• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.445-454
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• 2001

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$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 62$0^{\circ}C$ and 41$0^{\circ}C$, 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 fby van der Pauw method are 9.62x10$^{16}$ cm$^{-3}$ , 296$\textrm{cm}^2$/V.s at 293 K, respectively. 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 he values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 6.1 meV and 175.2 meV at 10K, respectively. From the photoluminescence measurement on CuInSe$_2$ single crystal thin film we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$,X) having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy of neutral donor bound excition were 7meV and 5.9meV, respectivity. by Haynes rule, an activation energy of impurity was 50 meV.

• Korean Journal of Materials Research
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• v.25 no.4
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• pp.196-201
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• 2015

This paper presents the impact of partial shading on $CuIn_xGa_{(1-x)}Se_2(CIGS)$ photovoltaic(PV) modules with bypass diodes. When the CIGS PV modules were partially shaded, the modules were under conditions of partial reverse bias. We investigated the characterization of the bypass diode and solar cell properties of the CIGS PV modules when these was partially shaded, comparing the results with those for a crystalline silicon module. In crystalline silicon modules, the bypass diode was operated at a partial shade modules of 1.67 % shading. This protected the crystalline silicon module from hot spot damage. In CIGS thin film modules, on the other hand, the bypass diode was not operated before 20 % shading. This caused damage because of hotspots, which occurred as wormlike defects in the CIGS thin film module. Moreover, the bypass diode adapted to the CIGS thin film module was operated fully at 60% shading, while the CIGS thin film module was not operated under these conditions. It is known that the bypass diode adapted to the CIGS thin film module operated more slowly than that of the crystalline silicon module; this bypass diode also failed to protect the module from damage. This was because of the reverse saturation current of the CIGS thin film, $1.99{\times}10^{-5}A/cm^2$, which was higher than that of crystalline silicon, $8.11{\times}10^{-7}A/cm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.503-509
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• 2013

In this study, $Cu(In_{1-x},Ga_x)Se_2$ (CIGS) thin films were prepared on the Mo coated soda-lime glass by the DC magnetron sputtering and a subsequent selenization process. For the selenization process, selenization rapid thermal process(RTP) with cracker cell, which was helpful to smaller an atomic of Se, was adopted. To make CIGS layer, they were then annealed with the cracked Se. Based on this selenization method, we made several CIGS thin film and investigated the effects of In deposition time, and selenization time. Through x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM), it is found that the Mo/In/CuGa structure and the high sputtering power shows the dominant chalcopyrite structure and have a uniform distribution of the grain size. The CIGS films with the In deposition time of 5 min has the best structure due to the smooth surface. And CIGS films with the selenization time of 50 min show good crystalline growth without any voids.

• 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.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.83-83
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• 2003

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$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 62$0^{\circ}C$ and 41$0^{\circ}C$, 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 are 9.62$\times$10$^{16}$ cm$^{-3}$ , 296 $\textrm{cm}^2$/V.s at 293 K, respectively 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 ΔSo and the crystal field splitting ΔCr were 6.1 meV and 175.2 meV at 10 K, respectively. From the photoluminescence measurement on CuInSe$_2$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$,X) having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral donor bound excition 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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• 2014.02a
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• pp.464.1-464.1
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• 2014

Among numerous material candidates, Cu(InxGa1-x)(SySe2-y) (CIGS) thin films have emerged as promising material candidates for thin film solar cell applications due to the high energy conversion efficiency and relatively low fabrication cost. The CIGS thin film solar cells consist of several materials, including Mo back contacts, ZnO-based window layers, and CdS buffer layers. All these materials have different crystal structures and contain quite distinct chemical elements, and hence the device characterization requires careful analyses. Most of all, identification of the major trap states resulting in the carrier recombination processes is a key step toward realization of high efficiency CIGS solar cells. We have carried out electrical investigations of CIGS thin film solar cells to specify the major trap states and their roles in photovoltaic performance. In particular, we have used the temperature-dependent transport characterizations and admittance spectroscopy. In this presentation, we will introduce some exemplary studies of DC and AC electrical characteristics of the CIGS solar cells.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.244-252
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• 2004

A stoichiometric mixture of evaporating materials for $CuInSe_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $_CuInSe2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the 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 with Hall effect by van der Pauw method are $9.62\times10^{16}/\textrm{cm}^3$, 296 $\textrm{cm}^2$/Vㆍs at 293 K, respectively. The temperature dependence of the energy band gap of the $CuInSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 1.1851 eV -($8.99\times10^{-4} eV/K)T^2$(T + 153 K). The crystal field and the spin-orbit splitting energies for the valence band of the CuInSe$_2$ have been estimated to be 0.0087 eV and 0.2329 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the Δso definitely exists in the $\Gamma$6 states of the valence band of the $CuInSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1-, B_1$-와 $C_1$-exciton peaks for n = 1.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.444.1-444.1
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• 2014

높은 광흡수 계수를 갖는 Cu(In,Ga)Se2(CIGS) 화합물 박막 소재는 고효율 태양전지 양산을 위해 가장 전도유망한 재료이나 상대적으로 매장량이 적은 In 및 Ga을 사용한다는 소재적 한계가 있다. Cu2ZnSnSe4(CZTSe) 혹은 Cu2ZnSnS4(CZTS)와 같은 Cu-Zn-Sn-Se계 화합물 반도체는 CIGS 내 희소원소인 In과 Ga이 범용원소인 Zn 및 Sn으로 대체된 소재로써 미래형 저가 태양전지 개발을 위해 활발히 연구되고 있는데, 그 화합물 조합에 따라 0.8eV부터 1.5eV까지의 에너지 밴드갭을 갖는 것으로 알려져 있다. 본 연구에서는 열분해법으로 CZTS 나노 입자를 합성하였다. 용매로 Oleylamine을 사용하였는데, $220^{\circ}C{\sim}340^{\circ}C$의 온도 범위에서 3시간 30분 동안 CZTS 나노입자를 합성하였고, $240^{\circ}C$에서 3시간~5시간까지 합성하였다. 헥산을 이용하여 원심분리기와 초음파세척기로 용매인 Oleylamine을 제거하였고, 진공오븐에서 건조된 CZTS 분말의 FE-SEM(Field Emission Scanning Electron Microscope), XRD(X-Ray Diffraction), EDS(Energy Dispersive Spectroscopy) 분석 등을 통해 합성온도에 따른 구조적, 화학적 조성 변화를 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.321.1-321.1
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• 2013

높은 광흡수 계수를 갖는 Cu(In,Ga)Se2(CIGS) 화합물 박막 소재는 고효율 태양전지 양산을 위해 가장 전도유망한 재료이나 상대적으로 매장량이 적은 In 및 Ga을 사용한다는 소재적 한계가 있다. Cu2ZnSnSe4(CZTSe) 혹은 Cu2ZnSnS4(CZTS)와 같은 Cu-Zn-Sn-Se계 화합물 반도체는 CIGS 내 희소원소인 In과 Ga이 범용원소인 Zn 및 Sn으로 대체된 소재로써 미래형 저가 태양전지 개발을 위해 활발히 연구되고 있는데, 그 화합물 조합에 따라 0.8eV부터 1.5eV까지의 에너지 밴드갭을 갖는 것으로 알려져 있다. 본 연구에서는 열분해법으로 CZTS 나노 입자를 합성하였다. 용매로 Oleylamine을 사용하였는데, $260{\sim}340^{\circ}C$의 온도 범위에서 5시간 30분 동안 CZTS 나노입자를 합성하였고, $300^{\circ}C$에서 5시간 30분~9시간까지 합성하였다. 헥산을 이용하여 원심분리기와 초음파세척기로 용매인 Oleylamine을 제거하였고, 진공오븐에서 건조된 CZTS 분말의 FE-SEM (Field Emission Scanning Electron Microscope), XRD (X-Ray Diffraction), EDS (Energy Dispersive Spectroscopy) 분석 등을 통해 합성온도에 따른 구조적, 화학적 조성 변화를 조사하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.108-111
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• 2002

CIGS film has been fabricated on soda-lime glass, which is coated with Mo film. by multi-source evaporation process. The films has been prepared with thickness of 1.0 ${\mu}m$, 1.75${\mu}m$, 2.0${\mu}m$, 2.3${\mu}m$, and 3.0${\mu}m$. X-ray diffraction analysis with film thickness shows that CIGS films exhibit a strong (112) preferred orientation. Furthermore. CIGS films exhibited distinctly decreasing the full width of half-maximum and (112) preferred peak with film thickness. Also, The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the interplanar spacing were examined by X-ray diffraction. The preparation condition and the characteristics of the unit layers were as followings ; Mo back contact DC sputter, CIGS absorber layer : three-stage coevaporation, CdS buffer layer : chemical bath deposition, ZnO window layer : RF sputtering, $MgF_2$ antireflectance : E-gun evaporation