• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.182-183
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• 2006

$CuInSe_2$ single crystal thin films was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. 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, $E_g(T)\;=\;1.1851\;eV\;-\;(8.99\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;153K)$. After the as-grown $CuInSe_2$ single crystal thin films was annealed in Cu-, Se-, and In-atmospheres, the origin of point defects of $CuInSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K.

• Journal of the Korean institute of surface engineering
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• v.30 no.2
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• pp.136-143
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• 1997

The photvoltaic power system has received considerable attention as the petroleumalterative energies to the environmental problems in the wored scale. $CuLnSe_2$is one ofthe most promising materials for the fabrication of large-area modules and low cost photovoltaic devices. Sulfur solute CuInSe2 thin films were prepared by RF sputtering using powder targer which were previously compacted by powder of $Cu_2Se, \;In_2Se_3, \;Cu_2S, \;and\;In_2S_3$ in various ratios. The results induicated that the sulfur ratio, the(112) texture, and the energy band gap were increased by the increase of the S/(S+Se) that was controlled by stoichiometric compound. The energy band gap can be shifted from 1.04eV to 1.50eV by abjusting the S/(S+Se) ratio, which maich it possible to obtain perfect match to the solar spectrum.

• New & Renewable Energy
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• v.3 no.4
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• pp.54-62
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• 2007

In this paper, we report the research highlight on the preparation and characterization of Indium-free $Cu_2ZnSnSe_4$ and Indium-reduced $CulnZnSe_2$ thin films in order to seek the viability of these absorber materials to be applied in thin film solar cells. The films of $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ were prepared using mixed binary chalcogenides powders. It was observed that Cu concentration was a function of substrate temperature as well as CuSe mole ratio in the target. Under an optimized condition, $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ thin films grew with strong [112]. [220/204] and [312/116] reflections. Both $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ films were found to exhibit a high absorption coefficient of $104^4cm^{-1}\;Cu_2ZnSnSe_4$ film showed a band gap of 1.5eV which closes to the optimum band gap of an ideal solar absorber for a solar cell. On the other side, an increase of optical band gap from 1.0 to 1.25eV was found to be proportional with an increase of Zn concentration in the $CulnZnSe_2$ film. All films in this study revealed a p-type semiconductor characteristic.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.396-396
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• 2009

Chalcopyrite semiconductor $CuInSe_2$ nanoparticles were prepared using a low temperature colloidal route by reacting the starting materials (CuI, $InI_3$ and $Na_2Se$) in solvents. After synthesised $CuInSe_2$ nanoparticles precursors were mixed with organic binder for the viscosity of the precursor slurry to be suitable for the doctor blade method. The mixture of $CuInSe_2$ and binder was deposited onto molybdenum-coated sodalime glass substrates to form thin film. The precursor thin films were preheated on the hot plate to remove remaining solvents and binder material. After subsequent thermal processing of the thin film under a selenium ambient, $CuInSe_2$ absorber layer with grain size significantly lager than that of the nanoparticles was formed.

• ETRI Journal
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• v.34 no.5
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• pp.779-782
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• 2012

$CuIn_{1-x}Ga_xSe_2$ (CIGS) thin films are grown on Mo/soda lime glass using a reactive sputtering process in which a Se cracker is used to deliver reactive Se molecules. The Cu and $(In_{0.7}Ga_{0.3})_2Se_3$ targets are simultaneously sputtered under the delivery of reactive Se. The effects of Se flux on film composition are investigated. The Cu/(In+Ga) composition ratio increases as the Se flux increases at a plasma power of less than 30 W for the Cu target. The (112) crystal orientation becomes dominant, and crystal grain size is larger with Se flux. The power conversion efficiency of a solar cell fabricated using an 800-nm CIGS film is 8.5%.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.59-70
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• 2003

A stoichiometric mixture of evaporating materials for $CuGaSe_2$ single crystal thin films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuGaSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.615{\AA}$ and $11.025{\AA}$, respectively. To obtain the single crystal thin films, $CuGaSe_2$ 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 $610^{\circ}C$ and $450^{\circ}C$, 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 $CuGaSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $5.01\times10^{17}cm^{-3}$ and $245cm^2/V{\cdot}s$ at 293K. respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T)=1.7998 eV-($8.7489\times10^{-4}$ eV/K)$T^2$/(T+335K). After the as-grown $CuGaSe_2$ single crystal thin films was annealed in Cu-, Se-, and Ga-atmospheres, the origin of point defects of $CuGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{CU},\;V_{Se},\;Cu_{int}$ and $Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuGaSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $CuGaSe_2$/GaAs did not form the native defects because Ga in $CuGaSe_2$ single crystal thin films existed in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.352-356
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• 2003

A stoichiometric mixture of evaporating materials for $CuGaSe_2$ single crystal am films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuGaSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.615\;{\AA}\;and\;11.025\;{\AA}$, respectively. To obtain the single crystal thin films, $CuGaSe_2$ 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 $610^{\circ}C$ and $450^{\circ}C$, 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 $CuGaSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;:\;1.7998\;eV\;-\;(8.7489\;{\times}\;10^{-4}\;eV/K)T^2(T\;+\;335\;K)$. After the as-grown $CuGaSe_2$ single crystal thin films was annealed in Cu-, Se-, and Ga-atmospheres, the origin of point defects of $CuGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{CU}$, $V_{Se}$, $CU_{int}$, and $Se_{int}$, obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuGaSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $CuGaSe_2/GaAs$ did not form the native defects because Ga in $CuGaSe_2$ single crystal thin films existed in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.258-259
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• 2005

[ $CuInSe_2$ ] thin films were fabricated at various fabrication conditions (substrate temperature, sputtering pressure, BC/RF power, vapor deposition, heat treatment). And structural and electrical properties were measured in order to certify optimum conditions for growth of the ternary compound semiconductor $CuInSe_2$ thin films with stoichiometric composition. $CuInSe_2$ thin film was well made at the heat treatment of 500[$^{\circ}C$] of SLG/Cu/In/Se stacked elemental layer which was prepared by sputter and thermal evaporator, and chemical composition of the thin film was analyzed nearly as the proportion of 1 : 1 : 2. At the same time, carrier concentration, hall mobility and resistivity of the thin films was $1.27\sim9.88\times10^{17}[cm^{-3}]$, $49.95\sim185[cm^2/V{\cdot}s]$ and $10^{-1}\sim10^{-2}[\Omega{\cdot}cm]$, respectively

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2273-2279
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• 2012

This research is based on fabricating Cu(In,Ga)$Se_2$ thin-film by co-evaporation method. On $1^{st}$ - stage, $In_2Se_3$ phase appeared when the substrate temperature reached to $400^{\circ}C$, however, there was small effect between the substrate temperature and absorbency spectrum on $2^{nd}$, $3^{rd}$ - stage because the average thickness of the thin-film was $1{\mu}m$ or higher. SEM and XRD was measured on $2^{nd}$ and $3^{rd}$ stage and it showed as the substrate temperature increases, the density of the crystal structure increased with the decreament of the vacancy. Furthermore, the formation of Cu(In0.7Ga0.3)$Se_2$ phase showed at $480^{\circ}C$ and $500^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.383-386
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• 2002

Polycrystalline Cu(In,Ga)Se$_2$(CIGS) thin-films were grown by co-evaporation on a soda lime glass substrate. In this paper the effects of the Se evaporation temperature on the properties of CuIn0.75Ga0.25Se2 (CIGS) thin films. Structure, surface morphology and optical properties of CIGS thin films deposited at various Se evaporation temperatures have been investigated using a number of analysis techniques. X-ray diffraction (XRD) analysis shows that CIGS films exhibit a strong <112> preferred orientation. As expected, at higher Se evaporation temperatures the films displayed a lower degree of crystallinity. The <112> peak was also enhanced and other CIGS peaks appeared simultaneously. These results were supported by experimental work using scanning electron microscopy When the Se evaporation temperature was increased, the average grain size also decreased together with a reduction Cu content. The Se evaporation temperature also had a significant inf1uence on the transmission spectra. Increasing the Se evaporation temperature, the cell efficiency was improved dramatically to 11.75% with Voc = 556 mV, Jsc = 32.17 mA/cm2 and FF = 0.66. The Se evaporation temperature is an important parameter in thin film deposition regardless of the deposition technique being used to deposit thin films