• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.319-322
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• 1989

Using pyrosol method, based on the pyrolysis of an aerosol produced by ultrasonic spraying, the deposition of transparent conducting oxides (TCO) such as $In_2O_3$ : Sn, $SnO_2$ : Sb and $SnO_2$ : F on glass substrates was studied. The electrical, optical and structural properties as functions of substrate temperature, dopant concentration, substrate type and carrier gas type were investigated.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.304-307
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• 2002

A zinc oxide (ZnO) single crystal was used as a substrate in the hydride vapor-phase epitaxy (HVPE) growth of GaN and the structural and optical properties of GaN layer were characterized by x- ray diffraction, transmission electron microscopy, secondary ion mass spectrometry, and photoluminescence (PL) analysis. Despite a good lattice match and an identical structure, ZnO is not an appropriate substrate for application of HVPE growth of GaN. Thick film could not be grown. The substrate reacted with process gases and Ga, being unstable at high temperatures. The crystallinity of ZnO substrate deteriorated seriously with growth time, and a thin alloy layer formed at the growth interface due to the reaction between ZnO and GaN. The PL from a GaN layer demonstrated the impurity contamination during growth possibly due to the out-diffusion from the substrate.

• Electrical & Electronic Materials
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• v.10 no.10
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• pp.1034-1040
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• 1997

A solar cell conversion effiency was degraded by grain boundary effect in polycrystalline silicon. Grain boundaries acted as potential barriers as well as recombination centers for the photo-generated carriers. To reduce these effects of the grain boundaries we investigated various influencing factors such as emitter thickness thermal treatment preferential chemical etching of grain boundaries grid design contact metal and top metallization along boundaries. Pretreatment in $N_2$atmosphere and gettering by POCl$_3$and Al were performed to obtain multicrystalline silicon of the reduced defect density. Structural electrical and optical properties of slar cells were characterized before and after each fabrication process. Improved conversion efficiencies of solar cell were obtained by a combination of pretreatment above 90$0^{\circ}C$ emitter layer of 0.43${\mu}{\textrm}{m}$ Al diffusion in to grain boundaries on rear side fine grid finger top Yb metal and buried contact metallization along grain boundaries.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.162-164
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• 2004

Nanocrystalline silicon(nc-Si) thin films on the silicon substrates have been prepared by pulsed laser deposition(PLD). The optical and structural properties of films have been investigated depending on deposition temperature, annealing, and oxidation process. When the deposition temperature increased, photoluminescence(PL) intensity abruptly decreased and peaks showed red shift. Annealing process could reduce the number of defect centers. Oxidation had a considerable effect upon the formation and isolation of the nanocrystals. These results indicate that the formation mechanism of Si nanocrystals grown by PLD can be explained by three steps of growth, passivating defect centers, and isolation, sequentially.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.432-433
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• 2005

In this study, Al doped ZnO(AZO) thin film were prepared on glass substrates by FTS(Facing Targets Sputtering) system. We investigated electrical, optical and structural properties of AZO thin film with the substrate temperature of the R.T, $100^{\circ}C$, $200^{\circ}C$ and the post-annealing. The crystallinity of AZO thin film was increased with increasing the substrate temperature and post-annealing temperature $600^{\circ}C$. The remarkable change of the resistivity with the substrate temperature didn't found and the resistivity with post-annealing was increased slightly.

• Bulletin of the Korean Chemical Society
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• v.19 no.9
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• pp.947-951
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• 1998

$K_2NiF_4$-type layered compounds of the ($C_nH_{2n+1}NH_3)_2SnCl_4$ (n=2, 4, 6, 8, and 10) system have been synthesized from a stoichiometric mixture of $SnCl_2$ and alkyl ammonium salt using a low temperature solution technique under the inert atmosphere condition. Their crystal structures are assigned to the orthorhombic system by X-ray powder diffraction analysis. The a and b cell parameters show small changes. However, the c parameter is varied significantly according to the increment of alkyl chains of the organic layer which is located between inorganic layers in the compounds. The conformational phase transitions of the compounds are studied by the DSC in the temperature range of 300 to 500 K. FT-IR and Raman spectra are analyzed in the ranges of 1300 to 4000 cm-1 and of 50 to 360 $cm^{-1}$ with Ar-laser (λ=514.5 nm) excitation, respectively. Photoluminescence phenomena are observed for some compounds. The bond-length of Sn-Cl is determined by the EXAFS spectroscopic analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.49-50
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• 2005

Nitrogen and phosphorus ions were implanted into ZnO thin film fabricated by pulsed laser deposition. ion implanted ZnO thin films were annealed from $700^{\circ}C$ to $1000^{\circ}C$ using rapid thermal annealing process. The electron concentration was changed form $10^{20}$ to $10^{18}/cm^3$. Effect of nitrogen and phosphorus in ZnO thin films was certified and the structural and optical properties of nitrogen and phosphorus doped ZnO thin films depending on concentration of nitrogen and phosphorus were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.270-270
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• 2010

OLED device is one of the most attractive and alternative display components, which stems primarily from the self-emission, large intrinsic viewing angle, and fast switching speed. However, because of its relatively short history of development, much remains to be studied in terms of its basic device physics, manufacturing processes, and reliability etc. Especially among several issues, it should be noted that the device characteristics are very sensitive to the surface properties of transparent conducting oxide (TCO) electrode materials. In this study, we have investigated the performance of OLED devices as a function of sheet resistance and surface roughness of TCO thin films. For this purpose, ITO and IZO thin films were deposited by r. f. magnetron sputtering under various ambient gases (Ar, Ar+O2 and Ar+H2, respectively). The crystal structure and surface morphology were examined by using XRD and FESEM. Also, electrical and optical properties were Investigated.

• Carbon letters
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• v.15 no.2
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• pp.77-88
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• 2014

Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.57-61
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• 1997

The effects of pH of solution on structural, electrical, and optical properties of CdS thin films prepared by solution growth method were investigated. With increasing pH of the solution, both crystallinity and transmittance of CdS thin film were deteriorated due to impurities and CdS particles, which were produced by homogeneous nucleation and adsorbed on the surface of CdS thin films. The films were strongly adherent to substrates and has low resistivity of 10~$10^2{\omega}cm$ regrardless of deposition conditions. After annealing at 30$0^{\circ}C$ in Ar atmosphere, the resistivity decreased due to desorption of impurity ions as well as the formation of S vacancies, but after annealing above 35$0^{\circ}C$ it increased by an agglomeration of S vacancies. After annealing in air atmosphere, the film resistivity increased because of the formation of oxide particle in grain boundaries.