• Applied Microscopy
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• v.35 no.4
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• pp.1-9
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• 2005

In this paper it is reported that a comprehensive study of the crystal structure of the fine size S-phase ($Al_2CuMg$) precipitate in Al-Cu-Mg alloy by electron diffraction experiments. The experiments involve taking the selected area diffraction pattern for a S-phase particle, simulations of the pattern based on the kinematical diffraction theory and quantitative data collection from the zone axis diffraction patterns for the comparison with calculated diffraction intensity using both the kinematical and the dynamical diffraction theory. As a result, a good fitting model of the S-phase structure turns out to be the model reported early by X-ray methods (Perlitz & Westgren, 1943), not the new model determined by HRTEM methods (Radmilovic et al., 1999).

• Applied Microscopy
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• v.25 no.2
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• pp.73-79
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• 1995

The oxidation of silicon wafers is an essential step in the fabrication of semiconductor devices. It is known to induce degradation of electrical properties and lattice strain of Si substrate from thermal oxidation process due to charged interface and thermal expansion mismatch from thermally grown SiO, film. In this study, convergent beam electron diffraction technique is employed to directly measure the lattice strains in Si(100) and $4^{\circ}$ - off Si(100) substrates with thermally grown oxide layer at $1200^{\circ}C$ for three hours. The ratios of {773}-{973}/{773}-{953} Higher Order Laue Zone lines were used at [012] zone axis orientation. Lattice parameters of the Si substrate as a function of distance from the interface were determined from the computer simulation of diffraction patterns. Correction value for the accelerating voltage was 0.2kV for the kinematic simulation of the [012]. HOLZ patterns. The change in the lattice strain profile before and after removal of oxide films revealed the magnitudes of intrinsic strain and thermal strain components. It was shown that $4^{\circ}$ -off Si(100) had much lower intrinsic strain as surface steps provide effective sinks for the free Si atoms produced during thermal oxidation. Thermal strain in the Si substrate was in compression very close to the interface and high concentration of Si interstitials appeared to modify the thermal expansion coefficient of Si.

• Applied Microscopy
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• v.44 no.4
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• pp.144-149
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• 2014

A strategy for phase identification of precipitates in high Al-containing austenitic and ferritic steels using electron diffraction (ED) is studied. Comparative studies of the various Al-containing precipitates (k-carbide, $Ni_3Al$, $Fe_3Al$, FeAl) show the similarities of crystal structure and lattice parameter. However, the slight differences of lattice parameter and structure display characteristic ED patterns (EDPs) which can be identified. $L1_2$ k-carbide and $Ni_3Al$ can be differentiated by the length of ${\rightarrow}_g$ (the reciprocal lattice vector), even though they show perfectly identical shapes of EDPs. $DO_3$ $Fe_3Al$ and $B_2$ FeAl show the characteristic EDs in [110] and [112] beam directions due to the differences of Fe site occupancies in unit cells. k-carbide, $Ni_3Al$, and FeAl show also the similar EDs in [112], [112], and [110] beam directions, respectively. All the possible similarities of EDs among each phases and the strategy for phase identification are discussed on the bases of kinematical ED simulation.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.177-180
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• 1997

Low Energy Electron Diffraction (LEED) apparatus was made to confirm the surface structure and to determine the direction of the structure for the Angle Resolved Ultraviolet Photoemission Spectroscopy(ARUPS) study. To determine the parameters needed for the design of the apparatus, computer simulation was used. Our LEED has 3 grids. The distance between sample and sccreen is 75 mm, and the viewing angle is $80^{\circ}$. The LEED apparatus was tested by investigating the Si(001) and $Al_2O_3$(0001) surface.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.148-154
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• 1992

With nonhardening fixer, dichromated bleacher and alcohol drying, the diffraction efficiency of over 71o/c has been achie'{ed for holographic phase gratings in silver halide emulsion. The swollen emulsion of Agfa 8E75 HD film is identified by scanning electron microscope (SEM) after chemical processing. Dichromated bleacher and rapid dehydration using alcohol drying make a strong modulation so that diffraction efficiency is. increased over 20%. The principal characteristic parameters in coupled wave theory are investigated and new modified parameter values are presented by computer simulation. Controlling the emulsion thickness has an important role as a potential source for high diffraction efficiency.ciency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.63-70
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• 1989

The ion beam extracted from the AuGe liquid metal ion source was implanted into GaAs substrate. The surface composition and the structure of ion implanted samples were investigated by AES, RHEED, SEM and EPMA. The depth profiles measured by AES were compared with the results of Monte Carlo simulation based on the two-body collision. As the results of AuGe ion implantation the preferential sputtering of As were revealed by AES and EPMA, and the outdiffusion of Ga and Ge was investigated by 300$^{circ}C$ annealing. The Au and Ge depth profiles measured by AES agreed with the results of Monte Carlo simulation based on the two-body collision.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.997-999
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• 2012

Digital X-ray image detector is widely used for radiodiagnosis. Amorphous selenium has been received attention as one of the major material that confirmed photoconductor of direct methode detector. We analysis the photocurrent using 2-dimensional device simulator when blue-ray (${\lambda}=486nm$) is irradiated and high voltage is biased. We evaluate electron-hole generation rate, electron-hole recombination rate, and electron/hole distribution in the amorphous selenium. This simulation methode is helpful to the analysis of digital X-ray image detector. We expect that many applications will be developed in digital X-ray image detector using 2-dimensional device simulator.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.143-144
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• 2015

Here we report the Ar-ion milling rates of ultrathin Si and GaAs single crystals. The thickness change is measured using convergent beam electron diffraction (CBED) technique with the help of Bloch wave simulation method. This study suggests the experimental procedures to determine the references for an etching rate to reduce a sample thickness or to remove the damaged sample surface using Ar-ion source.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.174-175
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• 2014

We fabricated a Ni/C composite thick film on ${\alpha}-Al_2O_3$ substrate. A number of precipitations were observed on the film surface. Structural characterization was performed on the observed precipitations using transmission electron microscopy (TEM) with help of the elemental mapping, electron diffraction (ED) and ED simulation. The structural characterization revealed that the precipitation is ${\theta}-Al_2O_3$ having the space group of C2/m (Monoclinic).

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.417-428
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• 2016

In this review, an attempt is made to calculate one-dimensional (1-D) electron density profiles from experimentally determined (00l) XRD intensities and possible structural models as well in an effort to understand the collective intracrystalline structures of intercalant molecules of two-dimensional (2-D) nanohybrids with heterostructures. 2-D ceramics, including layered metal oxides and clays, have received much attention due to their potential applicability as catalysts, electrodes, stabilizing agents, and drug delivery systems. 2-D nanohybrids based on such layered ceramics with various heterostructures have been realized through intercalation reactions. In general, the physico-chemical properties of such 2-D nanohybrids are strongly correlated with their heterostructures, but it is not easy to solve the crystal structures due to their low crystallinity and high anisotropic nature. However, the powder X-ray diffraction (XRD) analysis method is thought to be the most powerful means of understanding the interlayer structures of intercalant molecules. If a proper number of well-developed (00l) XRD peaks are available for such 2-D nanohybrids, the 1-D electron density along the crystallographic c-axis can be calculated via a Fourier transform analysis to obtain structural information about the orientations and arrangements of guest species in the interlayer space.