• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.589-593
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• 2014

AlNO multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. $Al_2O_3$/AlNO(LMVF)/AlNO(HMVF)/Al/substrate of 4 multi-layer has been prepared in an Ar and ($N_2+O_2$) gas mixture, and $Al_2O_3$ of top layer is anti-reflection layer on double AlNO(LMVF)/AlNO(HMVF) layers and Al metal of infrared reflection layer. In this study, the roughness and surface properties of AlNO thin films were estimated by field emission scanning electron microscopy(FE-SEM). The grain size of AlNO thin films increased with increasing sputtering power. The composition of thin films has been systematically investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The absorptance of AlNO films shows the increasing trend with swelling ($N_2+O_2$) gas mixture in HMVF and LMVF deposition. The excellent optical performance showed above 98% of absorptance in visible wavelength region.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.73.2-73.2
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• 2012

The far ultraviolet (FUV) wavelength (900-1750A) range includes a wealth of important astrophysical information related to the cooling of hot gas, fluorescent emission from H2 molecules, and starlight scattered off dust particles. Among these, we would like to focus on the scattered emission of the central star by dust with the example of the FUV halo surrounding ${\alpha}$ Vir (Spica). While scattering properties of dust have been studied with the GALEX data, the improved dataset of STSAT-1 revealed many detailed structures of this interesting region. For example, the FUV continuum map obtained from the STSAT-1 observations shows enhanced emission in the southern part of the Spica halo region, where the dust level is also high. In fact, the FUV continuum intensity is seen to have a good correlation with the IRAS 100${\mu}m$ emission data. It is also seen that the scattered spectrum is softer than the original one emitted by the central star, which is attributed to the increase in the dust-scattering albedo with wavelength. We have developed a Monte Carlo code that simulates dust scattering of light including multiple encounters. The code is applied to the present Spica halo region to obtain the scattering properties such as the albedo and the phase function asymmetry factor.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.325-330
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• 2004

We fabricated a vacuum ultraviolet spectre-reflectometer which consists of a deuterium light source, a vacuum monochromator, and a sample chamber and detector module. The operation was performed in the ultraviolet spectral ranges between 115 nm and 330 nm at the vacuum pressure of 3.0 ${\times}$ 10$^{-4}$ Pa. The wavelength of the vacuum monochromator was calibrated with the line spectrum of a low pressure Mercury lamp of 253.652 nm and 184.95 nm wavelengths, and its resolution was 0.012 nm, and the precision of wavelength was $\pm$ 0.03 nm. With this reflectometer and a deuterium lamp, we measured the spectral regular transmittance and reflectance of materials(MgF$_2$, CaF$_2$, BaF$_2$, SiO$_2$, Sapphire) used as optical components over the spectral range between 115 nm and 230 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.413-414
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• 2008

We have studied an organic layer thickness dependent optical properties and microcavity effects for top-emission organic light-emitting diodes. Manufactured top emission device, structure is Al(100nm)ITPD(xnm)/$Alq_3$(ynm)/LiF(0.5nm)/Al(23nm). While a thickness of hole-transport layer of TPD was varied from 35 to 65nm, an emissive layer thickness of $Alq_3$ was varied from 50 to 100nm for two devices. A ratio of those two layers was kept to about 2:3. Variation of the layer thickness changes a traverse time of injected carriers across the organic layer, so that it may affect on the chance of probability of exciton formation. View-angle dependent emission spectra were measured for the optical measurements. Top-emission devices show that the emission peak wavelength shifts to longer wavelength as the organic layer thickness increases. For instance, it shifts from 490 to 555nm in the thickness range that we used. View-angle dependent emission spectra show that the emission intensity decreases as the view-angle increases. The organic layer thickness-dependent emission spectra show that the full width at half maximum decreases as the organic layer thickness increases. Top emission devices show that the full width at half maximum changes from 90 to 35nm as the organic layer thickness increases. In top-emission device, the microcavity effect is more vivid as the organic layer thickness increases.

• Journal of Navigation and Port Research
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• v.26 no.2
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• pp.235-243
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• 2002

Theoretical analysis have been performed to design the high power semiconductor laser for an optical sensor at 1.55${\mu}{\textrm}{m}$ wavelength range which is the lowest loss wavelength in optical fiber. The materials of active region and SCH were $Ln_{1-x}Ga_xAs_yP_{1-y}$. In order to use the light source of optical sensors, it has to satisfy wide spectral width and short coherence length. Therefore, in order to suppress lasing oscillation, we proposed laterally tilted PBH type with a window region. Also, tapered stripe structure was applied for high coupling efficiency into a single mode fiber. From these analyses, the devices of laterally tilted angled and bending structure were fabricated and their characteristics were measured. In the results of the measurement, the fabricated devices have sufficient output power and wide FWHM to apply to the light source of optical fiber sensors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.820-824
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• 2014

TiNOx multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. 4 multi-layers of $TiO_2$/TiNOx(LMVF)/TiNOx(HMVF)/Ti/substrate have been prepared with ratio of Ar and ($N_2+O_2$) gas mixture. $TiO_2$ of top layer is anti-reflection layer on double TiNOx(LMVF)/TiNOx(HMVF) layers and Ti metal of infrared reflection layer. In this study, the crystallinity and surface properties of TiNOx thin films were estimated by X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM), respectively. The grain size of TiNOx thin films shows to increase with increasing sputtering power. The composition of thin films has been investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The TiNOx multi-layer films show the excellent optical performance beyond 9% of reflectance in those ranges wavelength.

• Current Photovoltaic Research
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• v.10 no.4
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• pp.95-100
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• 2022

Solar cell is a device that converts photon energy into electrical energy. Therefore, absorption of solar spectrum light is one of the most important characteristics to design the solar cell structures. Various methods have emerged to reduce optical losses, such as textured surfaces, back contact solar cells, anti-reflection layers. Here, the anti-reflection coating (ARC) layer is typically utilized whose refractive index value is between air (~1) and silicon (~4) such as SiN_x layer (~1.9). This research is to print a material called polydimethylsiloxane (PDMS) to form a double anti-reflection layer. Light with wavelength in the range of 0.3 to 1.2 micrometers does not share a wavelength with solar cells. It is confirmed that the refractive index of PDMS (~1.4) is an ARC layer which decreases the reflectance of light absorption region on typical p-type solar cells with SiN_x layer surface. Optimized PDMS printing with analyzing optical property for cell structure can be the effective way against outer effects by encapsulation.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.38.1-38.1
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• 2021

Dust polarization depends on the physical and mechanical properties of dust, as well as the properties of local environments. To understand how dust polarization varies with grain mechanical properties and the local environment, in this paper, we model the wavelength-dependence polarization of starlight and polarized dust emission by aligned grains by simultaneously taking into account grain alignment and rotational disruption by radiative torques (RATs). We explore a wide range of the local radiation field and grain mechanical properties characterized by tensile strength. We find that the maximum polarization and the peak wavelength shift to shorter wavelengths as the radiation strength U increases due to the enhanced alignment of small grains. Grain rotational disruption by RATs tends to decrease the optical-near infrared polarization but increases the ultraviolet polarization of starlight due to the conversion of large grains into smaller ones. In particular, we find that the submillimeter (submm) polarization degree at 850㎛(P850) does not increase monotonically with the radiation strength or grain temperature (Td), but it depends on the tensile strength of grain materials. Our physical model of dust polarization can be tested with observations toward star-forming regions or molecular clouds irradiated by a nearby star, which have higher radiation intensity than the average interstellar radiation field. Finally, we compare our predictions of the P850-Td relationship with Planck data and find that the observed decrease of P850 with Td can be explained when grain disruption by RATs is accounted for, suggesting that interstellar grains unlikely to have a compact structure but perhaps a composite one. The variation of the submm polarization with U (or Td)can provide a valuable constraint on the internal structures of cosmic dust

• Nanomaterials
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• v.12 no.10
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• pp.1618-1626
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• 2022

CdS films with a wide range of substrate temperatures as deposition parameters were fabricated on Corning Eagle 2000 glass substrates using RF magnetron sputtering. The crystallographic structure, microscopic surface texture, and stoichiometric and optical properties of each CdS film deposited at various substrate temperatures were observed to be highly temperature-dependent. The grown CdS thin films revealed a polycrystalline structure in which a cubic phase was mixed based on a hexagonal wurtzite phase. The relative intensity of the H(002)/C(111) peak, which represents the direction of the preferential growth plane, enhanced as the temperatures climbed from 25 ℃ to 350 ℃. On the contrary, the intensity of the main growth peak at the higher temperatures of 450 ℃ and 500 ℃ was significantly reduced and exhibited amorphous-like behavior. The sharp absorption edge revealed in the transmission spectrum shifted from the long wavelength to the short wavelength region with the rise in the substrate temperature. The bandgap showed a tendency to widen from 2.38 eV to 2.97 eV when the temperatures increased from 25 ℃ to 350 ℃. The CdS films grown at the temperatures of 450 ℃ and 500 ℃ exhibited glass-like transmittance with almost no interference fringes of light, which resulted in wide bandgap values of 3.09 eV and 4.19 eV, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.165-172
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• 2006

On the MgO single crystals doped artificially with Cr, Cu, Fe we observed thermally stimulated luminescence(TSL) glow curves and spectra, and analyzed them in the temperatures range from at liquid nitrogen temperature(77K) to about 500K after excitation with UV or X-ray irradiation. TSL glow curves obtained from these samples show five peaks at 136.5K, 223.5K, 360K, 390K, 440K, and their estimated activation energies are 0.27eV, 0.63eV, 1.08eV, 1.08eV, 1.19eV, and 1.33eV, respectively. When we measured TSL spectrum at the range of 200nm to 650nm on the MgO single crystals. we also analyzed the peak wavelength which obtained at 345nm, 375nm, and 410nm from measurement of TSL spectrum and described their luminescence mechanisms. TSL spectrum peaks emitted from MgO:Cr, MgO:Cu, and MgO:Fe appear at the wavelengths of 345nm, 360nm, and 375nm, respectively.