• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.751-755
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• 2007

We have studied the variable conditions of reactive sputtering to prepare AM thin film. The leakage current showed below $10^{-9}A/cm^2$ at the deposition temperature of $250^{\circ}C\;and\;300^{\circ}C$ in the field of 0.1 MV/cm, and it was gradually increased and to be saturated in 0.2 MV/cm. The C-V characteristics of the above mentioned deposition temperature conditions showed a deep depletion phenomenon at inversion region. The C-V characteristics showed similarly under the DC power conditions of 100 and 150 W but were degraded at 200W. When the DC power was 100, 200, and 300 W the dielectric breakdown phenomenon was shown in 2.8, 3.2 and 5.2 MV/cm, respectively. It was found that AIN film was dominated by Poole-Frenkel conduction mechanism.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.989-998
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• 2023

Under nuclear reactor severe accidents, the resuspension of radioactive aerosol may occur in the containment due to the disturbing airflow generated by hydrogen combustion, hydrogen explosion and containment depressurization resulting in the increase of radioactive source term in the containment. In this paper, for containment conditions, by considering the contact between particle and rough deposition surface, the distribution of the distance between two contact points of particle and deposition surface, rolling and lifting separation mechanism, resuspension model based on random contact with rough surface (RRCR) is established. Subsequently, the detailed torque and force analysis is carried out, which indicates that particles are more easily resuspended by rolling under low disturbing airflow velocity. The simulation result is compared with the experimental result and the prediction of different simulation methods, the RRCR model shows equivalent and better predictive ability, which can be applicable for simulation of aerosol resuspension in containment during severe accident.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.38-41
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• 2002

The variation of photoluminescence(PL) properties of Si thin films was investigated by changing deposition temperatures, Si-rich silicon oxide films on p-type (100) Si substrate have been fabricated by pulsed laser deposition(PLD) technique using a Nd:YAG laser. During deposition, the substrates were kept at the temperature range of room temperature(RT) to $400^{\circ}C$. After deposition, samples were annealed at $800^{\circ}C$ in nitrogen ambient, Strong Blue PL has been observed on RT-deposited Si nanocrystallites. When the deposition temperature was increased over $100^{\circ}C$, PL intensities abruptly decreased. The experimental results show the growing mechanism of Si nanocrystallites by PLD.

• Journal of the Semiconductor & Display Technology
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• v.6 no.2 s.19
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• pp.15-18
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• 2007

Effects of $O_2$ flow during deposition on Si crystallization at low substrate temperature were studied. Silicon thin films were prepared on $SiO_2$ substrates in a low-pressure chemical vapor deposition chamber using a mixture of $SiH_4$ and $H_2$. In some cases $O_2$ was intentionally introduced during deposition. Growth of poly silicon was observed at the substrate temperature as low as $480^{\circ}C$ when $O_2$ was flowed during deposition implying that crystallization of Si was enhanced by $O_2$ flow. On the other hand, $O_2$ flow did not show any significant effects at higher substrate temperature, where deposition rate is relatively fast. Enhancement mechanism of Si crystallization by $O_2$ flow was suggested from these results.

• 전기의세계
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• v.28 no.9
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• pp.43-50
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• 1979

Silicon nitride films were chemically deposited on silicon substrates by reacting SiCl$_{4}$ and NH$_{3}$ in a nitrogen atmosphere at 700~1100 .deg.C. The deposition rate increased rapidly with deposition temperature upto about 1000 .deg.C, and became less temperature dependent above this temperature. The etch rate of films in buffered HF solution decreased, with an increase of deposition temperature, and a heat treatment at a temperature higher than that of the deposition considerably reduced the etch rate. It indicates that the heat treatment resulted in a densification of the films. Surface charge density of 3~4 * 10$^{11}$ /cm$^{2}$ was determined from the C-V characteristics of MNS diode, and it was also found that surface charge density depended on deposition temperature, but not film thickness. The current-voltage characteristics displayed a logI-V$^{1}$2/ dependence in the temperature range of 300~500.deg.K. Measurement of the slope of this characteristics and its dependence on temperature and bias polarity suggest that conduction in sili con nitride films arises from the Poole-Frenkel mechanism.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1680-1690
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• 2006

As a promising and novel manufacturing technology, laser aided direct metal deposition (DMD) process produces near-net-shape functional metal parts directly from 3-D CAD models by repeating laser cladding layer by layer. The key of the build-up mechanism is the effective control of powder delivery and laser power to be irradiated into the melt-pool. A feedback control system using two sets of optical height sensors is designed for monitoring the melt-pool and real-time control of deposition dimension. With the feedback height control system, the dimensions of part can be controlled within designed tolerance maintaining real time control of each layer thickness. Clad nugget shapes reveal that the feedback control can affect the nugget size and morphology of microstructure. The pore/void level can be controlled by utilizing pulsed-mode laser and proper design of deposition tool-path. With the present configuration of the control system, it is believed that more innovation of the DMD process is possible to the deposition of layers in 3-D slice.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.134-147
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• 2019

Gadolinium-based contrast agents (GBCAs) are commonly used for enhancement in MR imaging and have long been considered safe when administered at recommended doses. However, since the report that nephrogenic systemic fibrosis is linked to the use of GBCAs in subjects with severe renal diseases, accumulating evidence has suggested that GBCAs are not cleared entirely from our bodies; some GBCAs are deposited in our tissues, including the brain. GBCA deposition in the brain is mostly linked to the specific chelate structure of the GBCA: linear GBCAs were responsible for brain deposition in almost all reported studies. This review aimed to summarize the current knowledge about GBCA brain deposition and discuss its clinical implications.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.246-251
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• 2005

Plasma enhanced chemical vapor deposition(PE-CVD) method has an advantage in synthesizing carbon nanotubes(CNTs) at lower temperature compared with thermal enhanced chemical vapor deposition(TE-CVD) method. In this study, CNTs was prepared by using PE-CVD method. The growth rate of CNT was faster more than 100 times on using Invar alloy than iron as catalyst. It was found that chrome silicide was formed at the interface between chrome layer and silicon substrate which should be considered in designing process. Nanoparticles of Invar catalyst were found oxidized on their surfaces with a depth of 10 m. Microstructure was analyzed by scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray spectrometry. Based on the result of analysis, growth mechanism at an initial stage was suggested.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.745-750
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• 2000

The (S $r_{0.85}$C $a_{0.15}$) Ti $O_3$(SCT) thin films are deposited on Pt-coated electrode (Pt/TiN/ $SiO_2$/Si) using RF sputtering method at various deposition temperature. The crystallinity of SCT thin films were increased with increase of deposition temperature in the temperature range of 200~500[$^{\circ}C$]. Also, the composition of SCT thin films were closed to stoichiometry (1.080~1.111 in A/B ratio). V-I characteristics of SCT thin films show the increasing leakage current with the increases of deposition temperature. The conduction mechanism of the SCT thin films observed in the temperature range of 25~100[$^{\circ}C$] can be divided into four regions with different mechanism by the increasing current. The region I below 0.8[MV/cm]shows the ohmic conduction. The region II between 0.9~2[MV/cm] is in proportion to J∝ $E^{1.5}$ , the region III between 2~4[MV/cm] can be explained by the Child’s law, and the region IV above 4[MV/cm]is dominated by the tunneling effect.ect.

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.155-162
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• 1999

Zirconia thin films of uniform structure were fabricated by plasma-enhanced metal-organic chemical vapor deposition. Deposition conditions such as substrate temperature were observed to have much influence on the formation of zirconia films, therefore the mechanism of decomposition of $Zr[TMHD]_4$precursor and film growth were examined by XRD, FT-IR etc., as well as the determination of the optimal deposition condition. From temperature dependence on zirconia, below the deposition temperature of 523K, the amorphous zirconia was formed while the crystalline of zirconia with preferred orientation of cubic (200) was obtained above the temperature. Deposits at low temperatures were investigated by FT-IR and the absorption band of films revealed that the zirconia thin film was in amorphous structure and has the same organic band as that of Zr precursor. In case of high temperature, it was found that Zr precursor was completely decomposed and crystalline zirconia was obtained. In addition, at 623K the higher RF power yielded the increased crystallinity of zirconia implying an increase in decomposition rate of precursor. However, it seems that RF power has nothing with the zirconia deposition process at 773K. It was found that the proper bubbler temperature of TEX>$Zr[TMHD]<_4$ precursor is needed along with high flow rate of carrier gas. Through AFM analysis it was determined that the growth mechanism of the zirconia thin film showed island model.