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ITO 박막의 전기저항과 광투과도 특성에 미치는 ZnO 첨가 효과
채홍철,홍주화,Chae, Hong-Choi,Hong, Joo-Wha 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.4
[ $In_2O_3-ZnO(IZO)$ ] and $In_2O_3-ZnO-SnO_2(IZTO)$ thin films were prepared on EAGLE 2000 glass webs in a Ar gas by RF-Magnetron sputtering. Electrical resistivity and optical transmittance of the films were investigated. IZO, IZTO film showed excellent optical transmittance of 85 % at the visible $400{\sim}$780 nm wavelength. Electrical properties of IZO film have $6.50{\times}10^{-4}{\Omega}cm$ (95 $In_2O_3$ : 5 ZnO wt.%) and $5.20{\times}10^{-4}{\Omega}cm$ (90 : 10 wt.%), IZTO film have $8.00{\times}10^{-4}{\Omega}cm$ (90 $In_2O_3$ : 3 ZnO : 7 $SnO_2$ wt.%) and $6.50{\times}10^{-4}{\Omega}cm$ (90 : 7 : 3 wt.%). Substitution of SnO to ZnO in ITO films showed slightly lower electrical conductivity than ITO film but showed similar optical transmittance.
채홍철 ( Hong Chol Chae ),백창현 ( Chang Hyun Baeg ),홍주화 ( Joo Wha Hong ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.2
The multi-layered thin film with an ITO/Ag/ITO structure was produced on PET by using magnetron reactive sputtering method. First, 30 nm of ITO thin film was coated on PET by using normal temperature process. Then 20-52 nm of the Ag thin film was coated. Lastly, 30 nm of ITO thin film was coated on Ag layer. The sample of the 20 nm Ag thin film showed more than 70% transmission and a 2.7Ω/□ sheet resistance. When compared to the existing single-layered transparent conducting thin film, multi-layered film was found to be superior with about 5Ω/□ less sheet resistance. However, since the Ag layer became thinner, the band gap energy needs to be increased to more than 3.5 eV.
채홍철 ( Hong Chol Chae ),우성용 ( Woo Seong Yong ),홍주화 ( Joo Wha Hong ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.9
Influences of surface oxygen plasma treatment on the work function of ITO thin films were studied. As a result of plasma etching, the roughness of the film was reduced with increasing plasma treatment time. The REELS measurement with primary electron energy of 300eV revealed that the band gap of the extreme surface of the thin film was increased by 1.03eV. At 1700eV, however, the band gap of the film remained unchanged. The UPS results indicated that the work function increased by 0.82eV and from the XPS spectra the valence band maximum was measured to be 5.32eV after the plasma treatment. The change in the work function of the extreme surface of the film was attributed to an increase in the amount of oxygen after the plasma treatment, which did not affect the electrical conductivity or the value of the band gap. XPS was used to examine whether the oxygen plasma treatment caused any change in the composition ratio of the ITO thin film. The spectra showed that almost all of the peaks for the carbon compounds of C-H-O were eliminated after the plasma treatment. In addition, In-O bonds and O=O bonds were increased as a result of abundant oxygen in the surface of the film. Our results demonstrated that the electronic, optical, and structural properties of plasma-treated ITO thin films in an oxygen environment were greatly improved.
유리기판에 O2 플라즈마 표면처리 후 제작된 ITO 박막의 특성
채홍철 ( Hong Chol Chae ),홍주화 ( Joo Wha Hong ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.7
The optical and electronic properties of Indium Tin Oxide (ITO) thin films deposited on a RFplasma treated glass substrate were investigated by X-Ray Photoelectron Spectroscopy (XPS), Ultra-violet Photoelectron Spectroscopy (UPS), Reflected Electron Energy Loss Spectroscopy (REELS). The modification of glass substrates was carried out by varying the time of the plasma surface treatment in an oxygen atmosphere. The focus of this research was to examine how the optical and electronic properties of ITO thin films change with the plasma treatment time. The surface energy increased since the carbon bonds were removed from the surface after the glass substrate received the surface treatment. The ITO thin films produced on the glass substrate with surface treatment showed that the high optical transmittance was approximately 85%. The measured band gap energy was as high as 3.23 eV when the plasma treatment time was 60 s and the work function after the treatment was increased by 0.5 eV in comparison to that before the treatment of 60 s. The ITO thin film exhibited an excellent sheet resistance of 2.79 Ω/□. We found that the optical and electronic properties of ITO thin films can be improved by RF-plasma surface treatment.
스크린 플라즈마 질화법에 의해 처리된 STS316L 강 표면의 질화층에 관한 연구
채홍철, 홍주화 충북대학교 산업과학기술연구소 2013 산업과학기술연구 논문집 Vol.27 No.2
Screen plasma nitrided surface layer of STS316L stainless steel was studied by AES and in-situ XPS. The nitriding treatment was done using ultra high purity nitrogen gas under workpiece temperature range from R.T. to 600℃. Nitride layer composition was uniform, thickness was about 1 um and thin nitrogen penetration was attributed to zero bias of workpiece in this screen plasma method. It was confirmed that oxygen present on sample surface reacted with nitrogen gas forming NOx, and this acted as a passive film interfering nitride formation. Increasing sample temperature promoted CrN and Cr2N formation, reducing NO and NO2, and accordingly maximum thickness of CrN phase was achieved at 600℃. Nano-indentation hardness of nitride layer, measured up to depth of 500nm from surface, showed a high value of exceeding 11GPa, when processed at 600℃.
Cu/Ni/Polyimide 시스템의 접착력 및 계면화학반응
최철민,채홍철,김명한,Choi, Chul-Min,Chae, Hong-Chul,Kim, Myung-Han 한국재료학회 2007 한국재료학회지 Vol.17 No.12
The magnetron sputtering was used to deposit Ni buffer layers on the polyimide surfaces to increase the adhesion strength between Cu thin films and polyimide as well as to prevent Cu diffusion into the polyimide. The Ni layer thickness was varied from 100 to $400{\AA}$. The adhesion strength increased rather significantly up to $200{\AA}$ of Ni thickness, however, there was no significant increase in strength over $200{\AA}$. The XPS analysis revealed that Ni thin films could increase the adhesion strength by reacting with the polar C=O bonds on the polyimide surface and also it could prevent Cu diffusion into the polyimide. The Cu/Ni/ polyimide multilayer thin films showed a high stability even at the high heating temperature of $200^{\circ}C$, however, at the temperature of $300^{\circ}C$, Cu diffused through the Ni buffer layer into polyimide, resulting in the drastic decrease in adhesion strength.
A Study on the Health Changes of Students in Long-Term Online Classes due to COVID-19
조선아,채홍철,민준식,이성재 국제문화기술진흥원 2023 International Journal of Advanced Culture Technolo Vol.11 No.3
The COVID-19 pandemic has had a significant impact on the educational landscape for students across the globe, leading to a shift towards long-term online learning. This study aims to examine the changes in the health status of college and university students before and after the transition to online classes. We conducted a survey questionnaire among 200 students enrolled at K University in Gangwon-do, including participants from both the Department of Visual Optics and the Department of Physical Therapy. The survey employed a 5-point Likert scale to evaluate a range of health-related factors, including physical and mental well-being, alterations in lifestyle, and academic performance. Both male and female students experienced a decline in physical strength and exercise during the online class period, while mental health and overall happiness showed improvement, particularly among female students. Notable shifts in lifestyle emerged, including an increased usage of electronic devices and enhanced familial connections. The study also shed light on intriguing trends related to academic accomplishments and adherence to official quarantine guidelines. In sum, the findings of this study offer valuable foundational information for the maintenance of students' well-being during online learning, as well as the development of effective strategies for online education in future academic settings.