• Title/Summary/Keyword: Complex refractive index

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Determination of the complex refractive index and thickness of MNA/PMMA thin film (MNA/PMMA 고분자박막의 복소굴절율 및 두께결정)

  • 김상열
    • Korean Journal of Optics and Photonics
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    • v.7 no.4
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    • pp.357-362
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    • 1996
  • The thickness and the spectrum of the complex refractive index in the region 1.5~4.5 eV, of an MNA/PMMA thin film fabricated by spin casting are determined. The film thickness and the refractive index in its transparent region is calculated by modeling the spectroscopic ellipsometry data. The extinction coefficient spectrum is obtained from the absorption spectrum in its non-transparent region. The best fit oscillator parameters of the classical Lorentz oscillator and a quantum mechanical oscillator are found. The complex refractive index spectrum by these oscillators are compared. The present technique can be applied to get the thickness and the complex refractive index of unknown polymer films and thus it will be useful in optical characterization of those films.

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Development of a Microspot Spectroscopic Ellipsometer Using Reflective Objectives, and the Ellipsometric Characterization of Monolayer MoS2

  • Kim, Sang Jun;Lee, Min Ho;Kim, Sang Youl
    • Current Optics and Photonics
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    • v.4 no.4
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    • pp.353-360
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    • 2020
  • Adopting an elaborately designed reflective objective consisting of four mirrors, we have developed a rotating-polarizer-type microspot spectroscopic ellipsometer (SE) with an ultra-small spot size. The diameter of the focused beam, whether evaluated using a direct-image method or a knife-edge method, is less than 8.4 ㎛. After proper correction for the polarizing effect of the mirrors in the reflective objective, we unambiguously determine the dispersion of the complex refractive index and the thickness of monolayer MoS2 using the measured microspot-spectroellipsometric data. The measured ellipsometric spectra are sensitive enough to identify small variations in thickness of MoS2 flakes, which ranged from 0.48 nm to 0.67 nm.

Analysis of the Spectro-ellipsometric Data with Backside Reflection from Semi-transparent Substrate by Using a Rotating Polarizer Ellipsometer (반투명 기층에 의한 후면반사를 고려한 회전검광자 방식의 타원측정 및 분석)

  • Seo, Yeong-Jin;Park, Sang-Uk;Yang, Seong-Mo;Kim, Sang-Youl
    • Korean Journal of Optics and Photonics
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    • v.22 no.4
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    • pp.170-178
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    • 2011
  • The spectroscopic ellipsometric constants are analyzed to determine the thickness and the complex refractive index of a film coated on a semi-transparent substrate, with the reflection from the backside of the substrate properly considered. Expressions representing the effect of the backside reflection on ellipsometric constants are derived using the thickness and the complex refractive index of the substrate. The thickness and the complex refractive of an ITO thin film coated on a glass substrate are obtained by using this method. The results agree quite well with the ones obtained by following the conventional modeling procedure where the backside reflection is neglected during ellipsometric measurement and analysis.

Refractive index change of nonlinear polymer thin films induced by corona poling and quantitative evaluation of poling effect (코로나 극성배향이 비선형 고분자박막의 복소굴절율에 미치는 영향 및 배향효과의 정량화)

  • 길현옥;김상준;방현용;김상열
    • Korean Journal of Optics and Photonics
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    • v.10 no.3
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    • pp.181-187
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    • 1999
  • We prepared the side-chain type nonlinear optical NPP(N-(6-nitrophenyl)-(L)-prolinol) polymer films by spin coating method. Ellipsometric spectra were in situ collected by using spectroscopic phase modulated ellipsometer while the NPP polymer films were being corona poled at the temperature above glass transition. We calculated film thickness and the refractive index dispersion by modeling the spectro-ellipsometry data in transparent region. We also calculated the refractive index and the extinction coefficient of the polymer films by numerically inverting the spectro-ellipsometry data in absorbing region, while the previously determined film thickness was used. The independently determined extinction coefficient spectra from the analysis of transmission spectra were compared with those by spectro-ellipsometry and they showed an excellent agreement with each other. From the analysis of the complex refractive index change of the NPP polymer thin films induced by the corona poling, we could determine the vertical complex refractive index and the horizontal complex refractive index separately. Using the volume fraction of the vertical component f⊥, the degree of poling of poled NPP polymer films was quantitatively addressed. It is suggested that the present method can be used to quantitatively address the degree of poling in an absolute manner and to depth profile the poled fraction of thick polymer films. It will be useful to understand the structural change of polymer films and hence the poling mechanism during the poling process.

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Particle Size Determination of Dye Dispersion by Specific Turbidity (Specific Turbidity에 의한 분산염료의 입도분포 측정)

  • 정용식;김진우
    • Textile Science and Engineering
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    • v.35 no.11
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    • pp.709-715
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    • 1998
  • By the application of the Mie and the Rayleigh theories of light scattering to the measurement of specific turbidity, particle size distributions of milled dye dispersions have been determined. The complex refractive index of C. I. Disperse Blue 56 and C. I. Disperse Blue 79 were measured, and extinction coefficients of disperse dyes were calculated. With the increase in milling time and temperature, the specific turbidity in the near-infrared gradually decreases, but increases in the visible range. The specific turbidity method can be utilized in determining the change of the particle size distributions of disperse dyes.

Complex refractive index of PECVD grown DLC thin films and density variation versus growth condition (PECVD 방법으로 성장시킨 DLC 박막의 복소굴절율 및 성장조건에 따른 박막상수 변화)

  • 김상준;방현용;김상열;김성화;이상현;김성영
    • Korean Journal of Optics and Photonics
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    • v.8 no.4
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    • pp.277-282
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    • 1997
  • The complex refractive index of Diamond-like Carbon (DLC) thin films, which can be applied to optical devices or electrical devices, have been determined using optical methods. DLC thin films are grown on Si(100) substrates and vitreous silica substrates respectively, using the technique of plasma enhanced chemical vapor deposition (PECVD). The spectroscopic ellipsometry data($\psi$, $\Delta$) and the transmission spectra of these DLC films are obtained. These optical spectra are analyzed with the help of the Sellmeier dipersion relation and a quantum mechanically derived dispersion relation. Using spectroscopic ellipsometry data at their transparent region, the refractive index and the effective thickness of DLC films on vitreous silica are model calculated, Then the transmission spectra are inverted to yield the extinction coefficient spectra k(λ) at absorbing region. These spectra are fit to the quantum mechanical dispersion relation and the best fit dispersion constants are determined. The complex refractive indices are easily calculated with these constants. The spectroscopic ellipsometry data at the absorbing region in model calculated to give the packing densities and the degrees of surface microroughness of DLC films. Discussions are made in correlation with the growth condition of DLC films.

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Optical and Dielectric Properties of Chalcogenide Glasses at Terahertz Frequencies

  • Kang, Seung-Beom;Kwak, Min-Hwan;Park, Bong-Je;Kim, Sung-Il;Ryu, Han-Cheol;Chung, Dong-Chul;Jeong, Se-Young;Kang, Dae-Won;Choi, Sang-Kuk;Paek, Mun-Cheol;Cha, Eun-Jong;Kang, Kwang-Yong
    • ETRI Journal
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    • v.31 no.6
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    • pp.667-674
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    • 2009
  • Terahertz time-domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: $Ge_{30}As_8Ga_2Se_{60}$, $Ge_{35}Ga_5Se_{60}$, and $Ge_{10}As_{20}S_{70}$. The absorption coefficients ${\alpha}({\nu})$, complex refractive index n(${\nu}$), and complex dielectric constants ${\varepsilon}({\nu})$ were measured in a frequency range from 0.3 THz to 1.5 THz. The measured real refractive indices were fitted using a Sellmeier equation. The results show that the Sellmeier equation fits well with the data throughout the frequency range and imply that the phonon modes of glasses vary with the glass compositions. The theory of far-infrared absorption in amorphous materials is used to analyze the results and to understand the differences in THz absorption among the sample glasses.

Passive Films on Chromium Studied by Three-parameter Ellipsometry

  • 이경희;백운기
    • Bulletin of the Korean Chemical Society
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    • v.16 no.3
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    • pp.214-216
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    • 1995
  • Passive films formed on chromium surface in citrate buffer solution were investigated by means of three-parameter ellipsometry. The citrate buffer was found to be a suitable medium in which oxide film on chromium could be removed by cathodic treatment, providing a reference surface for the optical study. The passive film effectively protecting the chromium surface from corrosion was found to have thicknesses in the range 0.65 to 1.25 nm depending on the potential in the range of -0.20 to 0.60 V (0.1M KCl calomel electrode). The complex refractive index of the passive film did not show significant potential-dependent changes, indicating that the composition of the film material does not depend on potential.

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