• Journal of Korean Vacuum Science & Technology
• /
• v.2 no.2
• /
• pp.107-117
• /
• 1998

Epitaxial undoped and Sb-doped si films have been grown on Si(001) substrates at temperatures T between 80 and 750$^{\circ}C$ using energetic Si in ultra-high-vacuum Kr+-ion-beam sputter deposition(IBSD). Critical epitaxial thicknesses te, The average thickness of epitaxial layers, in undoped films were found to range from 8nm at Ts=80$^{\circ}C$ to > 1.2 ${\mu}$m at Ts=300$^{\circ}C$ while Sb incorporation probabilities $\sigma$sb varied from unity at Ts 550$^{\circ}C$ to 0.1 at 750$^{\circ}C$. These te and $\sigma$Sb values are approximately one and one-to-three orders of magnitude, respectively, higher than reported results achieved with molecular-beam epitaxy. Plan-view and cross-sectional transmission electron microscopy, high-resolution x-ray diffraction, channeling and axial angular-yield profiles by Rutherford back scattering spectroscopy for epitaxial Si1-x Gex(001) alloy films (0.15$\leq$x$\leq$0.30) demonstrated that the films are of extremely high crystalline quality. critical layer thicknesses hc the film thickness where strain relaxation starts, I these alloys wre found to increase rapidly with decreasing growth temperature. For Si0.70 Ge0.30, hc ranged from 35nm at Ts=550$^{\circ}C$ to 650nm at 350$^{\circ}C$ compared to an equilibrium value of 8nm.

• Journal of the Korean Vacuum Society
• /
• v.16 no.2
• /
• pp.145-152
• /
• 2007

The evolution dynamics of nanoscale Ge islands on both Si (001) and (113) surfaces is explored using ultraviolet photoelectron emission microscopy (UV-PEEM). Real-time monitoring of the in-situ growth of the Ge island structures can allow us to study the variation of the size, the shape and the density of the nanostructures. For Ge depositions greater than ${\sim}4$ monolayer (ML) with a growth rate of ${\sim}0.4\;ML/min$ at temperatures of $450-550^{\circ}C$, we observed island nucleation on both surfaces indicating the transition from strained layer to island structure. During continuous deposition the circular islands grew larger via ripening processes. AFM measurements showed that the islands grown on Si (001) were dome-shaped while the islands on Si (113) were multiple-side faceted with flat tops of (113)-orientation. In contrast, for Ge deposition with a lower growth rate of ${\sim}0.15\;ML/min$ on Si(113), we observed the shape transition from circular into elongated island structures. The elongated islands grew longer along the [$33\bar{2}$] during continuous Ge deposition. The shape evolution of the islands is discussed in terms of strain relaxation and kinetic effects.

• Journal of the Mineralogical Society of Korea
• /
• v.17 no.2
• /
• pp.177-187
• /
• 2004

Measurements of the lattice parameters of albite and oligoclase from electron diffraction patterns with the Au internal standard resulted in errors of less than 1 %. An electron diffraction map for natural oligoclase samples was constructed and 11 stations of zone-axes diffraction patterns were obtained. This process is indispensible for reliable TEM studies of triclinic feldspars. Utilizing the [001] cleavage plane of feldspar and the double-tilting TEM holder the following information is obtainable: Si-Al ordering and chemistry of alkali feldspars could be estimated from the $\alpha$＊ - ＊ plot, where ＊ is measured from the [001] orientation, while $\alpha$＊ is measured from the [100] orientation. Si-Al ordering of Na-rich plagioclase could be estimated from ＊ [001] patterns. Structure and chemistry or Na-poor plagioclase could be estimated from existence of e-reflections, their intensity variations as well as their positional changes.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1994.02a
• /
• pp.59-60
• /
• 1994

• Journal of the Korean Magnetics Society
• /
• v.17 no.4
• /
• pp.147-151
• /
• 2007

We have investigated the half-metallicity and magnetism for the Heusler ferromagnet $Co_2$ZrSi interfaced with semiconductor ZnTe along the (001) plane by using the full-potential linearized augmented plane wave (FLAPW) method. We considered low types of possible interfaces: ZrSi/Zn, ZrSi/Te, Co/Zn, and Co/Te, respectively. From the calculated density of states, it was found that the half-metallicity was lost at all the interfaces, however for the Co/Te system the value of minority spin density of states was close to zero at the Fermi level. These facts are due to the interface states, appeared in the minority spin gap in bulk $Co_2$ZrSi, caused by the changes of the coordination and symmetry and the hybridizations between the interface atoms. At the Co/Te interface, the magnetic moments of Co atoms are 0.68 and $0.78{\mu}_B$ for the "bridge" and "antibridge" sites, respectively, which are much reduced with respect to that ($1.15{\mu}_B$) of the bulk $Co_2$ZrSi. In the case of Co/Zn, Co atoms at the "bridge" and "antibridge" sites have magnetic moments of 1.16 and $0.93{\mu}_B$, respectively, which are almost same or slightly decreased compared to that of the bulk $Co_2$ZrSi. On the other hand, for the ZrSi/Zn and ZrSi/Te systems, the magnetic moments of Co atoms at the sub-interface layers are in the range of $1.13{\sim}1.30\;{\mu}_B$, which are almost same or slightly increased than that of the bulk $Co_2$ZrSi.

• Journal of Electrical Engineering and information Science
• /
• v.3 no.1
• /
• pp.80-85
• /
• 1998

A theoretical calculation and an optical measurement method of normal-incidence absorption are proposed. By using a waveguide structure, optical interference and the problem of low level signal can be avoided in the measurement of normal-incidence absorption. The oscillator strength of intersubband absorption for a waveguide structure is calculated in Si(001), Si(110), and Ge(001) quantum wells. The polarization angle dependence of the measured and the calculated absorption strength can be obtained with the same waveguide structure, and be compared after normalization. The normal-incidence absorption in Si(110) and Ge(001) quantum wells is shown theoretically, and can be observed in the optical measurement using waveguide structures at the polarization angle of 90$^{\circ}$.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2004.02a
• /
• pp.63-63
• /
• 2004

• Korean Journal of Crystallography
• /
• v.3 no.1
• /
• pp.23-30
• /
• 1992

a-SiC crystals were grown on the (001) plane of a-SiC seed crystals by sublimation method to find effects of pressure-reduction rate of the crystal growth furnace own the growth rate and orientstion of grown SiC crystals. Pressure-reduction rate at the initial growth stage affected the crystallinity of grown SiC crystals. In case of high pressure-reduction rate, growth rate was high and 3csic polycrystalline was grown on the seed. On the other hand, low pressure-reduction rate caused the growth rate to be slow and 6H-SiC single crystal was grown on the seed. However, even after growing SiC for 2 hours under the condition in which.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.300-300
• /
• 2011

Si oxidation is a key process in developing silicon devices, such as highly integrated metal-oxide-semiconductor (MOS) transistors and antireflection-coating (ARC) on solar cell substrate. Many experimental and theoritical studies have been carried out for elucidating oxidation processes and adsorption structure using ab initio total energy and electronic structure calcultaions. However, the initial oxidation processes at step edge on vicinal Si surface have not been studied using the ReaxFF reactive force field. In this work, strucutural change, charge distribution of oxidized Si throughout the depth from Si surface were observed during oxidation processes on vicinal Si(001) surface inclined by $10.5^{\circ}$ of miscut angle toward [100]. Adsorption energys of step edge and flat terrace were calculated to compare the oxidation reaction at step edge and flat terrace on Si surface.

• Journal of Trauma and Injury
• /
• v.32 no.1
• /
• pp.17-25
• /
• 2019

Purpose: We investigated how prehospital, emergency room (ER), and delta shock indices (SI) correlate with outcomes including mortality in patients with polytrauma. Methods: We retrospectively reviewed the medical records of 1,275 patients who visited the emergency department from January 2015 to April 2018. A total of 628 patients were enrolled in the study. Patients were divided into survivor and non-survivor groups, and logistic regression analysis was used to investigate independent risk factors for death. Pearson coefficient analysis and chi-square test were used to examine the significant relationship between SI and clinical progression markers. Results: Of 628 enrolled patients, 608 survived and 27 died. Multivariate logistic regression analysis reveals "age" (p<0.001; OR, 1.068), "pre-hospital SI >0.9" (p<0.001; OR, 11.629), and "delta SI ${\geq}0.3$" (p<0.001; OR, 12.869) as independent risk factors for mortality. Prehospital and ER SIs showed a significant correlation with hospital and intensive care unit length of stay and transfusion amount. Higher prehospital and ER SIs (>0.9) were associated with poor clinical progression. Conclusions: SI and delta SI are significant predictors of mortality in patients with polytrauma. Moreover, both prehospital and ER SIs can be used as predictive markers of clinical progression in these patients.