• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.163-166
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• 2001

The stochiometric mix of evaporating materials for the $ZnGa_{2}Se_{4}$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $ZnGa_{2}Se_{4}$ 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 $610^{\circ}C$ and $450^{\circ}C$, 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 $ZnGa_{2}Se_{4}$ single crystal trun films measured from Hall effect by van der Pauw method are $9.63{\times}10^{17}cm^{-3}$, $296cm^{2}/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c axis of the $ZnGa_{2}Se_{4}$ single crystal thin film, we have found that the values of spin orbit splitting $\Delta$ So and the crystal field splitting $\Delta$Cr were 251.9 meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on $ZnGa_{2}Se_{4}$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton $(A^{0},X)$ having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.167-170
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• 2001

The stochiometric mix of evaporating materials for the $CdGa_{2}Se_{4}$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_{2}Se_{4}$ 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 $630^{\circ}C$ and $420^{\circ}C$, 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 $CdGa_{2}Se_{4}$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3},345cm^{2}/V{\cdot}s$ 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 $\Delta$ So and the crystal field splitting $\Delta$Cr were 106.5 meV and 418.9 meV at 10 K, respectively. From the photoluminescence measurement on $CdGa_{2}Se_{4}$ single crystal thin film, we observed free excition (Ex) existing only high Quality crystal and neutral bound exiciton $(D^{0},X)$ having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule, an activation energy of impurity was 137 meV.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.12
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• pp.587-592
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• 2017

In this paper, we raise a question: what makes presence in artistic works. Presence has been defined as a physiological and emotional feeling which feels that he or she is immerged in a specific artworks when he/she is very interested in the artwork. We design and implemented an abstract media art "The Light" which uses the color, trace, and interactivity of light to measure quantitative presence. Frequency spectrum of light on specific object which we perceive makes color; Motion of light and its impact on object makes shape which perceived in our human visual system; Interactivity or perceived distance between object and observer makes intensity of perception. We experimented our images with subjective survey which includes PQS (presence questionnaire survey) and objective test using brain signals (EEG). From our interactive experimental moving images tested on 30 subject, we conclude that we can make more presence as we interact more with images. Photo-realistic images is just pass-by and it is transformed to abstract images, as we more focused on the images, and the essential components of the abstraction includes color, trace, and interaction with subjects.

• Journal of Surface Science and Engineering
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• v.51 no.2
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• pp.126-132
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• 2018

SnS thin films with different substrate temperatures ($150 {\sim}300^{\circ}C$) as process parameters were grown on soda-lime glass substrates by RF magnetron sputtering. The effects of substrate temperature on the structural and optical properties of SnS thin films were investigated by X-ray diffraction (XRD), Raman spectroscopy (Raman), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and Ultraviolet-visible-near infrared spectrophotometer (UV-Vis-NIR). All of the SnS thin films prepared at various substrate temperatures were polycrystalline orthorhombic structures with (111) planes preferentially oriented. The diffraction intensity of the (111) plane and the crystallite size were improved with increasing substrate temperature. The three major peaks (189, 222, $289cm^{-1}$) identified in Raman were exactly the same as the Raman spectra of monocrystalline SnS. From the XRD and Raman results, it was confirmed that all of the SnS thin films were formed into a single SnS phase without impurity phases such as $SnS_2$ and $Sn_2S_3$. In the optical transmittance spectrum, the critical wavelength of the absorption edge shifted to the long wavelength region as the substrate temperature increased. The optical bandgap was 1.67 eV at the substrate temperature of $150^{\circ}C$, 1.57 eV at $200^{\circ}C$, 1.50 eV at $250^{\circ}C$, and 1.44 eV at $300^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.93-93
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• 2003

Photoluminescence(PL) properties of Silicon nanocrystals (nc-Si) as a function of temperature is reported to consider the mechanism of PL. Nc-Si has been made by $Si^+$ ion-implantation into thermal $SiO_2$ and subsequent annealing. And after gold had been diffused at the same samples above, the resultant PL spectra has been compared to the PL spectra from the non-gold doped nc-Si. PL peak energy variation from nc-Si is same with the variation of energy bandgap of bulk silicon as temperature changes from 6 K to room temperature. This result may mean nc-Si is still indirect transition material like bulk silicon. Gold doped nc-Si reveals short peak wavelength of PL spectrum than gold undoped one. PL peak shift through gold doing process shows clearly the PL mechanism is not from defect or interface states. PL intensity increases from 6K to a certain temperature and then decrease to room temperature. This characteristic with temperature shows that phonon have a role for the luminescence as theory explains that electron and hole can be recombined radiatively by phonon's assist in nc-Si, which is almost impossible in bulk silicon. Therefore luminescence is observed in nc-Si constructed less than a few of unit cell and the peak energy of luminescence can be higher than the bulk bandgap energy by the bandgap widening effect occurs in nanostructure.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.434-436
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• 2013

Ga-doped ZnO (GZO) was substitutes of the SnO2:F films on soda lime glass substrate in the photovoltaic devices such as CIGS, CdTe and DSSC due to good properties and low cost. However, it was reported that the electrical resistivity of GZO is unstable above $300^{\circ}C$ in air atmosphere. To improve thermal stability of GZO thin films at high temperature above $300^{\circ}C$ an $TiO_2$ thin film was deposited on the top of GZO thin films as a barrier layer by Pulsed Laser Deposition (PLD) method. $TiO_2$ thin films were deposited at various thicknesses from 25 nm to 100 nm. Subsequently, these films were annealed at temperature of $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$ in air atmosphere for 20 min. The XRD measurement results showed all the films had a preferentially oriented ( 0 0 2 ) peak, and the intensity of ( 0 0 2 ) peak nearly did not change both GZO (300 nm) single layer and $TiO_2$ (50 nm)/GZO (300 nm) double layer. The resistivity of GZO (300 nm) single layer increased from $7.6{\times}10^{-4}{\Omega}m$ (RT) to $7.7{\times}10^{-2}{\Omega}m$ ($500^{\circ}C$). However, in the case of the $TiO_2$ (50 nm)/GZO (300 nm) double layer, resistivity showed small change from $7.9{\times}10^{-4}{\Omega}m$ (RT) to $5.2{\times}10^{-3}{\Omega}m$ ($500^{\circ}C$). Meanwhile, the average transmittance of all the films exceeded 80% in the visible spectrum, which suggests that these films will be suitable for photovoltaic devices.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1633-1637
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• 2010

The UV-vis absorption spectrum of protoporphyrin IX shows a very sharp and strong absorption maximum peak at 398 nm in acetonitrile-water mixture solution (1:1 v/v). When divalent metal ions such as $Cu^{2+}$, $Zn^{2+}$, and $Ca^{2+}$ ion were added to protoporphyrin IX, metal protoporphyrin IX complexes were thereby produced. Cu-protoporphyrin IX complexes have the largest formation constant ($K_f$) among them. The fluorescence intensity of protoporphyrin IX was diminished by the presence of $Cu^{2+}$, $Zn^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and $Ni^{2+}$ ions as quenchers. However, $Mg^{2+}$, $Mn^{2+}$, and $Ni^{2+}$ ions are hardly combined with protoporphyrin IX. $Mg^{2+}$ ion does not take part in the fluorescence quenching process of protoporphyrin IX in acetonitrile-water mixture solution. According to the Stern-Volmer plots, fluorescence quenching by $Cu^{2+}$, $Zn^{2+}$, and $Ca^{2+}$ ions involves static quenching, which is due to complex formation. On the contrary, dynamic quenching has a large influence on the overall quenching process, when $Mn^{2+}$ and $Ni^{2+}$ ions were added to protoporphyrin IX in acetonitrile-water mixture solution.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2923-2928
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• 2010

This study examined the synthesis of the crystal structure of bis(2,2'-bipyridine)nitrato zinc (II) nitrate, $[Zn(bipy)_2(NO_3)]^+NO_3^-$ using a microwave treatment at 300 W and 60 Hz for the application to dye-sensitized solar cells. The simulated complex structure of the complex was optimized with the density functional theory calculations for the UV-vis spectrum of the ground state using Gaussian 03 at the B3LYP/LANL2DZ level. The structure of the acquired complex was expected a penta-coordination with four nitrogen atoms of bipyridine and the oxygen bond of the $NO_3^-$ ion. The reflectance UV-vis absorption spectra exhibited two absorptions (L-L transfers) that were assigned to the transfers from the ligand ($\sigma$, $\pi$) of $NO_3$ to the ligand ($\sigma^*$, $\pi^*$) of pyridine at around 200 - 350 nm, and from the non-bonding orbital (n) of O in $NO_3$ to the p-orbital of pyridine at around 450 - 550 nm, respectively. The photoelectric efficiency was approximately 0.397% in the dye-sensitized solar cells with the nanometer-sized $TiO_2$ at an open-circuit voltage (Voc) of 0.39 V, a short-circuit current density (Jsc) of $1.79\;mA/cm^2$, and an incident light intensity of $100\;mW/cm^2$.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.152-158
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• 2009

Spectrophotometric investigation of the interaction of Cefpodoxime proxetil (CFP) with $Ca^{2+},\;Mg^{2+},\;Mn^{2+},\;Fe^{3+},\;Co^{2+},\;Ni^{2+},\;Cu^{2+}$ and $Zn^{2+}$ in acidic medium showed the formation of 1:1 complex. The absorption spectrum of pure drug exhibits two prominent peaks at 270 and 345 nm. Its spectra scanned at several pH exhibited two isosbestic points (305 and 330 nm) indicating the presence of zwitterionic condition of drug in solution phase. The fluorescence emission spectra of CFP in presence of different concentrations of metal ions showed enhancement in fluorescence intensity which is ascribed to chelating enhancement fluorescence effect (CHEF). The stoichiometry of the complexes was determined by Job’s and Benesi-Hildebrand method. The stability of the complexes follow the order $Ca^{2+}\;<\;Mg^{2+}\;<\;Co^{2+}\;<\;Ni^{2+}\;<\;Zn^{2+}\;<\;Mn^{2+}\;<\;Cu^{2+}\;<\;Fe^{3+}$.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.397-401
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• 2009

The complexes of $C_2-\;and\;C_6$-dihydroceramides with transition metal ions have been investigated by using Electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The formation and fragmentation pathways of several doubly charged cluster ions as well as singly charged cluster ions of $C_2-\;and\;C_6$-dihydroceramides with transition metal ions have studied by ESI-MS/MS in the positive mode. Under ESI conditions, dihydroceramides form singly and doubly charged complexes with transition metal ions $(Mn^{2+},\;Fe^{2+},\;Co^{2+},\;Ni^{2+},\;and\;Zn^{2+}\;except\;Cu^{2+})$ with the compositions of $[DHCer+M+2H^2O-H]^+,\;[2DHCer+M+2H2O-H]^+,\;[3DHCer+M+2H2O-H]^+,\;[2DHCer+M]^{2+},\;[3DHCer+M]^{2+},\;[4DHCer+M]^{2+},\;[5DHCer+M]^{2+},\;and\;[6DHCer+M]^{2+}\;(DHCer\;=\;C_2-\;or\;C_6$-dihydroceramide, M = transition metal ion). The different complexation behavior of copper is responsible for relatively lower affinity of dihydroceramides to copper compared to those of other transition metals. It is also found that in the mass spectrum of the dihydroceramide complexes with copper(II), [2DHCer+Cu-H]$^+$ was observed with considerable intensity as well as [2DHCer+Cu+2$H_2O-H]^+$ due to its different geometry from those of other metals.