• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.289.2-289.2
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• 2016

In-Ga-Zn-O(IGZO) receive great attention as a channel material for thin film transistors(TFTs) as next-generation display panel backplanes due to its superior electrical and physical properties such as a high mobility, low off-current, high sub-threshold slope, flexibility, and optical transparency. For the purpose of fabricating high performance IGZO TFTs, a thermal recovery process above a temperature of $300^{\circ}C$ is required for recovery or rearrangement of the ionic bonding structure. However diffused metal atoms from source/drain(S/D) electrodes increase the channel conductivity through the oxidation of diffused atoms and reduction of $In_2O_3$ during the thermal recovery process. Threshold voltage ($V_{TH}$) shift, one of the electrical instability, restricts actual applications of IGZO TFTs. Therefore, additional investigation of the electrical stability of IGZO TFTs is required. In this paper, we demonstrate the effect of Ti diffusion and modulation of interface traps by carrying out an annealing process on IGZO. In order to investigate the effect of diffused Ti atoms from the S/D electrode, we use secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy, HSC chemistry simulation, and electrical measurements. By thermal annealing process, we demonstrate VTH shift as a function of the channel length and the gate stress. Furthermore, we enhance the electrical stability of the IGZO TFTs through a second thermal annealing process performed at temperature $50^{\circ}C$ lower than the first annealing step to diffuse Ti atoms in the lateral direction with minimal effects on the channel conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.407-407
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• 2008

무기EL 디스플레이는 고체재료에 전계를 가했을 때 발광하는 현상을 이용한소자로서, 급속도로 발전을 거듭하고 있으나, 유전체층에 강한전계를 가하여 발광하여야 하므로 낮은 Breakdown voltage와 효율의 한계로 인하여 휘도가 낮고 풀 컬러화 디스플레이 등 의 응용에는 적용되고 있지 못하는 실정이다. 본 연구에서는 강유전체 Perovskite 구조를 가지는 ABO3 물질 중 PMN(Lead Magnesium niobate) 과 PZT (Lead Zirconate titanate) 후막을 제조하여 Inorganic EL(Electro Luminance)에 적용하고 소자의 광전특성을 평가하였다. 소자에 사용된 기판은 고온소성에 알맞은 알루미나(Al2O3)기판을 채택 하였으며, 그 위 하부전극으로는 고온소성에 따른 화학적 안정성이 우수한 Au전극을 Screen Printing 하였다. 제조 되어진 PMN후막 페이스트는 PMN(Pb(Mg1/2 Nb2/3)O3) + Glass Frit(Pb-Zn-B) + BaTiO3(99.99%) 로 합성되었으며 하부전극위에 인쇄하였다. 그 다음 PZT sol-gel을 Spin coating으로 도포 하였다. 형광체로 ZnS:Cu.Cl 을 Screen Printing을로 형성하였으며, 평탄화를 위하여 유기물 충을 Screen Printing 공정으로 성막 하였다. 상부전극으로는 DC sputter로 ITO를 증착하여 EL소자 완성 후 Spectro - Chroma meter로 소자특성을 측정하였다. 평탄화를 통한 유기물층에 변화되는 Capacitance를 Oscilloscope로 전압 전류 pulse의 변화에 따른 opto-electronic 특성을 평가하였다.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.245-251
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• 2017

In this study, ZnO, which is widely known as a non $TiO_2$ photocatalyst, was synthesized using coprecipitation method and Ag was added in order to improve the catalytic performance. The physicochemical characteristics of the synthesized ZnO and Ag/ZnO particles were checked using X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL), and photocurrent measurements. The performance of catalysts was tested by $H_2$ production using the photolysis of $H_2O$ with MeOH. By adding Ag which plays a role as an electron capture on the ZnO catalyst, the performance increased due to the recombination of excited electrons and holes. In particular, $8.60{\mu}mol\;g^{-1}$ $H_2$ was produced after 10 h reaction over the 0.50 mol% Ag/ZnO.

• Journal of the Korean earth science society
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• v.28 no.3
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• pp.324-342
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• 2007

This study reports petrography and geochemical characteristics of the basalt lava flows in Seongsan-Ilchulbong area, the easternpart of Jeju island, Korea, to understand the evolutionary processes of magma. Basalt lavas are classified into the Pyoseon-ri basalt and the Seongsan-ri basalt. The Pyoseon-ri basalt is dark-gray colored with many vescicles, and mainly consists of olivine, feldspar and rarely of clinopyroxene as phenocrysts. The Seongsan-ri basalt is largely aphanitic basalt and bright-gray colored, divided into two lava-flow units: lower lava flow (B1) and upper lava flow (B2) by the intercalated yellowish lapillistone and paleosol. The lavas plotted into sub-alkaline tholeiitic basalt and alkaline basalt series. The tholeiitic basalts have characteristically higher $SiO_2,\;FeO^T$, and CaO contents, but lower $TiO_2,\;K_2O,\;P_2O_5$ and other incompatible elements compared to the alkali basalts. The tholeiitic basalts have higher $SiO_2$ to the same MgO contents than the alkalic basalts. The contents of Ni, Cr, and MgO show a strong positive correlation, which indicates that low-MgO phases like plagioclase and titanomagnetite were important during the differentiation of magma. The contents of incompatible elements against that of Th show a strong positive correlation. The chondrite-nomalized REE patterns of tholeiitic and alkalic basalts are subparallel each other. LREEs contents of the former are lower than, but HREEs contents are similar to the latter. They both are similar to their K/Ba ratios. The primitive-mantle normalized spider diagram demonstrates that the contents of Ba and Th of all basaltic magma are enriched, and yet Cr, Ni are depleted. The tholeiitic and alkalic basalts may be originated from a different degree of the partial melting of the same mantle material source, and one shows a higher degree of the partial melting than the other.

• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.1-21
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• 2011

Eoil basalt in the Eoil basin and Yeonil basalt and its related volcanic rocks in Guryongpo and Daebo area were researched and analyzed to purse the tectonic settings and magma characteristics of those Tertiary volcanic rocks in the south-east Korean peninsula. It is highly suggested that zoning, resorption and sieve texture in plagioclase and reaction rim in pyroxene indicate unstable tectonic environments and complex volcanism in the study area. Volcanic rocks from Janggi basin are identified as basalt and basaltic andesite in TAS diagram and sub-alkaline series in terms of magma differentiation. $Na_2O$ and $K_2O$ show positive trend however FeO, CaO, MgO and $P_2O_5$ indicate negative trend in Harker variation diagram with $SiO_2$. Basaltic rocks from Eoil area are identified as calc-alkaline series in AFM diagram and show medium K series calc-alkaline in $K_2O-SiO_2$ diagram. Compatible trace elements of Co, Ni, V, Zn, and Sc in Yeonil basalt show negative trend with crystallization but incompatible trace element of Ba, Rb show positive trend with $SiO_2$ 0.81~1.00 of $Eu/Eu^*$ value suggests minor effect of plagioclase fractionation in Yeonil basaltic rocks. Plagioclase composition of Eoil basalt ranges from $An_{63.46-98.38}\;Ab_{1.62-32.96}\;Or_{0-3.58}$ (anorthite-labradorite) in core to $An_{40.89-82.44}\;Ab_{17.10-46.43}\;Or_{0-12.68}$ (bytownite-labradorite) in rim. $^{87}Sr/^{86}Sr$ and 143Nd;t44Nd ranges 0.704090~0.704717 and 0.512705~0.512822 respectively. Negative linear trends in 87Sr/86Sr and $^{143}Nd/^{144}Nd$ correlation diagram indicate that magma produced Yeonil basalt and basaltic andesite has been originated as partial melting product of mantle wedge by subducting Pacific plate affected by oceanic crust with less effect of continental crust indicating calc-alkaline magma characteristics.

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.505-509
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• 1997

FRAM(Ferroelectric Random Access memory)에의 응용을 위해 rf magnetron sputtering법을 이용하여 SrB $i_{2}$T $a_{2}$ $O_{9}$(SBT)박막을 증착하였다. 사용된 기판은 Pt/Ti/Si $o_{2}$Si이었으며 50$0^{\circ}C$에서 증착한 후 80$0^{\circ}C$의 산소 분위기 하에서 1시간 동안 열처리하였다. 증착시 증착 압력을 변화시켜 가면서 이에 따른 특성의 변화를 고찰하였다. 박막내의 Bi와 Sr의 부족을 보상하기 위해 20mole%의 Bi $O_{2}$와 30mole%의 SrC $O_{3}$를 과잉으로 넣어 타겟을 제조후 사용하였고 박막들의 두께는 300nm의 두께를 가지며 증착압력에 따라 다른 미세 구조르 보였다. 10mtorr에서 증착한 박막의 조성은 S $r_{0.6}$B $i_{3.8}$Ta/ sub 2.0/ $O_{9.0}$이었다. 이 SBT 박막의 잔류 분극(2 $P_{r}$)과 보전계(2 $E_{c}$)값은 각각 인가 전압 5V에서 18.5 $\mu%C/$\textrm{cm}^2$과 150kV/cm이었고, signal/noise비는 3V에서 4.6을 나타내었다. 5V의 bipolar pulse하에서 $10^{10}$cycle까지 피로 현상이 나타나지 않았으며, 누설 전류 밀도는 133kV/cm에서 약 1x$10^{-7A}$$\textrm{cm}^2$의 값을 보였다.을 보였다.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.21.1-21
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.865-867
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• 2009

In this paper, we describe the fabrication of nano-scale ink particles with narrow size distribution to offer high optical density in electrophoretic display applications. Charged white ($TiO_2$ and polyester) and black (carbon black and polyester) nano size ink particles in size range of 200 ~ 700nm were made successively using modified non-aqueous base emulsion process. The EPD showed white reflectance of 58% and saturation voltage of ${\pm}10V$.

• Transactions of the Korean hydrogen and new energy society
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• v.2 no.1
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• pp.47-56
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• 1990

Pure titanium rods were oxidized by anodic oxidation, furnace oxidation and flame oxidation and used as a electrode in the photodecomposition of water. The maximum photoelectrochemical conversion efficiency(${\eta}$) was found for flame oxidized electrode ($1200^{\circ}C$ for 2 min in air), 0.8 %. Anodically oxidized electrodes have minimum photoelectrochemical conversion efficiencies, 0.3 %. Furnace oxidized electrode ($800^{\circ}C$ for 10min in air) has 0.5% phtoelectrochemical efficiency and shows a band-gap energy of about 2.9eV. The efficiency shows a parallelism with the presence of the metallic interstitial compound $TiO_{O+X}$(X < 0.33) at the metal-semiconductor interface, the thickness of the sub oxide layer and that of the external rutile scale.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.229-229
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• 2007

나노결정 합금재료를 전력선 통신 커플러용 자심재료로 응용하기 위해서는 고주파 대역에서의 손실 특성이 제어되어야 한다. 즉 고속 전력선 통신을 위한 자심재료의 투자율 및 완화 주파수 등의 전자기적 특성은 30MHz까지 우수하고 안정적으로 유지되어야 하며, 높은 투자율 및 자속밀도, 공진주파수뿐만 아니라 낮은 전력손실 값을 가져야 한다. 따라서 본 연구에서는 나노결점 합금 리본 표면에 딥 코팅, 졸-겔법, 진공함침 등의 방법을 이용하여 PZT, $TiO_2$ 및 $SiO_2$ 등의 산화물 고저항층을 형성시켜 자기적 성질을 유지하면서 고주파 대역의 와전류 손실을 감소시켜 통신용 자심재료로의 응용성을 향상시키고자 하였다. PZT 슬러리의 제타전위 조절을 통해 최적의 분산조건을 얻을 수 있었고, 평균 150nm인 PZT 입자의 초미립자와 가소제, 분산제, 결합제의 첨가조건을 확립할 수 있었다. 딥-코팅은 슬러리 내 유지시간 10초, 인상속도 5mm/min로 30회 반복되었을 때 가정 우수한 특성을 나타내었으며, 고주파 대역에서의 손실 감소효과를 나타내었다. 그리고 졸-겔법에 의해 제조된 슬러리를 이용한 $TiO_2$와 $SiO_2$ 산화물 저항층 코팅을 통해 금속 알콕사이드의 혼합조건 및 저항층 형성용 슬러리의 제조조건을 확립하였고, 합금 리본표면에 균일하고 우수한 점착력을 가지는 저항층을 형성시킬 수 있었으며, 이에 따른 코어손실의 감소효과를 나타낼 수 있었다. 또한 진공 함침법을 통한 저항층 형성에서, $TiO_2$ 나노분말을 표면 저항층으로 코팅했을 때, 가장 높은 코어손실 감소효과를 나타내었다. 한편, 표면 저항층이 형성된 나노결정 합금으로 제조한 자심재료를 이용하여 전력선 통신용 비접촉식 커플러에의 적용과 시험을 통해 고주파 손실 감소효과에 의한 신호전송 특성과 전류특성을 향상시킬 수 있었다.