• Korean Journal of Materials Research
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• v.12 no.3
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• pp.200-204
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• 2002

We fabricated TMR devices which have double oxidized tunnel barrier using plasma oxidation method to form homogeneously oxidized AlO tunnel barrier. We sputtered 10 $\AA$-bottom Al layer and oxidized it by varying oxidation time for 5, 10, 20 sec. Subsequent sputtering of 13 $\AA$ - Al was performed and the matallic layer was oxidized for 120 sec. The electrical resistance changed from 700$\Omega$ to 2700$\Omega$ with increase of oxidation time, while variation of MR ratio was little spreading 27~31% which is larger than that of TMR device of ordinary single tunnel barrier. We calculated effective barrier height and width by measuring I-V curves, from which we found the barrier height was 1.3~1.5 eV, sufficient for tunnel barrier, and the barrier width(<16.2 $\AA$) was smaller than that of directly measured value by the tunneling electron microscopy. Our results may be caused by insufficient oxidation of Al precursor into $Al_2O_3$. However, double oxidized tunnel barriers were superior to conventional single tunnel barrier in uniformity and density. We found that the external magnetic field to switch spin direction of ferromagnetic layer of pinned layer breaking ferro-antiferro exchange coupling was increased as bottom layer oxidation time increased. Our results imply that we were able to improve MR ratio and tune switching field by employing double oxidized tunnel barrier process.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.127-131
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• 2002

We fabricated MTJ devices that have doubly oxidized tunnel barrier using plasma oxidation method to from oxidized AlO$\sub$x/ tunnel barrier. Doubly oxidation I, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it with oxidation time of 10 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 50, 80 and 120 s., respectively. Doubly oxidation II, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it varying oxidation time for 30∼120 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 210 sec. Double oxidation process specimen showed MR ratio of above 27％ in all experiment range. Singly oxidation process. 13 ${\AA}$-Al layer and oxidized up to 210 s, showed less MR ratio and more narrow process window than those of doubly oxidation. Cross-sectional TEM images would that doubly oxidized barrowers were thinner and denser than singly oxidized ones. XPS characterization confirmed that doubly oxidation of Fe with bottom insulating layer. As a result, doubly oxidation could have superior MR ratio in process extent during long oxidation time because of preventing oxidation of bottom magnetic layer than singly oxidation.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.201-206
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• 2020

A SiOxCy(-H) thin film was synthesized by atmospheric pressure dielectric barrier discharge(APDBD), and a SiO₂-like layer was formed on the surface of the film by oxidation treatment using oxygen plasma. Hexamethylcyclotrisiloxane was used as a precursor for the SiOxCy(-H) synthesis, and He gas was used for stabilizing APDBD. Oxygen permeability was evaluated by forming an oxidized SiOxCy(-H) thin film on a PET film. When the single-layer oxidized SiOxCy(-H) film was coated on the PET, the oxygen gas permeability decreased by 46% compared with bare PET. In case of three-layer oxidized SiOxCy(-H) film, the oxygen gas permeability decreased by 73%. The oxygen permeability was affected by the thickness of the SiO₂-like layer formed by oxidation treatment rather than the thickness of the SiOxCy(-H) film. The excellent corrosion resistance was demonstrated by coating an oxidized SiOxCy(-H) thin film on the silver-coated aluminum PCB for light emitting diode (LED).

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.151-152
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• 2002

An oxidized surface layer was intentionally formed on a sputtered $MoS_2$ film by introducing oxygen gas in the final stage of sputtering process. The film showed longer life than the normal Ar-sputtered film when the surface layer was slightly oxidized. A XPS analysis revealed co-existence of $MoS_2$ and $MoO_3$ in the surface layer. suggesting that the existence of some amount of oxides in the surface layer had beneficial effect. A confusing result was obtained: the life was much shorter than normal Ar-sputtered film when the film was exposed to $O_2$ environment for 1 minute after normal Ar-sputtering, although almost no oxide was detected in XPS analysis.

• Journal of Sensor Science and Technology
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• v.8 no.2
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• pp.202-209
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• 1999

Microstrip line was fabricated on the oxidized porous silicon layer which has nearly electrically and chemically identical properties with thermally oxidized silicon layer. Thick oxidized porous silicon layer of few tenth of micrometers was prepared by thermal oxidation of porous silicon layer on silicon substrate. Multi-step thermal oxidation process was used to obtain high Quality and thick oxidized silicon layer and to release thermal stress. Microstrip line was fabricated on the oxidized porous silicon layer. Its microwave characteristics were measured and the availability for MMIC substrate was investigated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.412-422
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• 1999

Scale defects generated on the strip surface in a tandem finishing mill line are collected from the strip trapped among the production mills by freezing the growing scale on the strip by the melt glass coating and shutting down the line simultaneously. The samples observed of its cross sectional figure showed the process of scale defect formation where the defects are formed at the base metal surface by thicker oxidized scale during each rolling passes. The properties of the oxidized layer growth both at rolling and inter-rolling are detected down sized rolling test simulating carefully the rolling condition of the production line. The thickness of the oxidized layer at each rolling pass are simulated numerically. The critical scale thickness to avoid the defect formation is determined through the expression of mutual relation between oxidized layer thickness and the lanks of the strip called quality for the scale defects. The scale growth of scale less than the critical thickness and also to keep the bulk temperature tuning the water flow rate and cooling time appropriately. Two units of Inerstand Cooler are designed and settled among the first three stands in the production line. Two units of scale defect is counted from the recoiled strip and the results showed distinct decrease of the defects comparing to the conventionaly rolled products.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.93-99
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• 1996

The formation properties and oxidation mechanism of electrochemically oxidized porous silicon(OPS) films have been studied. To examine the humidity-sensitive properties of OPS films, surface-type and bulk-type humidity sensors were fabricated. The oxidized thickness of porous silicon layer(PSL) increases with the charge supplied during electrochemical humidity sensor shows high sensitivity at high relative humidity in low temperature. The sensitivity and linearity can be improved by optimizing a porosity of PSL. (author). refs., figs.

• Journal of Powder Materials
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• v.19 no.3
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• pp.196-203
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• 2012

$TiO_2$ was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in $Na_3PO_4$ electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile $TiO_2$, which is able to effectively separate excited electrons and holes at the surface.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.8
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• pp.560-564
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• 2003

Thick oxide layer was fabricated by anodic reaction and complex oxidation performed by combining low temperature thermal oxidation (50$0^{\circ}C$, 1 hr at $H_2O$/O$_2$) and a RTO (rapid thermal oxidation) process (105$0^{\circ}C$, 1 min). Electrical characteristics of OPSL (oxidized porous silicon layer) were almost the same as those of thermal silicon dioxide prepared at high temperature. The leakage current through the OPSL of 20${\mu}{\textrm}{m}$ thickness was about 100 - 500 ㎀ in the range 0 V to 50 V. The average value of breakdown field was about 3.9 MV/cm. From the XPS analysis, surface and internal oxide films of OPSL prepared by complex process were confirmed completely oxidized and also the role of RTO process was important for the densification of PSL (porous silicon layer) oxidized at low temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.225-230
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• 2016

Effect of electrolyte composition and concentration on PEO coating layer were investigated. Mg alloy, Surface of AZ31 and AZ91 were oxidized using PEO with different electrolyte system, Na-P and Na-Si. and applied voltage and concentration. We measured thickness, roughness, X-ray crystallographic analysis and breakdown voltage of the oxidized layer. When increasing concentration of electrolyte, the thickness of oxide layer also increased too. And roughness also increased as concentration of electrolyte increasing. Breakdown voltage of coated layer showed same behavior, the voltage goes high as increasing thickness of coating layer, as increasing concentration of electrolyte, and increasing applied voltage of PEO. $Mg_2SiO_4$ phase were observed as well as MgO.