• 대한치과보철학회지
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• 제43권5호
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• pp.684-693
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• 2005

Statement of problem: Ti-6Al-7Nb alloy is used instead of Ti-6Al-4V alloy that was known to have toxicity. Purpose: This study was performed to investigate the effect of electrolyte concentration on the surface characteristics of anodized and hydrothermally-treated Ti-6Al-7Nb alloy Materials and methods: Discs of Ti-6Al-7Nb alloy of 20 mm in diameter and 2 mm in thickness were polished sequentially from #300 to 1,000 SiC paper ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. Anodizing was performed at current density $30mA/cm^2$ up to 300 V in electrolyte solutions containing $\beta-glycerophosphate$ disodium salt hydrate $(\beta-GP)$ and calcium acetate (CA). Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. All samples were soaked in the Hanks' solution with pH 7.4 at $36.5^{\circ}C$ for 30 days. Results and conclusion: The results obtained were summarized as follows: 1. After hydrothermal treatment, the precipitated HA crystals showed the dense fine needle shape. However, with increasing the concentration of electrolyte they showed the shape of thick and short rod. 2. When the dense fine needle shape crystals was appeared after hydrothermal treatment, the precipitation of HA crystals in Hanks' solution was highly accelerated. 3. The crystal structures of $TiO_2$ in anodic oxide film were composed of strong anatase peak and weak rutile peak as analyzed with thin-film X-ray diffractometery. 4. The Ca/P ratio of the precipitated HA layer was equivalent to that of HA crystal in Hanks' solution.

• 구강회복응용과학지
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• 제21권1호
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• pp.33-42
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• 2005

This study was performed to investigate the surface properties and in vitro biocompatibility of electrochemically oxidized Ti-6Al-7Nb alloy by anodic spark discharge technique. Discs of Ti-6Al-7Nb alloy of 20 mm in diameter and 2 mm in thickness were polished sequentially from #300 to 1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. Anodizing was performed using a regulated DC power supply. The applied voltages were given at 240, 280, 320, and 360 V and current density of $30mA/cm^2$. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. Samples were soaked in the Hanks' solution with pH 7.4 at $36.5^{\circ}C$ during 30 days. The results obtained were summarized as follows; 1. The oxide films were porous with pore size of $1{\sim}5{\mu}m$. The size of micropores increased with increasing the spark forming voltage. 2. The main crystal structure of the anodic oxide film was anatase type as analyzed with thin-film X-ray diffractometery. 3. Needle-like hydroxyapatite (HA) crystals were observed on anodic oxide films after hydrothermal treatment at $300^{\circ}C$ for 2 hours. The precipitation of HA crystals was accelerated with increasing the spark forming voltage. 4. The precipitation of the fine asperity-like HA crystals were observed after being immersed in Hanks' solution at $37^{\circ}C$. The precipitation of HA crystals was accelerated with increasing the spark forming voltage and the time of immersion in Hanks' solution. 5. The Ca/P ratio of the precipitated HA layer was equivalent to that of HA crystal as increasing the spark forming voltage and the time of immersion in Hanks' solution.

• 구강회복응용과학지
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• 제22권1호
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• pp.101-110
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• 2006

This study was performed to investigate the surface properties and in vitro biocompatibility of electrochemically oxidized Ti-6Al-7Nb alloy by anodic spark discharge technique. Discs of Ti-6Al-7Nb alloy of 20 mm in diameter and 2 mm in thickness were polished sequentially from #300 to 1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. Anodizing was performed using a regulated DC power supply. The applied voltages were given at 240, 280, 320, and 360 V and current density of $30mA/cm^2$. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. Samples were soaked in the Hanks' solution with pH 7.4 at $36.5^{\circ}C$ during 30 days. The results obtained were summarized as follows; 1. The oxide films were porous with pore size of $1{\sim}5{\mu}m$. The size of micropores increased with increasing the spark forming voltage. 2. The main crystal structure of the anodic oxide film was anatase type as analyzed with thin-film X-ray diffractometery. 3. Needle-like hydroxyapatie (HA) crystals were observed on anodic oxide films after hydrothermal treatment at $300^{\circ}C$ for 2 hours. The precipitation of HA crystals was accelerated with increasing the spark forming voltage. 4. The precipitation of the fine asperity-like HA crystals were observed after being immersed in Hanks' solution at $37^{\circ}C$. The precipitation of HA crystals was accelerated with increasing the spark forming voltage and the time of immersion in Hanks' solution. 5. The Ca/P ration of the precipitated HA layer was equivalent to that of HA crystal as increasing the spark forming voltage and the time of immersion in Hanks' solution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.143-143
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• 2010

In this study, we demonstrate that ZnO deposited onto $SiO_2$ substrates by magnetron sputtering produces p-type ZnO at higher $O_2$ pressure and n-type ZnO at lower $O_2$ pressure. We also report the effect of hydrogen peroxide ($H_2O_2$) on the stability of undoped ZnO thin films. The films were immersed in 30% $H_2O_2$ for 1 min at $30^{\circ}C$ and annealed in $O_2$at $450^{\circ}C$. The carrier concentration, mobility. and conductivity were measured by a Hall effect measurement system. The Hall measurement results for ZnO films untreated with $H_2O_2$ but annealed in $O_2$ indicate that oxygen fraction greater than ~0.5 produces undoped p-type ZnO films, whereas oxygen fraction less than ~0.5 produces undoped n-type ZnO films. This is attributed to the fact that the oxygen vacancies ($V_o$) decrease and the oxygen interstitials ($O_i$) or zinc vacancies ($V_{Zn}$) increase with increasing oxygen atoms incorporated into ZnO films during deposition and $O_2$ post-annealing.

• 한국전기전자재료학회논문지
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• 제28권5호
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• pp.300-305
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• 2015

$WO_3$, $SiO_2$, and $TiO_2$ films with hydrophilic property are deposited by rf-magnetron sputtering. Their wettability is strongly depends on the presence or absence of the oxygen plasma etching on the glass substrates. The $TiO_2$ film of 50 nm-thick on the plasma etched glass shows a water contact angle (WCA) below $5^{\circ}$ which means a super-hydrophilic surface. However, WCA values are gradually degraded when the films are exposed under atmosphere, especially $WO_3$. In order to improve hydrophilic property, the degraded films can be again recovered by UV illumination for 10 sec using UV-light and the $TiO_2$ film shows a super-hydrophilic surface about $3^{\circ}$.

• 한국재료학회지
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• 제17권2호
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• pp.96-99
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• 2007

The effects of post-annealing of high-k $HfO_2$ thin films grown by atomic layer deposition method were investigated by the annealing treatments of $400-600^{\circ}C$. $Pt/HfO_2/p-Si\;MOS$ capacitor structures were fabricated, and then the capacitance-voltage and current-voltage characteristics were measured to analyze the electrical characteristics of dielectric layers. The X-ray diffraction analyses revealed that the $500^{\circ}C-annealed\;HfO_2$ film remained to be amorphous, and the $600^{\circ}C-annealed\;HfO_2$ film was crystallized. The annealing treatment at $500^{\circ}C$ resulted in the highest capacitance and the lowest leakage current due to the reduction of defects in the $HfO_2$ films and non-crystallization. Our results suggest that post-annealing treatments are a critical factor in improving the characteristics of gate dielectric layer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1133-1136
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• 1995

RF-magnetron sputtering 방법으로 형성한 $BaTa_2O_6$의 공정변수에 따른 전기, 광학적 특성변화를 관찰하여 $BaTa_2O_6$ 박막의 TFELD(thin film electroluminescent display) 절연막으로서 응용 가능성을 연구하였다. $BaTa_2O_6$ 박막의 유전특성은 증착시의 $O_2$ 함량과 sputtering 압력의 변화에는 큰 영향을 받지 않으나 기판온도에는 영향을 받는 것으로 확인되었다. 이들 공정변수를 가변하여 실험한 결과, $BaTa_2O_6$ 박막 형성의 최적조건으로 플라즈마 압력을 6 mtorr, sputtering gas 내의 $O_2$ 혼합비율은 40%, 기판온도는 $100^{\circ}C$로 결정하였다. 이상의 조건에서 제조된 $BaTa_2O_6$ 박막은 10.2 ${\mu}C/cm^2$의 매우 우수한 성능지수를 보였다. 이상의 $BaTa_2O_6$ 박막을 하부절연층으로, 절연파괴강도가 높은 $SiO_xN_y$를 상부 절연층으로 사용하여 제조된 EL 소자는 1 kHz, 삼각파 구동시 발광 임계전압은 약 32 volts, 최대휘도는 54 $cd/m^2$으로 측정되었다.

• 대한기계학회논문집A
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• 제37권4호
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• pp.467-473
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• 2013

본 연구에서는 SU-8 박막의 마이크로시스템으로의 트라이볼로지적 응용을 목적으로 하여, 원자간 힘 현미경(AFM) 과 콜로이드 프로브를 이용한 실험 및 유한요소해석 기법을 이용하여 SU-8 코팅층의 두께에 따른 트라이볼로지적 특성을 고찰하였다. SU-8 시편은 스핀 코팅기법을 이용하여 두께를 다르게하여 제작하였다. 실험결과 코팅두께가 증가함에 따라 마찰력과 점착력이 감소하여 박막두께에 따른 차이가 존재함을 알 수 있었고, SU-8 표면이 Si 표면에서보다 더 낮은 점착력과 마찰력을 보여주었다. 또한, 시뮬레이션을 통해 두께별로 박막 파손을 유발시키는 임계하중(압력)이 존재하며, 본 연구에서의 200~800 nm 두께범위에서는 1.2~1.8 GPa 로 측정되었다.

• 한국재료학회지
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• 제9권7호
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• pp.735-739
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• 1999

본 연구에서는 sol-gel법으로 제조된 $PbTiO_3$ (PT) 단층박막내의 실시간 응력과 두께 수축거동, 그리고 다층박막의 미세경도를 온도의 함수로 측정하여 열처리에 따른 PT박막내의 물리화학적 변화를 설명하였다. 단층박막은 상온에서 $220^{\circ}C$까지 급격한 수축을 보였으며 총수축량의 83%가 이 온도구간에서 일어났다. as-spun된 박막 내에는 이미 75MPa의 인장응력이 존재하였으며 13$0^{\circ}C$부터 뚜렷이 증가하여 $250^{\circ}C$에서 147MPa의 최대 인장응력을 나타냈다. 인장응력의 급격한 감소가 일어나는 $370^{\circ}C$부터는 본격적으로 치밀화된 PT박막과 Si 기판과의 열팽창계수 차이가 주로 박막내의 응력을 결정하며, 이것은 다층박막의 미세경도가 $300^{\circ}C$ 이후에서 급격히 증가하는 사실로도 뒷받침된다. 한편 다층박막에서 단층박막과 달리 $550^{\circ}C$까지 열처리후 Perovskite 상이 많이 생성되었으며 이는 박막 두께의 증가에 따른 homogenous 핵생성 site의 증가 때문이라고 생각된다

• 한국재료학회지
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• 제14권12호
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• pp.835-839
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• 2004

The diamond thin films was deposited on Si(100) substrate by Hot Filament Chemical Vapor Deposition (HFCVD) method using supplied the $CH_{3}OH/H_{2}O$ mixtured gas with excess H_{2} gas. The role of hydrogen ion as the growth mechanism of the diamond deposit was examined and compared the $CH_{3}OH/H_{2}O$ with the $CH_4/H_2$. Pressures in the range of $1.1\sim290{\times}10^2$ Pa were applied and using $3.4\sim4.4$ kw power. It was investigated by Scanning Electron Microscopy(SEM) and Raman spectroscopy The H ion was etching the graphite and restrained from $sp^3\;to\;sp^2$. But excess $H_2$ gas was not helped diamond deposit using $CH_{3}OH/H_{2}O$ mixtured gas. It was shown that the role of hydrogen ion of deposited diamond films using $CH_{3}OH/H_{2}O$ was different from $CH_4/H_2$.