• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.104-105
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• 2005

• Korean Journal of Optics and Photonics
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• v.21 no.1
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• pp.33-37
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• 2010

We performed time-domain terahertz (THz) spectroscopy to determine optical constants of highly conductive carbon nanotube (CNT) films. The CNT films have been fabricated on a flexible plastic substrate by using spin-coating or vacuum filtration. We found that the transmission of THz waves can be controlled by manipulating the thickness of the films and by post-treatments. From amplitude and phase information of the transmitted THz waves, we obtain optical constants such as refractive indices and dielectric constants of the CNT films. The frequency dependent dielectric constants show good metallic behaviors, relevant to the Drude free electron models with high plasma frequencies. It is also found that the dielectric constants are higher for the acid-treated films. Finally, the frequency dependent dielectric constants which are free from substrate effects have been demonstrated by using CNT films deposited on cellulose membranes.

• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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• pp.196-199
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• 2012

CdS thin film was prepared on glass substrate by chemical bath deposition in an alkaline solution. The optical properties of CdS thin film were investigated using spectroscopic ellipsometry. The real (${\varepsilon}_1$) and imaginary (${\varepsilon}_2$) parts of the complex dielectric function ${\varepsilon}(E)={\varepsilon}_1(E)+i{\varepsilon}_2(E)$, the refractive index n(E), and the extinction coefficient k(E) of CdS thin film were obtained from spectroscopic ellipsometry. The normal-incidence reflectivity R(E) and absorption coefficient ${\alpha}(E)$ of CdS thin film were obtained using the refractive index and extinction coefficient. The critical points $E_0$ and $E_1$ of CdS thin film were shown in spectra of the dielectric function and optical constants of refractive index, extinction coefficient, normal-incidence reflectivity, and absorption coefficient. The dispersion of refractive index was analyzed by the Wemple-DiDomenico single-oscillator model.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.205-216
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• 1992

Distribution of electric fields of surface plasmons at resonance and off-resonance angles were calculated and compared. As applications of surface plasmon resonance, (1) optical constants of ZnS films overcoated on Ag films were measured as the thickness of ZnS films increased, (2) four surface plasmon resonances distributed spatially due to the different thickness of SiO thin films overcoated on Ag films were observed in a picture frame by employing diverging waves of incidence, and (3) patterns of SiO thin films such as a grating and a character "가" overcoated on Ag films were measured by employing collimated waves of incidence.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1505-1511
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• 2005

The excitation energy transfer process occurring in energy donor-acceptor linked porphyrin array system is theoretically simulated using the on-the-fly filtered propagator path integral method. The compound consists of an energy donating meso-meso linked Zn(II) porphyrin array and an energy accepting 5,15-bisphenylethynylated Zn(II) porphyrin, in which the donor array and the acceptor are linked via a 1,4-phenylene spacer. Real-time path integral simulations provide time-evolution of the site population and the excitation energy transfer rate constants are determined. Simulations and experiments show an excellent agreement indicating that the path integration is a useful tool to investigate the energy transfer dynamics in molecular assemblies.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.184.1-184
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• 2000

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.343-344
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.11
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• pp.141-145
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• 1982

Optical absorption properties of an orphous Se film due to interband electronic transitions are observed in the visible range by varying the folm thickness. Amorphous Se films were prepared by evaporation method. As the experimental results, it is found that optical energy gap is around 2.07(e V), and the optical constants depend on the film thickness, evaporation-deposition conditions, and incident photon energy.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.1-7
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• 2003

We determined the optical constants of organic light emitting material of Alq$_3$ in a spectral range between 1.5 and 6 eV using the physical model introduced by Forouhi and Bloomer［Phys. Rev. B 34, pp. 7018-7026, 1986.］. The initial parameters of $A_i,\;B_i,\;C_i$ of Forouhi-Bloomer dispersion relations were determined from the absorption peaks and widths of absorption spectra of the Alq$_3$ film. The refractive index of substrate, a fused silica, is derived from the Sellmeier equation with the measured transmittance and reflectance spectra. Then, the complex refractive index and thickness of the Alq$_3$ film were calculated by use of a nonlinear least square fitting program with the Forouhi-Bloomer dispersion relation and the measured transmittance and reflectance spectra.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.361-361
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• 2012

PZT (Pb(Zr,Ti)O3) thin films have been used widely in the MEMS application, due to their inherent ferroelectric and piezoelectric properties. Such ferroelectricity induces much higher dielectric constants compared to those of the nonperovskite materials. In this work, the PZT thin films were deposited onto Indium-Tin-oxide (ITO) substrates through the spin-coating of PZT sols. The deposited PZT thin films were characterized in terms of the electrical and optical properties with special emphases on conductivity and optical constants. The detailed analysis techniques incorporate the dc-based current-voltage characteristics for the electrical properties, spectroscopic ellipsometry for optical characterization, atomic force microscopy for surface morphology, X-ray Photoelectron Spectroscopy for chemical bonding, Energy-dispersive X-ray Spectrometry for chemical analyses and X-ray diffraction for crystallinity. The ferroelectric phenomena were confirmed using capacitance-voltage measurements. The integrated physical/chemical features are attempted towards energy-oriented applications applicable to next-generation high-efficiency power generation systems.