• Journal of the Korean Ceramic Society
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• v.35 no.1
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• pp.55-65
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• 1998

The oxidation behavior of Ag-36.8a%Cu-7.4at%Ti alloy brazed on Si3N4 substrate was investigated at 400, 500 and 600$^{\circ}C$ in air. Under this experimental condition Si3N4 and Ag were not oxidized whereas Cu and Ti among the brazing alloy components were oxidizied obeying the parabolic oxidation rate law. The activation energy of oxidation was found to be 80kj/ mol which was smaller than that of pure Cu owing to the presence of oxygen active element of Ti. The outer oxide scale formed from the initial oxidation state was always composed of Cu oxides which were known to be growing by the outward diffusion of Cu ions. As the oxidation progressed the concentration gradient occurred due to the continuous consumption of Cu as Cu oxides and consequently build-up of an Ag-enriched layer below the Cu oxides resulted in the formation of multiple oxide scales composed of Cu oxide (CuO) /Ag-enriched layer/Cu oxide (Cu2O) /Ag-enriched layer. Also the inward diffusing of oxygen through Cu oxide and Ag-enriched layers led to the formation of internal oxides of TiO2.

• Analytical Science and Technology
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• v.6 no.2
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• pp.239-246
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• 1993

The structure of $(BaSr)TiO_3$ thin film deposited on ITO coated glass, bare glass and (100) Si substrates was not changed, but the crystallinity was improved by the polycrystalline ITO layer and (100) Si substrate. The composition of $(BaSr)TiO_3$ thin film deposited on ITO coated glass was nearly stoichiometric ((Ba+Sr)/Ti=1.08~1.09) and very uniform through all deposition process. But as the deposition temperature increases, the interdiffusion between grown thin film and ITO layer and between ITO layer and base glass is severer. $(BaSr)TiO_3$ thin film deposited on ITO coated glass substrate was highly transparent. The refractive index($n_f$) of $(BaSr)TiO_3$ thin film deposited on ITO coated glass was 2.138~2.286 as a function of substrate temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.65-65
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• 2000

반도체 소자의 고집적화는 배선에서 많은 문제점을 야기 시킨다. 이러한 문제점들 중에서 대표적인 것이 과도한 전류밀도에 의한 electro-migration(EM)이다. 이는 앞으로 배선의 선폭이 0.25$mu extrm{m}$미만일 경우 더욱 심화될 전망이다. 이에 대안으로 Al-합금에서 Cu로 대체하여 이러한 문제를 해결하려 하고 있다. 그런데, Cu는 Si 및 SiO2와 높은 반응성과 빠른 확산속도를 가지기 때문에 확산방지막이 필요로 되어진다. 현재에는 TiN, TaN 등의 확산방지막이 사용되어지고 있으나, TiN 박막의 경우 표면에 Ti와 oxide와의 결합에 의해 Ti-O 성분이 존재하는데, 이럴 경우 Cu 증착을 하는데 있어 부정적인 요인이 된다. 또한, 이러한 화합물은 Cu와 TiN 계면사이에 밀착성을 나쁘게 하여 고전류 인가시 EM에 있어 높은 저항성을 가질 수가 없다. 따라서, 본 연구는 MOCVD방식으로 Cu 박막을 증착하기에 앞서 수소플라즈마를 이용하여 TiN 표면에 형성된 산소 화합물을 제거한 후 Cu를 증착하여 동일한 조건에서 EM 가속화 실험을 하였다. 그림 1은 Cu/TiN 구조에 있어 수소 전처리를 한 배선의 구조의 MTF(mean time to failure)가 65분이고 전처리를 하지 않은 배선구조는 40분으로 약 50% 긴 MTF를 가지는 것으로 나왔다. 결론적으로 Cu와 TiN 계면에 좋은 밀착성은 EM에 있어 우수한 저항성을 가지는 것으로 나왔다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.35-35
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• 2018

물리적 증착법에 의해 제조되는 초고경도 박막은 나노다층과 나노복합 구조가 대표적이며, 본 연구에서는 음극 아크 증착법으로 TiAlN과 AlTiiN 층 조합을 이용하여 나노다층구조를 포함하는 다층막 시편을 제작하였다. 초격자 두께 주기 12.1 ~ 15.6 nm에서 35 ~ 55 GPa의 경도값을 가졌으며, 절삭공구 코팅분야에 적용할 예정이다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.85-86
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• 2020

With the increasing importance of environmental issues, the cementitious materials with self-cleaning or photocatalytic properties by introducing TiO₂ materials have been gaining a lot of attention. In this work, the influence of TiO₂ particle size and structure on its photocatalytic effect in cement paste was investigated. The degradation of methylene blue solution was used as the parameter for evaluating the photocatalytic effect of micro-TiO2 (m-TiO₂), nano-TiO2 (n-TiO₂), and TiO₂ nanotube (TNT). Moreover, the effect of these three TiO₂ materials on the cement hydration products was characterized by X-ray diffraction (XRD) and thermgravimetric analysis (TG). According to the results, it can be found that all of the TiO₂ materials promoted the formation of hydration products, especially TNT. On the other hand, the m-TiO₂ exhibited a better photocatalytic effect compared to other materials.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.19-24
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• 1985

The synthetic method was studied on the $SrTiO_3$ powder of pure and homogeneous ultra fine particle of $SrTiO_3$. Pure and ultra fine particle was synthesized from $Sr(OH)_2$.$8H_2O$ and Ti(OH) at 3$0^{\circ}C$~9$0^{\circ}C$ in the $N_2$ gas atmosphere.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.248-248
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• 2009

GaN 기반 LED 소자의 ITO 표면에 sol-imprinting 기술을 이용하여 잔여층 없이 $TiO_2$ 나노 패턴을 형성하였다. 알콕사이드 계열의 $TiO_2$ sol과 Si 몰드로부터 복제된 PDMS 몰드를 사용하여 표면에 패턴을 형성하고, 이 후 annealing을 통해 내부에 남아있던 불순물을 제거하고 다결정 $TiO_2$을 형성하였다. 표면에 형성된 $TiO_2$ 나노 패턴이 LED 소자 내부에서 발생한 빛의 전반사를 억제하기 때문에 소자의 광추출 효율이 증가하였다.

• Carbon letters
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• v.9 no.2
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• pp.131-136
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• 2008

In order to investigate the effect of doping C, N, B and F elements on $TiO_2$ for reducing the band gap, the heat treatment of $TiO_2$ was carried out with tetraethylammonium tetrafluoroborate. Through XRD and XPS analysis, the C, N, B and F doped anatase $TiO_2$ was confirmed. According to the increase of temperature during treatment, the particle size was increased due to aggregation of $TiO_2$ with elements (B, C, N and F). To investigate the capacity of photocatalyst for degradation of dye under solar light, the degradation of acridine orange and methylene blue was conducted. The degradation of dyes was carried out successfully under solar light indicating the effect of doping elements (B, C, N and F) on $TiO_2$ for reducing the band gap effectively.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.62-65
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• 2017

Passivation of surface defects by the formation of chemically inert structure at the surface of $TiO_2$ nanocrystals can be potentially useful in enhancing their photocatalytic activity. In this regard, we have studied the surface chemical states of $TiO_2$ surfaces prepared by a treatment in the afterglow of $N_2$ microwave plasma using X-ray photoemission spectroscopy (XPS). We find that nitrogen is incorporated into the surface after the treatment up to a few atomic percent. Interestingly, the surface oxynitride layer is found to be chemically stable when it's in contact with water at room temperature (RT). The surface nitrogen species were also found to be thermally stable upon annealing up to $150^{\circ}C$ in the atmospheric pressure. Thus, we conclude that the treatment of oxide materials such as $TiO_2$ in the afterglow of $N_2$ plasma can be effective way to passivate the surface with nitrogen species.

• Journal of the Korean Ceramic Society
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• v.24 no.5
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• pp.470-476
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• 1987

The system of 0.1Pb(Mg1/3N2/3)O3-yPbTiO3-zPbZrO3 piezoelectric ceramics was made in the radial model disk and ring dot type filter. The resonant frequency(fr) variations were investigated for 100 hours and the temperature range from 20$^{\circ}C$ to 100$^{\circ}C$. As the results, the morphotropic phase boundary was supposed to be the composition of 45 y 50 and 40 z 45. The best characteristic of againg effect, after 10-hours, was composed of y, z=45. The stabilized characteristic of temperature varition, to become 0.1% up to 100$^{\circ}C$, was composed of y=50 and z=40. The bandwidth was broadened with increasing the electromechanical coefficient(kp), and the filter characteristics was approached ideal mode with increasing mechanical quality factor(Qm). Kp and Qm affected combinationally on filter characteristics.