• Journal of Powder Materials
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• v.19 no.4
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• pp.264-270
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• 2012

In this study, we mainly focus on the study of densification of gas-atomized Cu-50 wt.%In-13 wt.%Ga alloy powder without occurrence of crack during the forming process. Cu-50 wt.%In-13 wt.%Ga alloy powder was consolidated by sintering and rolling processes in order to obtain high density. The phase and microstructure of formed materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM), respectively. Warm rolling using copper can result in the improvement of density. The specimen obtained with 80% of rolling reduction ratio at $140^{\circ}C$ using cooper can have the highest density of $8.039g/cm^3$.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.89-95
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• 2010

The chalcopyrite $Cu(In_xGa_{(1-x)})Se_2$ (CIGS) is considered to be one of the effective light-absorbing materials for thin film photovoltaic solar cells. We describe the electrodeposition of CIGS thin films in ambient laboratory conditions, and suggest the electrochemical conditions to prepare stoichiometric CIGS thin films of Ga/(In + Ga) = 0.3. In acidic solutions containing $Cu^{2+}$, $In^{3+}$, $Ga^{3+}$ and $Se^{4+}$ ions, the CIGS films of different Cu/In/Ga/Se chemical compositions were electrodeposited onto Mo/Glass substrate. The structure, morphology and chemical composition of electrodeposited CIGS films were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive X-ray spectroscopy (EDS), respectively.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.14-18
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• 2023

We have investigated the behavior induced by Ga substitution in B-1212 system and observed an anomalous superconductor-like resistivity drop with an onset near 260 K and an offset at 248 K in the nominal (B_0.65Ga_0.35)(Ba_1.25Sr_0.75)(Er_0.5Ca_0.5)Cu₂O_z compound. However, this property degraded with repeated cycling. Systematic studies of the superconducting properties of the (B_1-xGa_x)(Ba_1.25Sr_0.75)(Er_0.5Ca_0.5)Cu₂O_z compounds are reported and discussed in the context of the anomalous resistivity transition.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.391-393
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• 2012

CuInGa 전구체를 여러 분위기에서 급속 열처리 공정 (rapid thermal processing; RTP)을 이용하여 셀렌화하여 CuInGaSe 박막을 제작하였다. 공정조건은 각각 진공상태, 아르곤 가스 유동 상압상태, 아르곤 분위기 상압밀폐에서 덮개 유리를 사용한 상태 및 아르곤 밀폐상압에서 추가로 Se을 공급한 상태이었다. 제작된 CuInGaSe의 특성을 ICP 측정을 통하여 분석하였다. 열처리 조건에서 시스템이 밀폐상태에 가까울수록 Se 증기압이 높을수록 CuInGaSe 박막의 Se 함량이 증가하였다. 아르곤 분위기 상압 밀폐상태에서 제작된 CuInGaSe 박막을 이용하여 제작한 태양전지의 효율은 9.6%이었다.

• Prospectives of Industrial Chemistry
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• v.20 no.2
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• pp.1-12
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• 2017

Cu(In,Ga)Se₂ (CIGS)계 박막 태양전지 기술은 1970년대 처음으로 소개된 이래 지속적인 기술적 진보를 이루어 왔으며, 저가·고안정성·고효율이라는 다양한 장점으로 태양광 시장에서 성공적인 안착을 노리고 있다. 이 논문은 CIGS 박막 태양전지의 개발 이력 및 요소 기술에 대해서 살펴보고 국가별 연구·개발 활동에 대해서 약술하였다. 아울러, 앞으로의 사회·시장에 변화에 대응한 연구 개발 방향에서 대해서도 논하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.585-585
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• 2012

$Cu(In_{1-x}Ga_x)Se_2$(CIGS) 박막 태양전지는 Chalcopyrite 계 박막 태양전지로 Cu, In, Ga, Se 각 원소의 조성을 적절히 조절하여 박막을 성장시킨다. 성장시킨 CIGS 박막은 광흡수계수가 $10^5cm^{-1}$로 다른 물질보다 뛰어나고 직접 천이형 반도체로서 얇은 두께로도 고효율의 박막 제작이 가능하다. CIGS 태양전지를 제조하는 방법은 3-stage 동시 증착법, 금속 전구체의 셀렌화 공정법, 전기 증착법 등이 있다. 그 중에 금속 전구체의 셀렌화 공정법은 다른 제조 방법에 비해 대면적 생산에 유리한 장점이 있다. 하지만 아직 상대적으로 3-stage 동시 증착법에 비해 낮은 에너지 변환 효율이 보고된다. 본 실험에서는 기존의 금속 전구체의 셀렌화 공정법과는 달리 전구체 증착과 셀렌화 공정을 동시에 하고, Se cracker를 통하여 Se 원료를 주입하는 방식인 반응성 스퍼터링 공정에서 reservoir zone의 온도 변화에 따른 특성을 분석하였다. Se cracker의 reservoir zone 온도가 증가할수록 Cu/(In+Ga) 비가 증가한다. CIGS 박막 태양전지의 구조는 Al/Ni/ITO/i-ZnO/CdS/CIGS/Mo/Soda lime glass이다. CIGS 박막의 조성비가 Cu/(In+Ga)=0.89, Ga/(In+Ga)=0.17인 박막 태양전지에서 개방전압 0.34 V, 단락전류밀도 $32.61mA/cm^2$, 충실도 56.2% 그리고 변환 효율 6.19%를 얻었다. 본 연구는 2011년도 지식경제부의 재원으로 한국에너지 기술평가원(KTEP)의 지원을 받아 수행한 연구 과제입니다(No.20093020010030).

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.44-48
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• 1997

The nanocrystalline Nd-Fe-B alloys with low Nd content were prepared by rapid solidification technique. The alloys consist of both$\alpha$-Fe as the main phase and $Nd_2Fe_{14}B_1$ as a secondary phase and have an ultrafine grain structure of about 30 nm. The addition of Ga in $Nd_4Fe_{82}B_{10}Mo_3Cu_1$ alloy increases remanence up to 1.29 T and improves squareness. The nanocrystalline $Nd_5Fe_{81}B_9Mo_3Cu_1Ga_1$ alloy has a volume fraction of $Nd_2Fe_{14}B_1$ phase of around 35% due to the increase of Nd content and shows an improved coercivity. The remanence, coercivity and energy product of optimally annealed nanocrystalline $Nd_5Fe_{81}B_9Mo_3Cu_1Ga_1$ alloy are 1.24 T, 257.4 kA/m (3.23 kOe), and 100.3 kJ/ ㎥ (12.6 MGOe), respectively.

• Current Photovoltaic Research
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• v.7 no.1
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• pp.1-8
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• 2019

The $Cu(In,Ga)Se_2$ (CIGS) thin film obtained by two-step process (metal deposition and Se annealing) has a rough surface morphology and many voids at the CIGS/Mo interface. To solve the problem a precursor that contains Se was employer by depositing a (In,Se)/(Cu,Ga) stacked layer. We devised a two-step annealing (vacuum pre-annealing and Se annealing) for the precursor because direct annealing of the precursor in Se environment resulted in the small grains with unwanted demarcation between stacked layers. After vacuum pre-annealing up to $500^{\circ}C$ the CIGS film consisted of CIGS phase and secondary phases including $In_4Se_3$, InSe, and $Cu_9(In,Ga)_4$. The secondary phases were completely converted to CIGS phase by a subsequent Se annealing. A void-free CIGS/Mo interface was obtained by the two-step annealing process. Especially, the CIGS film prepared by vacuum annealing $450^{\circ}C$ and subsequent Se annealing $550^{\circ}C$ showed a densely-packed grains with smooth surface, well-aligned bamboo grains on the top of the film, little voids in the film, and also little voids at the CIGS/Mo interface. The smooth surface enhanced the cell performance due to the increase of shunt resistance.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.73-73
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• 2002

• Current Photovoltaic Research
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• v.3 no.1
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• pp.21-26
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• 2015

High efficiency $Cu(In,Ga)Se_2$ solar cells are generally prepared above $500^{\circ}C$. Lowering the process temperature can allow wider selection of substrate material and process window. In this paper, the three-stage co-evaporation process widely used to grow CIGS thin film at high temperature was modified to reduce the maximum substrate temperature. Below $400^{\circ}C$ the CIGS films show poor crystal growth and lower solar cell performance, in spite of external Na doping by NaF. As a new approach, Cu source instead of Cu with Se in the second stage was applied on the $(In,Ga)_2Se_3$ precursor at $400^{\circ}C$ and achieved a better crystal growth. The distribution of Ga in the films produce by new method were investigated and solar cells were fabricated using these films.