• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.240-242
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• 1994

Spectroscopic ellipsometry(SE) was employed to characterize the Si/$Si_{1-x}Ge_x$ heterostructure. The dielectric function spectrum of $Si_{1-x}Ge_x$ at an arbitrary x value in the spectral range of $1.5{\sim}4.5\;eV$ was computed by EMA (effective medium approximation) model using the available optical constants measured at a number of fixed x values of Ge composition. The thickness and the Ge composition of $Si_{1-x}Ge_x$ measured by SE was compared with those measured by RBS. DC bias effect on the $E_2$ peak of dielectric function spectra was studied.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.61-64
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• 2008

Electrical optical switching and structural transformation of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ were studied to investigate the phase change characteristics for PRAM application. Sb-based materials were deposited by a RF magnetron co-sputtering system and the phase change characteristics were analyzed using an X-ray diffractometer (XRD), a static tester and a four-point probe. Doping Ge, Se or Si atoms reinforced the amorphous stability of the Sb-based materials, which affected the switching characteristics. The crystallization temperature of the Sb-based materials increased as the concentration of the Ge, Se or Si increased. The minimum time of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ for crystallization was 120, 50 and 90 ns at 12 mW, respectively. $Sb_{65}Se_{35}$ was crystallized at $170^{\circ}C$. In addition, the difference in the sheet resistances between amorphous and crystalline states was higher than $10^4{\Omega}/{\gamma}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.183-189
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• 2013

The chalcogenide glass has superior optical properties in IR region transmittances. We have determined the composition of GeSbSe chalcogenide glass for the application of good IR lenses, resulting in the composite rate of $Ge_{19}Sb_{23}Se_{58}$. The optical, structural, thermal and physical properties were measured by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Differential scanning calorimeter (DSC), X-ray computed tomography (X-ray CT) respectively. The fabrication of the chalcogenide glass lens for infrared optics applications was proposed using a diamond turning machining technology which is known as the suitable ways for the production cost reduction and the accurate fabrication process control.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3217-3220
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• 2010

The electronic structures and bonding configuration of histidine on Ge(100) have been investigated with various sample treatments using core-level photoemission spectroscopy (CLPES). Interpretation of the Ge 3d, C 1s, N 1s, and O 1s core level spectra being included in these systems revealed that both the imino nitrogen in the imidazole ring and the carboxyl group in the glycine moiety concurrently participate in the adsorption of histidine on a Ge(100) surface at 380 K. Moreover, we could clearly confirm that the imino nitrogen with a free lone pair in the imidazole group adsorbs on Ge(100) more strongly than the carboxyl group in the glycine moiety by examining systems annealed at various temperatures.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.445-449
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• 1997

The complex refractive indices of $Ge_2Se_2Te_5$ which show reversible phase change between the crystalline phase and an amorphous one depending upon the annealing process have been determined in the spectral range of 0.7-4.5 eV. The $Ge_2Se_2Te_5$ films were DC sputter deposited on the crystalline silicon substrate. The spectro-ellipsometry data of a thick film were analyzed following the modelling procedure where the quantum mechanical dispersion relation were used for the complex refractive indices of both the cryastalline phase $Ge_2Se_2Te_5$ and and amorphous phase $Ge_2Se_2Te_5$, respectively. On the other hand, with the surface micro-roughness layer whose effective thickness was determined from AFM analysis, the spectro-ellipsometry data were numerically inverted to yield the complex refractive index of $Ge_2Se_2Te_5$ at each wavelength. With these set of complex refractive indices, the reflectance spectra were calculated and those spectra obtained from the numerical inversion showed better agreement with the experimental reflection spectra for both the cryastalline phase and an amorphous phase. Finally, the thin $Ge_2Se_2Te_5$ film which has the optimum thickness of 26 nm as the medium for optical recording was also analyzed and the quantitative result of the film thickness and the surface microroughness has been reported.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.106-107
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• 2007

A detailed investigation of cell structure and electrical characteristic in chalcogenide-based phase-change random access memory(PRAM) devices is presented. We used compound of Ge-Se-Te material for phase-change cell. Actually, the performance properties have been improved surprisingly then conventional Ge-Sb-Te. However, crystallization time was as long as ever for amorphization time. We conducted this experiment in order to solve that problem by doping-Sb with annealing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.91-94
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• 1988

This paper is investigated on the diffraction grating formation of the amorphous As-Se-S-Ge films. AS$\_$40/Se$\_$15/S$\_$36/Ge$\_$10/ film of thickness 0.76 $\mu\textrm{m}$ has achieved a high diffraction efficiency of 4.6%. In this film, high diffraction efficiency is increased to 18% by chemical etching.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.25-32
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• 2005

Purpose : To evaluate the degree of the artifact which is caused by the mascara and the eye shadow when acquiring MR images and compare the difference of the image distortion according to the change of various pulse sequence. Material and Method : The popular domestic mascara and eye shadow products were selected from three different companies respectively and divided into two groups mascara (M1, M2, M3 ), eye shadow (E1, E2, E3). Self-designed quadrature type saddle coil which has 4 cm inside diameter, 8 cm length and which is for both Tx and Rx was used. MR image was acquired respectively after applying the mascara to the tape from study 1, the eye shadow to the tape from study 2 and adding the eye shadow to the mascara from study 3. The FSE(fast spin echo), the SE(spin echo), the GE(gradient echo) were used as pulse sequences. The degree of the image distortion which was measured from each sequence was analyzed in quality and quantity. Result : The mascara and the eye shadow caused the artifacts to the MR images partially and induced the image distortion. There was a little difference in terms of the degree of artifact according to the change of pulse sequence. From the study 3 in which the eye shadow was applied to the mascara, on the axial plane image, the width of artifact was 16.73 mm in the GE pulse sequence, 6.64 mm in the SE pulse sequence, and 6.19 mm in the FSE pulse sequence. The degree of the artifact appeared highly in order of the GE, the SE and the FSE. On the sagittal plane image, the length of artifact was 22.84 mm in the GE, 17.81 mm in the SE and it appeared highly with the SE and the FSE technique order. Conclusion : When examining the eyeball and the brain of a woman with the mascara and the eye shadow, we have to consider that the artifact caused by them can have an effect on the image diagnosis. We concluded that it is more suitable for a brain and a eyeball T2 emphasizing image to use the FSE technique than the GE technique.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.252-252
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• 2009

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.525-527
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• 1987