• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.103-108
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• 2002

We investigated magnetoresistance(MR) and exchange bias properties by annealing in top and bosom type spin valves (SV) with nano-oxide layers (NOL). In top SVs with NOL, MR ratio of 9.2% is obtained after postdeposition annealing at 250$\^{C}$. In bottom SVs with NOL, MR ratio of 10.1 % is obtained after postdeposition annealing at 250$\^{C}$. Therefore, specular reflection of the NOL in bottom SVs is higher than that of the NOL in top SVs. Exchange biasing of bottom SVs with NOL is 28% higher than that of bottom SVs without NOL after annealing. This enhancement of exchange biasing is thought to be due to the reduced magnetic moment of the pinned layer with NOL and enhanced (111) FeMn texture.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.1-5
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• 2005

An experimental study was conducted to develop an understanding of failure of ceramic coating when subjected to a thermal cycling. Number of cycles to failure were decreased as the coating thickness and the oxide of bond coat were increased. Using the finite element method, an analysis of stress distribution in ceramic coatings was performed. Radial compressive stress was increased in the top/bond coat interface with increasing coating thickness and oxide of bond coat.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.304-305
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• 2013

We report a positive exchange bias (HE) in thinmultilayered filmscontaining nano-oxide layer. The positive HE, obtained for our system results from an antiferromagnetic coupling between the ferromagnetic (FM) CoFe and the antiferromagnetic (AFM) CoO layers, which spontaneously form on top of the nano-oxide layer (NOL). The shift in the hysteresis loop along the direction of thecooling field and the change in the sign of exchange bias are evidence of antiferromagnetic interfacial exchange coupling between the CoO and CoFe layers. Our calculation indicates that uncompensated oxygen moments in the NOL results in antiferromagnetic interfacial exchange coupling between the CoO and CoFe layers. One of the interesting features observed with our system is that it displays the positive HE even above the bulk Neel temperature (TN) of CoO. Although the positive HEsystem has a different AFM/FM interfacial spin structure compare to that of the negative HE one, the results of the angular dependence measurements show that the magnetization reversal mechanism can be considered within the framework of the coherent rotation model.

• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.43-48
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• 1999

Oxidation behavior of 304 and 316 stainless steels was studied. After solution heat treatment, specimens were polished up to 1$mu \textrm{m}$ using $Al_2O_3$ powder and then subjected to oxidation between $300^{\circ}C$ and 50$0^{\circ}C$ in dry air. TEM and EDS were used for analyzing the components and structure of oxide film. TEM analysis of oxide film revealed that thin amorphous Fe oxide ($Fe_2O_3$) was formed on the top of surface while polycrystalline (Cr, $Fe_2O_3$ was formed below the amorphous Fe oxide layer. The specimens oxidized at $500^{\circ}C$ showed that 316 stainless steel had higher oxidation resistance than 304 stainless steel. These results suggest that Mo component of 316 stainless steel suppresses the formation of Cr carbide which may result in a local Cr depleted area.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.65-71
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• 1997

We present heterojunction solar cells with a structure of metal/a-Si:H(n-i-p)/poly-Si(n-p)/metal for the terrestrial applications. This cell consists fo two component cells: a top n-i-p junction a-Si:Hi cell with wide-bandgap 1.8eV and a bottom n-p junction poly-Si cell with narrow-bandgap 1.1eV. The efficiency influencing factors of the solar cell were investigated in terms of simulation an experiment. Three main topics of the investigated study were the bottom cell with n-p junction poly-Si, the top a-Si:H cell with n-i-p junction, and the interface layer effects of heterojunction cell. The efficiency of bottom cell was improved with a pretreatment temperature of 900$^{\circ}C$, surface polishing, emitter thickness of 0.43$\mu\textrm{m}$, top Yb metal, and grid finger shading of 7% coverage. The process optimized cell showed a conversion efficiency about 16%. Top cell was grown by suing a photo-CVD system which gave an ion damage free and good p/i-a-Si:H layer interface. The heterojunction interface effect was examined with three different surface states; a chemical passivation, thermal oxide passivation, and Yb metal. the oxide passivated cell exhibited the higher photocurrent generation and better spectral response.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.1
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• pp.31-39
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• 1999

In the present study, oxidation behavior of 304 and 316 stainless steels was investigated. After solution treatment, specimens were polished up to $1{\mu}m$ $Al_2O_3$ grade and then subjected to oxidation treatment in dry air. The range of temperature was used for oxidation treatment at $300^{\circ}C{\sim}500^{\circ}C$ and TEM was used for analyzing the components and structure of oxide film. Also, these results were compared with the results of ESCA and TG. According to the results of TEM analysis, it was found that Cr oxide film was formed on top of the surface after room temperature oxidation but amorphous Fe oxide was formed on top of the surface and polycrystalline $(Cr,Fe)_2O_3$ was formed below the amorphous Fe oxide layer after $500^{\circ}C$ oxidation treatment. The oxidized specimens at $500^{\circ}C$ showed that 316 stainless steel resists more strongly to grain and grain boundary oxidation than 304 stainless steel. These results suggested that Mo component resolved in 316 stainless steel matrix suppressed the formation of Cr carbide which may results in local Cr deplete area.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.164-169
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• 2008

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.313-318
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• 2007

Single-wall carbon nanotube field-effect transistors (SWCNT FETs) of top gate structure were fabricated in a conventional metal-oxide-semiconductor field effect transistor (MOSFET) with gate electrodes above the conduction channel separated from the channel by a thin $SiO_{2}$ layer. The carbon nanotubes (CNTs) directly grown using thin Fe film as catalyst by thermal chemical vapor deposition (CVD). These top gate devices exhibit good electrical characteristics, including steep subthreshold slope and high conductance at low gate voltages. Our experiments show that CNTFETs may be competitive with Si MOSFET for future nanoelectronic applications.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.23-27
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• 2010

We prepared Al doped ZnO thin film as a top electrode on a glass substrate with a deposited $Alq_3$ for the top emission organic Light emitting device (TEOLED) with facing target sputtering (FTS) method and radio-frequency (RF) sputtering method, respectively. Before the deposition of AZO thin film, we evaporated the $Alq_3$ on glass substrate by thermal evaporation. And we evaluated the damage of organic layer. As a result, PL intensity of $Alq_3$ on grown by FTS method showed higher than that of grown by RF sputtering method, so we found that the FTS showed the lower damage sputtering than RF sputtering. Therefore, we can expect the FTS method is promising the low-damage sputtering system that can be used as a direct sputtering on the organic layer.