• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.548-551
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• 2007

최근에 유기물 전계효과 트랜지스터의 연구는 전자 소자 분야에서 널리 알려져 있다. 특히 본 연구에서는 CuPc 물질을 기본으로 하여 소자를 제작하고, 또한 기판의 온도를 달리 하여 제작하였다. CuPc FET 소자는 top-contact 방식으로 제작하였으며, 기판의 온도는 상온과 $150^{\circ}C$로 달리 하였다. 또한 CuPc의 두께는 40nm로 하였고, 채널의 길이는 $50{\mu}m$, 폭은 3mm로 하였다. 제작된 소자를 이용하여 전압-전류 특성을 측정하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.60.1-60.1
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• 2011

비정질 indium-gallium-zinc-oxide (a-IGZO)는 thin film transistor (TFT)에 적용되는 대표적인 active layer로써 높은 이동도를 갖고, 도핑 농도의 제어가 용이하며 낮은 온도에서도 대면적에 증착할 수 있는 특성을 가지고 있다. 특히 저온에서 대면적 증착이 가능한 장점을 갖고 있어 LCD 분야뿐만 아니라 다양한 분야에서 상용화하려는 연구가 시도되고 있다. a-IGZO를 구성하는 물질 중에 이동도에 중요한 역할을 미치는 In은 대표적인 투명전극물질인 indium-tin oxide (ITO)에서 고전류 구동에 의한 확산이 널리 알려져 이에 대한 증명과 개선을 위한 연구가 진행되고 있다. 보고된 결과에 따르면 device에 지속적인 구동 전압을 가했을 때 In이 유기층로 확산되어 organic light emitting diode(OLED)의 성능을 저하시키는 것으로 알려져 있다. 따라서, a-IGZO에서도 고전류 구동에 의한 indium의 이동이 필수불가결하다고 판단된다. 본 연구에서는 a-IGZO TFT에 고전압 구동을 반복적으로 시행함으로써 발생하는 전기적 특성의 변화를 확인하였고, 동일한 소자의 전극과 채널 사이의 계면에서 In 분포를 energy dispersive spectrometer (EDS)로 관찰하여 In 분포와 전기적 특성 간의 상관관계에 대해 연구하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1103-1106
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• 2006

We have presented a comprehensive study on threshold voltage $(V_{th})$ control of organic thin-film transistors (OTFTs) with dual-gate structure. The fabrication of dual-gate pentacene OTFTs using plasma-enhanced atomic layer deposited (PEALD) 150 nm thick $Al_2O_3$ as a bottom gate dielectric and 300 nm thick parylene or PEALD 200 nm thick $Al_2O_3$ as both a top gate dielectric and a passivation layer is reported. The $V_{th}$ of OTFT with 300 nm thick parylene as a top gate dielectric is changed from 4.7 V to 1.3 V and that with PEALD 200 nm thick $Al_2O_3$ as a top gate dielectric is changed from 1.95 V to -9.8 V when the voltage bias of top gate electrode is changed from -10 V to 10 V. The change of $V_{th}$ of OTFT with dual-gate structure has been successfully understood by an analysis of electrostatic potential.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1572-1575
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• 2005

Poly(vinyl phenol)(PVP)/$TiO_2$ nanocomposite the films have been prepared incorporating metal alkoxide with vinyl polymer to obtain high dielectric constant gate insulating material for a organic thin film transistor. The surface composition, the morphology, and the thermal and electrical properties of the hybrid nanocomposite films were observed by ESCA, scanning electron microscopy (SEM), atomic force microscopy(AFM), and thermogravimetric analysis (TGA). Thin hybrid films exhibit much higher dielectric constants (7.79 at 40wt% metal alkoxide).

• Journal of Information Display
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• 제10권3호
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• pp.131-136
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• 2009

This is a report on the fabrication of a flexible OTFT backplane for electrophoretic display (EPD) using a printing technology. A practical printing technology for a polycarbonate substrate was developed by combining the conventional screen and inkjet printing technologies with the wet etching and oxygen plasma processes. For the gate electrode, the screen printing technology with Ag ink was developed to define the minimum line width of ${\sim}5{\mu}m$ and the thickness of ${\sim}70nm$ with the resistivity of ${\sim}10^{-6}{\Omega}{\cdot}cm$, which are suitable for displays with SVGA resolution. For the source and drain (S/D) electrodes, PEDOT:PSS, whose conductivity was drastically enhanced to 450 S/cm by adding 10 wt% glycerol, was adopted. In addition, the modified PEDOT:PSS could be neatly confined in the specific S/D electrode area that had been pretreated with oxygen. The OTFTs that made use of the developed printing technology produced a mobility of ${\sim}0.13cm^2/Vs.ec$ and an on/off current ratio of ${\sim}10^6$, which are comparable to those using thermally evaporated Au for the S/D electrode.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.341.1-341.1
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• 2014

In the advanced material for the next generation display device, transparent amorphous oxide semiconductors (TAOS) are promising materials as a channel layer in thin film transistor (TFT). The TAOS have many advantages for large-area application compared with hydrogenated amorphous silicon TFT (a-Si:H) and organic semiconductor TFT. For the reasonable characteristics of TAOS, The a-IGZO has the excellent performances such as low temperature fabrication (R.T~), high mobility, visible region transparent, and reasonable on-off ratio. In this study, we investigated how the electric characteristics and physical properties are changed as various oxygen ratio when magnetron sputtering. we analysis a-IGZO film by AFM, EDS and I-V measurement. decreasing the oxygen ratio, the threshold voltage is shifted negatively and mobility is increasing. Through this correlation, we confirm the effect of oxygen ratio. We fabricated the bottom-gate a-IGZO TFTs. The gate insulator, SiO2 film was grown on heavily doped silicon wafer by thermal oxidation method. a-IGZO channel layer was deposited by RF magnetron sputtering. and the annealing condition is $350^{\circ}C$. Electrode were patterned Al deposition through a shadow mask(160/1000 um).

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.19.1-19.1
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• 2010

The process of manufacturing printed electronics using printing technology is attracting attention because its process cost is lower than that of the conventional semiconductor process. This technology, which offers both a lower cost and higher productivity, can be applied in the production of organic TFT (thin film transistor), solar cell, RFID(radio frequency identification) tag, printed battery, E-paper, touch screen panel, black matrix for LCD(liquid crystal display), flexible display, and so forth. In general, in order to implement printed electronics, narrow width and gap printing, registration of multi-layer printing by several printing units, and printing accuracy of under $20\;{\mu}m$ are all required. These electronic products require high precision to the degree of tens of microns - in a large area with flexible material, and mass productivity at low cost. As such, the roll-to-roll printing process is attracting attention as a mass production system for these printed electronic devices. For the commercialization of this process, two basic electronic ink technologies, such as conductive ink and polymers, and printing equipment have to be developed. Therefore, this paper addressed basis design and test to develop fine patterning equipment employing the roll-to-roll printing equipment and electronic ink.

• Journal of Information Display
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• 제10권4호
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• pp.137-142
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• 2009

Transparent top-gate Al-Zn-Sn-O (AZTO) thin-film transistors (TFTs) with an $Al_2O_3$ protective layer (PL) on an active layer were studied, and a transparent 2.5-inch QCIF+AMOLED (active-matrix organic light-emitting diode) display panel was fabricated using an AZTO TFT backplane. The AZTO active layers were deposited via RF magnetron sputtering at room temperature, and the PL was deposited via two different atomic-layer deposition (ALD) processes. The mobility and subthreshold slope were superior in the TFTs annealed in vacuum and with oxygen plasma PLs compared to the TFTs annealed in $O_2$ and with water vapor PLs, but the bias stability of the TFTs annealed in $O_2$ and with water vapor PLs was excellent.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.112-112
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• 2011

유기박막 트랜지스터(Organic Thin Film Transistor: OTFT)는 낮은 공정비용과 기존의 고체 실리콘 트랜지스터로서 실혐 할 수 없는 플렉시블 디스플레이, 스마트카드, 태양전지 등의 매우 넓은 활용범위로 각광받고 있는 연구 분야 중 하나이다. 본 연구에서는 열 증발 증착장비(Thermal Evaporator)를 이용하여 펜타센을 활성층으로 사용한 유기박막 트랜지스터를 제작하였다. Heavily doped된 N형 실리콘 기판을 메탄올, 에탄올, 불산 처리를 하여 세척을 한 후 PECVD를 이용하여 SiO2를 200 nm 증착하였다. 그 후 열 증발 증착 장비를 사용하여 펜타센을 활성층으로 사용하였고, 분말 형태의 펜타센의 질량을 15~60 mg으로 조절하여 활성층의 두께를 조절하였다. 펜타센 증착 후 100도에서 열처리를 하고, 그 후 Shadow Mask를 이용하여 전극을 150nm 증착하였다. 이때 전극은 Au, Al, Ni 세가지 종류를 사용하였다. 펜타센의 질량을 조절하여 증착한 활성층의 두께는 60 mg일 때 약 60 nm, 45 mg일 때 약 45 nm로 1:1의 비율로 올라가는 것을 확인 할 수 있었고, 펜타센의 두께가 30 nm일 때 특성이 가장 잘 나오는 것을 볼 수 있었다. 펜타센의 두께가 두꺼울수록 게이트에서 인가되는 전압의 필드가 제대로 걸리지 않아 특성이 나쁘게 나온 것으로 보인다. 또한 활성층을 30 nm로 고정하고 전극의 종류를 바꿔가며 전기적 특성(캐리어 이동도, 문턱전압, 전달특성 등)을 측정 했을 때 전극으로 Al보다는 Au와 Ni를 사용했을 때 전기적 특성이 더 우수하게 나오는 것을 볼 수 있었다. 메탈과 펜타센과의 일함수 차이에 따른 결과로 보여진다.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1358-1362
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• 2007

The structures, energetics and transfer integrals of the acene tetramers up to pentacene are investigated with the ab initio molecular orbital method at the level of second-order Møller-Plesset perturbation theory (MP2). Calculated geometries for the herringbone-style structures found in the crystal structure were characterized as local minima, however the geometrical discrepancy between crystal and MP2 theoretical structure is reasonably small. The binding energy of pentacene tetramer was calculated up to 40 kcal/mol (MP2/6-31G(d)) and about 90 kcal/mol (MP2/aug-cc-pVDZ), and the latter seems to be too much overestimated. The tendency of the hole transfer integrals computed with ab initio MP2/3-21G(d) geometry is well agreement with those estimated with crystal structure with some discrepancy, and the gradual increment of the transfer integrals at the crystal geometry is attributed to mainly packing structure rather than the intrinsic property of acene such as a size of acene.