• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.307.2-307.2
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• 2016

In this study, we synthesized Au nanoparticles (AuNPs) in polyacrylonitrile (PAN) thin films using a simple annealing process in the solid phase. The synthetic conditions were systematically controlled and optimized by varying the concentration of the Au salt solution and the annealing temperature. X-ray photoelectron spectroscopy (XPS) confirmed their chemical state, and transmission electron microscopy (TEM) verified the successful synthesis, size, and density of AuNPs. Au nanoparticles were generated from the thermal decomposition of the Au salt and stabilized during the cyclization of the PAN matrix. For actual device applications, previous synthetic techniques have required the synthesis of AuNPs in a liquid phase and an additional process to form the thin film layer, such as spin-coating, dip-coating, Langmuir-Blodgett, or high vacuum deposition. In contrast, our one-step synthesis could produce gold nanoparticles from the Au salt contained in a solid matrix with an easy heat treatment. The PAN:AuNPs composite was used as the charge trap layer of an organic nano-floating gate memory (ONFGM). The memory devices exhibited a high on/off ratio (over $10^6$), large hysteresis windows (76.7 V), and a stable endurance performance (>3000 cycles), indicating that our stabilized PAN:AuNPs composite film is a potential charge trap medium for next generation organic nano-floating gate memory transistors.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.162-162
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• 2016

We present multifunctional indium tin oxide (ITO) thin films formed at room temperature by a normal sputtering system equipped with a plasma limiter which effectively blocks the bombardment of energetic negative oxygen ions (NOIs). The ITO thin film possesses not only low resistivity but also high gas diffusion barrier properties even though it is deposited on a plastic substrate at room temperature without post annealing. Argon neutrals incident to substrates in the sputtering have an optimal energy window from 20 to 30 eV under the condition of blocking energetic NOIs to form ITO nano-crystalline structure. The effect of blocking energetic NOIs and argon neutrals with optimal energy make the resistivity decrease to $3.61{\times}10-4{\Omega}cm$ and the water vapor transmission rate (WVTR) of 100 nm thick ITO film drop to $3.9{\times}10-3g/(m2day)$ under environmental conditions of 90% relative humidity and 50oC, which corresponds to a value of ~ 10-5 g/(m2day) at room temperature and air conditions. The multifunctional ITO thin films with low resistivity and low gas permeability will be highly valuable for plastic electronics applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.650-650
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• 2013

Although imprinted nanopatterns of organic polymer can be modified by the heat treatment [1], it generally requires high process temperatures and is material-dependent since the heat-induced mass loss of the organic polymer is greatly affected by its chemical characteristics. When oxygen is added during the annealing process, one can reduce the process temperature as well as the dependence of the materials. With the oxygen, line width reduction of a polymer (SU-8) patterns could be accomplished at temperature of as low as $250^{\circ}C$ which was not possible in the heat only process. This oxidative line width reduction can be dramatically promoted with the introduction of oxygen plasma. The oxygen plasma, with its highly-reactive oxygen species, vigorously etches away the organic materials, proven to be extremely effective line with reduction method. It is, however, very hard to control the extent and homogeneity of the etching, particularly of very fine patterns. Here, we report an effective and reliable line width reduction method of imprinted nanopatterns by combined plasma and heat treatment. The merits of this process include the reduction of process temperature, time and material-dependence.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.190-190
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• 2010

Zinc oxide is the most attractive material due to the large direct band gap (3.37 eV), excellent chemical and thermal stability, and large exciton binding energy (60 meV). Recently, ZnO nanorods were used as the high efficient antireflection coating layer of solar cells based on silicon (Si). In this reports, we studied the effects of rapid thermal annealing (RTA) treatment on optical properties of ZnO nanorods. For fabrication of ZnO nanorods, there are many methods such as hydrothermal method, sol-gel method, and metal organic chemical vapor deposition method. Among of them, we used the conventional wet chemical method which is simple and low temperature growth. In order to synthesize the ZnO nanorods, the ZnO films were deposited on Si substrate by RF magnetron sputtering at room temperature and the samples were dipped to aqua solution containing the zinc nitrate and hexamethylentetramines (HMT). The synthesis process was achieved in keeping with temperature of $90-95^{\circ}C$ and under constant stirring. The morphology of ZnO nanorods on glass and Si was characterized by scanning electron microscopy. For the analysis of antireflection performance, the reflectance and transmittance were measured by spectrophotometer. And for analyzing the effects of RTA treatment on ZnO nanorods, crystalline properties were investigated by X-ray diffraction measurements and optical properties was estimated by photoluminescence spectra.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.2
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• pp.130-133
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• 1999

Paraelectric ZrTiO4 thin films were synthesized on a Si(100) substrate using DC magnetron reactive sputtering. Films deposited above-400$^{\circ}C$ exhibited crystalline characteristics. The dielectric constants ($\varepsilon$) and dielectric losses (tan$\delta$) of as-deposited and annealed films were measured in the 1 MHz range using a Pt upper electrode and a phosphorous-doped si bottom electrode. Preliminary data showed that as the deposition temperature increased, the dielectric losses decreased while the dielectric constants did not change significantly. similar trends for dielectric losses were observed when the as-deposited samples were annealed at 800$^{\circ}C$. The reduction of dielectric losses at high-deposition temperatures and post annealing correlated well with the x-ray diffraction peak widths.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.168-170
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• 2001

The NiCr is an important material for present thin-film resistor application owing to its low TCR and thermal stability. In this work, the NiCr thin films were deposited on corning glass substrate by reactive magnetron sputtering and the annealing at temperatures range from 300 to $500^{\circ}C$ for 20 min in vacuum. X-ray, AFM, $R_s$(surface leakage current) have been used to study the structural and electrical properties of the NiCr thin films. The high precision NiCr thin films resistor with TCR(temperature coefficient of resistance) of less then 10 ppm/$^{\circ}C$ was obtained under in in-situ annealing at $300^{\circ}C$ on Cr buffer layer substrate. It is clear that the NiCr thin-films resistor electrical properties are low TCR related with it's annealing and buffer layer condition. NiCr thin film resistor having a good thermal stability and low TCR properties are expected for the application to the dielectric material of passive component.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.81-84
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• 2004

The NiCr is an important material for present thin-film resistor application owing to its low TCR and thermal stability. In this work, the NiCr thin films were deposited on coming glass substrate by reactive magnetron sputtering and the annealing at temperatures range from 300 to $500^{\circ}C$ for 20 min in vacuum. X-ray, AFM, $R_s$(surface leakage current) have been used to study the structural and electrical properties of the NiCr thin films. The high precision NiCr thin films resistor with TCR(temperature coefficient of resistance) of less then $10\;ppm/^{\circ}C$ was obtained under in in-situ annealing at $300^{\circ}C$ on Cr buffer layer substrate. It is clear that the NiCr thin-films resistor electrical properties are low TCR related with it's annealing and buffer layer condition. NiCr thin film resistor having a good thermal stability and low TCR properties are expected for the application to the dielectric material of passive component.

• Journal of Korean Vacuum Science & Technology
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• v.2 no.2
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• pp.63-77
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• 1998

The oxidation of NiAl(110) was investigated in the temperature regime between 300K and 1300 K using LEED (low energy electron diffraction), TPD (temperature programmed desorption) and HREELS (high resolution electron energy loss spectroscopy). The adsorption of N2O and O2 up to reconstructions. Stepwise annealing of the oxygen-saturated sample from 600 K to 1300K in UHV (ultra-high vacuum,) results in firstly the onset of randomly oriented then finally fairly well-ordered. 5 ${\AA}$ Al2O3 film with quasi-hexagonal periodicity. Ordered thicker oxide films of 18-30 ${\AA}$ seem to be grown on this interfacial oxide layer by direct oxidation of sample at elevated temperature between 1150 and 1300 K because of the LEED pattern consisting of new broad hexagonal spots and the previous 5 ${\AA}$ spots. Although the periodicity of surface oxygen arrays shows no significant change from an hexagonal close-packing, the O-O distance changes from ∼3.0 ${\AA}$ film to ∼2.9 ${\AA}$ for thicker oxides. with the appearance of Auger parameter, for the 5${\AA}$ film can be described better as an interfacial oxide layer. The observation of three symmetric phonon peaks can be also a supporting evidence for this phase assignment since thicker oxide films on the Same Ni2Al3(110) show somewhat different phonon structure much closer to that of the ${\gamma}$-Al2O3. The adsorption/desorption of methanol further proves the preparation of less-defective and/or oxygen-terminated Al2O3 films showing ordered phase transitions with the change of oxide thickness between 5 ${\AA}$ to 30 ${\AA}$.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.43-48
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• 2017

Conductive $Sn_xO_y$ thin films were fabricated via RF reactive sputtering using SnO:Sn (80:20 mol%) composite target. The composite target was used to produce a chemically stable composition of $Sn_xO_y$ thin film while controlling structural defects by chemical reaction between tin and oxygen. During sputtering pressure, RF power, and substrate temperature were fixed, and oxygen partial pressure was varied from 0% to 12%. Annealing process was carried out at $300^{\circ}C$ for 1 hour in vacuum. Except $P_{O2}=0%$ sample, all samples showed the transmittance of 80~90% and amorphous phase before and after annealing. Electrically stable p-type $Sn_xO_y$ thin film with high transmittance was only obtained from the oxygen partial pressure at 12%. The carrier concentration and mobility for the $P_{O2}=12%$ were $6.36{\times}10^{18}cm^{-3}$ and $1.02cm^2V^{-1}s^{-1}$ respectively after annealing.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.41-46
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• 2022

The superconducting properties of high temperature superconducting (HTS) GdBCO coated conductor (CC) tape (Ag/GdBCO/Buffer-layers/Stainless Steel) were investigated, specifically a series of samples prepared by vacuum heat treatment (200℃ to 600℃), using a Quantum Design PPMS-14. The critical current density J_c value was obtained by applying the modified Bean model to the irreversible magnetization ∆M_irr(H) data which was estimated from the magnetization M(H) loop. The reduction rates of lnJ_c and T_c values according to the increase of the vacuum annealing temperature T_an were d(lnJ_c)/dT_an = - 0.016 A/(cm²∙℃) and dT_c/dT_an = - 0.24, respectively. We examined the effect of recovery temperature T_re (475℃ to 700℃) and recovery duration time t (0.5 h to 24 h) on the restoration of previously completely lost superconductivity in samples that subsequently received heat treatment in an O₂ gas flow space. All samples were fully restored to superconductivity by heat treatment in an O₂ gas flow space. The recovery temperatures T_re (475℃ to 700℃) and recovery duration times t (0.5 h to 24 h) were both independent of the superconductivity recovery characteristics.