• Journal of the Korean Electrochemical Society
• /
• v.12 no.1
• /
• pp.75-80
• /
• 2009

The effect of polyoxometalate monolayers on the electrodeposition of Au nanoparticles (AuNPs) on glassy carbon (GC) surfaces was examined by electrochemical and scanning electron microscope techniques. The presence of $SiMo_{12}O^{4-}_{40}$-layers resulted in average particle sizes of ca. 60 nm, which is larger than AuNPs deposited on bare GC surfaces. AuNPs electrodeposited on $SiMo_{12}O^{4-}_{40}$-modified GC surfaces for 20 s exhibited the best electrocatalytic activity for oxygen reduction. This system exhibited similar or slightly better efficiency for oxygen reduction than a bare Au electrode. Rotating disk electrode experiments were also performed and revealed that the catalytic reduction of oxygen on AuNPs deposited on $SiMo_{12}O^{4-}_{40}$-modified GC electrodes is a two-electron process.

• Journal of the Korean Society of Safety
• /
• v.10 no.4
• /
• pp.9-12
• /
• 1995

Detection of small defects by medical ultrasonic testing when the thermal sprayed coating by $MoSi_2$ on the metal is done. The defects may occur at the bonded surface. So, the detecting method of the defects by non-destructive in spection is desired. Here, in order to examine the possibility of the detection of the small defects by the ultrasonic. The electronic scanning ultrasonic equipment using an array probe developed as the medical ultrasonic diagnostic equipment is applied for the detection of the metal material defects. It's validity is investigated.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2002.05a
• /
• pp.241-246
• /
• 2002

극자외선 노광공정(EUVL: Extreme Ultraviolet Lithography)은 반도체 공정에서 0.1$\mu\textrm{m}$ 이하의 해상도를 실현하기 위해 연구되고 있는 유력한 차세대 노장공정(NGL: Next Generation Lithography)이다. [1] 본 연구에서는 극자외선 노광공정에서 사용되는 반사형 다층박막 미러를 제조하기 위해서 직접 제작한 전산모사 도구를 이용하여 130~135$\AA$의 파장 영역에서 고반사도를 가지는 효율적인 다층박막의 구조인자를 예측하였으며, 그러한 구조인자를 실현하기 위해서 상온(~300K)에서 마그네트론 스퍼터링을 이용하여 다층박막을 증착하였다. 증착조건 중에서, 공정압력에 따른 다층박막 계면 성장의 질적 의존성이 나타났으며, 결과적으로는 낮은 공정압력에서 더좋은 계면특성을 가지는 다층박막이 형성되었다. 다층박막의 구성물질로 Ru, Mo, Si을 사용하였으며, 다층박막의 구조분석은 high/low angle XRD, 단면 TEM images 등을 이용하여 분석되었다.

• Journal of Powder Materials
• /
• v.3 no.3
• /
• pp.167-173
• /
• 1996

The effect of ball milling on the pressureless sintering of MoSi$_2$ was investigated. Ball milling was conducted at 70 rpm for 72 hours using different balls and vessels: one used tungsten carbide balls in a plastic vessel(referred as B-powder) and the other stainless steel ball in a stainless steel vessel(referred as C- powder). The powder was compacted with 173MPa and subsequently sintered at the temperature range of 1150 $^{\circ}C$ and 1450 $^{\circ}C$ in H$_2$, atmosphere. Sintered density was measured and scanning electron micrograph was observed. Over 90% of the theoretical density was attained at 1250 $^{\circ}C$ within 10 minutes for C-powders, while the similar densification required a sintering temperature of 1450 $^{\circ}C$ for B-powders. Such a difference in sinterability between B and C-powders was discussed in terms of the effect of particle size reduction and activated sintering caused by Ni and/or Fe introduced during ball milling.

• Journal of the Korean Magnetics Society
• /
• v.17 no.1
• /
• pp.22-25
• /
• 2007

In this research, magnetic properties of spin valve structures using IrMn layers as antiferromagnetic were studied depending on the thickness of the pinned layer. The spin valve structure was Si substrate/$SiO_2(2,000\;{\AA})/Mo(17\;{\AA})NiFe(21\;{\AA})/CoFe(28\;{\AA})/Cu(22\;{\AA})/CoFe(18\;{\AA})/IrMn(t\;{\AA})/Ta(25\;{\AA})$. Also, Mo film was deposited on Si substrates and the thermal annealing effect was analyzed. The resistivity of the Mo film was increased as an annealing temperature was increased up to $600^{\circ}C$. The variations of MR ratio were related with magnetic exchange coupling field of the spin valve structures for various IrMn pinned layer thickness up to 130 ${\AA}$. MR ratio and $H_{ex}$ of spin valves was about 9.05% and 277.5 Oe when the thickness of the IrMn pinned layer was $32.5\;{\AA}(t=32.5\;{\AA})$. It was increased to 9.65% and 337.5 Oe for $t=65\;{\AA}$. For $t=97.5\;{\AA}$, the MR ratio and Hex decreased to 8.2% and 285 Oe, and further decrease was observed up to $t=130\;{\AA}$.

• Proceeding of EDISON Challenge
• /
• 2015.03a
• /
• pp.373-377
• /
• 2015

이 연구에서는 원자 궤도 함수 기반 DFT 전자구조 계산을 이용해서 최근 각광받고 있는 이차원 물질인 MoS2 monolayer의 S 자리와 Mo 자리에 각각 전자가가 다른 원자를 치환하였을 때의 도핑 특성을 Density of States (DOSs)와 밴드구조 등의 전자구조를 통해 분석해 보았다. S자리에 Cl, Si, I, B, C, Mo 자리에는 Hf, Ta, 그리고 Re을 치환해 보았으며 계산 결과 S자리에 Cl을 치환했을 때 가장 얕은 acceptor level (VBM으로부터 0.08 eV)이 형성되었으며, Mo자리에 Re를 치환했을 때에는 resonant state를 형성하였다. 또한 Mo자리에 Ta를 치환했을 ? 가장 얕은 donor level (CBM으로부터 0.02 eV)가 형성되었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.8 no.5
• /
• pp.35-41
• /
• 2008

This paper presents the design method of current-mode signal processing for high speed and low power digital audio signal processing. The digital audio processor requires a digital signal processing such as fast Fourier transform (FFT), which has a problem of large power consumption according to the settled point number and high speed operation. Therefore, a current-mode signal processing with a switched Current (SI) circuit was employed to the digital audio signal processing because a limited battery life should be considered for a low power operation. However, current memory that construct a SI circuit has a problem called clock-feedthrough. In this paper, we examine the connection of dummy MOS that is the common solution of clock-feedthrough and are willing to calculate the relation of width between dummy MOS for a proposal of the design methodology for improvement of current memory. As a result of simulation, in case of that the width of memory MOS is 20um, ratio of input current and bias current is 0.3, the relation of width between switch MOS and dummy MOS is $W_{M4}=1.95W_{M3}+1.2$ for the width of switch MOS is 2~5um, it is $W_{M4}=0.92W_{M3}+6.3$ for the width of switch MOS is 5~10um. Then the defined relation of MOS transistors can be a useful design guidance for a high speed low power digital audio processor.

• Journal of the Korean Ceramic Society
• /
• v.25 no.3
• /
• pp.251-260
• /
• 1988

Ion-exchange porous glasses were prepared by heat treatment and subsequently hydro thermalor acid leaching treatment $10Li_2O$.$(90-x)B_2O_3$.$xSiO_2$ base glasses containing various amount of $Al_2O_3$ or $MoO_3$. It was investigated how the phase separation and the cation exchange capacity(CEC) were affected by the addition of $Al_2O_3$ or $MoO_3$. The optimum condition of phase separation in these glasses was about 48$0^{\circ}C$ for 10 hrs. The degree of phase separation was rapidly suppressed by the addition of $Al_2O_3$ up to 10 mol% and thereafter suppression effect was decreased. The maximum value of CEC, about 252meq/100g, was observed with the $1OLi_2O$.$45B_2O_3$.$45SiO_2＋7.5Al_2O_3$ porous glass prepared by hydrothermal treatment and its mean pore radius was about 16.3A. The addition of $MoO_3$ accelerated phase separation and leaching rate. Looking at the remakable increment of pore diameter and pore volume of these porous glasses by the addition of $MoO_3$, the effect of $MoO_3$ may be ascribed to the lowering of silica concentration in the borate phase and to the forming of water-soluble complex with silica during the leaching treatment.

• Korean Journal of Materials Research
• /
• v.10 no.5
• /
• pp.343-349
• /
• 2000

Fabrication of various carbide fibers from carbon fibers and elementary powders of Ti, Zr, Nb, Zi, W, B, and Mo by self-propagating high temperature synthesis was attempted. It was found the almost pure phase of TiC, ZrC, NbC, SiC, $B_4$C, and $Mo_2$C carbides were successfully produced. The three types of morphologies were ob-served, TiC, ZrC, NbC, and $B_4$C had a hollow-type fibrous shape. SiC had fiber shape consisting of smaller particles and fine whiskers. WC and $Mo_2$C had non-fibrous shapes. The reason for the different morphologies was explained. The formation mechanism of hollow fibers was suggested.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.277.1-277.1
• /
• 2016

We report on synthesis of large-area MoS2 using chemical vapor deposition (CVD). Relatively uniform MoS2 are obtained. To fabricate field-effect transistor (FET) devices, MoS2 films are transferred to another SiO2/Si substrate using polystyrene (PS) and patterned using oxygen plasma. In addition, to reduce contact resistance, synthesis of graphene used as channel. Device characteristics are presented and compared with the reported results.