• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.594-599
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• 2005

In this paper, we report the properties of Mo metal employed as PMOS gate electrode. Mo on $SiO_2$ was observed to be stable up to $900^{\circ}C$ by analyzing the Interface with XRD. C-V measurement was performed on the fabricated MOS capacitor with Mo Bate on $SiO_2$. The stability of EOT and work-function was verified by comparing the C-V curves measured before and after annealing at 600, 700, 800, and $900^{\circ}C$. C-V hysteresis curve was performed to identify the effect of fired charge. Gate-injection and substrate-injection of carrier were performed to study the characteristics of $Mo-SiO_2$ and $SiO_2-Si$ interface. Sheet resistance of Mo metal gate obtained from 4-point probe was less than $10\;\Omega\Box$ that was much lower than that of polysilicon.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.669-680
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• 1994

Oxidation behaviour of TiAl intermetallic compounds with the addition of Cr, V, Si, Mo, or Nb was investigated at 900~$1100^{\circ}C$ under the atmospheric environment. The reaction products were examined by XRD, SEM equipped with WDX. The weight gain by continuous oxidation increased with the addition of Cr or V, but there was less weight gain when Mo, Si or Nb was added individually. he oxidation rate of Cr- or V-added TiAl was always larger than that of TiAI. However, oxidation rate of Si-, Mo- or Nb-added TiAl was almost same or smaller than that of TiAI. Thus, it is concluded that the addition of Cr or V did not improve the oxidation resistance, whereas the addition of Si, Mo or Nb improved the oxidation resistance. Oxides formed on TiAl with Mo, Si, and Nb were found to be more protective, resulting from the decrease in diffusion rate of the alloying elements and oxygen. Nb strengthened the tendency to form $AI_{2}O_{3}$ in the early stage of oxidation, due to the continuous $AI_{2}O_{3}$ layer formation and dense $Tio_{2}+AI_{2}O_{3}$ layer. According to the Pt-marker test of TiAI- 5wt%Nb, oxygen diffused mainly inward while oxides were formed on the substrate surface. Upon thermal cyclic oxidation at $900^{\circ}C$, it is shown that the addition of Cr or Nb improved the adherence of oxide scale to the substrate.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.191-196
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• 1997

The isothermal reduction on $Pt/MoO_3/SiO_2$ at $50^{\circ}C$ demonstrates that the rate of hydrogen spillover is increased as calciantion temperature increases. That is due to the overlayer formation over the surface of Pt crystallites, investigated by TEM and CO chemisorption. It is known that reaction mechanism of skeletal isomerization of 1-butene into iso-butene is composed of 2 step such as formation of carbonium ion and isomerization of methyl group. It is expected that the increase of i-butene yield after calcination at $250^{\circ}C$ is due to increased rate of hydrogen spillover coming from first, overlayer formation over Pt surface and second, chlorine lessoning from $PtCl_x$ precursor.

• Korean Journal of Metals and Materials
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• v.50 no.9
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• pp.653-657
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• 2012

In this study, a molybdenum disilicide ($MoSi_2$) coating process was investigated by hydrogen reduction and Si-pack cementation. At first, the metallic Mo coating was carried out by hydrogen reduction of $MoO_3$ powder at $750^{\circ}C$ for various holding times (1, 2, 3 h) in hydrogen atmosphere. A $4.3{\mu}m$ thick metallic molybdenum thin film was formed at 3 h. $MoSi_2$ was obtained by Si-pack cementation on molybdenum thin film through hydrogen reduction processing. It was carried out using $Si:Al_2O_3:NH_4Cl=5:92:3$ (wt%) packs at $900^{\circ}C$ for various holding times (30, 60, 90 min) in Ar atmosphere. When the holding time was 90 min, a $MoSi_2$ layer was coated successfully and a $15.4{\mu}m$ thickness was observed.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.126-126
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• 1999

본 실험의 목적은 FED의 상부, 하부 전극으로 사용되는 Mo를 건식, 습식 식각함으로써 DED 소자의 공정을 개발하는 것이다. Mo는 $261^{\circ}C$의 높은 융점을 지니고 있으며, 우수한 열적 안정성과 비교적 낮은 비저항을 가지는 재료로써 FED와 같은 전계 방출 소자의 cathod 팁 및 전극물질로 사용되어지는 가장 보편적인 물질이다. FED와 같은 전계방출소자가 갖추어야 할 요건은 전자 방출 영역이 소자 동작시 변형되지 않아야 하고, 기계적 ,화학적, 열적 내구성이 좋아야 함인데 이러한 요건을 충족시킬 수 있고 가장 범용적으로 사용되는 물질이 Mo이다. 실험에서 사용된 Mo는 DC magnetron sputter를 사용하여 Ar 가스를 첨가하여 5mTorr하에서 Si 기판위에 증착속도를 300$\AA$/min로 하여 1.6$\mu\textrm{m}$ 증착하였다. 본 실험의 Mo 식각은 고밀도 플라즈마원인 ICP를 이용하였다. 식각특성은 식각 가스조합, inductive power, bias voltage, 공정 압력의 다양한 공정 변수에 따른 식각특성 변화를 관찰하였다. 식각시 chlorine 가스를 주요 식각 가스로 사용하고 BCl3, O2, Ar을 첨가가스로 사용하였으며, inductive power는 300-600, bias voltage는 120-200V 사용하였고 압력은 15-30mTorr, 기판온도는 7$0^{\circ}C$로 유지하였으며 식각마스크로는 electron-beam evaporator로 1$\mu\textrm{m}$ 증착한 SiO2를 patterning하여 사용하였다. 식각속도는 stylus profiler를 이용하여 측정하였으며 식각후 profile은 scanning electron microscopy (SEM)을 통하여 관찰하였다. 실험 결과 순수한 Cl2 BCl3 가스만을 사용한 경우 보다는 Cl2 가스에 O2를 첨가하였을 때 좋은 선택비를 얻었다. 또한, inductive power와 bias voltage, Mo의 식각속도의 적절한 조절을 통해 SiO2에 대한 선택도를 변화시킬 수 있었다. Cl2:O2비를 1:1로 하고 400W/-150V, 20mTorr의 압력, 7$0^{\circ}C$ 기판온도에서 식각시 200$\AA$/min의 Mo 식각속도, SiO2와의 선택비 8:1을 얻을 수 있었다. 또한 실제 FED 소자 구조형성에 적용한 결과 비등방적인 식각형상을 형성할 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.277-279
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• 2004

$300^{\circ}C$ 소성 Pt/MoO3가 수소를 흡착후 탈착하는 속도를 측정하였다. 두가지 흡착 속도를 나타내는 Pt/MoO3 촉매에서 탈착량은 흡착량과 탈착 온도의 증가에 비례하는 것을 알 수 있었다. 또한 X-Ray Photoelectron Spectroscope(XPS) 결과로부터 Pt와 MoO3간의 활성점에 존재하는 Cl의 존재가 수소 이동 속도를 결정하는 것으로 판단되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.650-653
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• 2004

We have synthesized some phosphors in the system MO-$Al_2O_3-SiO_2$(M=Sr, Ba) by combinatorial polymerized-complex method. Composition and synthetic temperature of phosphors in the liblary was screened from the emission intensities of individual samples under 365nm excitation. As we were screened the higher luminescent candidate composition (or candidate host lattice) at 365nm excitation, investigated whether good radiation was possible at the 405 or 465nm excitation by give the host lattice to be discovered more various change. From libraries about 2 systems, the compound to be expected in long wavelength among the compound to be screened are $Sr_4Al_{14}O_{25}$, $Sr_3Al_2O_6$, $SrAl_2Si_2O_8$, and $BaAl_2Si_2O_8$.

• Korean Journal of Materials Research
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• v.34 no.6
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• pp.275-282
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• 2024

In this work, we investigated the photo-degradation performance of MnO₂-SiC fiber-TiO₂ (MnO₂-SiC-TiO₂) ternary nanocomposite according to visible light excitation utilizing methylene blue (MB) and methyl orange (MO) as standard dyes. The photocatalytic physicochemical characteristics of this ternary nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photocurrent and cyclic voltammogram (CV) test. Photolysis studies of the synthesized MnO₂-SiC-TiO₂ composite were conducted using standard dyes of MB and MO under UV light irradiation. The experiments revealed that the MnO₂-SiC-TiO₂ exhibits the greatest photocatalytic dye degradation performance of around 20 % with MB, and of around 10 % with MO, respectively, within 120 min. Furthermore, MnO₂-SiC-TiO₂ showed good stability against photocatalytic degradation. The photocatalytic efficiency of the nanocomposite was indicated by the adequate photocatalytic reaction process. These research results show the practical application potential of SiC fibers and the performance of a photocatalyst composite that combines these fibers with metal oxides.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.921-928
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• 1995

MoSi$_2$heating elements were fabricated using MoSi$_2$, powder prepared by SHS. Their apparent density, electrical resistivity, bending strength and victors hardness were measured as a function of sintering temperature, time and the amount of ceramic additives. The additives were A1$_2$O$_3$, SiO$_2$and bentonite which were added as a plastisizer. The electrical resistivity of MoSi$_2$decreased with the increase in the apparent density as expected. It decreased when the additives were added and the increase was the largest for the case of SiO$_2$. The bending strength and hardness decreased when the grain size becomes larger which is opposite to the expectation from the Hall-Petch type relation. Instead, they showed inverse proportionality with the volume fraction of pores probably in an exponential manner. The strength and hardness also decreased with the additives.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.195.1-195.1
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• 2014

최근 반자성 물질인 $MoS_2$를 수소 기체 속에서 열처리하게 되면 약한 강자성이 유발된다는 연구가 보고되었다. 본 연구에서는 강자성 발현을 수반하는 물리적 및 화학적 변화를 이해하기 위해서 단일층 $MoS_2$에 대한 라만분광 및 광발광 연구를 수행하였다. 기계적 박리법을 이용하여 $MoS_2$ 결정으로부터 단일층 및 이중층 $MoS_2$를 분리하여 $SiO_2/Si$ 기판에 전사한 후, $200^{\circ}C{\sim}500^{\circ}C$ 영역의 특정 온도에서 1시간 동안 열처리하였다. 배경 기체가 열처리 도중 $MoS_2$에 미치는 영향을 이해하기 위하여 수소 속 반응을 진공 상태와 비교하였다. 라만 스펙트럼에서는 큰 변화가 없었으나, 광발광의 세기는 수소 속 반응 후에 감소하고 진공 속 반응 후에는 증가하는 대조적인 결과를 보였다. AFM 측정으로부터는 열처리 후에 $MoS_2$ 표면에 뚜렷한 변화가 일어나지 않는다는 사실을 확인하였다. 본 발표에서는 수소와 진공 조건에서 관찰된 상이한 광발광 특성과 그래핀/$SiO_2/Si$에서 관찰된 p-형 도핑과의 상관관계를 설명하고자 한다.