• Title/Summary/Keyword: amorphous TFTs

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Silicon Thin-film Transistors on Flexible Foil Substrates

  • Wagner, Sigurd;Gleskova, Helena
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.263-267
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    • 2002
  • We are standing at the beginning of the industrialization of flexible thin-film transistor backplanes. An important group of candidates is based on silicon thin films made on metal or plastic foils. The main features of amorphous, nanocrystalline and microcrystalline silicon films for TFTs are summarized, and their compatibility with foil substrate materials is discussed.

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Development of a Low Temperature Doping Technique for Applications in Poly-Si TFT on Plastic Substrates

  • Hong, Wan-Shick;Kim, Jong-Man
    • Journal of Information Display
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    • v.4 no.3
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    • pp.17-21
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    • 2003
  • A low temperature doping technique to be applied in poly-Si TFTs on plastic substrates was investigated. Heavily-doped amorphous silicon layers were deposited on poly-Si and the dopant atoms were driven in by subsequent excimer laser annealing. The entire process was carried out under a substrate temperature of 120 $^{\circ}C$, and a sheet resistance of as low as 300 ${\Omega}$/sq. was obtained.

DETERMINATION OF THERMAL CONDUCTIVITY FROM TRANSIENT REFLECTIVITY MEASUREMENTS OF AMOPHOUS SILICON THIN FILMS (A-Si 박막의 반사율변화에 따른 열전달계수 결정)

  • Ryu, Ji-Hyung;Kim, Hyang-Jung;Moon, Seung-Jae
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2453-2458
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    • 2007
  • The performance of polysilicon thin film transistor (p-Si TFT) has an important role in the operation of active matrix liquid crystal displays. To fabricate the p-Si TFTs that have uniform characteristics, understanding of the recrystallization mechanism of silicon is crucial. Especially, the analysis of the transient temperature variation and the liquid-solid interface motion is required to find the mechanism. The thermal conductivity is one of the most important parameters to understand the mechanism. In this work, a KrF eximer laser beam was irradiated to amorphous silicon thin films. We measured the transient reflectivity at the wavelength of 633 nm. We carried out the numerical simulation of one dimension conduction equation so that we determined the most well-fitted thermal conductivity by comparing the numerically obtained transient reflectivity with the experimentally measured one. The experimentally determined thermal conductivity of amorphous silicon thin films is 1.5 W/mK.

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Charge Trapping Mechanism in Amorphous Si-In-Zn-O Thin-Film Transistors During Positive Bias Stress

  • Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.6
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    • pp.380-382
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    • 2016
  • The mechanism for instability under PBS (positive bias stress) in amorphous SIZO (Si-In-Zn-O) thin-film transistors was investigated by analyzing the charge trapping mechanism. It was found that the bulk traps in the SIZO channel layer and the channel/dielectric interfacial traps are not created during the PBS duration. This result suggests that charge trapping in gate dielectric, and/or in oxide semiconductor bulk, and/or at the channel/dielectric interface is a more dominant mechanism than the creation of defects in the SIZO-TFTs.

열처리에 따른 a-IGZO 소자의 전기적 특성과 조성 분포

  • Gang, Ji-Yeon;Lee, Tae-Il;Myeong, Jae-Min
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.10a
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    • pp.43.1-43.1
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    • 2011
  • Hydrogenated amorphous Si (a-Si:H), low temperature poly Si (LTPS) 등 기존 thin film transistors (TFTs)에 사용되던 채널 물질을 대체할 재료로써 다양한 연구가 진행되고 있는 amorphous indium-gallium-zinc-oxide (a-IGZO)는 TFT에 적용하였을 때 뛰어난 전기적 특성과 재연성을 나타낼 뿐만 아니라 넓은 밴드갭을 가져 투명소자로도 응용이 가능하다. 본 연구에서는 a-IGZO의 열처리에 따른 소자의 전기적 특성과 조성 분포의 관계를 확인하기 위해 다음과 같이 실험을 진행하였다. Si/SiO2 기판 위에 DC sputter를 이용하여 IGZO를 증착하고 $350^{\circ}C$에서 열처리를 한 후 evaporator로 Al 전극을 형성시켰다. 이 때 전기적 특성의 변화를 비교하기 위해 열처리 한 샘플과 열처리 하지 않은 샘플에 대해 I-V 특성을 측정하였고, 채널 내부의 조성 분포 변화를 transmission electron microscopy (TEM)의 energy dispersive spectrometer (EDS)를 이용하여 관찰하였다. 그 결과 열처리 된 a-IGZO 채널 층의 산소 비율이 감소하였으며 전체적인 조성이 고르게 분포 되었고 전기적 특성은 향상되었다.

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Threshold Voltage Instability in a-Si:H TFTs and the Implications for Flexible Displays and Circuits

  • Allee, D.R.;Venugopal, S.M.;Shringarpure, R.;Kaftanoglu, K.;Uppili, S.G.;Clark, L.T.;Vogt, B.;Bawolek, E.J.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1297-1300
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    • 2008
  • Electrical stress degradation of low temperature, amorphous silicon thin film transistors is reviewed, and the implications for various types of flexible circuitry including active matrix backplanes, integrated drivers and general purpose digital circuitry are examined. A circuit modeling tool that enables the prediction of complex circuit degradation is presented.

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Stability of Hydrogenated Amorphous Silicon TFT Driver

  • Bae, Byung-Seong;Choi, Jae-Won;Oh, Jae-Hwan;Kim, Kyu-Man;Jang, Jin
    • Journal of Information Display
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    • v.6 no.1
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    • pp.12-16
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    • 2005
  • Gate and data drivers are essential for driving active matrix display. In this study, we integrate drivers with a-Si:H to develop a compact, better reliability and cost effective display. We design and fabricate drivers with conventional a-Si:H thin film transistors (TFTs). The output voltages are investigated according to the input voltage, temperature and operation time. Based on these studies, we propose here a new driver to prevent gate line from the floated state. For the external coupled voltage fluctuation, the proposed driver shows better stability.

Electrical Performance of Amorphous SiZnSnO TFTs Depending on Annealing Temperature (실리콘산화아연주석 산화물 반도체의 후열처리 온도변화에 따른 트랜지스터의 전기적 특성 연구)

  • Lee, Sang-Yeol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.9
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    • pp.677-680
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    • 2012
  • The dependency of annealing temperature on the electrical performances in amorphous silicon-zinc-tin-oxide thin film transistors (SZTO-TFT) has been investigated. The SZTO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different annealing treatment. The field effect mobility (${\mu}_{FE}$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing annealing temperature. As a result, oxygen vacancies generated in SZTO channel layer with increasing annealing temperature resulted in negative shift in $V_{th}$ and increase in on-current.

Polysilicon Thin Film Transistor for Improving Reliability using by LDD Structure

  • Jung, Eun-Sik;Jang, Won-Su;Bea, Ji-Chel;Lee, Young-Jae
    • Proceedings of the IEEK Conference
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    • 2002.07b
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    • pp.1050-1053
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    • 2002
  • In this paper, Amorphous silicon on glass substrate was recrystallized to poly-crystalline silicon by solid phase crystallization (SPC) technology. The active region of thin film transistor (TFT) was fabricated by amorphous silicon. The output and transfer characteristics of thin film transistor with lightly doped drain (LDD) structure was measured and analyzed. As a results, analyzed TFTs reliability with LDD's length by various kinds argument such as sub-threshold swing coefficient, mobility and threshold voltages were evaluated. Stress effects in TFT were able to improve to the characteristics of turn-on current and hot carrier effects by LDD's length variations.

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An Optical Study on ELC Process of Amorphous Silicon (비정질 실리콘의 ELC 공정에 대한 광학적 연구)

  • 김우진;윤창환;박승호;김형준
    • Laser Solutions
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    • v.6 no.2
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    • pp.9-17
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    • 2003
  • Due to the heat confinement in the shallow region of the target for a short time scale, pulsed laser annealing has received an increasing interest for the fabrication of poly-Si thin film transistors(TFTs) on glass as a low cost substrate in the flat panel displays. The formation and growth mechanisms of poly silicon(poly-Si) grains in thin films are investigated using an excimer laser crystallization system. To understand the crystallization mechanism, the grain formations are observed by FESEM photography. The optical reflectance and transmittance during the crystallization process are measured using HeNe laser optics. A two-step ELC(Excimer Laser Crystallization) process is applied to enhance the grain formation uniformity.

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