• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.66-66
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• 2011

Anodic titanium dioxide (TiO2) nanotubes are very attractive materials for gas sensors due to its large surface to volume ratios. The most widely known method for fabrication of TiO2 nanotubes is anodic oxidation of metallic Ti foil. Since the remaining Ti substrate is a metallic conductor, TiO2 nanotube arrays on Ti are not appropriate for gas sensor applications. Detachment of the TiO2 nanotube arrays from the Ti Substrate or the formation of electrodes onto the TiO2 nanotube arrays have been used to demonstrate gas sensors based on TiO2 nanotubes. But the sensitivity was much lower than those of TiO2 gas sensors based on conventional TiO2 nanoparticle films. In this study, Ti thin films were deposited onto a SiO2/Si substrate by electron beam evaporation. Samples were anodized in ethylene glycol solution and ammonium fluoride (NH4F) with 0.1wt%, 0.2wt%, 0.3wt% and potentials ranging from 30 to 60V respectively. After anodization, the samples were annealed at $600^{\circ}C$ in air for 1 hours, leading to porous TiO2 films with TiO2 nanotubes. With changing temperature and CO concentration, gas sensor performance of the TiO2 nanotube gas sensors were measured, demonstrating the potential advantages of the porous TiO2 films for gas sensor applications. The details on the fabrication and gas sensing performance of TiO2 nanotube sensors will be presented.

• 한국세라믹학회지
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• 제30권6호
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• pp.441-448
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• 1993

The Ba1-xSrxTiO3 thin films deposited on ITO-coated glass substrate at 55$0^{\circ}C$ by rf magnetron sputtering method have individual preferential orientations as a function of composition (X=0, 0.25, 0.5, 0.75, 1) due to the stress relief interactions among the intrinsic compressive stress, thermal tensile stress adn extrinsic compressive stress (compressive stress in case of BaTiO3(Tc=12$0^{\circ}C$) and Ba0.75Sr0.25TiO3(Tc=57$^{\circ}C$)). This behavior also appears on the (BaSr)TiO3 thin films (X=0.5) deposited on ITO-coated glass substrate at deposition temperature between 35$0^{\circ}C$ and 55$0^{\circ}C$. The composition of Ba1-xSrxTiO3 thin films deposited on ITO-coated glass substrate at 55$0^{\circ}C$ is close to stoichiometry (1.009~1.089 in A/B ratio), but the compositional deviation from a stoichiometry is larger as SrTiO3 is added. The morphology of Ba1-xSrxTiO3 thin films is very similar for over all substrate temperatures, and the roughness due to the differences of cluster size is the smallest at X=0.25.

• 한국세라믹학회지
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• 제50권6호
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• pp.523-527
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• 2013

Ti-based coatings following laser ablation were studied to compare degradation behaviors by thermomechanical stress. TiN, TiCN, and TiAlN coatings were degraded by a Nd:YAG pulsed laser with an increase in the laser pulses. A decrease in the hardness was identified as the pulses increased, and the hardness levels were in the order of TiAlN > TiCN > TiN. The TiN showed cracks on the surface, and cracks with pores formed along the cracks were observed in the TiCN. The dominant degradation behavior of the TiAlN was surface pore formation. EDS results revealed that diffusion of substrate atoms to the coating surface occurred in the TiN. Delamination occurred in the TiN and TiCN, while the TiAlN which has higher thermal stability than the TiN and TiCN maintained adhesion to the substrate. It was considered that the decrease in the hardness of the Ti-based hard coatings is attributed to surface cracking and the diffusion of substrate atoms.

• 한국진공학회지
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• 제7권3호
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• pp.208-213
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• 1998

최근 셀리사이드(salicide) 제조시 $COSiO_2$의 에피텍셜 성장을 돕기 위하여 Ti층을 삽 입한 Co/Ti/Si 이중층 구조의 실리사이드화가 관심을 끌고 있다. Co/Ti 이중층을 이용한 salicide 트랜지스터가 성공적으로 만들어지기 위해서는 gate 주위의 spacer oxide위에 증착 된 Co/Ti 이중층을 급속열처리할 때 Co/Ti와 $SiO_2$간의 계면에서의 상호반응에 대하여 조사 하였다. Co/Ti 이중층은 $600^{\circ}C$에서 열처리한 후 면저항이 급격하게 증가하기 시작하였는데, 이것은 Co층이 $SiO_2$와의 계면에너지를 줄이기 위하여 응집되기 때문이다. 이때 Co/Ti의 열 처리후 Ti에 의하여 $SiO_2$기판의 일부가 분해됨으로써 절연체의 Ti산화물이 형성되었으나, 이외의 도전성 반응부산물은 발견되지 않았다.

• 한국세라믹학회지
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• 제45권6호
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• pp.358-362
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• 2008

$BiFeO_3$ films were hetero-epitaxially grown on $SrTiO_3$ substrate with a various orientation by pulse laser deposition. $BiFeO_3$ films grown on (111) $SrTiO_3$ substrate have a rhombohedral structure, identical to that of single crystals. On the other hand, films grown on (110) or (001) $SrTiO_3$ substrate are monoclinically distorted from the rhombohedral structure due to the epitaxial constraint. The easy axis of spontaneous polarization is close to [111] for the variously oriented films. Dramatically enhanced polarization and magnetization have been found for $BiFeO_3$ thin films grown on $SrTiO_3$ substrate comparing to that of $BiFeO_3$ crystals. The results are explained in terms of an epitaxially-induced transition between cycloidal and homogeneous spin states, via magneto-electric interactions.

• 한국표면공학회지
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• 제29권1호
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• pp.3-14
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• 1996

High temperature anneal of W-rich silicides, inferior to adherence compared with Si-rich silicides, resulted in the film peeling off from the Si-substrate when WSix thickness reached more than critical thickness. Investigation of the W-rich silicide films peeling off from the substrate revealed that the voids underneath the $WSi_2$ produced through silicide reaction were responsible for the poor adherence of W-rich silicide. In addition, internal stress in the film increased as the silicide thickness increased. In order to promote the adhesion of WSix to Si-substrate, thin Ti-layer was formed between WSi and Si-substrate(WSix/Ti/Si). No voids were observed in $WSi_2$/Ti/Si $N_2$-annealed at $1000^{\circ}C$, thereby leading to an increase of the critical thickness from ～1700$\AA$ to more than 2500$\AA$. However, higher resisiti-vity was obtained in WSix/Ti/Si than in WSix/Si. Finally, different silicide reaction mechanism for the structures(WSix/Si, WSix/Ti/Si) was proposed to explain the formation of voids as well as the role of thin Ti-layer.

• 한국표면공학회지
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• 제35권3호
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• pp.165-171
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• 2002

TiN coating were deposited onto different WC-Co substrates using arc ion plating (AIP) technique. The structure and morphology for the deposited coating were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The adhesion behavior of the deposited TiN coating was investigated with a conventional scratch test. Effects of WC particle size and Co content on the adhesion strength between the deposited TiN coating and substrate were studied. During the scratch test, the value of critical load was dependent of WC particle size and Co content on substrate. As the WC particle size and Co content on substrate decreased, the critical load increased. The highest critical load, approximately 110N, was obtained at WC particle size of 1$\mu\textrm{m}$ and Co content of 10wt.%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.492-495
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• 2000

In order to develop an ultra-thin CoCr perpendicular magnetic recording layer, we prepared CoCrTa/Ti double layer for perpendicular magnetic recording media by new facing targets sputtering system, Crystallgraphics and magnetic characteristics of CoCrTa on underlayer substrate temperature have been investigated. Crystallgraphic and magnetic characteristic of thin films were evaluated by X-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and atomic force microscopy(AFM). The coercivity and anisotropy field was increased by increasing under layer substrate temperature, c-axis orientation of CoCrTa magnetic recording layer was improved 8$^{\circ}$ to 5.6$^{\circ}$when under layer substrate temperature was 250[$^{\circ}C$]. Also, through annealing effect for CoCrTa/Ti double layer, it was certain that crystallgraphics and magnetic characteristics was improved.

• 한국표면공학회지
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• 제24권2호
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• pp.73-79
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• 1991

Recent studies son surface coatings have shown that the change of physical, chemical and crystallographic structure analysed and observed according to the deposition process variables has the effects on the resultant film properties. Under the same preparation condition conditions of the substrate and process variables, physical morphology variations characterized by substrate temperature and bias which offect the surface mobility of adatom and adhesion variations related to the formation of Ti interlayer were considered in the present study. Microhardness showed the highest value around 40$0^{\circ}C$ of the substrate temperature and increased with the substrate bias. Adhesion was improved with the increase of substrate temperature and bias. An interlayer of pure titanium formed prior to deposition of TiN improves the adhesion at its optimum thickness. These results were explained by the change of physical morphology and phase analysis.

• International Journal of Ocean System Engineering
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• 제2권2호
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• pp.106-115
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• 2012

In the present study, TiN and CrN films were coated by arc ion plating equipment onto aluminum alloy substrate, A2024. The film thickness was about 4.65 ${\mu}m$. TiN and CrN films were analyzed by X-ray diffraction and energy dispersive X-ray equipments. The Young's modulus and the micro-Vickers hardness of aluminum substrate were modified by the ceramic film coatings. The difference in Young's modulus between substrate and coating film would affect on the wear resistance. The critical load, Lc, was 75.8 N for TiN and 85.5 N for CrN. It indicated from the observation of optical micrographs for TiN and CrN films that lots of cracks widely propagated toward the both sides of scratch track in the early stage of MODE I. TiN film began to delaminate completely at MODE II stage. The substrate was finally glittered at MODE III stage. For CrN film, a few crack can be observed at MODE I stage. The delamination of film was not still occurred at MODE II and then was happened at MODE III. This agrees with critical load measurement which the adhesive strength was greater for CrN film than for TiN film. Consequently, it was difficult for CrN to delaminate because the adhesive strength was excellent against Al substrate. The wear process, which the film adheres and the ball transfers, could be enhanced because of the increase in loading. The wear weight of ball was less for CrN than for TiN. This means that the wear damage of ball was greater for TiN than for CrN film. It is also obvious that it was difficult to delaminate because the CrN coating film has high toughness. The coefficient of friction was less for CrN coating film than for TiN film.