• 한국재료학회지
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• 제12권4호
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• pp.304-307
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• 2002

A zinc oxide (ZnO) single crystal was used as a substrate in the hydride vapor-phase epitaxy (HVPE) growth of GaN and the structural and optical properties of GaN layer were characterized by x- ray diffraction, transmission electron microscopy, secondary ion mass spectrometry, and photoluminescence (PL) analysis. Despite a good lattice match and an identical structure, ZnO is not an appropriate substrate for application of HVPE growth of GaN. Thick film could not be grown. The substrate reacted with process gases and Ga, being unstable at high temperatures. The crystallinity of ZnO substrate deteriorated seriously with growth time, and a thin alloy layer formed at the growth interface due to the reaction between ZnO and GaN. The PL from a GaN layer demonstrated the impurity contamination during growth possibly due to the out-diffusion from the substrate.

• Corrosion Science and Technology
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• 제5권4호
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• pp.137-140
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• 2006

The effect of pre-existing barrier-type film on porous aluminum oxide film formation during anodization was investigated to control the uniform film growth rate. Initial potential fluctuations during anodization indicated that the breakdown of barrier-film is preceded before the porous formation and the induction time for the porous film growth increases with the increases of pre-existing film thickness. The porous film growth mechanism is lot affected by the presence of barrier film on aluminum surface. In parallel, uniform growth of barrier film underneath the porous structure was attained by two-step anodization processes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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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.

• 한국전기전자재료학회논문지
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• 제29권6호
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• pp.321-326
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• 2016

Minimizing the carrier recombination and electrical loss through surface passivation is required for high efficiency c-Si solar cell. Usually, $SiN_X$, $SiO_X$, $SiON_X$ and $AlO_X$ layers are used as passivation layer in solar cell application. Silicon oxide layer is one of the good passivation layer in Si based solar cell application. It has good selective carrier, low interface state density, good thermal stability and tunneling effect. Recently tunneling based passivation layer is used for high efficiency Si solar cell such as HIT, TOPCon and TRIEX structure. In this paper, we focused on silicon oxide grown by various the method (thermal, wet-chemical, plasma) and passivation effect in c-Si solar cell.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.282-284
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• 2007

The superconductor characteristics of BSCCO spray films by Heat treatment was studied. $Bi_2Sr_2CaCu_2O_x$(Bi-2212) is high-Tc superconductor(HTS) coatings have been prepared by Heat treatment. Where high current carrying capabilities are required and therefore thick film and bulk material are called for, the Bi2Sr2Ca1Cu2O8-d(Bi-2212)compound has evoleved as one of the most promising. and the Bi-2212 HTS coating layer is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating layer by partial melting process. The superconducting characteristics depends on the spray distance which was related to the spray particle melt. The Bi-2212 HTS layer consists of the whisker growth and secondary phase in 2212 layer were observed.

• 한국재료학회지
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• 제17권5호
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• pp.273-277
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• 2007

Vertically aligned Zinc Oxide rod arrays were grown by the self-assembly hydrothermal process on the GaN epitaxial layer which has a same lattice structure with ZnO. Zinc nitrate and DETA solutions are used in the hydrothermal process. The $(HfO_2)$ thin film was deposited on GaN and the patterning was made by the photolithography technique. The selective growth of ZnO rod was achieved with the patterned GaN substrate. The fabricated ZnO rods are single crystal, and have grown along hexagonal c-axis direction of (002) which is the same growth orientation of GaN epitaxial layer. The density and the size of ZnO rod can be controlled by the pattern. The optical property of ordered array of vertical ZnO rods will be discussed in the present work.

• 한국표면공학회지
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• 제32권1호
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• pp.49-60
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• 1999

The protective oxide scales and coatings formed on high temperature materials must be preserved in high temperature atmosphere. And the thermal stresses induced by thermal cycling and the growth stresses by the formation of oxide scales can cause the loss of adherence and spalling of the oxide scales and coated layers. Among the coating processes Al diffusion coating is favored due to thermochemical stability and superior adherence in an hostile atmosphere. In this study, protective oxide forming element, Al was coated on Ni, Inconel 600 and 690 by diffusion coating process varying coating temperature and time. And the surface stability and adherence of oxide scales formed on those Al diffusion coated materials were evaluated by thermal cycling test. Al diffusion coated specimens showed superior cyclic oxidation resistance compared to bare ones and specimens coated for longer period had better cyclic oxidation resistance, due to the abundant amount of Al in the coated layer. Meanwhile Al diffusion coated Inconel 600 and 690 showed improved cyclic oxidation resistance by the effect of Al in the coated layer and Cr in the substrate. Comparing both Al diffusion coated Inconel 600 and 690, Al diffusion coated Inconel 690 maintained better adhesion between coated layer and substrate by virtue of the bridging effect resulting from the segregation of Cr in the interdiffusion zone.

• 동력기계공학회지
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• 제11권2호
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• pp.44-50
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• 2007

The oxidation behavior of commercial pure titanium is investigated in the temperature range of $727^{\circ}C{\sim}950^{\circ}C$ in mixed gases. The weight change is measured by TGA during oxidation in mixed gases. The oxidation behavior indicated by weight gain or the growth of oxide layer is based on the linear rate law at high temperatures. The structure of the oxide scale formed during oxidation is analysed by optical microscopy, electron probe microanalyzer, scanning electron microscope and x-ray diffraction. Oxide scales have a $TiO_2$ structure, and are constituted with multi-layered or two layered porous external one and a dense internal one. Ti-O solid solution region is formed at the interface of metal and scale layer. The formation of oxide scale is influenced by the oxidation temperature, time, crystal structure and the condition of atmosphere.

• Corrosion Science and Technology
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• 제9권6호
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• pp.247-253
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• 2010

The characteristics of selective oxidation prior to hot-dip galvanizing with the annealing atmosphere dew point and chemical composition in dual-phase steels and their effect on the inhibition layer formation relevant to coating adhesion have been studied using a combination of electron microscopic and surface analytical techniques. The annealed and also galvanized samples of 3 kinds of Si/Mn ratios with varied amounts of Si addition were prepared by galvanizing simulator. The dew point was controlled at soaking temperature $800^{\circ}C$ in 15%$H_2$ -85%$N_2$ atmosphere. It was shown that good adhesion factors were mainly uniformity of oxide particle distribution of low number density and low Si/Mn ratio prior to hot-dip galvanizing. Their effect was the greatly reduced coating bare spots and the formation of uniform inhibition layer leading to good adhesion of Zn overlay. The mechanism of good adhesion is suggested by two processes: the formation of inhibition layer on the oxide free surface uncovered with no $SiO_2$-containing particles in particular, and the inhibition layer bridging of oxide particles. The growth of inhibition layer was enhanced markedly by the delayed reaction of Fe and Al with the increase of Si/Mn ratio.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.449-452
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• 1998

We have studied the oxidatio nrte of $Si_{1-x}Ge_{x}$ epitaxial layer grown by MBE(molecular beam epitaxy). Oxidation were performed at 700.deg. C, 800.deg. C, 900.deg. C, and 1000.deg. C. After the oxidation, the results of AES(auger electron spectroscopy) showed that Ge was completely rejected out of the oxide and pile up at $SiO_{2}/$Si_{1-x}Ge_{x}$ interface. It is shown that the presence of Ge at the $SiO_{2}$/$Si_{1-x}Ge_{x}$ interface changes the dry oxidation rate. The dry oxidation rate was equal to that of pure Si regardless of Ge mole fraction at 700.deg. C and 800.deg.C, while it was decreased at both 900.deg. C and 1000.deg.C as the Ge mole fraction was increased. The ry oxidation rates were reduced for heavy Ge concentration, and large oxidation time. In the parabolic growth region of $Si_{1-x}Ge_{x}$ oxidation, The parabolic rate constant are decreased due to the presence of Ge-rich layer. After the longer oxidation at the 1000.deg.C, AES showed that Ge peak distribution at the $SiO_{2}$/$Si_{1-x}Ge_{x}$ interface reduced by interdiffusion of silicon and germanium.