• 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.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.102-105
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• 2012

The structural, electrical, and optical properties of layer-by-layer ZnO nanoparticles deposited using sol-gel spin coating technique were studied and now presented. Thicknesses of the thin films were varied by increasing the number of deposited layers. As part of our characterization process, XRD and FE-SEM were used to characterize the structural properties, current-voltage measurements for the electrical properties, and UV-Vis spectra and photoluminescence spectra for the optical properties of the ZnO thin films. ZnO thin films with thicknesses ranging from 14.2 nm to 62.7 nm were used in this work. Film with thickness of 42.7 nm gave the lowest resistivity among all, $1.39{\times}10^{-2}{\Omega}{\cdot}cm$. Photoluminescence spectra showed two peaks which were in the UV emission centered at 380 nm, and visible emission centered at 590 nm. Optical transmittance spectra of the samples indicated that all films were transparent (>88%) in the visible-NIR range. The optical band gap energy was estimated to be 3.21~3.26 eV, with band gap increased with the thin film thickness.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1021-1021
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• 2001

Sample presentation, which means how to set samples to an NIR instrument, is very important in Near Infrared (NIR) Spectroscopy. When sample presentation is not suitable for the samples that you use, very good spectra can not be obtained even if you use a sophisticated NIR instrument. In my presentation, various NIR sample presentations for agricultural products such as intact fruits, single grains, vegetable juice and the others will be explained. In case of peaches with thin peel, the fiber optics of Interactance can be used. However, the fiber optics are not suitable for oranges with relatively thick peel. In this case, transmittance method is useful. As for a small sample such as single grains, a specially designed cell is needed. The cell in transmittance mode has been developed and then applied to single kernels of rice and soybean. In this case we also used the fiber optics. As regards liquid type of sample, a cuvette cell made of quartz in transmittance mode is popular. However, it is time-consuming to wash and dry it. In order to compensate this disadvantage the sample presentation using normal test tubes as sample cells have been developed and applied to milk, rumen juice and urine of a milking cow. An individual test tube can be used for each sample if you use the calibration equation with sample cell compensation. The test tube cell has also been applied to spinach juice for determination of undesirable constituents. It is concluded that sample presentation is most important for NIR Spectroscopy.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.604-607
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• 2005

Dependence of the crystallinity, surface roughness, carrier concentration, carrier mobility, electrical resistivity and transmittance of Al-doped ZnO films deposited on glass substrates by RF-magnetron sputtering on effects of the ratio of the RF power for AlZnO to that for ZnO (R) have been investigated. X-ray diffraction spectra show strong preferred orientation along the c-axis. The full width at half maximum (FWHM) of the ZnO (002) peak decreases slightly as R increases in the range of R<1.0, whereas it increases substantially in the range of R>1.0. Scanning electron micrographs (SEM) show that the ZnO film surface becomes coarse as R increases. The carrier concentration and the carrier mobility in the ZnO thin film are maximal for R=1.5 and 1.0, respectively. The electrical resistivity is minimal for R=1.0 The transmittance of the ZnO:Al film tends to increase, but to decrease slightly in the range of R>0.5. It may be concluded that the optimum R value is 1.0, considering all these analysis results. The cause of the changes in the structure and physical properties of ZnO thin films with R are also discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.179-182
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• 1994

We have investigated the optical and electrochromic properties of molybdenum oxide(MoO$_3$) films by thermal evaporation. The MoO$_3$films deposited at substrate temperatures below 200$^{\circ}C$ are found to be amorphous and annealed films at temperature 300$^{\circ}C$ for 1 hour in air are crystalline. The optical energy gap calculated from the transmittance and reflectance spectra of MoO$_3$ films is near 2.75 eV and 3.25 eV for amorphous films and crystalline films, respectively. The MoO$_3$ thin films exhibit light blue to dark blue optical modulation on lithium intercalation and have a uniform transmittance modulation over a wavelength range of 300∼1100 nmcompared to tungsten oxide films.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.242-243
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• 2007

Highly transparent conducting aluminum-doped zinc oxide (AZO) thin films were deposited on Corning glass substrate using an Nd:YAG pulsed laser deposition technology. AZO thin films deposited with 650nm thickness showed the best electrical properties of the electrical resistivity of $4.6{\times}10^{-4}[{\Omega}{\cdot}cm]$, a carrier concentration of $9.3{\times}10^{20}[cm^{-3}]$, and a carrier mobility of $31[cm^2/V{\cdot}s]$. Besides, the optical transmittance spectra in visible region (200-800nm) of AZO thin films show an high average transmittance over 90%.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.461-466
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• 1999

Diamond-like carbon(DLC) films were directly deposited onto germanium(Ge) witness pieces and lenses by a capacitively coupled 13.56 MHz RF glow discharge plasma with $CH_4$ gas. The characterizations of DLC films were measured using a Raman and FTIR spectrometer. The configuration of Raman and FTIR spectra had a traditional shape. The IR transmittance was measured using an IR spectrophotometer. The maximum values of the IR transmission of Ge with the DLC/Ge/DLC, DLC/Ge/BBAR (broad band antireflection), DLC/Ge, and BBAR/Ge structures are 98%, 93%, 64%, and 63.5%, respectively, which come up to the theoretical values. The uniform DLC films were obtained by a rotation of the cathode at certain conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.468-468
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• 2013

Self-assembled silver nanoparticles were synthesized on a graphene film to investigate plasmonic effect. Graphene was synthesized on glass substrate using chemical vapor deposition method and transfer process. Silver nanoparticles were formed using thermal evaporator and post-annealing process. The shape of silver nanoparticles was measured using a scanning electron microscopy. The resonance wavelength of plasmonic effect on graphene-silver nanoparticles was measured using transmittance spectra. The plasmon resonance wavelength was increased from 400 nm to 424 nm according to the lateral dimension of silver nanoparticles. Also we confirmed a strong plasmon effect form Raman spectra, which were measured on graphene-silver nanoparticles. The result shows that plasmon resonance wavelength could be controlled by lateral dimension of silver nanoparticles, and transparent conductive films based on plasmonic graphene could be developed.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1733-1736
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• 2008

ZnO thin films with preferred orientation along the (0 0 2) plane were fabricated by a sol-gel method. The effects of the annealing temperature, time, and thickness were studied by investigating UV-visible spectra, FT-IR spectra, and XRD of ZnO films. The films were dried and annealed ed at $100^{\circ}C,\;200^{\circ}C$, and $300^{\circ}C$ for 1hr, 2hrs, and 3hrs, respectively. The film showed the preferred (0 0 2) orientation and high transmittance near 90% in the visible range. Also, SEM images of the films exhibited very smooth surfaces without holes and cracks. Schottky diodes were fabricated by using ZnO sol-gel material. Au and Al were used as electrodes to make Ohmic and Schottky contacts, respectively. The annealing temperature, time and the thickness dependent I-V characteristics were presented in this article.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.289.1-289.1
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• 2003

Three types of near infrared spectrometer, a photo diode array type, a dispersive type and a FT type, were evaluated and compared the systematic difference in blood glucose measurement. The fundamental study was performed by adding glucose to buffer solution and bovine blood as the preceding study of non-invasive blood glucose. Spectra were collected using a 1.0 mm optical pathlength quartz cell by transmittance method. (omitted)