• Carbon letters
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• v.6 no.4
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• pp.227-233
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• 2005

Carbonization products C1, C2, C3, C4 and C5 were prepared by the carbonization of date pit in limited air, at 500, 600, 700, 800 and $1000^{\circ}C$, respectively. C1-V-600, C3-V-600, C1-V-1000 and C3-V-1000 were prepared by thermal treatment of C1 and C3 under vacuum at 600 and $1000^{\circ}C$. The textural properties were determined from nitrogen adsorption at 77 K and from carbon dioxide adsorption at 298 K. The surface pH, the FTIR spectra and the acid and base neutralization capacities of some carbons were investigated. The amounts of surface oxygen were determined by out-gassing the carbon-oxygen groups on the surface as $CO_2$ and CO. The adsorption of water vapor at 308 K on C1, C2, C3 and C4 was measured and the decomposition of $H_2O_2$ at 308 K was also investigated on C1, C2, C3, C4 and C5. The surface area and the total pore volume decreased with the rise of the carbonization temperature from 500 to $1000^{\circ}C$. The adsorption of water vapor is independent on the textural properties, while it is related to the amount of acidic carbon-oxygen groups on the surface. The catalytic activity of $H_2O_2$ decomposition does not depend on the textural properties, but directly related to the amount of basic carbon-oxygen complexes out-gassed as CO, at high temperatures.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.102-105
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• 2011

This work describes the characteristics of zinc oxide (ZnO) thin films formed on a polycrystalline (poly) 3C-SiC buffer layer using a sol-gel process. The deposited ZnO films were characterized using X-ray diffraction, scanning electron microscopy, and photoluminescence (PL) spectra. ZnO thin films grown on the poly 3C-SiC buffer layer had a nanoparticle structure and porous film. The effects of post-annealing on ZnO film were also studied. The PL spectra at room temperature confirmed the crystal quality and optical properties of ZnO thin films formed on the 3C-SiC buffer layer were improved due to close lattice mismatch in the ZnO/3C-SiC interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.441-445
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• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.223-227
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• 1996

The effect of ZrC and VC addition on the diffusion induced recrystallization (DIR) of TiC-Cr3C2 has been investigated. With in creasing the amount of added ZrC to Cr3C2 the DIR of TiC was suppressed at the begining and then occurred. On the contrary the DIR was accelerated with the addition of VC to Cr3C2 Because the lattice parameters of (Ti, Cr)C and (Ti,V)C are smaller and that of (Ti, Zr)C is larger than that of TiC the lattice parameter of (Ti,Cr,Zr)C is expected to be similar to that of TiC,. The results indicate that the strain energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed DIR.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.457-461
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• 2007

This paper describes the characteristics of poly (polycrystalline) 3C-SiC grown on $SiO_{2}$ and AlN substrates, respectively. The crystallinity and the bonding structure of poly 3C-SiC grown on each substrate were investigated according to various growth temperatures. The crystalline quality of poly 3C-SiC was improved from resulting in decrease of FWHM (full width half maximum) of XRD and FT-IR by increasing the growth temperature. The minimum growth temperature of poly 3C-SiC was $1100^{\circ}C$. The surface chemical composition and the electron mobility of poly 3C-SiC grown on each substrate were investigated by XPS and Hall Effect, respectively. The chemical compositions of surface of poly 3C-SiC films grown on $SiO_{2}$ and AlN were not different. However, their electron mobilities were $7.65{\;}cm^{2}/V.s$ and $14.8{\;}cm^{2}/V.s$, respectively. Therefore, since the electron mobility of poly 3C-SiC films grown on AlN buffer layer was two times higher than that of 3C-SiC/$SiO_{2}$, a AlN film is a suitable material, as buffer layer, for the growth of poly 3C-SiC thin films with excellent properties for M/NEMS applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.164-167
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• 2002

SiC direct bonding technology is very attractive for both SiCOI(SiC-on-insulator) electric devices and SiC-MEMS applications because of its application possibility in harsh environments. This paper presents on pre-bonding according to HF pre-treatment conditions in SiC wafer direct bonding using PECVD oxide. The characteristics of bonded sample were measured under different bonding conditions of HF concentration, and applied pressure. The 3C-SiC epitaxial films grown on Si(100) were characterized by AFM and XPS, respectively. The bonding strength was evaluated by tensile strength method. Components existed in the interlayer were analyzed by using FT-IR. The bond strength depends on the HF pre-treatment condition before pre-bonding (Min : 5.3 kgf/$\textrm{cm}^2$∼Max : 15.5 kgf/$\textrm{cm}^2$).

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.152-157
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• 2000

Si3N4/SiC nanocomposite ceramics containing 5 wt%dispersed SiC particles were prepared by gas-pressure-sintering at 200$0^{\circ}C$ under nitrogen atmosphere. SiC particles with average sizes of 0.2 and 0.5${\mu}{\textrm}{m}$ were used, and the effect of the SiC particle size on the microstructure was investigated. The addition of SiC particles effectively suppressed the growth of the Si3N4 matrix grains. The effect of grain growth inhibition was higher in the nanocomposites dispersed with fine SiC. SiC particles were dispersed uniformly inside Si3N4 matrix grains and on grain boundaries. When the fine SiC particles were added, large fraction of the SiC particles was trapped inside the grains. On the other hand, when the large SiC particles were added, most of the SiC particles were located on grain boundaries. Typically, the fraction of SiC particles located at grain boundaries was higher in the specimen prepared from $\beta$-Si3N4 than in the specimen prepared from $\alpha$-Si3N4.

• Food Science and Preservation
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• v.14 no.5
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• pp.451-456
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• 2007

The vitamin C content in extruded comstarch matrix was shown to depend on extrusion process variables (barrel temperature and water content), the packaging method, and the storage period. In addition, loss rates of vitamin C under different processing conditions were calculated. Extrusion process variable were barrel temperature ($80^{\circ}C,\;90^{\circ}C,\;100^{\circ}C$ and $110^{\circ}C$), and water content (25% 30% both w/w). The vitamin C content decreased as barrel temperature increased from $80^{\circ}C$ to $110^{\circ}C$ and water content increased from 25% to 30% when either LDPE plastic film packaging or ON film vacuum packaging were employed. As barrel temperature and water content increased, vitamin C decreased in comstarch packed in either LDPE film or ON film. As temperature increased, vitamin C loss rate increased under both packaging conditions, but the loss tate was only 50% of the LDPE film packaging rate when ON film vacuum packaging was used. In conclusion, the higher the temperature, and the greater the water content, the less vitamin C was inactivated during extrusion cooking, although the loss rah of vitamin C became faster as temperature and water content rose. In conclusion, extrusion process could be applied for making vitamin C matrix to extend vitamin C preservation.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.825-833
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• 1997

Silicon carbide films were deposited by low pressure chemical vapor deposition(LPCVD) using MTS(CH3SICl3) in hydrogen atmosphere on (100) Si substrate. To prevent the unstable interface from being formed on the substrate, the experiments were performed through three deposition processes which were the deposition on 1) as received Si, 2) low temperature grown SiC, and 3) carbonized Si by C2H2. The microstructure of the interface between Si substrates and SiC films was observed by SEM and the adhesion between Si substrates and SiC films was measured through scratch test. The SiC films deposited on the low temperature grown SiC thin films, showed the stable interfacial structures. The interface of the SiC films deposited on carbonized Si, however, was more stable and showed better adhesion than the others. In the case of the low temperature growth process, the optimum condition was 120$0^{\circ}C$ on carbonized Si by 3% C2H2, at 105$0^{\circ}C$, 5 torr, 10 min, showed the most stable interface. As a result of XRD analysis, it was observed that the preferred orientation of (200) plane was increased with Si carbonization. On the basis of the experimental results, the models of defect formation in the process of each deposition were compared.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.3-6
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• 2009

Aluminum nitride (AIN) thin films were deposited on a polycrystalline 3C-SiC intermediate layer by a pulsed reactive magnetron sputtering system. Characteristics of the AIN/SiC heterostructures were investigated by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The columnar structure of AIN thin films was observed by FE-SEM. The surface roughness of AlN films on the 3C-SiC buffer layer was measured using AFM. The XRD pattern of AlN films on SiC buffer layers was highly oriented at (002). Full width at half maximum (FWHM) of the rocking curve near (002) reflections was $1.3^{\circ}$. The infrared absorbance spectrum indicated that the residual stress of AIN thin films grown on SiC buffer layers was nearly negligible. The 3C-SiC intermediate layers are promising for the realization of nitride based electronic and mechanical devices.