• Korean Journal of Materials Research
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• v.4 no.5
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• pp.550-555
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• 1994

The effects of RTA treatment on the leakage current have been studied for tantalum pentoxide( $Ta_2O_5$) films deposited by PECVD on P-type(100) Si substrate using $TaCl_5$(99.99%) and $N_2O$(99.99%) gaseous mixture. The refractive index increased with increasing the deposition temperature and the maximum deposition rate was obtained at $500^{\circ}C$. The Ta-0 bond peak intensity of as-deposited $Ta_2O_5$ increased with increasing the deposition temperature through FT-IR analysis and the leakage current value was decreased with increasing the deposition temperature. The small leakage current value obtained after RTA treatment of as-deposited $Ta_2O_5$ was found to be due to the reduction of 0-deficient structure in the film. The increases of the oxygen coacentration and the Ta-0 bond peak intensity in the film after RTA treatment were measured by AES and FT-IR analyses.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.37-43
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• 2009

Silicon dioxide as gate dielectrics was grown at $400^{\circ}C$ on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of $O_2$ and $N_2O$ to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature $N_2O$ annealing, nitrogen can be supplied to the $Si/SiO_2$ interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/$SiO_2$ interface by plasma oxidation as the $N_2O$ molecule is broken in the plasma and because a dense Si-N bond is formed at the $SiO_2$ surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the $Si/SiO_2$ interface by the plasma oxidation of mixtures of $O_2/N_2O$ gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

• The Journal of Advanced Prosthodontics
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• v.10 no.1
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• pp.43-49
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• 2018

PURPOSE. The purpose of this in vitro study is to examine the effects of a nano-structured alumina coating on the adhesion between resin cements and zirconia ceramics using a four-point bending test. MATERIALS AND METHODS. 100 pairs of zirconium bar specimens were prepared with dimensions of $25mm{\times}2mm{\times}5mm$ and cementation surfaces of $5mm{\times}2mm$. The samples were divided into 5 groups of 20 pairs each. The groups are as follows: Group I (C) - Control with no surface modification, Group II (APA) - airborne-particle-abrasion with $110{\mu}m$ high-purity aluminum oxide ($Al_2O_3$) particles, Group III (ROC) - airborne-particle-abrasion with $110{\mu}m$ silica modified aluminum oxide ($Al_2O_3+SiO_2$) particles, Group IV (TCS) - tribochemical silica coated with $Al_2O_3$ particles, and Group V (AlC) - nano alumina coating. The surface modifications were assessed on two samples selected from each group by atomic force microscopy and scanning electron microscopy. The samples were cemented with two different self-adhesive resin cements. The bending bond strength was evaluated by mechanical testing. RESULTS. According to the ANOVA results, surface treatments, different cement types, and their interactions were statistically significant (P<.05). The highest flexural bond strengths were obtained in nano-structured alumina coated zirconia surfaces (50.4 MPa) and the lowest values were obtained in the control group (12.00 MPa), both of which were cemented using a self-adhesive resin cement. CONCLUSION. The surface modifications tested in the current study affected the surface roughness and flexural bond strength of zirconia. The nano alumina coating method significantly increased the flexural bond strength of zirconia ceramics.

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.327-332
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• 2006

The effect of the processing parameters on the sintered density and strength of silica-bonded SiC (SBSC) ceramics was investigated for three types of batches with different particle sizes. The SBSC ceramics were fabricated by an oxidation-bonding process. The process involves the sintering of powder compacts in air so that the SiC particles bond to each other by oxidation-derived $SiO_2$ glass or cristobalite. A finding of this study was that a higher flexural strength was obtained when the starting powder was smaller. When a ${\sim}0.3_{-{\mu}m}$ SiC powder was used as a starting powder, a high strength of $257{\pm}42\;MPa$ was achieved at a relative density of ${\sim}80%$.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2013-2018
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• 2014

The adsorption and decomposition of trimethylene oxide ($C_3H_6O$) molecule on the Al(111) surface were investigated by the generalized gradient approximation (GGA) of density functional theory (DFT). The calculations employed a supercell ($6{\times}6{\times}3$) slab model and three-dimensional periodic boundary conditions. The strong attractive forces between $C_3H_6O$ molecule and Al atoms induce the C-O bond breaking of the ring $C_3H_6O$ molecule. Subsequently, the dissociated radical fragments of $C_3H_6O$ molecule oxidize the Al surface. The largest adsorption energy is about -260.0 kJ/mol in V3, V4 and P2, resulting a ring break at the C-O bond. We also investigated the decomposition mechanism of $C_3H_6O$ molecules on the Al(111) surface. The activation energies ($E_a$) for the dissociations V3, V4 and P2 are 133.3, 166.8 and 174.0 kJ/mol, respectively. The hcp site is the most reactive position for $C_3H_6O$ decomposing.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.182-188
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• 2011

Polysilazane and polymethylsilazane based precursor films were deposited on Si-substrate by spin-coating, subsequently annealed at $150{\sim}850^{\circ}C$, and characterized. Structural analysis, shrink, compositional change, etch rate, and gap-filling were observed. Annealing the precursor films led to formation of spin-on dielectric films. C-containing precursor films showed that less loss of N, H, and C while less gain of O than that of C-free precursor films at $400^{\circ}C$, but more loss of N, H, and C while more gain of O at $850^{\circ}C$. Thus polysilazane based precursor films exhibited less reduction in thickness of 14.5% than silazane based one of 15.6% at $400^{\circ}C$ but more 37.4% than 19.4% at $850^{\circ}C$. FTIR indicated that C induced smaller amount of Si-O bond, non-uniform property, and lower resistance to chemical etching.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.925-933
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• 1990

The possible use of bioglass,, which is one of the surface active biomaterials, as implants materials has drawn great attention due to their ability to bond to human living tissue. In the present work, the investigation was carried out to find the bonding phenomena between alumina substrate and bioglass(45S5) or fluorine-containing bioglass(45S5$.$4F), and the properties of coated bioglass. The stable bonding between alumina and bioglass was formed when heat-treated at 1150$^{\circ}C$ for 120 minutes or at 1250$^{\circ}C$ for 30 minutes for the 45S5, and at 1150$^{\circ}C$ for 30 minutes for the 45S5$.$4F. When bioglass coated alumina was heat-treated, great amount of Al was diffused into bioglass from alumina substrate. More Al was diffused into fluorine-containing bioglass than into bioglass without fluorine. At early stage of heat-tretment, the diffused alumina content was increased with the square root of time and it was also increased with the thickness of coating layer and heat-treatment temperatures. The alumina content became constant after its saturation for longer heat-treatment time. Coated bioglasses were crystallized to Na2O$.$CaO$.$3SiO2 when heat-treated at lower temperature, and to CaO$.$SiO2 at higher temperature.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.247-252
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• 2015

ZSM-5 crystals grew on the surface of ${\alpha}$-SiC and ${\beta}$-SiC particles by hydrothermal synthesis method. SiC particles which were > $50{\mu}m$ of size were used, and oxide layer were developed on the surface of the particles to induce growth of ZSM-5 from the surface. Then, synthesis time and temperature condition were considered growing ZSM-5. In this study, oxide layer was formed on ${\beta}$-SiC at $900^{\circ}C$ in air, and it was controlled to grow ZSM-5 grew from the ${\beta}$-SiC surface with $150^{\circ}C$ synthesis condition. This is due to Si-O-Si or Si-O-Al bond, which is basic framework of ZSM-5 can be easily formed, from the silicon oxide film on the surface of ${\beta}$-SiC. When the synthesis temperature was $200^{\circ}C$, the size of ZSM-5 was increased, and it covered much area of the SiC surface with better crystal shapes with longer synthesis time.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.78-78
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• 2011

수열합성법을 이용하여 Si(111) 기판에 ZnO 박막을 성장하였다. ZnO 박막의 성장을 위한 씨앗층은 plasma-assisted molecular beam epitaxy (PA-MBE)를 이용하였다. 씨앗층의 표면 거칠기(root-mean-square roughness)는 2.5 nm이고, 씨앗층 위에 성장된 ZnO 박막은 다양한 크기의 입자들로 이루어져 있었으며 두께는 약 $1.8{\mu}m$로 매우 일정하였다. 배향성을 알아보기 위하여 texture coefficient (TC)를 계산해 보았다. TC(100)과 TC(200)은 a-축 배향성을, TC(002)는 c-축 배향성을 나타내는데, c-축으로 더 우세한 배향성(99.5%)을 보였다. TC 비율(TCa-axis/TCc-axis)은 열처리 온도를 $700^{\circ}C$까지 올렸을 때, 점차적으로 증가하였고, 그 이상의 열처리 온도(< $900^{\circ}C$)에서는 급격히 감소하였다. 잔류응력과 Zn와 O의 bond length도 유사한 경향을 보였다. $700^{\circ}C$까지 열처리 온도가 증가함에 따라, 잔류응력은 증가하였고 bond length는 감소하였다. Near-band-edge emission (NBE)의 피크 강도는 열처리 온도가 $700^{\circ}C$까지 증가함에 따라 점차적으로 증가하였다. 열처리 온도가 $800^{\circ}C$ 이상 증가함에 따라 deep-level emission (DLE)가 적색편이(red-shift)하였다. $700^{\circ}C$로 열처리를 한 ZnO 박막이 가장 우세한 (002)방향의 배향성을 보였을 뿐만 아니라 가장 큰 발광효율 증가를 보였다.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2162-2166
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• 2013

The tailored surface modification of electrode materials is crucial to realize the wanted electronic and electrochemical properties. In this regard, a dexterous carbon encapsulation technique can be one of the most essential preparation methods for the electrode materials for lithium rechargeable batteries. For this purpose, DL-malic acid ($C_4H_6O_5$) was here used as the carbon source enabling an amorphous carbon layer to be formed on the surface of Si nanoparticles at enough low temperature to maintain their own physical or chemical properties. Various structural characterizations proved that the bulk structure of Si doesn't undergo any discernible change except for the evolution of C-C bond attributed to the formed carbon layer on the surface of Si. The improved electrochemical performance of the carbon-encapsulated Si compared to Si can be attributed to the enhanced electrical conductivity by the surface carbon layer as well as its role as a buffering agent to absorb the volume expansion of Si during lithiation and delithiation.