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김동환(Kim Donghwan) 원광대학교 원불교사상연구원 2017 원불교사상과 종교문화 Vol.71 No.-
이 글은 근대 유교지식인의 인식 변화를, 김교헌이라는 인물의 행적을 통해 살펴본 글이다. 김교헌은 조선조 명문가의 후예로서, 구한말 과거급제를 통해 여러 벼슬을 거쳐 종2품 벼슬까지 오른 인물이다. 특히『(증보)문헌비고』와『국조보감』의 참여 경험은, 후일 그의 여러 역사서술의 소중한 경험이 되었다. 그러나 그의 유교에 대한 인식은 대종교를 경험한 이후 완전히 바뀌었다. 그의 스승 나철의 ‘국망도존(國亡道存)’의 가르침이 교훈이 된 것이다. 그러므로 역사인식에서는 중화주의 역사관을 탈피한 민족주의 역사관을 구현했으며, 일제강점기라는 시대적 상황 아래 독립투쟁의 정신적 지주 역할을 담당했다. 더불어 대종교 제2세 교주로 취임하면서 교세확장과 독립운동의 거점 마련을 병행하기도 하였다. This paper is aware of the change of modern Confucian intellectuals, Kim Kyo-Heon is shown through that. Kim Kyo-Heon after the example of the famous House of the Joseon Dynasty, an important position, they are rough figures. In particular, the experiences involved in 『MUN-HEON-BIGO(文獻備考)』 and 『GOOK-JO-BO-GAM(國朝寶鑑)』, authored many books on the history of the latter days was an important experience. However, Kim Kyo-Heon only Confucianism awareness has changed completely since the Daejonggyo experienced. Na-Cheol, who was his teacher gave the ‘The country is ruined, even if spirit exists(國亡道存)’ was this teaching of the lesson. Therefore, the interpretation of history, the history of the interpretation center of sinocentrism off the nationalists realized the history, and the struggle for independence during the Japanese occupation plays a central role. In addition, he became General Manager of Daejonggyo, has been developed based on statues of the Daejonggyo.
Passivation properties of tunnel oxide layer in passivated contact silicon solar cells
Kim, Hyunho,Bae, Soohyun,Ji, Kwang-sun,Kim, Soo Min,Yang, Jee Woong,Lee, Chang Hyun,Lee, Kyung Dong,Kim, Seongtak,Kang, Yoonmook,Lee, Hae-Seok,Kim, Donghwan Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.409 No.-
<P><B>Abstract</B></P> <P>Passivated contact in advanced high-efficiency silicon solar cells based on the full back surface field (BSF) is reported here in based on the application of a tunnel oxide layer that is less than 2nm thick. The open-circuit voltage (<I>V<SUB>oc</SUB> </I>) was significantly improved via interface passivation due to insertion of the tunnel oxide layer. During oxide layer growth, a transition region, such as a sub-oxide, was observed at a depth of about 0.75nm in the growth interface between the silicon oxide layer and silicon substrate. The properties of the less than 2nm thick tunnel oxide layer were primarily affected by the characteristics of the transition region. The passivation characteristics of tunnel oxide layer should depend on the physical properties of the oxide. The interface trap density D<SUB>it</SUB> is an important parameter in passivation and is influenced by the stoichiometry of the oxide which in turn strongly affected by the fabrication and the post annealing conditions. During heat treatment of a-Si:H thin films (for the purpose of crystallization to form doped layers), thin film blistering occurs due to hydrogen effusion on flat substrate surfaces. To minimize this behavior, we seek to control the surface morphology and annealing profile. Also, the passivation quality of passivataed contact structure declined for the sample annealed above 900°C. This decline was attributed not only to local disruption of the tunnel oxide layer, but also to phosphorus diffusion. The resistivity of the tunnel oxide layer declined precipitously for the sample annealed above 900°C. On the basis of these, implied V<SUB>oc</SUB> over 740mV was achieved in n-type Si wafer through the control of the oxide stoichiometry via optimizing the annealing conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The tunnel oxide passivated contact structure has attracted attention for achieving high efficiency solar cells. </LI> <LI> The passivation quality is associated with the stoichiometry and properties of tunnel oxide. </LI> <LI> Thin film blistering occurs due to hydrogen effusion on flat substrate surfaces in tunnel oxide passivated contact structure. </LI> <LI> To improve the passivation quality must be consider about the physical properties and thermal stability of tunnel oxide layer. </LI> </UL> </P>
Synthesis and Characterization of CdS Nanocrystals in a Novel Phosphate Glass
Donghwan Kim,Chawon Hwang,Donggun Gwoo,Taehee Kim,Youngseok Kim,Namjin Kim,류봉기 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.4
Zinc-borophosphate glasses doped with various concentrations (≤ 5 wt. %) of cadmium sulfide (CdS) were synthesized. Nanocrystals of CdS were developed in the glass matrices at different concentrations, with emphasis on the quantum confinement effect. The effects of CdS content on the optical and various other properties were investigated. The optical characterization of the glasses was carried out using UV-Visible spectrophotometry. There was a red shift in the optical cut-off with increasing CdS content in the glass. The band gap of the CdS nanocrystals doped in the glass matrix ranged from 3.5 eV to 4.2 eV. The structural characterization,which was carried out using X-ray diffraction, shows the CdS to have hexagonal crystal structure. The average size and shape of the nanocrystals doped in the glass matrix were determined using transmission electron microscopy (TEM). The particle sizes of the doped CdS crystals were in the range of 3 nm to 6 nm for 2 wt. % CdS, and 15 nm to 20 nm for 5 wt. % CdS.
Ultraconformal contact transfer of monolayer graphene on metal to various substrates
Donghwan Kim(김동환),Wonsuk Jung,Mingu Lee,Soohyun Kim,Jae-Hyun Kim,Chang-Soo Han 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
We demonstrate clean and dry transfer of monolayer graphene of 7 x 7 cm² by ultraconformal contact of the graphene with the target substrate by using a mechano-electro-thermal(MET) process, which enables direct detachment of the graphene from a Cu substrate. We directly transferred the monolayer graphene from Cu foils onto PDMS, PET and glass, without any additional carrier layers and metal etching process. In addition, the transferred graphene strongly adhered to the substrate and was free from physical contaminants and damage over its whole area. The transfer of large area monolayer graphene by direct detachment from the metal foil without any carrier material is highly desirable and valuable, particularly with respect to reducing contamination and manufacturing cost and process.
Properties of ZnO thin films co-doped with hydrogen and fluorine.
Kim, Yong Hyun,Kim, Jin Soo,Jeong, Jeung-Hyun,Park, Jong-Keuk,Baik, Young Joon,Lee, Kyeong-Seok,Cheong, Byung-Ki,Kim, Donghwan,Seong, Tae-Yeon,Kim, Won Mok American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.4
<P>ZnO films co-doped with fluorine and hydrogen were prepared on Corning glass by radio frequency magnetron sputtering of ZnO targets with varying amounts of ZnF2 in H2/Ar gas mixtures of varying H2 content. The ZnO films' electrical, optical, and structural properties in combination with their compositional properties were investigated. A small addition of H2 to the sputtering gas caused a drastic increase of Hall mobility with a marginal increase in carrier concentration, indicating an effective passivation of grain boundaries due to hydrogenation. For further increase of H2 in sputter gas, the Hall mobility remained at a relatively constant level while the carrier concentration increased steadily. Most of the ZnO films co-doped with fluorine and hydrogen showed average transmittance higher than 83% in the 400-800 nm range, while the average absorption coefficients were lower than 600 cm(-1), implying very low absorption loss in these films. It was discovered that the fabrication of ZnO films with a Hall mobility higher than 40 cm2/Vs and a very low absorption loss in the visible range is possible by co-doping hydrogen and fluorine.</P>
Kim, DongHwan,Lee, Rochelle,Kim, Sung,Kim, TaeWan ELSEVIER SCIENCE 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.789 No.-
<P><B>Abstract</B></P> <P>Two-dimensional (2D) crystal growth allows wafer-scale van der Waals epitaxial integration of transition metal dichalcogenides (TMDs) semiconductors onto a Si substrate. 2D MoTe<SUB>2</SUB> and WTe<SUB>2</SUB> among TMDs are considered as possible candidates for high-performance near-infrared photodetector, due to its relatively low band gap energy (0.8–1.1 eV). Herein, 2D MoTe<SUB>2</SUB> was selected for the development of high-performance visible–near-infrared (0.5–1.1 μm) photodetectors. Phase-engineered MoTe<SUB>2</SUB> films of four atomic layers were grown by metal–organic chemical vapor deposition on an 8-inch SiO<SUB>2</SUB>/Si substrate. 1T′ and 2H phase MoTe<SUB>2</SUB> films were verified by Raman spectra and scanning transmission electron microscopy. A fabricated 2H-MoTe<SUB>2</SUB>-based field-effect transistor (FET) was found to have p-type electrical transport with a mobility of 22.8 cm<SUP>2</SUP>/V·s—the fastest among all currently reported 2H phase films synthesized by bottom-up methods—and an on/off ratio of 1.3 × 10<SUP>4</SUP>. Moreover, a photodetector based on the 1T′ phase (semimetal) film exhibited excellent performance, including photoresponsivity as high as 62–109 mA/W at 500–1000 nm—a 900% enhancement over that with a 2H phase (p-type semiconductor) film—and extremely fast response (a rise time of 0.82 μs and a fall time of 7.29 μs at a wavelength of 1000 nm).</P> <P><B>Highlights</B></P> <P> <UL> <LI> 2D MoTe<SUB>2</SUB> were grown by metal–organic chemical vapor deposition on an 8-inch Si wafer. </LI> <LI> Phase-engineered (1T′ and 2H) MoTe<SUB>2</SUB> has been achieved by optimizing MOCVD growth conditions. </LI> <LI> 2D MoTe<SUB>2</SUB> was selected for the development of visible–near-infrared photodetectors. </LI> <LI> The responsivity of 1T′-MoTe<SUB>2</SUB>-based photodetector is about ten times higher than 2H phase. </LI> <LI> Ultra-fast response time of 0.82–7.29 μs and photoresponsivity of 62–109 mA/W at 500–1000 nm. </LI> </UL> </P>
Kim, Seongtak,Park, Sungeun,Kim, Young Do,Bae, Soohyun,Boo, Hyunpil,Kim, Hyunho,Lee, Kyung Dong,Tark, Sung Ju,Kim, Donghwan American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.10
<P> The effect of peak firing temperature and grid width on the contact properties between Ag metal and silicon (n<SUP>+</SUP> emitter) was investigated for screen-printed silicon solar cells. We confirmed the factors that control the specific contact resistance as follows: (1) the Ag coverage fraction on the silicon surface, d(2) the thickness of the glass layer and (3) the etching depth on the n<SUP>+</SUP> emitter region. The lowest specific contact resistance (8.27 mΩ·cm<SUP>2</SUP>) was obtained at the optimum firing temperature (720 °C). We also found that the grid width affected the contact quality of Ag paste because the contact width related to the absorbed heat of samples in RTP system. For this reason, when the grid width was further reduced, meaning more heat absorption, more Ag crystallites grew and the glass layer thickened. Light I?V results of a 6-inch silicon solar cell with minimum busbar width were similar to the PC1D simulation results. The efficiency was improved by 0.2% with the reduction of the busbar width. </P>