• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.18.2-18.2
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• 2008

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1183-1191
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• 2001

The metallorganic chemical vapor deposition (MOCVD) method has been used to prepare TiO2 thin films for the degradation of hazardous organic compounds, such as 2-chlorophenol (2-CP). The effect of supporting materials and metal doping on the photocatalytic activity of TiO2 thin films also has been studied. TiO2 thin films were coated onto various supporting materials, including stainless steel cloth(SS), quartz glass tube (QGT), and silica gel (SG). Transition metals, such as Pd(II), Pt(IV), Nd(III) and Fe(III), were doped onto TiO2 thin film. The results indicate that Nd(Ⅲ) doping improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 ${\mu}m)$ appears to be the best support. An optimal amount of doping material at 1.0 percent (w/w) of TiO2-substrate thin film gives the best photodegration of 2-CP.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.85-85
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.132.1-132
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• 1998

• Korean Journal of Materials Research
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• v.20 no.12
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• pp.686-690
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• 2010

$TiO_2$ nanowires were self-catalytically synthesized on bare Si(100) substrates using metallorganic chemical vapor deposition. The nanowire formation was critically affected by growth temperature. The $TiO_2$ nanowires were grown at a high density on Si(100) at $510^{\circ}C$, which is near the complete decomposition temperature ($527^{\circ}C$) of the Ti precursor $(Ti(O-iPr)_2(dpm)_2)$. At $470^{\circ}C$, only very thin (< $0.1{\mu}m$) $TiO_2$ film was formed because the Ti precursor was not completely decomposed. When growth temperature was increased to $550^{\circ}C$ and $670^{\circ}C$, the nanowire formation was also significantly suppressed. A vaporsolid (V-S) growth mechanism excluding a liquid phase appeared to control the nanowire formation. The $TiO_2$ nanowire growth seemed to be activated by carbon, which was supplied by decomposition of the Ti precursor. The $TiO_2$ nanowire density was increased with increased growth pressure in the range of 1.2 to 10 torr. In addition, the nanowire formation was enhanced by using Au and Pt catalysts, which seem to act as catalysts for oxidation. The nanowires consisted of well-aligned ~20-30 nm size rutile and anatase nanocrystallines. This MOCVD synthesis technique is unique and efficient to self-catalytically grow $TiO_2$ nanowires, which hold significant promise for various photocatalysis and solar cell applications.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.346-347
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• 2006

New manufacturing processes, such as thermochemical, mechanochemical and chemical vapor condensation processes have been developed to obtain nanostructured WC/Co materials. Nanoscale size WC/Co composite powders of near 100-150nm can be synthesizes by thermochemical and mechanochemical processes using water soluble precursors. Non-agglomerated and nano sized WC powder can be synthesized by the chemical vapor condensation process using metallorganic precursors as starting materials. In this paper, the scientific and technical issues on synthesis and consolidation of nanostructured WC/Co alloys produced by new chemical processes are introduced.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.49-54
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• 2003

TiO₂nanoparticles were synthesized using the metallorganic chemical vapor deposition process. Particles with and without metal ion dopants were obtained. X-ray photoelectron and energy dispersive X-ray spectroscopic measurements confirmed the stoichiometry of the TiO₂nanoparticles. X-ray diffraction patterns showed a polycrystalline anatase structure of TiO₂. Transmission electron microscopy revealed that these particles are of nanoscale dimensions. Exact particle size and size distribution analyses were carried out by dynamic light scattering. The average particle size was determined to be 22 nm. The nanosize particles provided large surface area for photocatalysis and a large number of free surface-charge carriers, which are crucial for the enhancement of photocatalytic activity. To improve the photocatalytic activity, metal ions, including transition metal ions $(Pd^{2+},\;Pt^{4+},\;Fe^{3+})$ and lanthanide ion $(Nd^{3+})$ were added to pure TiO₂nanoparticles. The effects of dopants on photocatalytic kinetics were investigated by the degradation of 2-chlorophenol under an ultraviolet light source. The results showed that the TiO₂nanoparticles with the metal ion dopants have higher photocatalytic activity than undoped TiO₂. The $Nd^{3+}$ ion of these dopant metal ions showed the highest catalytic activity. The difference in the photocatalytic activity with different dopants is related to the different ionic radii of the dopants.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.166-166
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• 2003

Si (100) 기판위에서 에피텍셜하게 자란 CoSi$_2$층은 우수한 열적안정성, 낮은 junction leakage, ultra-Shallow junction형성 등의 장점으로 인하여 많은 주목을 받아왔다. 그래서 에피텍셜 CoSi$_2$층을 형성하기 위한 많은 방법들이 보고되어 왔다. 그 방법으로는 Ti나 TiN층을 이용한 interlayer mediated epitaxy, Co의 제한적 공급을 통한 molecular beam epitaxy와 molecular beam allotaxy, 그리고 금속유기소스를 이용한 반응성화학기상증착법등이 있다. 하지만 이 방법들은 복잡한 증착공정과 열처리 후 잔류층 제거의 어려움등을 가지고 있다. 본 연구는 일반적으로 사용되는 Ti나 oxide의 중간층없이 에피층을 형성시키는 새로운 방법으로 CO-O-N 박막으로부터 열처리에 의해 확산된 Co로부터 CoSi$_2$에피층을 형성시켰다.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.379-383
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• 2008

We report on the light-emitting diode (LED) characteristics of core-shell CdSe/ZnS nanocrystal quantum dots (QDs) embedded in $TiO_2$thin films on a Si substrate. A simple p-n junction could be formed when nanocrystal QDs on a p-type Si substrate were embedded in ${\sim}5\;nm$ thick $TiO_2$ thin film, which is inherently an n-type semiconductor. The $TiO_2$ thin film was deposited over QDs at $200^{\circ}C$ using plasma-enhanced metallorganic chemical vapor deposition. The LED structure of $TiO_2$/QDs/Si showed typical p-n diode currentvoltage and electroluminescence characteristics. The colloidal core-shell CdSe/ZnS QDs were synthesized via pyrolysis in the range of $220-280^{\circ}C$. Pyrolysis conditions were optimized through systematic studies as functions of synthesis temperature, reaction time, and surfactant amount.

• Korean Journal of Materials Research
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• v.6 no.5
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• pp.483-488
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• 1996

InP 기판위에 InP와 격자정합된 undoped-InGaAs에서 zine의 확산 특성을 Electrochemical Capacitance-Voltage 법(polaron)과 Secondary Ion Mass Spectrometry(SIMS)로 조사하였다. Metallorganic Chemical Vapor Deposition (MOCVD)를 이용하여 undoped-InGaAs 층을 성장시켰으며 확산방법으로는 Zn3P2 확산원 박막과 Rapid Thermal Annealing (RTA)를 이용하였다. 450-55$0^{\circ}C$온도범위에서 30-300초 동안 확산을 수행한 결과 zinc의 확산계수는 D=Doexp(-$\Delta$E/kT)의 특성을 만족하였으며, Do와 $\Delta$E는 각각 1.3x105$\textrm{cm}^2$/sec와 2.3eV였다. 얻어진 확산계수는 다른 확산방법을 이용한 값들에 비해 매우 큰 값인데, 이것은 RTA 처리시 빠른 온도 증가에 의한 확산원 박막, 보호막, 그리고 InGaAs 에피층이 가지는 열팽창계수의 차이로인한 응력의 효과에 의한 것으로 생각되며, 이를 sealed-ampoule 법을 사용한 경우의 확산특성과 비교를 통하여 확인할 수 있었다.