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아르곤 플라즈마로 처리한 n - GaAs의 표면특성에 관한 Photoreflectance 연구
이동율(Dong-Yul Lee),김인수(In-Soo Kim),김동렬(Dong-Lyeul Kim),김근형(Geun-Hyoung Kim),배인호(In-Ho Bae),김규호(Kyoo-Ho Kim),한병국(Byung-Kuk Han) 한국진공학회(ASCT) 1997 Applied Science and Convergence Technology Vol.6 No.4
Power를 40 W로 고정하고 시간을 5~120초간 변화시켜 아르콘 플라즈마로 처리시킨 n-GaAs(100)의 특성을 photoreflectance(PR) 측정으로 조사하였다. 아르곤 플라즈마 처리시간을 증가시킴에 따라 E。 피크의 세기는 처리시간이 5초일 때 최소로 관측되었으며, 이때 표면전기장(E_S), 순수 캐리어농도(N_D-N_A) 및 표면상태 밀도 (Q_(SS))는 각각 1.05×10^5 V/㎝, 1.31×10^(17) ㎝-³ 및 1.64×10^(-7) C/㎡로 이 값들은 bulk 시료에 비해 약 57.1, 81.4 및 56.9% 감소하였다. 반면에 5초일 때 compensation center 농도(N_A)는 5.57×10^(17) ㎝-³로 최대였다. 그리고 아르곤 플라즈마 처리시 유발된 결함들의 침투깊이는 표면에서 약 450 Å 정도였다. We have investigated the surface characteristics of n-GaAs (100) treated with Ar plasma (40 W, 5~120 sec) by photoreflectance (PR) measurement. With increasing Ar plasma treatment time, the intensity of E。 peak observed to the minimum at 5 sec. The surface electric field (E_S), net carrier concentration (N_D-N_A), and surface state density (Q_(SS)) are 1.05×10^5 V/㎝, 1.31×10^(17) ㎝-³ and 1.64×10^(-7) C/㎡, respectively. These values were about 57.1, 81.4 and 56.9% smaller than those of bulk n-GaAs. On the other hand, the concentration of compensation centers (N_A) was maximum with value of 5.57×10^(17) ㎝-³ at 5 sec. And penetration depth of defects generated after treated with Ar plasma was about 450 Å from surface.
Cu, Zn, Sn, Se 혼합 분말의 소결특성에 미치는 볼밀링 영향
안종헌,정운화,장윤정,이성헌,김규호,Ahn, Jong-Heon,Jung, Woon-Hwa,Jang, Yun-Jung,Lee, Seong-Heon,Kim, Kyoo-Ho 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.3
In order to make a $Cu_2ZnSnSe_4$ (CZTSe) sputtering target sintered for solar cell application, synthesis of CZTSe compound by solid state reaction of Cu, Zn, Sn and Se mixed powders and effects of ball milling condition on sinterability such as ball size, combination of ball size, ball milling time and sintering temperature, was investigated. As a result of this research, sintering at $500^{\circ}C$ after ball milling using mixed balls of 1 mm and 3 mm for 72 hours was the optimum condition to synthesis near stoichiometric composition of $Cu_2ZnSnSe_4$ and to prepare sintered pellet with high density relatively.
팽루(Peng Lu),김규호(Kim Kyu-Ho),양희천(Yang Hei-Cheon),박상규(Park Sang-Kyoo) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Slurry pumps have a wide range of industrial applications. However, as slurries contain abrasive and erosive solid particles, slurry pump components are subjected to severe wear and the pump system may even fail. Numerical simulations for developing a slurry pump model with 4 plate-type rotors were conducted using water as the pumping fluid. A commercial CFD package, STAR-CCD+, was used to simulate the flow characteristics depending on the atmospheric pressure through the inlet boundary. It is found that the simulation results are available in qualitatively studying the correlation of flow behaviors for a better pump design.
광흡수층 적용을 위한 PLD용 Cu<sub>2</sub>ZnSnSe<sub>4</sub> 타겟 제조와 증착 박막의 특성
정운화(Jung, Woon-hwa),라흐멧 아드히 위보우(Rachmat, Adhi Wibowo),김규호(Kim, Kyoo-ho) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
Cu₂ZnSnSe₄(CZTSe) is one of the promising materials for the solar cell due to its abundant availability in the nature. In this study, we report the fabrication of CZTSe thin film by Pulsed Laser Deposition(PLD) method using quaternary compound target on sodalime glass substrate. The quaternary CZTSe compound target was synthesized by solid state reaction method using elemental powders of Cu, Zn, Sn and Se. Powders were milled in high purity ethanol using zirconia ball with mixed size of 1 and 3 mm at the same proportions for 72 hours milling time. The structural, chemical and mechanical properties of the synthesized CZTSe powders were investigated prior to the deposition process. The CZTSe compound powder, and 500?C of sintering temperature shows the best properties for PLD target. Results show that the as-deposited CZTSe thin films with the precursors by PLD have a composition near-stoichiometric.
아말 무하마드(Amal, M. Ikhlasul),힐미 무함마드(Alfaruqy, M. Hilmy),장윤정(Jang, Yun-Jung),김규호(Kim, Kyoo Ho) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Cu₂ZnSnSe₄ (CZTSe) is one of candidate to alternate Cu(In,Ga)Se₂ as solar absorber material for solar cell. The expensive elements of In and Ga are replaced by Zn and Sn, respectively to lower the material cost. In this study we fabricated CZTSe thin film by selenization of single precursor layer consisted metallic constituent. Precursor compositions ratio were selected to have Cu-poor and Zn-rich content and prepared by RF magnetron sputtering. Thermal processing was applied to introduce selenium into as-deposited films at temperatures ranging from 350 to 500 for time up to 120 minutes. Single precursor films showed amorphous structure and consist of individual elements of Cu, Zn, and Sn. It was confirmed by XRD analysis that synthesis of CZTSe compound is occurred from lower temperature process, although concurrently additional phases such as binary cooper selenides are also existed. The quality of CZTSe crystal was improved as temperature increased. We also investigated the optical and electrical properties of as-selenized CZTSe as well.
장윤정(Jang, Yun-Jung),아말 무하마드(Amal, M. Ikhlasul),힐미 무함마드(Alfaruqy, M. Hilmy),김규호(Kim, Kyoo Ho) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Cu2ZnSnSe4는 CIS 태양전지의 In 대체 물질계로 주목을 받고 있는 저가형 태양전지 재료로 장차 차세대 태양전지 재료로 응용이 기대되고 있다. 그러나 에너지 밴드갭이 0.9~1.1eV로 다소 낮아 태양전지 광흡수층 재료로 사용하기 위해서는 wide band gab화 처리가 필요하다. 본 연구에서는 CZTSe에 S를 첨가하여 에너지 밴드갭을 확장하고자 하며, S의 첨가가 CZTSe 박막의 특성에 미치는 영향에 대하여 조사하였다. 실험의 편의성을 도모하고자 펄스레이저 법을 사용하여 증착하였다. 박막 조성 제어에는 Cu, Zn, Sn, Se, S 분말을 볼밀로 분쇄, 혼합하여 균질 혼합상 프리커서를 제조하고 이를 Cold Isostatic Press(CIP) 성형하여 Source target을 사용하였다. Pulsed YAG-Laser를 사용하여 soda lime glass상에 증착하고 조성, 구조, 조직을 관찰하고 에너지 밴드갭, 광흡수계수, 면저항, 전하밀도 등 특성을 조사하였다.
RF sputtering 법으로 제조된 CuInSe₂박막의 특성
김규호,김효준,이해석,김민호,정상현 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.1
CuInSe₂ thin films were prepared on Si(100) wafer by RF magnetron sputtering from powder target which was prepared by reacting high purity Cu₂Se and In₂Se₃(99.999%, Cu₂Se: In₂Se₃=1:1 mole ratio), in argon gas The XRD results suggest that deposited thin films were mainly composed of crystalline CuInSe₂ with the typical chalcopyrite structure, whereas film deposited showed the mixed phase of Cu₂Se+CuInSe₂at 50W. Deposited film showed (204), (220) preferred orientation at 50W and deposited films from 75W were strongly oriented along th e(112) plane. In the EDS analysis, Cu/In mole ratio of the thin films was decreased and Se/(Cu+In) mole ratio was increased with increasing RF power. The lattice parameters of a, c axis and c/a ratio of deposited films were decreased with increasing RF power. The grain size of the thin films measured by SEM became coarse with the increase of RF power.
CO가스에 依한 酸化鐵의 還元時 還元過程에서의 組織變化가 還元速度에 미치는 影響의 硏究
金圭鎬,金星秀 嶺南大學校 工業技術硏究所 1980 연구보고 Vol.8 No.1
Sintered hematite pellets were reduced in CO-CO₂mixtures at 700˚, 800˚, 900˚and 1000℃. Weight loss was recorded by a thermobalance and the structural changes were studied microscopically. In the reduction of hematite to wustite, at 900℃, rate minimum phenomenon was observed. Wustite formed at 900℃ is less permeable to gas than wustite formed at 800℃, which indicates that reduction mechanism changes at a certain temperature region between 800˚and 900℃. The observation of wustite with thinner layer and finer pore at lower temperature implies that the reduction of hematite to wustite at low temperature is controlled by gaseous pore diffustion. Wustite formed by reduction of hematite had been sintered until it was reduced to iron. Decrease of partial pressure of CO and inward movement of the wustite-iron interface lead to the longer sintering period. The structures of wustite and reduced iron were porous, dense or coarse depending on the extent of sintering and influenced the removal of oxygen in the later stage of reduction. The thickness of reaction zone between iron and wustite layer appears to depend on the ratio of the pore diffusivity to the reaction area per unit volume. Retained wustite, which significantly hamper the reaction rate at final stage of the 700℃ reduction, was not observed in porous and coarse iron layer but in dense iron layer at the final stage of reduction. This observation indicates that densification of reduced iron enveloping a wustite grain occurs significantly in case of dense wustite layer reduction.