• 한국초전도학회:학술대회논문집
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• v.9
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• pp.280-290
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• 1999

The microstructures of a Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.6}Ca_2Cu_3O_{9+{\delta}}$/Ag tape (tape I ) with J$_c$ of 17,600 A/cm$^2$ at 77 K and 0 T and three Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.8}Ba_{0.2}Ca_{2.2}Cu_3O_{9+{\delta}}$/Ag tapes with J$_c$'s of 9,300 (tape II), 16,700 (tape III) and 25,200 A/cm$^2$ (tape IV)prepared using the powder-in-tube method and an in-situ reaction method, were investigated using scanning electron microscopy and high-resolution transmission electron microscopy, and compared each other. ln the tape preparation, an intermediate rolling process was incorporated during final heat-treatment for the last tape, but not for the rest of the tapes. The microstructural analysis revealed clear differences in grain-texturing, crystallographic defects and impurity phases, depending on the chemical composition of the tape. Tendency of directional grain-alignment increased in an order of tapes I, II III and IV. In tape IV, T1-1223 grains are textured, at least in local regions. In crystallographic defects, while stacking faults were prevalent in the former composition, dislocations and voids were frequently observed in the latter. Also impurity phases were appeared to be more abundant in the former than in the latter. The relationship between 1,and the microstructure in the tapes was attempted to explain in a term of grain-linking.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.92-98
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• 1998

Degradation and recovery of damping capacity in a Cu-65%Mn alloy have been studied. When the alloy was isothermally aged at $400^{\circ}C$, the highest damping capacity was observed after aging for 4 hours. In case when the alloy aged at $400^{\circ}C$ for 4 hours was maintained at $100^{\circ}C$, the damping capacity gradually decreased with time. The microstructural observations showed that the formation of subdomains and ${\alpha}$-Mn precipitates are responsible for the degradation of damping capacity. When the degraded specimen was reheated at $250^{\circ}C$ for 30 minutes, the damping capacity was recovered considerably owing to the redistribution of impurity atoms, the extinction of subdomains and the release of damping sources from ${\alpha}$-Mn precipitates during the repeated transformation, fcc${\leftrightarrow}$fct.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.297-301
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• 1999

High quality CdTe single crystal for the solar cell fabrication was grown by vertical Bridgman method. The etch pits patterns of {111} surfaces of CdTe etched by Nakagawa solution was observed the {11} A composed of Cd atoms with typical triangle etch pits of pyramid mode. From the photoluminescence measurement of {111} A, we observed free exciton $(E_x)$ existing only high quality crystal and neutral acceptor bound exciton ($A^{\circ}$, X) having very strong peak intensity. Then, the full width at half maximum and binding energy of neutral acceptor bound exciton were 7 meV and 5.9 meV, respectively. By Haynes rule, and activation energy of impurity was 59meV. Therefore, the origins on impurity level acting as a neutral acceptor were associated Ag or Cu elements.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.3
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• pp.161-168
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• 1996

The purpose of this study is to investigate the effect of impurity level and fabrication processes on the strength, fracture toughness and fatigue resistance of 7075, 7050 and 7175 high strength aluminum forgings. It has been verified that plane strain fracture toughness and fatigue characteristics of a specially processed 7175S-T74 alloy is superior to a conventionally processed 7075-T6/T73, 7050-T74 and 7175-T74 alloys. These beneficial effects primarily arise from two view points, i.e., the effect of reducing the impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as $Al_7Cu_2Fe$ and $Mg_2Si$. Futher reduction of the amount of nonequilibrium second phase particles has been observed by applying a special fabrication process.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.6-11
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• 2012

In order to understand a process of contaminants removal on surface of Cu seed layer (Cu seed/Ti/Si) by sputter deposition, we investigated the changed morphology and states of Cu seed surface after pretreatment in alkali degreasing Metex TS-40A solution according to dipping time. After TS-40A pretreatment, the surface morphology with clearer grains was observed by Field emission scanning electron microscope and the changed surface chemical states and impurities on surface of samples were checked by X-ray photoelectron spectroscopy. Dipping time in TS-40A solution had very little effect on surface of Cu seed layer. After pretreatment, much carbons and little oxygens on surface of Cu seed were eliminated and the decrease of peaks corresponded to O=C and $Cu(OH)_2$ was estimated. However, Si content (=silicate) was detected on sample surface. We think that the silicate impurity forms on Cu seed by chemical reaction of TS-40A solution included silicate component. By pretreatment of alkali degreasing Metex TS-40A solution, it showed an excellent effect in removal of O=C and $Cu(OH)_2$ on Cu seed layer, but the silicate was formed on surface of Cu seed. Therefore, another cleaning process such as acid cleaning is required for removal of this silicate in use of this alkali degreasing.

• 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.

• 보존과학연구
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• s.10
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• pp.1-40
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• 1989

Between 1976 and 1984 approximately 26.7 tons of Chinese coins were recovered from a shipwreck which was found at the seabed of the Shin an area in the south-western coast of the Korean peninsula. Elements, Cu, Pb, Sn, Fe, Sb, As, Zn, Ag, Ni, Co and Mn, of 54 pieces of the coins were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AIS). The result shows that Ch, Pb, and Sn were found to be major elements roughly the coins with the ratio of 7 : 2 : 1, respectively. Trace elements were classified into 3 levels according to the avarage concentration : Fe,As and Sb(0.1-0.5%), Ag, Mi, Co and Zn(100-1000ppm) and Mn(10ppm). Some systematic tendencies are observed in the composition change with a function of their minting ages .The Wuzhu coins(오수전) from the Eastern Han dynasty(A.D.25-219 )are much more abundant in Cu than the coins of Tang dynasty(A.D.618-907) and later periods. Major element compositions of the Kai -tong Vuan-Bao(개통원보) coins from the Tang dynasty, were remarkably variable. In general, however, the Tang dynasty coins were much more abundant in Cu than the Song dynasty(A.S.S60-1279) coins. The amount of major elements Cu and Sn decreases while that of Pb in creasesby passage of age from the Bei Song dynasty(A.D.960-1127) to later Nam Song dynasty (A.D.1127-1279 ). It means that the quality of coins mere degraded. The amounts of trace elemends(Fe, As, Co, Hn) increases with the above age. High amounts of trace elements are supposed to be a reflection of immaturity of minting techniques or use of impurity-rich raw materials. The Jin dynasty(A.D.1125-1234) coins are found to be rich in Sn and thus contain Pb as the third component. It is quite different from the coins of the Song dynasty. The Zhi-dai Tong-Bao(지대통보) coins of the Yuan dynasty from A.0.1310 are much more abundant in Cu and Sn than those of the Nam Song dynasty .

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.32-35
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• 2008

Thermally stable diffusion barrier of tungsten carbon nitride(W-C-N) and of tungsten boron carbon nitride(W-B-C-N) thin films have studied to investigate the impurity behaviors of boron and nitrogen. In this paper we newly deposited tungsten boron carbon nitride(W-B-C-N) thin film for various $W_2B$ target power on silicon substrate. The impurities of the 100nm-thick W-C-N and W-B-C-N thin films provide stuffing effect for preventing the inter-diffusion between W-C-N or W-B-C-N thin films and silicon during the high temperature($700^{\circ}C{\sim}1000^{\circ}C$) annealing process.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.1-11
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• 2005

The stoichiometric mixture of evaporating materials for the $CuInSe_2$ single crystal thin film was prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuInSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.783\;{\AA}$ and $11.621\;{\AA}$, respectively. To obtain the $CuInSe_2$ single crystal thin film, $CuInSe_2$ mixed crystal was deposited on throughly etched GaAs(100) by the HWE(Hot Wall Epitaxy) system. The source and substrate temperature were $620^{\circ}C$ and $410^{\circ}C$ respectively. The crystalline structure of $CuInSe_2$ single crystal thin film was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of Van der Pauw and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by impurity scattering in the temperature range 30 K to 100 K and by lattice scattering in the temperature range 100 K to 293 K. 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, $E_g(T)=1.1851\;eV-(8.99{\times}10^{-4}\;eV/K)T^2/(T+153\;K)$. The open-circuit voltage, short current density, fill factor, and conversion efficiency of $n-CdS/p-CuGaSe_2$ heterojunction solar cells under $80\;mW/cm^2$ illumination were found to be 0.51V, $29.3\;mA/cm^2$, 0.76 and 14.3 %, respectively.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.495-502
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• 2005

Copper was plated on the tungsten substrate by use of a direct copper electroless plating. The optimum deposition conditions were found to be with a concentration of $CuSO_4$ 7.615 g/L, EDTA of 10.258 g/L, and glyoxylic acid of 7 g/L, respectively. The solution temperature was maintained at $60^{\circ}C$. The pH was varied from 11.0 to 12.8. After the deposition, the properties of the copper film were investigated with X-ray diffractometer (XRD), Field emission secondary electron microscope (FESEM), Atomic force microscope (AFM), X-ray photoelectron spectroscope (XPS), and Rutherford backscattering spectroscope (RBS). The best deposition condition was founded to be the solution pH of 11.8. In the case of 10 min deposition at the pH of 11.8, the grain shape was spherical, Cu phase was pure without impurity peak ($Cu_2O$ peak), and the surface root mean square roughness was about 11 nm. The thickness of the film turned out to be 140 nm after deposition for 12 min and the deposition rate was found to be about 12 nm/min. Increase in pH induced a formation of $Cu_2O$ phase with a long rectangular grain shape. The pH control seems to play an important role for the orientation of Cu in electroless deposition. The deposited copper concentration was 99 atomic percent according to RBS. The resulting Cu/W film yielded a good adhesive strength, because Cu/W alloy forms during electroless deposition.