• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.453-457
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• 2007

Zinc oxide (ZnO) and Ga doped zinc oxide (GZO) with different thickness in range of 10nm to 100nm are prepared on glass substrate by RF magnetron sputtering at room temperature. The structural and optical properties of the thin films is evaluated. The structural properties of ZnO and GZO are investigated by Tunneling Electron Microscopy (TEM) and scanning electron microscopy (SEM). Optical properties are also investigated by UV-VIS-NIR spectrophotometer (200$\sim$1400nm). The much larger grain size of ZnO compared to GZO decreased the light scattering at the grain boundary and improved the transmittance. The transmittance of ZnO is higher than that of GZO through all of the ranges of wavelengths. In case of over 50nm, we found that the transmittance of ZnO is 20% higher than that of GZO.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.23-29
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• 2022

To detect harmful chemical substances in seawater, we fabricated a prototype sensor and evaluated its performance. The prototype sensor consisted of a detector, housing, and driving circuit. We built the detector by printing an Indium-Tin-Oxide (ITO) nanoparticle film on a flexible substrate, and it had two detection parts for simultaneous detection of temperature and HNS concentration. The housing connected the detector and the driving circuit and was made of Teflon material to prevent chemical reactions that may affect sensor performance. The driving circuit supplied electric power, and display measured data using a bridge circuit and an Arduino board. We evaluated the sensor performances such as response (ΔR), the limit of detection (LOD), response time, and errors to confirm the specification.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.40-44
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• 2002

The motivation of this work is to use SAM(Self-Assembled Monolayer) for developing a rapid and flexible non-photolithographic nano-structure fabrication technique which can be utilized in micro-machining of metals as well as silicon-based materials. The fabrication technique implemented in this work consists of a two-step process, namely, mechanical scribing followed by chemical etching. From the experimental results, it was found that thiol on copper surface could be removed even under a few nN normal load. The nano-tribological characteristics of thiol-SAM on various metals were largely dependent on the native oxide layer of metals. Based on these findings, nano-patterns with sub-micrometer width and depth on metal surfaces such as Cu, Au and Ag could be obtained using a diamond-coated tip.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.65-65
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• 2003

Chemical mechanical polishing (CMP) is one of the most important processes in recent ULSI (Ultra Large Scale Integrated Circuit) manufacturing technology. Recently, ceria slurries with surfactant have recently been used in STI-CMP,[1] became they have high oxide-to-nitride removal selectivity and widen the processing margin The role of the abrasives, however, on the effect of planarization on STI-CMP is not yet clear. In this study, we investigated how the crystal characteristic affects the planarization efficiency of wafer surface with controlling crystallite size and poly crystalline abrasive size independently.

• Journal of Powder Materials
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• v.11 no.1
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• pp.22-27
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• 2004

The Indium Tin Oxide(ITO) nano powders were prepared by spray drying and heat treatment process. The liquid solution dissolved Indium and Tin salts was first spray dried to prepare chemically homogeneous recursor powders at the optimum spray drying conditions. Subsequently, the precursor powders were subjected to eat treatment process. The nano size ITO powders was synthesized from the previous precursor powders and the npuities also were decreased with increasing heat treatment temperature. Furthermore, the lattice parameter of TO nano powders was increased by doping Tin into Indium with increasing heat treatment temperature. The par icle size of the resultant ITO powders was about 20∼50nm and chemical composition was composed of In:Sn =86:10 wt.％ at 80$0^{\circ}C$.

• Applied Microscopy
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• v.44 no.4
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• pp.133-137
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• 2014

We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.636-640
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• 2011

Nano-sized cobalt (II) oxide nanoparticles with a high crystallinity were synthesized using thermolysis of a $Co^{2+}$-oleate precursor at 310$^{\circ}C$. The phase and morphology of as-prepared cobalt oxide nanoparticles were characterized using X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller surface area measurements. The cobalt oxide nanoparticles were found to be spherical nanoclusters with an average diameter of approximately 200 nm, consisting of tiny nanocrystals (10-20 nm). Furthermore, the Li electroactivites of the cobalt oxide nanoparticles were investigated using cyclic voltammetry and galvanostatic cycling. The cobalt oxide nanoparticles could deliver high capacities over 420 mA h $g^{-1}$ at a C/5 current rate.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.2
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• pp.49-53
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• 2018

Recently, technologies for integrating various devices such as a flexible device, a transparent device, and a MEMS device have been developed. The key processes of heterogeneous device manufacturing technology are chip or wafer-level bonding process, substrate grinding process, and thin substrate handling process. In this study, the effect of Si substrate grinding process on the electrical properties of tin oxide thin films applied as transparent thin film transistor or flexible electrode material was investigated. As the Si substrate thickness became thinner, the Si d-spacing decreased and strains occurred in the Si lattice. Also, as the Si substrate thickness became thinner, the electric conductivity of tin oxide thin film decreased due to the lower carrier concentration. In the case of the thinner tin oxide thin film, the electrical conductivity was lower than that of the thicker tin oxide thin film and did not change much by the thickness of Si substrate.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.335-340
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• 2002

In this paper, the stress induced leakage currents of thin silicon oxides is investigated in the ULSI implementation with nano structure transistors. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The stress and transient currents were due to the charging and discharging of traps generated by high stress voltage in the silicon oxides. The transient current was caused by the tunnel charging and discharging of the stress generated traps nearby two interfaces. The stress induced leakage current will affect data retention in electrically erasable programmable read only memories. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between 113.4${\AA}$ and 814${\AA}$, which have the gate area $10^3cm^2$. The stress induced leakage currents will affect data retention and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.532-537
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• 2014

In this study, highly sensitive hydrogen micro gas sensors of the multi-layer and micro-heater type were designed and fabricated using the micro electro mechanical system (MEMS) process and palladium catalytic metal. The dimensions of the fabricated hydrogen gas sensor were about $5mm{\times}4mm$ and the sensing layer of palladium metal was deposited in the middle of the device. The sensing palladium films were modified to be nano-honeycomb and nano-hemisphere structures using an anodic aluminum oxide (AAO) template and nano-sized polystyrene beads, respectively. The sensitivities (Rs), which are the ratio of the relative resistance were significantly improved and reached levels of 0.783% and 1.045 % with 2,000 ppm H2 at $70^{\circ}C$ for nano-honeycomb and nano-hemisphere structured Pd films, respectively, on the other hand, the sensitivity was 0.638% for the plain Pd thin film. The improvement of sensitivities for the nano-honeycomb and nano-hemisphere structured Pd films with respect to the plain Pd-thin film was thought to be due to the nanoporous surface topographies of AAO and nano-sized polystyrene beads.