the 0.1 M NaOH + 0.05 M NaF solution, about 4 μm thick PEO film was formed within 1 min and then PEO film did not grow but white spots were formed by local burning. Addition of Na₂SiO₃ up to 0.2 M caused more increased formation voltage and growth of PEO film with uniform generation of arcs. Addition of Na₂SiO₃ from 0.2 M to 0.4 M showed nearly the same voltage-time behavior and uniform arc generation. Addition of Na₂SiO₃ more than 0.5 M resulted in a decrease of formation voltage and non-uniform arc generation due to local burning. PEO film growth rate increased with increasing added Na₂SiO₃ concentration but maximum PEO film thickness was limited by local burning if added Na₂SiO₃ concentration is higher than 0.5 M. Surface roughness of PEO film increased with increasing added Na₂SiO₃ concentration and appeared to be proportional to the PEO film thickness. PEO film hardness increased with increasing added Na₂SiO₃ concentration and reached a steadystate value of about 930 HV at more than 0.5 M of added Na₂SiO₃ concentration.