• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.83-84
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• 2009

Thin film solar cells based on CIGS continue to be a leading candidate for thin film photovoltaic devices due to their appropriate bandgap, long-term stability, and low-cost production. To date, the most successful technique for the deposition of a CIGS absorber layer has been based on the co-evaporation However, the evaporation process is difficult to scale-up for large-area manufacturing the sputtering and Selenizaton process has been a promising method for low-cost and large-scale production of high quality CIGS In this study, we have used Cu and CuIn alloy targets for precursor deposition the precursor deposited by sputtering Cu and CuIn targets and $CuInSe_2$ thin film is manufactured by Selenization process

• Current Photovoltaic Research
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• v.3 no.1
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• pp.16-20
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• 2015

Ag addition in chalcopyrite materials is known to lead beneficial changes in aspects of structural and electronic properties. In this work, the effects of Ag alloying of $Cu(In,Ga)Se_2$-based solar cells has been investigated. Wide bandgap $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x = 0.75~0.8) films have been deposited using a three-stage co-evaporation with various Ag/(Ag+Cu) ratios. With Ag alloying the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films were found to have greater grainsize and film thickness. Device were also fabricated with the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films and their J-V and quantum efficiency measurements were carried out. The highest-efficiency $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ solar cell with Eg > 1.5 eV had an efficiency of 12.2% with device parameters $V_{OC}=0.810V$, $J_{SC}=21.7mA/cm^2$, and FF = 69.0%.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.404-405
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• 2011

Cu(InGa)$Se_2$ (CIGS) 박막 태양전지의 저가 및 대면적화를 위한 양산화 공정인 two-step process (sputter/selenization) 공정에서는 sputtering으로 형성한 metal precursor stack을 $H_2$ Se gas를 이용하여 selenization하는 공정을 주로 이용한다. 하지만 이러한 selenization 공정은 유독한 $H_2$ Se gas를 이용해야 한다는 점과 긴 시간 동안 열처리를 해야 하는 단점을 가지고 있다. 이에 metal precursor stack 위에 Se 막을 우선 증착하고, Rapid Thermal Process (RTP)를 이용하여 selenization하는 방법이 현재 많은 관심을 끌고 있다. 본 논문에서는 sputtering 이후 RTP를 이용한 CIGS 흡수층 제작에 대한 선행연구의 일환으로 co-evaporator 장비를 이용하여 다양한 구조의 precursor를 제작하고 RTP 조건에 따른 selenization 효과를 연구하였다. Co-evaporator를 이용하여 CIGS, CIG/Se, CuGa/In/Se, In/CuGa/Se 4가지 구조의 precursor stack을 Mo coated soda lime glass 위에 제작하였다. 이때 amorphous 상태의 precursor stack을 만들기 위하여 기판에 열은 가하여 주지 않았으며, 각각의 stack 구조에서 가지고 있는 Cu, In, Ga, Se의 총량을 동일하게 유지하기 위하여 각 stack의 증착 시간을 동일하게 유지하였다. Selenization을 위한 RTP 조건은 550, $600^{\circ}C$ 각각에 대하여 1, 5, 10분으로 split을 진행하였다. Precursor stack의 증착 후 관찰한 XRD 결과는 비정질 상태를 잘 나타내었으며, SEM 결과 CIGS precursor stack을 제외한 나머지 구조의 stack에서는 In 박막의 surface roughness로 인하여 박막의 평탄화가 좋지 않음을 확인하였다. CIGS precursor stack의 경우, RTP 온도와 시간 split와 상관없이 결정화가 잘 이루어졌으나 grain의 성장이 부족하였다. 이에 비하여 CIG/Se, CuGa/In/Se, In/CuGa/Se 구조의 precursor stack의 경우, $550^{\circ}C$ 열처리에서는 InSe의 결정상이 관찰 되었으며 $600^{\circ}C$, 5분 이상 열처리에서 CIGS 결정상이 관찰되었다. 이러한 결과는 Se이 metal 원소들과 함께 있는 CIGS 구조에 비하여 metal precursor stack 위에 Se을 증착한 stack 구조들의 경우는 CIGS 결정을 형성하기 위해 Se이 metal 층들로 확산되어 반응을 하여야 하므로 상대적으로 많은 열에너지가 필요한 것으로 이해할 수 있으며, RTP를 이용한 selenization 공정으로 CIGS 박막 태양전지의 흡수층 형성이 가능함을 확인하였다.

• Journal of Powder Materials
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• v.22 no.4
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• pp.254-259
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• 2015

$Bi_2Te_3$ related compounds show the best thermoelectric properties at room temperature. However, n-type $Bi_2Te_{2.7}Se_{0.3}$ showed no improvement on ZT values. To improve the thermolectric propterties of n-type $Bi_2Te_{2.7}Se_{0.3}$, this research has Cu-doped n-type powder. This study focused on effects of Cu-doping method on the thermoelectric properties of n-type materials, and evaluated the comparison between the Cu chemical and mechanical doping. The synthesized powder was manufactured by the spark plasma sintering(SPS). The thermoelectric properties of the sintered body were evaluated by measuring their Seebeck coefficient, electrical resistivity, thermal conductivity, and hall coefficient. An introduction of a small amount of Cu reduced the thermal conductivity and improved the electrical properties with Seebeck coefficient. The authors provided the optimal concentration of $Cu_{0.1}Bi_{1.99}Se_{0.3}Te_{2.7}$. A figure of merit (ZT) value of 1.22 was obtained for $Cu_{0.1}Bi_{1.9}Se_{0.3}Te_{2.7}$ at 373K by Cu chemical doping, which was obviously higher than those of $Cu_{0.1}Bi_{1.9}Se_{0.3}Te_{2.7}$ at 373K by Cu mechanical doping (ZT=0.56) and Cu-free $Bi_2Se_{0.3}Te_{2.7}$ (ZT=0.51).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.86-90
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• 2008

$CuInSe_2$ thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and heat treatment conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the $CuInSe_2$, Cu, In and Se were deposited in the named order. Among them, Cu and In were deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1:1, while the annealing temperature having an effect on the quality of the thin film was changed from $200^{\circ}C$ to $350^{\circ}C$ at intervals of $50^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1396-1397
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• 2006

Process variables for manufacturing the $CuInSe_2$ thin film were established in order to clarify optimum conditions for growth of the thin film depending upon process conditions (substrate temperature, sputtering pressure, DC/RF Power), and then by changing a number of vapor deposition conditions and Annealing conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the $CuInSe_2$, Cu, In and Se were vapor-deposited in the named order. Among them, Cu and In were vapor-deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1 : 1, while the surface temperature haying an effect on the quality of the thin film was changed from $100[^{\circ}C]$ to $300[^{\circ}C]$ at intervals of $50[^{\circ}C]$.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.88-94
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• 2014

The structural, optical and electrical properties of sputter-deposited CIGS films were directly influenced by the sputtering process parameters such as substrate temperature, working pressure, RF power and distance between target and substrate. CIGS thin films deposited by using a quaternary target revealed to be Se deficient due to Se low vapor pressure. This Se deficiency affected the overall stoichiometry of the films, causing the films to be Cu-rich. Current tends to pass through the Cu-Se channels which act as the shunting path increasing the film conductivity. The crystal structure of CIGS thin films depends on the substrate orientation due to the influence of surface morphology, grain size and stress of Mo substrate. The excess of Cu was removed from the CIGS films by KCN treatment, achieving a suitable Cu concentration (referred as Cu-poor) for the fabrication of solar cell. Due to high Cu concentrations on the CIGS film surface induced by Cu-Se phases after CIGS film deposition, KCN treatment proved to be necessary for the fabrication of high efficiency solar cells. Also during KCN treatment, dislocation density and lattice parameter decreased as excess Cu was removed, resulting in increase of bandgap and the decrease of conductivity of CIGS films. It was revealed that Cu-Se secondary phase could be removed by KCN wet etching of CIGS films, allowing the fabrication of high efficiency absorber layer.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.853-856
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• 2009

Highly polycrystalline copper indium diselenide (CuInSe2, CIS) thin films were deposited on glass or ITO glass substrates by two-stage metal organic chemical vapor deposition (MOCVD) at relatively mild conditions, using Cuand In/Se-containing precursors. First, pure Cu thin film was prepared on glass or ITO glass substrates by using a single-source precursor, bis(ethylbutyrylacetate)copper(II) or bis(ethylisobutyrylacetato)copper(II). Second, on the resulting Cu films, tris(N,N-ethylbutyldiselenocarbamato)indium(III) was treated to produce CuInSe2 films by MOCVD method at 400 ${^{\circ}C}$. These precursors are very stable in ambient conditions. In our process, it was quite easy to obtain high quality CIS thin films with less impurities and uniform thickness. Also, it was found that it is easy to control the stoichiometric ratio of relevant elements on demands, leading to Cu or In rich CIS thin films. These CIS films were analyzed by XRD, SEM, EDX, and Near-IR spectroscopy. The optical band gap of the stoichiometric CIS films was about 1.06 eV, which is within an optimal range for harvesting solar radiation energy.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.202-209
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• 2002

The stochiometric mix of evaporating materials for the $CuInSe_2$single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CuInSe_2$compound crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $620^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuInSe_2$single crystal thin films measured from Hall effect by van der Pauw method. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $CuInSe_2$single crystal thin film, we have found that the values of spin orbit splitting $\Delta$So and the crystal field splitting $\Delta$Cr. From the photoluminescence measurement on $CuInSe_2$single crystal thin film, we observed free exciton ($E_x$) existing only high quality crystal and neutral bound exciton ($A^{\circ}$, X) having very strong peak intensity. Then, the full-width-at-half-maximum (FWHM) and binding energy of neutral donor bound exciton were 7 meV and 5.9 meV, respectivity. By haynes rule, an activation energy of impurity was 59 meV.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.295-295
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• 2010

Nanoparticles of the compound semiconductor, Cu(In, Ga)Se2 (CIGS), were synthesized in solution under ambient pressure below $100^{\circ}C$ and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption spectroscopy and energy-dispersive X-ray (EDX) analyses. These materials have chalcopyrite crystal structures and the particle sizes less than 100 nm. Synthetic conditions were studied for the crystallized CIGS nanoparticles formation to prevent from side products of Cu2Se, Cu2-xSe, and CuSe etc. The single phase CIGS nanoparticles were applied to coating of thin films photovoltaic cells. The electro deposition of CIGS thin films is also a good non-vacuum technology and under investigation. In aqueous solutions, the different chemical compositions of CIGS thin films were obtained, depending on pH, concentration of starting materials and deposition potentials. The surface morphology of the prepared CIGS thin films depends on the complexing ligands to the solutions during the electrochemical deposition.