• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.430-436
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• 1996

We have grown superconducting thin films on various substrates using a pulsed laser deposition (PLD) method. $YBa_2Cu_3O_7-\delta$ (YBCO) superconducting thin films with the superconducting transition temperature ($T_{c. offset}$) of 87K were grown on Si substrates using yittria-stabilized zirconia (YSZ) and $CeO_2$ double buffer layers. We have developed a large area pulsed laser deposition system. The system was designed to deposit up to 6 different materials on a large area substrate up to 7.5cm in diameter without breaking a vacuum. The preliminary runs of the deposition of YBCO superconducting thin films on $SrTiO_3$ substrate using this system showed a very uniform thickness profile over the entire substrate holder area. $T_{c}$ of the deposited YBCO thin film, however, was scattered depending on the position and the highest value was 85K.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.697-703
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• 2021

Aluminum nitride having a dense hexagonal structure is used as a high-temperature material because of its excellent heat resistance and high mechanical strength; its excellent piezoelectric properties are also attracting attention. The structure and residual stress of AlN thin films formed on glass substrate using TFT sputtering system are examined by XRD. The deposition conditions are nitrogen gas pressures of 1 × 10^-2, 6 × 10^-3, and 3 × 10^-3, substrate temperature of 523 K, and sputtering time of 120 min. The structure of the AlN thin film is columnar, having a c-axis, i.e., a <00·1> orientation, which is the normal direction of the glass substrate. An X-ray stress measurement method for crystalline thin films with orientation properties such as columnar structure is proposed and applied to the residual stress measurement of AlN thin films with orientation <00·1>. Strength of diffraction lines other than 00·2 diffraction is very weak. As a result of stress measurement using AlN powder sample as a comparative standard sample, tensile residual stress is obtained when the nitrogen gas pressure is low, but the gas pressure increases as the residual stress is shifts toward compression. At low gas pressure, the unit cell expands due to the incorporation of excess nitrogen atoms.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.423-430
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• 2013

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition (CVD) system. Prior to the carbon coils deposition reaction, two kinds of samples having different combination of Ni catalyst and substrate were employed, namely, a commercially-made $Al_2O_3$ ceramic boat with Ni powders and a commercially-made $Al_2O_3$ substrate with Ni layer. By using a commercially-made $Al_2O_3$ ceramic boat, the synthesis of carbon coils could be enhanced as much as 10 times higher than that of $Al_2O_3$ substrate. Furthermore, the dominant formation of the microsized carbon coils could be obtained by using $Al_2O_3$ ceramic boat. The surface roughness of the supporting substrate of $Al_2O_3$ ceramic boat was understood to be associated with the large scale synthesis of carbon coils as well as the dominant formation of the larger-sized, namely the microsized carbon coils.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.605-608
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• 2008

The preparation and characteristics of flexible indium tin oxide electrodes grown on polyethylene terephthalate (PET) substrates using a specially designed roll-to-roll sputtering system for use in flexible optoelectronics In spite of low a PET substrate temperature, we can obtain the flexible electrode with a sheet resistance of 47.4 ohm/square and an average optical transmittance of 83.46 % in the green region of 500~550 nm wavelength. Both x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis results showed that all flexible ITO electrodes grown on the PET substrate were an amorphous structure with a very smooth and featureless surface, regardless of the Ar/$O_2$ flow ratio due to the low substrate temperature, which is maintained by a cooling drum. In addition, the flexible ITO electrode grown on the Ar ion beam treated PET substrates showed more stable mechanical properties than the flexible ITO electrode grown on the wet cleaned PET substrate, due to an increased adhesion between the flexible ITO and the PET substrates.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1474-1476
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• 2005

ZnO:Al(AZO) has been investigated for the photovoltaic cell or TCO(Transparent Conductive Oxide) of the display, because it has good electrical and optical properties. In this study, the ZnO:Al(AZO) thin film prepared on variation of substrate temperature by FTS(Facing Targets Sputtering) system. In case of TCO, because resistivity and roughness values affect the lighting of the OLED, their factors are very important. Therefore, in this paper, the electrical and optical properties of the AZO thin film were investigated with the deposition conditions and its roughness was investigated on variation of the substrate temperature. In results, AZO thin film deposited with the transmittance over 80% and the resistivity was reduced from $1.36{\times}10^{-3}$ [O-cm] to $4{\times}10^{-4}$ [O-cm] with increasing the substrate temperature from R.T to $200[^{\circ}C]$. Especially, we could obtain the resistivity $4{\times}10^{-4}$ [O-cm] of AZO thin film prepared at working pressure 1[mTorr], input current 0.4[A] and substrate temperature $200[^{\circ}C]$.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.12-18
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• 2010

Irrigation management methods controlled by integrated solar radiation (ISR) or drainage level sensor were evaluated in rockwool or coir bag culture as tomato (Solanum lycopersicum L.) production system. Substrate water content and drainage percentage were more stable in the drainage level sensor method than in the ISR method regardless of substrate type. Total yield and marketable yield were high in the drainage level sensor method, but not between substrates in the same irrigation management method. Sugar content was affected more by the substrate type than irrigation method. The drainage level sensor method was elucidated to be better than the ISR method regardless of substrate type.

• Elastomers and Composites
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• v.50 no.1
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• pp.55-61
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• 2015

Manufacturing process of OLED contains adsorption-desorption process of glass substrate. There are several adsorption methods of glass substrate such as atmospheric pressure, vacuum and electrostatic adsorption. However, these methods are very complex to connect system. Therefore, the adsorption method using silicone rubber based sticking chuck was proposed in this study. Three types of silicone rubbers having 0, 19.3 and 32.2 wt% of fluorine were used and their mechanical properties, surface energies and adsorption properties were examined. According to the results ${\sigma}_{300}$ and hardness increased with increasing fluorine contents, but elongation was decreased. Also, fluorosilicone rubber containing 32.2 wt% of fluorine showed the lowest surface tension, among three types of rubber and resulted in the highest initial tack with glass substrate. After the adsorption-desorption test of 300,000 cycles was performed, the adsorption force of S-1 (silicone rubber) decreased largely from 2.34 to 0.73 MPa. However, the S-3 (fluorosilicone rubber having 32.2 wt%. of fluorine) decreased only from 3.15 to 2.24 MPa. From this study, we obtained the valuable equations related to long term durability of silicone based sticking chuck. Finally the transfer of silicone rubber to glass substrate with the adsorption-desorption process was not occurred and this phenomenon was examined by UV-Visible spectroscopy.

• Journal of the Korean institute of surface engineering
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• v.28 no.6
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• pp.368-375
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• 1995

Thermal CVD method is in general used for the fabrication of TiC/$Al_2O_3$-coated carbide tools. The growth of TiC layer and the coating morphology depended on the chemical composition of the hard metal substrate on which the tool properties were strongly influenced. TiC-coated layer was grown by the diffusion of carbon from the substrate, whereas the growth of $Al_2O_3$ layer was unrelated to the composition of substrate. In the nitride hard coatings of Zr, Nb and Mo metals deposited on high speed steel substrate by magnetron sputtering, the reactivity of the metal elements was decreased with increasing group number in one period of the periodic system. The hard material films exhibited the highest adhesion with the chemical composition of stoichiometry or substoichiometry. The critical load as a measure of adhesion was evaluated using scratch tester. The CVD tools indicated the values of 80 and 40N in the coated layers with proper bonding to the substrate and with $\eta$ phase of 1$\mu\textrm{m}$ in the interface respectively, but the nitride films prepared by sputtering of PVD showed only the values between 10 and 20N.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.93-93
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• 2011

The Indium Zinc Tin Oxide (IZTO) and Indium Tin Oxide (ITO) thin films are grown on PI substrate at different substrate temperature by pulsed DC magnetron sputtering with a sintered ceramic target of IZTO (In2O3 70 wt.%, ZnO 15 wt.%, SnO2 15 wt.%) and ITO (In2O3 90wt.%, SnO2 10wt.%). The structural, electrical, and optical properties are investigated. The IZTO thin films deposited at low temperature showed relatively low electrical resistivity compared to ITO thin films deposited at low temperature. As a result, we could prepare the IZTO thin films with the resistivity as low as $5.6{\times}10^{-4}({\Omega}{\cdot}m)$. Both of the films deposited on PI substrate showed an average transmittance over 80% in visible range (400.800nm). Overall, IZTO thin film is a promising candidate as an alternative TCO material to ITO in flexible and OLED devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.94-94
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• 2010

Scanning tunneling microscopy (STM) was used to study the electronic structure of cobalt(II) tetraphenylporphyrin (CoTPP) on the Fe/W(110) substrate. Clover-like conformation of CoTPP was observed and showed bias dependent STM images. The central Co(II) ion of this porphyrin was protruded on the positive biases, but it was depressed on the negative biases. On the positive biases, the phenyl rings of CoTPP appeared to be bright contrary to the invisible pyrrole rings. These results were compared the first-principles calculations using GGA and GGA+U to elucidate the influence of the Fe substrate. GGA+U results agreed well with the experimental results; however, GGA did not. These results show that proper treatment of the on-site Coulomb repulsion of the Fe ions is crucial to describe the electronic structure of this system. By the comparison between the GGA+U calculations on the Fe substrate and the gas phase calculations, it can be noted that chemical potential shift occurred accompanying charge transfer from the Fe ions of the substrate to the pyrrole ligand of the porphyrin.