• Title/Summary/Keyword: transparent thin film transistor

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Challenge to Future Displays: Transparent AM-OLED driven by PEALD grown ZnO TFT

  • Ko Park, Sang-Hee;Hwang, Chi-Sun;Byun, Chun-Won;Ryu, Min-Ki;Lee, Jeong-Ik;Chu, Hye-Yong;Cho, Kyoung-Ik;Chae, Jang-Youl;Han, Se-Jin
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1249-1252
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    • 2007
  • We have fabricated 3.5” transparent AM-OLED panel driven by PEALD grown ZnO TFT. The performance of ZnO thin film transistor was improved by adapting top gate structure, protection layer for ZnO from photolithography process, optimizing temperature and plasma power of ZnO growth process. The ZnO-TFT has a mobility of $8.9cm^2/V.s$, a subthreshold swing of 0.95V, and an on/off ratio of $10^7$.

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Effect of Si grinding on electrical properties of sputtered tin oxide thin films (Si 기판의 연삭 공정이 산화주석 박막의 전기적 성질에 미치는 영향 연구)

  • Cho, Seungbum;Kim, Sarah Eunkyung
    • Journal of the Microelectronics and Packaging Society
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    • v.25 no.2
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    • pp.49-53
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    • 2018
  • Recently, technologies for integrating various devices such as a flexible device, a transparent device, and a MEMS device have been developed. The key processes of heterogeneous device manufacturing technology are chip or wafer-level bonding process, substrate grinding process, and thin substrate handling process. In this study, the effect of Si substrate grinding process on the electrical properties of tin oxide thin films applied as transparent thin film transistor or flexible electrode material was investigated. As the Si substrate thickness became thinner, the Si d-spacing decreased and strains occurred in the Si lattice. Also, as the Si substrate thickness became thinner, the electric conductivity of tin oxide thin film decreased due to the lower carrier concentration. In the case of the thinner tin oxide thin film, the electrical conductivity was lower than that of the thicker tin oxide thin film and did not change much by the thickness of Si substrate.

Electrical, Structural, Optical Properties of the AZO Transparent Conducting Oxide Layer for Application to Flat Panel Display (평판디스플레이 응용을 위한 AZO 투명전도막의 전기적, 구조적 및 광학적 특성)

  • No, Im-Jun;Kim, Sung-Hyun;Park, Dong-Wha;Shin, Paik-Kyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1976-1981
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    • 2009
  • Transparent conducting aluminum-doped zinc oxide (AZO) thin films were deposited on Coming glass substrate using an Gun-type rf magnetron sputtering deposition technology. The AZO thin films were fabricated with an AZO ceramic target (Zn: 98wt.%, $Al_2O_3$: 2wt.%). The AZO thin films were deposited with various growth conditions such as the substrate temperature, oxygen pressure. X -ray diffraction (XRD), UV/visible spectroscope, atomic force microscope (AFM), and Hall effect measurement system were done in order to investigate the properties of the AZO thin films Among the AZO thin films prepared in this study, the one formed at conditions of the substrate temperature $100^{\circ}C$, Ar 50 sccm, $O_2$ 5 sccm and working pressure 5 motor showed the best properties of an electrical resistivity of $1.763{\times}10^{-4}\;[{\Omega}{\cdot}cm]$, a carrier concentration of $1.801{\times}10^{21}\;[cm^{-3}]$, and a carrier mobility of $19.66\;[cm^2/V{\cdot}S]$, which indicates that it could be used as a transparent electrode for thin film transistor and flat panel display applications.

Characteristics of ZnO Thin Films by Means of ALD for the Application of Transparent TFT

  • ParkKo, Sang-Hee;Hwang, Chi-Sun;Kwack, Ho-Sang;Kang, Seung-Youl;Lee, Jin-Hong;Chu, Hye-Yong;Lee, Yong-Eui
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1564-1567
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    • 2005
  • Zinc oxide thin films were grown at the t emperature of $100^{\circ}C$ and $150^{\circ}C$ by means of plasma enhanced atomic layer deposition (PEALD) and conventional atomic layer deposition for applying to the transparent thin film transistor (TTFT). The growth rate of $1.9{\AA}/cycle$ with oxygen plasma is similar to that of film grown with water. While the sheet resistivity of ZnO grown with water is 1233 ohm/sq, that of film grown with oxygen plasma was too high to measure with 4 point probe and hall measurement system. The resistivity of the films grown with oxygen plasma estimated to be $10^6$ times larger than that of the films grown with water. The difference of electrical property between two films was caused by the O/Zn atomic ratio. We fabricated ZnO-TFT by means of ALD for the first time and the ZnO channel fabricated with water showed saturation mobility of $0.398cm^2/V{\cdot}s$ with bottom gate configuration.

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4.1” Transparent QCIF AMOLED Display Driven by High Mobility Bottom Gate a-IGZO Thin-film Transistors

  • Jeong, J.K.;Kim, M.;Jeong, J.H.;Lee, H.J.;Ahn, T.K.;Shin, H.S.;Kang, K.Y.;Park, J.S.;Yang, H,;Chung, H.J.;Mo, Y.G.;Kim, H.D.;Seo, H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.145-148
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    • 2007
  • The authors report on the fabrication of thin film transistors (TFTs) that use amorphous indium-gallium-zinc oxide (a-IGZO) channel and have the channel length (L) and width (W) patterned by dry etching. To prevent the plasma damage of active channel, a 100-nm-thckness $SiO_{x}$ by PECVD was adopted as an etch-stopper structure. IGZO TFT (W/L=10/50${\mu}m$) fabricated on glass exhibited the high performance mobility of $35.8\;cm^2/Vs$, a subthreshold gate voltage swing of $0.59V/dec$, and $I_{on/off}$ of $4.9{\times}10^6$. In addition, 4.1” transparent QCIF active-matrix organic light-emitting diode display were successfully fabricated, which was driven by a-IGZO TFTs.

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A Study on the Formation of Polycrystalline Silicon Film by Lamp-Scanning Annealing and Fabrication of Thin Film Transistors (램프 스캐닝 열처리에 의한 다결정 실리콘 박막의 형성 및 TFT 제작에 관한 연구)

  • Kim, Tae-Kyung;Kim, Gi-Bum;Lee, Byung-Il;Joo, Seung-Ki
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.1
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    • pp.57-62
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    • 1999
  • Polycrystaline thin film transistors are fabricated on the transparent glass substrate by a lamp-scan annealing. The line-shaped lamp scanning method, which is profitable for large area process, effectively radiated silicon film on glass substrate. Amorphous silion film absorbs the light which is emitted from halogen-lamp and it transformed into crystalline silicon by metal-induced lateral crystallization. In order to enhance the annealing effect, capping layer was deposited on the whole substrate. When the scan speed was 1-2mm/sec, lateral crystallization of amorphous silicon under capping layer was 18~27${\mu}m/scan$. The thin film transistor fabricated by this method shows high electron mobility over 130$cm^2/V{\cdot}sec$

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Electrical Properties of Transparent Indium-Tin-Zinc Oxide Semiconductor for Thin-Film Transistors

  • Lee, Gi-Chang;Choe, Jun-Hyeok;Han, Eon-Bin;Kim, Don-Hyeong;Lee, Jun-Hyeong;Kim, Jeong-Ju;Heo, Yeong-U
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.159-159
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    • 2008
  • 투명전도체 (transparent conducting oxides: TCOs) 는 일반적으로 $10^3\Omega^{-1}Cm^{-1}$의 전도도, 가시광 영역에서 80%이상의 투명성을 가지는 재료로서, 액정 박막 표시 장치(TFT-LCD), 광기전성 소자, 유기 발광 소자, 에너지 절약 창문, 태양전지(sollar cell) 등 전극으로 사용되고 있다. 최근에는 TCO의 전도도특성을 조절하여 반도성특성을 가진 투명 산화물 반도체(transparent oxide semiconductor: TOS) 을 이용한 박막 트랜지스터 연구가 활발히 진행 중이다. 기존의 실리콘을 기반으로 하는 박막 트랜지스터의 낮은 이동도, 불투명성의 특성을 가지고 있지만, 산화물 박막트랜지스터는 높은 이동도를 발현 할 수 있을 뿐만 아니라, 넓은 밴드갭 에너지를 갖는 산화물을 이용하므로 투명한 특성도 발현 할 수 있어 차세대 디스플레이의 구동소자로서 응용연구가 되고 있다. 이에 본 연구에서는 박막트랜지스터 channel layer로서의 Indium-Tin-Zinc oxide 적용특성을 조사하였다. Indium, Tin, Zinc 의 혼합비율을 다양하게 조절하여 타겟을 제작하였다. 이를 RF magnetron sputtering 를 이용하여 박막으로 성장시켰으며, 기판으로는 glass 기판을 사용하였다. 박막 성장시 아르곤과 산소의 비율을 다양하게 조절하였다. 성장시킨 박막은 Hall effect, Transmittance, Work function, XRD등을 이용하여 전기적, 광학적, 구조특성을 평가하였다. Indium-Tin-Zinc Oxide(ITZO) 을 channel layer로 사용하여 Thin-film transistor 을 제작하여, TFT의 I-V 및 stability특성을 평가하였다.

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Influence of Oxygen Partial Pressure on ZnO Thin Films for Thin Film Transistors

  • Kim, Jae-Won;Kim, Ji-Hong;Roh, Ji-Hyoung;Lee, Kyung-Joo;Moon, Sung-Joon;Do, Kang-Min;Park, Jae-Ho;Jo, Seul-Ki;Shin, Ju-Hong;Yer, In-Hyung;Koo, Sang-Mo;Moon, Byung-Moo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.106-106
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    • 2011
  • Recently, zinc oxide (ZnO) thin films have attracted great attention as a promising candidate for various electronic applications such as transparent electrodes, thin film transistors, and optoelectronic devices. ZnO thin films have a wide band gap energy of 3.37 eV and transparency in visible region. Moreover, ZnO thin films can be deposited in a poly-crystalline form even at room temperature, extending the choice of substrates including even plastics. Therefore, it is possible to realize thin film transistors by using ZnO thin films as the active channel layer. In this work, we investigated influence of oxygen partial pressure on ZnO thin films and fabricated ZnO-based thin film transistors. ZnO thin films were deposited on glass substrates by using a pulsed laser deposition technique in various oxygen partial pressures from 20 to 100 mTorr at room temperature. X-ray diffraction (XRD), transmission line method (TLM), and UV-Vis spectroscopy were employed to study the structural, electrical, and optical properties of the ZnO thin films. As a result, 80 mTorr was optimal condition for active layer of thin film transistors, since the active layer of thin film transistors needs high resistivity to achieve low off-current and high on-off ratio. The fabricated ZnO-based thin film transistors operated in the enhancement mode with high field effect mobility and low threshold voltage.

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Properties of IZTO Thin Film prepared by the Hetero-Target sputtering system (ITO-IZO 이종 타겟 이용한 Indium Zinc Tin Oxide(IZTO)박막의 특성)

  • Kim, Dae-Hyun;Rim, You-Seong;Jang, Kyung-Uk;Kim, Kyung-Hwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.439-440
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    • 2008
  • Indium Zinc Tin Oxide (IZTO) thin films for transparent thin film transistor (TTFT) were deposited on glass substrate at room temperature by facing targets sputtering (FTS). The FTS system was designed to array two targets facing each other and forms the high- density plasma between. Two different kinds of targets were installed on FTS system. One is ITO ($In_2O_3$ 90wt.%, $SnO_2$ 10wt.%), the other is IZO($In_2O_3$ 90wt%, ZnO 10wt%). The conductive and optical properties of IZTO thin film is determined depending on variation of DC power and working pressure. Therefore, IZTO thin films were prepared with different DC power and working pressure. As-deposited IZTO thin films were investigated by a UV/VIS spectrometer, an X-ray diffractometer (XRD), a scanning electron microscopy (SEM), a Hall Effect measurement system. As a result, all IZTO thin films deposited on glass substrate showed over 80% of transmittance in visible range (400~800 nm) at $O_2$ gas flow rate. We could obtain IZTO thin films with the lowest resistivity $5.67\times10^{-4}$ [$\Omega{\cdot}cm$] at $O_2$ gas flow rate 0.4 [sccm).

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