• Journal of the Korean institute of surface engineering
• /
• v.40 no.3
• /
• pp.117-124
• /
• 2007

The ITO films were deposited on glass substrates by RF-superimposed dc reactive magnetron sputtering and were annealed in $N_2$ vacuum furnace with temperatures in the range of $403K{\sim}573K$ for 30 minutes. Electrical, optical and structural properties of ITO films were examined with varying annealing temperatures from 403 K to 573 K. The resistivity of as-deposited ITO films was $5.4{\times}10^{-4}{\Omega}cm$ at the sputter conditions of applied RF/DC power of 200/200 W, $O_{2}$ flow of 0.2 seem and Ar flow of 0.2 seem. As a result of annealing in the temperature range of $403K{\sim}573K$, the crystallization occurred at 423 K that is lower than the crystallization temperature caused by a conventional sputtering method. And the resistivity decreased from $5.4{\times}10^{-4}{\Omega}cm\;to\;2.3{\times}10^{-4}{\Omega}cm$, the carrier concentration and mobility of ITO films increased from $4.9{\times}10^{20}/cm^3\;to\;6.4{\times}10^{20}/cm^3$, from $20.4cm^2/Vsec\;to\;41.0cm^2/Vsec$, respectively. The transmittance of ITO films in visible became higher than 90% when annealed in the temperature range of $423K{\sim}573K$. High quality ITO thin films made by RF-superimposed dc reactive magnetron sputtering and annealing in $N_2$ vacuum furnace will be applied to transparent conductive oxides of the advanced flat panel display.

• Journal of the Korean Ceramic Society
• /
• v.33 no.9
• /
• pp.1057-1063
• /
• 1996

Y2O3-CeO2-ZrO2 powders were prepared from water-soluble salts using a coprecipitation method. The forming process of oxide and the characteristics of the calcined powders treated in different drying conditions were investigated. The oxidation was occurred at the temperature of around 40$0^{\circ}C$ and the main crystallization of ZrO2 around $600^{\circ}C$. On calcination at $600^{\circ}C$ heating lamp-dried powders consisted of agglomerates of globular morphology with average agglomerate size of 2.27${\mu}{\textrm}{m}$ and specific surface area of 68.3m2/g and spray dried powders contained dense spheric particles with average agglomerate size of 1.35${\mu}{\textrm}{m}$ and specific surface area of 11.0m2/g which exhibited low agglomeration tendency. Removal of the water by a freeze-drying technique produced calcined powders containing flake-like secondary particle structures with wide agglomerate size distri-bution of 0.1-60${\mu}{\textrm}{m}$ and specific surface area of 24.5${\mu}{\textrm}{m}$. The 20 MPa-pressed density (36.8-41.4% T,D) of calcined powders did not nealy depend on drying methods whilst compaction ratio of calcined powders derived from freeze-drying was the highest ( 6.24) among three drying methods. On continuous heating up to 150$0^{\circ}C$ the sinterability of calcined powders derived from heating lamp-drying was superior to those derived from spray-and freeze-drying. The final sintered density of calcined powders was the highest (96% T,D at 150$0^{\circ}C$) in case of heating lamp-drying.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.6 no.5
• /
• pp.696-702
• /
• 2002

The BST $({Bal-xSrxTiO_3})$ (50/50) thin film has been grown by RF magnetron reactive sputtering and its characteristics such as crystallization, surface roughness, and electrical properties have been investigated with varying the film thickness. The crystallization and surface roughness of BST thin film are investigated by using XRD and AFM, respectively. The BST thin film annealed at $800^{\circ}C$ for 2 min has pure perovskite structure and good surface roughness of 16.1$\AA$. As the film thickness increases from 80 nm to 240 nm, the dielectric constant at 10 KHz increases from 199 to 265 and the leakage current density at 250 ㎸/cm decreases from $0.779 {\mu}A/{cm^2} to 0.184 {\mu}A/{cm^2}$. In the case of 240 nm-thick BST thin film, the charge storage density and leakage current density at 5V are 50.5 fC/${{\mu}m^2} and 0.182 {\mu}A/{cm^2}$, respectively. The values indicate that the BST thin film is a very useful dielectric material for the DRAM capacitor.

• Applied Chemistry for Engineering
• /
• v.22 no.5
• /
• pp.490-494
• /
• 2011

Nanocomposites of blends of polyethyleneterephthalate (PET) and polyamide66 (Nylon66) containing natural and organically modified montmorillonite clays (PM, $Cloisite^{(R)}$ 25A and 15A) were prepared by melt mixing. DSC results showed that the addition of clay changed the crystallization behavior of PET/Nylon66 nanocomposites. Clay C25A was observed to most significantly change the crystallization temperature than other clays in blends of PET and Nylon66, which may be caused by the difference in interaction with matrix polymers. AFM results also showed that the lowest value of surface roughness was observed for nanocomposites containing C25A indicating the smooth and relatively homogenous surface. Mechanical properties measurement showed the similar results. Contact angle was measured to study the difference in hydrophobicity. An increase in contact angle was observed for nanocomposites with C25A or C15A due to the increased hydrophobicity.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.1
• /
• pp.5-14
• /
• 2003

Principles of a novel pulse growing method are described. The method realized in the crystal growing on a seed from melts under raw melt feeding provided a more reliable control of the crystallization process when producing large alkali halide crystals. The slow natural convection of the melt in the crucible at a constant melt level is intensified by rotating the crucible, while the crystal rotation favors a more symmetrical distribution of thermal stresses over the crystal cross-section. Optimum rotation parameters for the crucible and crystal have been determined. The spatial position oi the solid/liquid phase interface relatively to the melt surface, heaters and the crucible elements are considered. Basing on that consideration, a novel criterion is stated, that is, the immersion extent of the crystallization front (CF) convex toward the melt. When the crystal grows at a <> CF immersion, the raised CF may tear off from the melt partially or completely due to its weight. This results in avoid formation in the crystal. Experimental data on the radial crystal growth speed are discussed. This speed defines the formation of a gas phase layer at the crystal surface. The layer thickness il a function of time a temperature at specific values of pressure in the furnace and the free melt surface dimensions in the gap between the crystal and crucible wall. Analytical expressions have been derived for the impurity component mass transfer at the steady-state growth stage describing two independent processes, the impurity mass transfer along the <> path and its transit along the <> one. The heater (and thus the melt) temperature variation is inherent in any control system. It has been shown that when random temperature changes occur causing its lowering at a rate exceeding $0.5^{\circ}C/min$, a kind of the CF decoration by foreign impurities or by gas bubbles takes place. Short-term temperature changes at one heater or both result in local (i.e., at the front) redistribution of the preset axial growth speed.

• Resources Recycling
• /
• v.12 no.4
• /
• pp.20-29
• /
• 2003

In order to efficiently recycle the waste solution resulting from shadow mask processing, nano-sized Ni-ferrite powder was fab-ricated through spray pyrolysis process. The average particle size of the powder was below 100nm. In this study, the effects of the reaction temperature. the concentration of raw material solution and the injection speed of solution on the properties of powder were respectively investigated. As the reaction temperature increased from $800^{\circ}C$ to $1100^{\circ}C$, average particle size of the powder significantly Increased and power structure became more solid, whereat its specific surface area was greatly reduced. Formation rate and crystallization of($NiFe_2$$O_4$) phale increased along with the temperature rise. As the concentrations of iron and nickel components in wastere solution increased, particle size of the powder became larger, particle size distribution became more irregular, and specific surface area was reduced. Formation rate and crystallization of $NiFe_2$$O_4$ phase increased significantly along with the increase of the concentration of solution. As the inlet speed of solution increased, particle size of the powder became larger, particle size distribution became wider, specific surface area was reduced and powder structure became less solid. As the inlet speed of solution decreased, formation rate and crystallization of $NiFe_2$$O_4$ phase significantly increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.9
• /
• pp.607-614
• /
• 2015

To provide the clear images from the direct light on electrical board and display devices, anti glare treatment of display cover glass is needed. In this study, the effects of surface treatment temperature, concentration, and etching solution coating thickness of the gel phase on optical elements control such as gloss, haze of reflected light and transmittance, were investigated. Cover glasses were treated at different coating thickness and additive concentration. The optical properties were examined using spectrophotometer, gloss and haze meter. The surface morphology and roughness were measured by the optical microscope and Ra measuring instrument. The etching rate and surface morphologies were dramatically affected by the concentration of acid additive in the viscous gel because of re-crystallization of components in the etching solution, hydrogel formation and coagulant after coating on glass substrate. In our experimental range, cover glass which is surface-treated with various optical properties as well as the morphology uniformity was obtained; in particular, optical properties could be controlled by etching solution coating thickness of the gel phase and the concentration of additive. The gloss was depended on the surface roughness and it showed the linear relationship between optical transmittance and haze of reflected light, respectively.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.683-685
• /
• 2003

We report on a surface planarization process that produces more planar surface than previous sequential lateral solidification crystallized poly silicon films. By applying the single shot laser irradiation with optimum energy density ($(817mJ/cm^{2})$ on the ridge area after SLS crystallization, the ridge height can be decreased.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.172-177
• /
• 1996

We have characterized XeCl excimer-laser-induced crystallization of thin amorphous silicon films deposited by PECVD (${\alpha}$-Si:H) and LPCVD (${\alpha}$-Si). The electrical properties, surface roughness and crystallinity of crystallized thin films have been measured. The dc conductivities, crystallinity andsurface roughness of the films increased as the laser energy density and shot density were increased. The properties of laser annealed films deposited by LPCVD were better than those of thin films deposite by PECVD. We have also found that the multiple shots with relative low energy density were more benifical to the improsvement of surface roughness than the single shot with high energy density preserving the crystallinity.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.6
• /
• pp.621-627
• /
• 1996

$SrBi_{2x}TaO_9$ ferroelectric thin films were prepared on platinized silicon substrates using MOD proces, and crystallization behavior of the films was investigated with variation of the annealing temperature and Bi content x. Crystalline phase of bismuth layered perovskite structure was formed even by baking the films at $800^{\circ}C$ for 5 minutes in air, and was not changed by annealing at temperatures raning from $700^{\circ}C$ to $900^{\circ}C$ for 1 hour in oxygen ambient. When $SrBi_{2x}TaO_9$ thin films ($0.8\lex\ie1.6$) were annealed at $800^{\circ}C$, Preferred orientation of the films along c-axis was observed with $x\ge1.2$. With increasing Bi content x, surface morphology of the films was changed from equiaxed grains to elongated grains.