• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.5
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• pp.1-4
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• 1982

Single crystals of InSe were obtained by the Bridgman method. The crystal structure was hombohedral(R3m) with lattice paramete. a=4.02A, c=24.96A. At 300$^{\circ}$K the electrical conductivity was about ~10-2($\Omega$.cm)-1, reslpectively. The electrical conductivity type was n- type. The donor level located at 0.072eV below the conduction band. The Photosensitivity was observed in range from 840nm to 1120nm. The energy gap of InSe single crystal measured from the photoconductivity and the optical transmittance spectrum was 1.20eV, 1.21eV, respectively.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1341-1346
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• 2004

Detailed flame structures of the opposed flames formed for different oxidant compositions are studied numerically. The detailed chemical reactions are modeled by using the CHEMKIN code. Only the $CO_{2}$ and $H_{2}O$ are assumed to participate by absorbing the radiative energy while all other gases are assumed to be transparent. The discrete ordinates method and a narrow band based WSGGM with a gray gas regrouping technique are applied for modeling the radiative transfer through non-homogeneous and non-isothermal combustion gas mixtures generated by the opposed flow flames. The results show that the different radiation model can cause different results for flame structures and the WSGGM with gray gas regrouping is successful in modeling the opposed flames with non-gray gas mixture. The results also show that a reasonable information on the flame structure can be obtained from the modeling by considering different chemical compositions of the oxidant.

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.293-300
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• 2005

ZnO:Li epilayers were synthesized on sapphire substrates by the pulesd laser deposition (PLD) after the surface of the ZnO:Li sintered pellet was irradiated by the ArF (193 nm) excimer laser. The growth temperature was fixed at $400^{\circ}C$. The crystalline structure of epilayers was investigated by the photoluminescence (PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of epilayers measured by van der Pauw-Hall method are $2.69\times10cm^{-3}$ and $52.137cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of epilayers obtained from the absorption spectra is well described by the Varshni's relation, $E_g(T)=3.5128eV{\cdot}(9.51\times10^{-4}eV/K)T^2/(T+280K)$. After the as-grown ZnO:Li epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO:Li has been investigated by PL at 10 K. The Peaks of native defects of $V_{zn},\;V_o,\;Zn_{int},\;and\;O_{int}$ showned on PL spectrum are classified as a donors or accepters type. We confirm that $ZnO:Li/Al_2O_3$ in vacuum do not form the native defects because ZnO:Li epilayers in vacuum existe in the form of stable bonds.

• Journal of Ginseng Research
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• v.14 no.2
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• pp.310-316
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• 1990

This study was focused on the characterization of mitochondrial DNA (mtDNA) for molecular 9enetical approach of energy Production related mechanism in Panax ginseng. The simple and efficient method of mtDNA isolation from ginseng has been developed by modification of recently advanced methods. This procedure can successfully apply to mtDNA isolation of several plants. mtDNA of etiolated shoot and one-year root were digested with restriction endonucleases, but that of 6-year root not. Any difference was not observed in the restriction endonuclease digestion patterns among the ginseng variants. Molecular size of ginseng mtDNA was estimated at least 159 kb by the restriction endonuclease fragment analysis. The 4.5 kb extra band at the lane of EcoRII treatment could be observed in restriction patterns digested with the methylation sensitive endonucleases, BstN I and EcoRII. For construction of mitochondrial genomic library of ginseng, mtDNA was partially digested with EcoRl, and packaged with EMBL4 phage vector. Genomic library was screened and purified for further research including restriction mapping of ginseng mtDNA, and cloning of the genes. The gene of ATP synthase A subunit was cloned from the purified EMBL4 library clone No. 16. Now, clone No. 16 is subcloned for structure gene sequence analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.712-718
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• 2003

The effects of nitrogen ion implantation on vacuum evaporated cadmium sulphide (CdS) thin films were investigated by X-ray diffraction, optical transmittance spectra, and Raman scattering studies. The as-deposited CdS films have a hexagonal structure with preferential (0 0 2) orientation. Formation of Cd metallic clusters was observed in ion implanted films from the XRD patterns. The band gap of N+ implanted films decreased, whereas the optical absorption coefficient values increased with the increase of implantation dose. The Raman peak position appeared at 299 cm-1 and the FWHM increased with the ion dose. A decrease in the area of Raman peak of CdS Al(LO) mode is seen on implantation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.562-568
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• 2008

In this paper, the hole injection layer(HIL) materials have been synthesized and analyzed. Their HOMO levels are $4.93{\sim}5.22\;eV$, and their energy band gaps are $2.74{\sim}3.19\;eV$. Their glass transition temperatures($T_g$) are all above $114^{\circ}C$, which implies that they are highly thermal-stable. The green OLED devices with a structure of ITO(150 nm)/NEW_HIL(50 nm)/NPB(30 nm)/$Alq_3$(50 nm)/Al:Li(100 nm) were fabricated and tested, incorporating these newly synthesized HIL materials. According to the test results of OLED devices, the I-V-L performances of these devices increase in the following sequence: ELM307 > ELM200 > ELM321 > ELM327 > ELM325. In addition, the OLED device with ELM307 as a HIL has the highest brightness and efficiency at the same driving voltage. These experimental results have shown that ELM307 can be used as one of the most promising candidates for HIL materials.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.257-260
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• 2007

In this study, $CuInSe_{2}$ (CISe) and $CuInZnSe_{2}$ (CIZSe) thin films were prepared on Corning 1737 glass by radio frequency (RF) magnetron sputtering from binary chalcogenide mixed powder targets. The targets were initially prepared by mixing appropriate weights of CuSe, InSe powder and various ZnSe contents. From the film bulk analysis result, it is observed that Zn concentration in the films increases proportionally with the addition of ZnSe in the sputtering targets. Under optimized conditions, CISe and CIZSe thin films grow as a chalcopyrite structure with strong (112), (220/204) and (312/116) reflections. Films are found to exhibit a high absorption coefficient of $10^{4}$ $cm^{-1}$. An increasing of optical band gap from 1.0 eV (CISe) to 1.25 eV (CIZSe) is found to be proportional with an increasing of Zn concentration as expected. All films have a p-type semiconductor characteristic with a carrier concentration in the order of 1014 $cm^{-3}$, a mobility about $10^{1}$ $cm^{2{\cdot}-1}{\cdot}s^{-1}$ and a resistivity at the range of $10^{2}-10^{6}$ W${\cdot}$m.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.645-645
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• 2013

Applying a first-principles computational approach combining density-functional theory and matrix Green's function calculations, we have studied the effects [2+2] cycloaddition olligormerization of fullerene $C_{60}$ chains on their junction charge transport properties. Analyzing first the microscopic mechanism of the switching realized in recent scanning tunneling microscope (STM) experiments, we found that, in agreement with experimental conclusions, the device characteristics are not significantly affected by the changes in electronic structure of $C_{60}$ chains. It is further predicted that the switching characteristics will sensitively depend on the STM tip metal species and the associated energy level bending direction in the $C_{60}-STM$ tip vacuum gap. Considering infinite $C_{60}$ chains, however, we confirm that unbound $C_{60}$ chains with strong orbital hybridizations and band formation should in principle induce a much higher conductance state. We demonstrate that a nanoelectromechanical approach in which the $C_{60}-STM$ tip distance is maintained at short distances can achieve a metal-independent and drastically improved switching performance based on the intrinsically better electronic connectivity in the bound $C_{60}$ chains.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.823-827
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• 2001

The AgInS$_2$epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on the AgInS$_2$/GaAs was derived as the Varshni's relation of Eg(T)=2.1365 eV-(9.89${\times}$10$\^$-3/ eV)T$^2$/(2930+T). After the as-grown AgInS$_2$/GaAs was annealed in Ag-,S-, and In-atmosphere, the origin of point defects of the AgInS$_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of V$\_$Ag/, V$\_$s/, Ag$\_$int/, and S$\_$int/ obtained from PL measurement were classified to donors or acceptors type. And, we concluded that the heat-treatment in the S-atmosphere converted the AgInS$_2$/GaAs to optical p-type. Also, we confirmed that the In in the AgInS$_2$/GaAs did net from the native defects because the In in AgInS$_2$did exist as the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.239-242
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• 2004

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by hot wall epitaxy(HWE) system. The source and substrate temperatures 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 $CdIn_2S_4$ single crystal thin films measured from Hall effect by van der Pauw method are $9.01{\times}10^{16}\;cm^{-3}$ and $219\;cm^2/V{\cdot}s$ at 293 K, respectively. From the optical absorption measurement, the temperature dependence of energy band gap on $CdIn_2S_4$ single crystal thin films was found to be $E_g(T)\;=\;2.7116\;eV\;-\;(7.74{\times}10^{-4}\;eV)T^2/(T+434)$. After the as-grown $CdIn_2S_4$ single crystal thin films was annealed in Cd-, S-, and In-atmospheres, the origin of point defects of $CdIn_2S_4$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K.