Soon Yong Hwang
Kyung Hee University
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Featured researches published by Soon Yong Hwang.
Langmuir | 2009
Sangjun Seok; Tae Jung Kim; Soon Yong Hwang; Young Dong Kim; David Vaknin; Doseok Kim
In situ imaging ellipsometry is employed to monitor the morphology of collapsed films of fatty acid Langmuir monolayers on pure water and on CaCl2 solution. The ellipsometry images reveal the existence of multilayer domains in the collapsed region, and analysis of the images yields the thicknesses of these domains. The multilayer films formed on water are mainly trilayers, while those on CaCl2 solution are mainly bilayers. The structure of the collapsed films also changes sensitively depending on the history of compression of the molecular layer.
Applied Physics Letters | 2010
Tae Jung Kim; Jae Jin Yoon; Soon Yong Hwang; Y. W. Jung; T. H. Ghong; Young Dong Kim; HyeJung Kim; Yia-Chung Chang
We report dielectric function data from 0.74 to 6.54 eV for InAs at 22 K, obtained by spectroscopic ellipsometry. Critical-point (CP) structures are blueshifted and significantly sharpened relative to those seen at room-temperature (RT). The E0′, E2Δ, E2, E0′+Δ0′, and E2′ features in the E2 energy range of 4.0 to 5.6 eV cannot be resolved at RT but are clearly separated at 22 K. The energies of the CPs giving rise to these structures are determined by line shape fitting to numerically calculated second energy derivatives, and their Brillouin-zone locations identified by band structure calculations using the linear augmented Slater-type orbital method.
Applied Physics Letters | 2009
T. J. Kim; J. J. Yoon; Soon Yong Hwang; D. E. Aspnes; Young-Sick Kim; H.J. Kim; Yia-Chung Chang; J. D. Song
We report pseudodielectric-function spectra from 1.5 to 6.0 eV of InAsxSb1−x ternary alloys obtained by spectroscopic ellipsometry. Energies of the E1, E1+Δ1, E0′, E0′+Δ0′, E2, E2+Δ2, E2′, E2′+Δ2, and E1′ critical points (CPs) were obtained from numerically calculated second derivatives, and identifications established by band-structure calculations using the linear augmented Slater-type orbital method. The E2, E2+Δ2, E2′, and E2′+Δ2 CP structures cross with increasing As-composition. Two saddle-point transitions, Δ5cu-Δ5vu and Δ5cl−Δ5vu, are found for InSb.
Journal of Applied Physics | 2013
Tae Jung Kim; Soon Yong Hwang; Jun Seok Byun; Mangesh S. Diware; Junho Choi; Han Gyeol Park; Young Dong Kim
We report the complex dielectric function of InSb for temperatures from 31 to 675 K and energies from 0.74 to 6.42 eV. The spectra were obtained by rotating-compensator spectroscopic ellipsometry on bulk InSb. The critical point (CP) energies were determined using numerically calculated second energy derivatives of the data. At low temperature, the CP structures are blue-shifted and significantly sharpened relative to those seen at high temperature. The temperature dependence of the E1, E1+Δ1, E0′, Δ5cu-Δ5vu (0.35, 0, 0), E0′+Δ0′, Δ5cl-Δ5vu (0.35, 0, 0), E2, E2′, E2+Δ2, E2′+Δ2, E1′, E1′+Δ1′, and E1′+Δ1′+Δ1 CPs was determined by fitting to a phenomenological expression that contains the Bose-Einstein statistical factor or to a linear equation. In particular, temperature dependences of CPs below 100 K and those of the E0′, E0′+Δ0′, E2′, E2+Δ2, E2′+Δ2, E1′+Δ1′, and E1′+Δ1′+Δ1 transitions have not previously been reported.
AIP Advances | 2014
Tae Jung Kim; Soon Yong Hwang; Jun Seok Byun; Nilesh Barange; Han Gyeol Park; Young Dong Kim
The complex dielectric function ɛ and the E0 excitonic and band-edge critical-point structures of hexagonal GaN are reported for temperatures from 30 to 690 K and energies from 0.74 to 6.42 eV, obtained by rotating-compensator spectroscopic ellipsometry on a 1.9 μm thick GaN film deposited on a c-plane (0001) sapphire substrate by molecular beam epitaxy. Direct inversion and B-splines in a multilayer-structure calculation were used to extract the optical properties of the film from the measured pseudodielectric function ⟨ɛ⟩. At low temperature sharp E0 excitonic and critical-point interband transitions are separately observed. Their temperature dependences were determined by fitting the data to the empirical Varshni relation and the phenomenological expression that contains the Bose-Einstein statistical factor.
Journal of Applied Physics | 2012
Tae Jung Kim; Soon Yong Hwang; Jun Seok Byun; Mangesh S. Diware; Junho Choi; Han Gyeol Park; Young Dong Kim
We present an analytic expression that accurately represents the dielectric function ɛ = ɛ1 + iɛ2 of InP from 1.19 to 6.57 eV for temperatures from 25 to 700 K. The original data were obtained on a InP substrate by spectroscopic ellipsometry. The analytic representation is based on the parametric model, which is known to accurately portray ɛ without unphysical assumptions. The ɛ data are successfully reconstructed by eight Gaussian-broadened polynomials and a pole and can be used to determine ɛ as a continuous function of energy and temperature within the limits given above. Our results should be useful in a number of contexts, including device design and in situ monitoring of deposition. A representative deposition example is discussed.
Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena | 2011
Jae Jin Yoon; Seung Muk Lee; Tae Jung Kim; Soon Yong Hwang; M. Diware; Young Dong Kim; Soo Min Hwang; Jinho Joo
We report optical properties of amorphous and tetragonal ZrO2 films grown on Si substrates by sol-gel deposition and formed by annealing at different temperatures. Pseudodielectric-function spectra ⟨e⟩ from 1.12 to 6.52 eV were acquired by spectroscopic ellipsometry at angles of incidence of 50, 55, 60, 65, and 70° with the samples at room temperature, then analyzed with the Tauc–Lorentz (TL) model for the refractive index and extinction coefficient of the films. These depend significantly on annealing temperature, and consistent with X-ray diffraction data, showing that amorphous ZrO2 crystallizes into the tetragonal phase between 300 and 500 °C, and that it coexists with the monoclinic phase after annealing at 700 °C. The dielectric functions of these materials can be calculated analytically within this spectral range from the TL parameters given.We report optical properties of amorphous and tetragonal ZrO2 films grown on Si substrates by sol-gel deposition and formed by annealing at different temperatures. Pseudodielectric-function spectra ⟨e⟩ from 1.12 to 6.52 eV were acquired by spectroscopic ellipsometry at angles of incidence of 50, 55, 60, 65, and 70° with the samples at room temperature, then analyzed with the Tauc–Lorentz (TL) model for the refractive index and extinction coefficient of the films. These depend significantly on annealing temperature, and consistent with X-ray diffraction data, showing that amorphous ZrO2 crystallizes into the tetragonal phase between 300 and 500 °C, and that it coexists with the monoclinic phase after annealing at 700 °C. The dielectric functions of these materials can be calculated analytically within this spectral range from the TL parameters given.
Applied Physics Letters | 2013
Tae-Woong Kim; J. J. Yoon; Jun Seok Byun; Soon Yong Hwang; D. E. Aspnes; S.H. Shin; J. D. Song; C.-T. Liang; Yu-Jen Chang; Nilesh Barange; Jiyoung Kim; Young-Sick Kim
We report pseudodielectric functions of In1−xGaxSb ternary alloy films from 1.5 to 6.0 eV determined by spectroscopic ellipsometry. Artifacts were minimized by real-time assessment of overlayer removal, leading to accurate representations of the bulk dielectric responses of these materials. Critical-point (CP) energies were obtained from numerically calculated second energy derivatives, and their Brillouin-zone origins identified by band-structure calculations. The E2′ and E2 + Δ2 CP energies cross with increasing In content as a result of increasing spin-orbit splitting Δ2.
Journal of The Optical Society of Korea | 2014
Soon Yong Hwang; Tae Jung Kim; Jun Seok Byun; Han Gyeol Park; Junho Choi; Yu Ri Kang; Jae Chan Park; Young Dong Kim
The collapse of Langmuir monolayers of arachidic acid (AA) on water at various rates of molecular area compression has been investigated in situ by imaging ellipsometry (IE). The thickness of the collapsed AA molecules, which are inherently inhomogeneous, was determined by IE with a spatial resolution of a few microns. For the analysis, we determined the dielectric function of AA monolayers from 380 to 1690 nm by conventional spectroscopic ellipsometry. Compression rates ranged from 0.23 to
Journal of Nanoscience and Nanotechnology | 2014
Tae Jung Kim; Han Gyeol Park; Sang Hyub Lee; Soo Min Hwang; Soon Yong Hwang; Jun Young Kim; Junho Choi; Yu Ri Kang; Young Dong Kim; Jinho Joo
0.94{\AA}^2/min