• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.167.2-167.2
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• 2014

In this work, ZnO shell on mesoporous $SiO_2$ ($ZnO/SiO_2$) was prepared by atomic layer deposition (ALD). Diethylzinc (DEZ) and $H_2O$ were used as precursor of ZnO shell. $ZnO/SiO_2$ sample was characterized by X-ray diffraction (XRD), N2 sorption isotherms, X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). $ZnO/SiO_2$ showed higher adsorption capacity of MB than that of bare mesoporous $SiO_2$ and the adsorption capacities of $ZnO/SiO_2$ could be regenerated by UV exposure through the photocatalytic degradation of the adsorbed MB. This system could be used for removing organic dye from water by adsorption and reused after saturation of adsorption due to its photocatalytic regeneration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1028-1032
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• 2009

In this study, the influences of silicon-based gas barrier films fabricated by using a facing target sputtering(FTS) system on the gas permeability for flexible displays have been investigated. Under these optimum conditions on the $SiO_x$ film with oxygen concentration($O_2/Ar+O_2$) of 3.3% and the $SiO_xN_y$ film with nitrogen concentration($N_2/Ar+O_2+N_2$) of 30% deposited by the FTS system, it was found that the films were grown about 4 times higher deposition rate than that of the conventional sputtering system and showed high transmittance about 85% in the visible light range. Particularly, the polyethylene naphthalate(PEN) substrates with the $SiO_x$ and/or $SiO_xN_y$ films showed the enhanced properties of decreased water vapor transmission rate (WVTR) over $10^{-1}\;g/m^2{\cdot}day$ compared with the PEN substrate without any gas barrier films, which was due to high packing density in the Si-based films with high plasma density by FTS process and/or the denser chemical structure of Si-N bond in the $SiO_xN_y$ film.

• Publications of The Korean Astronomical Society
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• v.16 no.1
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• pp.15-20
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• 2001

We observed the thermal transitions of SiO (J=I-0, 2-1) and $^{29}SiO$ (J=l-O) toward the Sgr A molecular clouds. The distribution and the velocity structure of SiO are very similar to previous results for 'quiet' interstellar molecules. We think· that the SiO has been well mixed with other molecules such as $H_2$ which may indicate that the formation of Sgr A molecular clouds was affected by the activities, such as shock waves or energetic photons, from the Galactic center in large scales. The total column density of SiO is about $4.1\times10^{14} cm^{-2}$ and the fractional abundance $SiO/H_2$ appears to be about 10 times larger than those of other clouds in the central region of our galaxy. The derived values are thought to be lower limits since the optical depths of the observed SiO lines are not very thin. The formation of SiO has been known to be critically related to shocks, and our results provide informative data on the environment of our Galactic center.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.24-25
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• 2008

The effect of heat treatment in $HfO_2$ as charge trap with $SiO_2/Si_3N_4/SiO_2$ as tunnel oxide layer in capacitors has been investigated. Rapid thermal annealing (RTA) were carried out at the temperature range of 600 - $900^{\circ}C$. It is found that all devices carried out heat treatment have large threshold voltage shift Especially, device performed heat treatment at $900^{\circ}C$ has been confirmed the largest memory window. Also, Threshold voltage shift of device used conventional $SiO_2$ as tunnel oxide layer was smaller than that with $SiO_2/Si_3N_4/SiO_2$.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.659-667
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• 1997

The influence of SiO$_2$on the microstructure and electrical properties of zinc oxide varistor was investigated. Zn$_2$SiO$_4$third phase in the sintered body was found at grain boundaries, multiple grain junctions, and occasionally within ZnO grains. This phase acted as a grain growth inhibitor, which retard the grain growth of the ZnO matrix by impeding migration on the grain boundaries. As SiO$_2$ addition increases, average grain size decreased from 40.6${\mu}{\textrm}{m}$ to 26.9${\mu}{\textrm}{m}$ due to the pinning effect by Zn$_2$SiO$_4$ and drag effect by Si segregation at grain boundaries, the breakdown voltage consequently increased. When SiO$_2$ addition is increased, interface state density decreased, however, the barrier height increased by decrease of donor concentration, as a result, the nonlinear exponent increased and leakage current decreased. While, as SiO$_2$ addition increase, it was found that the apparent dielectric loss factor shows a tendency of decrease. Wholly, electrical properties of zinc oxide varistor can be said to be improved by SiO$_2$addition.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.389-393
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• 2003

The effect of antireflection layer on the reduction of optical loss has been investigated in Si photodiodes detecting red light with central wavelength of 670 nm. The theoretical analysis showed minimum reflection loss of 6% for the $SiO_2$thickness of about $1100∼1200\AA$ in the $SiO_2$-Si system with the single antireflection layer and no reflection loss for the X$N_3$N$_4$$SiO_2$thickness of $2000\AA$/$1200\AA$ in the $Si_3$$N_4$$SiO_2$-Si system with double antireflection layer. In our experiments, Si photodiodes with the web-patterned $p^{＋}$-shallow diffusion region were fabricated by bipolar IC process technology and the devices were classified into three kinds according to the structure of $Si_3$$N_4$/$SiO_2$antireflection layer. The fabricated devices showed maximum spectral response in the optical spectrum of 650∼700 nm. The average photocurrents of the devices with the $Si_3$$N_4$$SiO_2$thickness of $1000\AA$/X$SiO\AA$, and $2000\AA$$1800\AA$ under the incident power, of -17 dBm were 3.2 uA, 3.5 uA and 3.1 uA, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.41-45
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• 2014

We have investigated the passivation property of $SiN_x$ and $SiO_2$ thin films formed using various process conditions for the application of crystalline Si solar cells. An increase in the thickness of $SiN_x$ deposited using plasma enhanced chemical vapor deposition (PECVD) led to the improvement of passivation quality. This could be associated with the passivation of Si dangling bonds by hydrogen atoms which were supplied during PECVD deposition. The $SiO_2$ thin films grown using dry oxidation process exhibited better passivation behavior than those using wet oxidation process, implying the dry oxidation process was more effective in the formation of high quality $SiO_2$ thin films. The relative effective life time gradually decreased with increasing dry oxidation temperature. Such a degradation of passivation behavior could be attributed to the increase in interface trap density caused by thermal damages.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.860-868
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• 2015

The effect of Si supplied during plant cultivation on tolerance to high temperature stress in Euphorbia pulcherrima Willd. 'Ichiban' was investigated. Rooted cuttings were transplanted into 10-cm pots and a complete nutrient solution, containing 0 or $50mg{\cdot}L^{-1}$ Si as either $K_2SiO_3$, $Na_2SiO_3$, or $CaSiO_3$, was supplied through subirrigation or weekly foliar applications. After two months of cultivation, plants were placed in an environment-controlled chamber and subjected to $35{\pm}1^{\circ}C$ (high temperature) conditions for 18 days. Enhanced specific activities of enzymatic antioxidants (APX) and suppressed specific activities of non-enzymatic antioxidants (ELP) were observed in the high temperature-stressed plants with Si application. The Fv/Fm (maximum quantum yield of photosystem II), photosynthetic rate, and Si contents in the shoot increased in the treatments of $K_2SiO_3$ and $Na_2SiO_3$ supplied through subirrigation. The Si-treated plants had more tolerance of high temperature stress than the control plants. Of the Si sources and application methods tested, $K_2SiO_3$ and $Na_2SiO_3$ supplied through subirrigation were found to be the most effective in enhancing tolerance to high temperature stress.

• Journal of the Korean Ceramic Society
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• v.16 no.4
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• pp.206-212
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• 1979

The phase relations and microstructure appeared at 1700℃ in a system of Si3N4-Al2O3-SiO2 were studied. The samples were pressurelessly sintered at 1700℃ for 1hr and reheated at 1600℃ for 1hr under nitrogen atmosphere. The compounds formed were identified by X-ray diffraction method and the microstrues were observed by SEM. The stable phases appeared in this system were X-phase, Si2ON2, β'-Si3N4 and Mullite. From the results of those experiments, it was concluded that the X-phase has very close composition to that proposed by G, K. Layden, Si3Al6O12N2. SEM photographs showed that Si2ON2 was a plate phase and X-phase was a rectagular plate phase.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.597-603
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• 2002

Photocatalytic degradation of phenol was carried out with UV-illuminated TiO$_2$-SiO$_2$ in aqueous suspension. TiO$_2$-SiO$_2$ catalysts were prepared by sol-gel method from the titanium isopropoxide and tetraethylorthosilicate at different Ti/Si ratio and some commercial TiO$_2$ catalysts were used as purchased. All catalysts were characterized by X-ray Diffraction(XRD) and BET surface area analyzer. The effect of reaction conditions, such as initial concentration of phenol, reaction temperature and catalyst weight on the photocatalytic activity was studied. In addition, TiO$_2$-SiO$_2$(49: 1) prepared by sol-gel method showed higher activity than commercial TiO$_2$catalysts on the photocatalytic degradation of phenol. The addition of SiO$_2$ into TiO$_2$hepled to increase the thermal stability of titania which suppressed the formation of anatase into rutile. The photocatalytic degradation of phenol showed pseudo-1st order reaction and the degradation rate increases with decreasing initial phenol concentration.