• Title/Summary/Keyword: IZO thin-film transistor

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Improved Stability Sputtered IZO Thin Film Transistor Using Solution Processed Al2O3 Diffusion Layer (Solution-Processed Al2O3 확산층을 이용한 Sputtering IZO Thin Film Transistor의 안정성 향상)

  • Hwang, Namgyung;Lim, Yooseong;Lee, Jeong Seok;Lee, Sehyeong;Yi, Moonsuk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.5
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    • pp.273-277
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    • 2018
  • This research introduces the sputtered IZO thin film transistor (TFT) with solution-processed $Al_2O_3$ diffusion layer. IZO is one of the most commonly used amorphous oxide semiconductor (AOS) TFT. However, most AOS TFTs have many defects that degrade performance. Especially oxygen vacancy in the active layer. In previous research, aluminum was used as a carrier suppressor by binding the oxygen vacancy and making a strong bond with oxygen atoms. In this paper, we use a solution-processed $Al_2O_3$ diffusion layer to fabricate stable IZO TFTs. A double-layer solution-processed $Al_2O_3$-sputtered IZO TFT showed better performance and stability, compared to normal sputtered IZO TFT.

Effects of Nitrogen Additive Gas on the Property of Active Layer and the Device Characteristic in Indium-zinc-oxide thin Film Transistors (산화인듐아연 박막 트랜지스터에서 질소 첨가가스가 활성층의 물성 및 소자의 특성에 미치는 영향)

  • Lee, Sang-Hyuk;Bang, Jung-Hwan;Kim, Won;Uhm, Hyun-Seok;Park, Jin-Seok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.11
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    • pp.2016-2020
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    • 2010
  • Indium-zinc-oxide (IZO) films were deposited at room temperature via RF sputtering with varying the flow rate of additive nitrogen gas ($N_2$). Thin film transistors (TFTs) with an inverted staggered configuration were fabricated by employing the various IZO films, such as $N_2$-added and pure (i.e., w/o $N_2$-added), as active channel layers. For all the deposited IZO films, effects of additive $N_2$ gas on their deposition rates, electrical resistivities, optical transmittances and bandgaps, and chemical structures were extensively investigated. Transfer characteristics of the IZO-based TFTs were measured and characterized in terms of the flow rate of additive $N_2$ gas. The experimental results indicated that the transistor action occurred when the $N_2$-added (with $N_2$ flow rate of 0.4-1.0 sccm) IZO films were used as the active layer, in contrast to the case of using the pure IZO film.

Dynamic Response Behavior of Femtosecond Laser-Annealed Indium Zinc Oxide Thin-Film Transistors

  • Shan, Fei;Kim, Sung-Jin
    • Journal of Electrical Engineering and Technology
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    • v.12 no.6
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    • pp.2353-2358
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    • 2017
  • A femtosecond laser pre-annealing process based on indium zinc oxide (IZO) thin-film transistors (TFTs) is fabricated. We demonstrate a stable pre-annealing process to analyze surface structure change of thin films, and we maintain electrical stability and improve electrical performance. Furthermore, dynamic electrical characteristics of the IZO TFTs were investigated. Femtosecond laser pre-annealing process-based IZO TFTs exhibit a field-effect mobility of $3.75cm^2/Vs$, an $I_{on}/I_{off}$ ratio of $1.77{\times}10^5$, a threshold voltage of 1.13 V, and a subthreshold swing of 1.21 V/dec. And the IZO-based inverter shows a fast switching behavior response. From this study, IZO TFTs from using the femtosecond laser annealing technique were found to strongly affect the electrical performance and charge transport dynamics in electronic devices.

Solution-Processed Inorganic Thin Film Transistors Fabricated from Butylamine-Capped Indium-Doped Zinc Oxide Nanocrystals

  • Pham, Hien Thu;Jeong, Hyun-Dam
    • Bulletin of the Korean Chemical Society
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    • v.35 no.2
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    • pp.494-500
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    • 2014
  • Indium-doped zinc oxide nanocrystals (IZO NCs), capped with stearic acid (SA) of different sizes, were synthesized using a hot injection method in a noncoordinating solvent 1-octadecene (ODE). The ligand exchange process was employed to modify the surface of IZO NCs by replacing the longer-chain ligand of stearic acid with the shorter-chain ligand of butylamine (BA). It should be noted that the ligand-exchange percentage was observed to be 75%. The change of particle size, morphology, and crystal structures were obtained using a field emission scanning electron microscope (FE-SEM) and X-ray diffraction pattern results. In our study, the 5 nm and 10 nm IZO NCs capped with stearic acid (SA-IZO) were ligand-exchanged with butylamine (BA), and were then spin-coated on a thermal oxide ($SiO_2$) gate insulator to fabricate a thin film transistor (TFT) device. The films were then annealed at various temperatures: $350^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, and $600^{\circ}C$. All samples showed semiconducting behavior and exhibited n-channel TFT. Curing temperature dependent on mobility was observed. Interestingly, mobility decreases with the increasing size of NCs from 5 to 10 nm. Miller-Abrahams hopping formalism was employed to explain the hopping mechanism insight our IZO NC films. By focusing on the effect of size, different curing temperatures, electron coupling, tunneling rate, and inter-NC separation, we found that the decrease in electron mobility for larger NCs was due to smaller electronic coupling.

Indium-Zinc Oxide Thin Film Transistors Based N-MOS Inverter (Indium-Zinc 산화물 박막 트랜지스터 기반의 N-MOS 인버터)

  • Kim, Han-Sang;Kim, Sung-Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.7
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    • pp.437-440
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    • 2017
  • We report on amorphous thin-film transistors (TFTs) with indium zinc oxide (IZO) channel layers that were fabricated via a solution process. We prepared the IZO semiconductor solution with 0.1 M indium nitrate hydrate and 0.1 M zinc acetate dehydrate as precursor solutions. The solution- processed IZO TFTs showed good performance: a field-effect mobility of $7.29cm^2/Vs$, a threshold voltage of 4.66 V, a subthreshold slope of 0.48 V/dec, and a current on-to-off ratio of $1.62{\times}10^5$. To investigate the static response of our solution-processed IZO TFTs, simple resistor load-type inverters were fabricated by connecting a $2-M{\Omega}$ resistor. Our IZOTFTbased N-MOS inverter performed well at operating voltage, and therefore, isa good candidate for advanced logic circuits and display backplane.

Study on Electrical Characteristic Improvement of PVP-IZO TFT Prepared by Solution Process Using UV-O3 Treatment (용액공정으로 제작한 PVP-IZO TFT의 UV-O3 처리를 통한 전기적 특성 향상 연구)

  • Kim, Yu Jung;Jeong, Jun Kyo;Park, Jung Hyun;Jung, Byung Jun;Lee, Ga Won
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.2
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    • pp.66-69
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    • 2017
  • In this paper, solution based Indium Zinc Oxide thin film transistors (IZO TFTs) were fabricated with PVP gate dielectric. To enhance the electrical properties, UV-O3 treatment is proposed on solution based IZO TFTs. The gate leakage current and interface trap density is compatible with conventional ZnO-based TFT with inorganic gate insulator. Especially, the UV-treated device shows improved electrical characteristics compared to the untreated device. These results can be explained by X-ray photoelectron spectroscopy (XPS) analysis, which shows that the oxygen vacancy of UV-O3 treatment is higher than that of no treatment.

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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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Effect of Titanium Addition on Indium Zinc Oxide Thin Film Transistors by RF-magnetron Sputtering (RF-magnetron sputtering을 이용한 TiIZO 기반의 산화물 반도체에 대한 연구)

  • Woo, Sanghyun;Lim, Yooseong;Yi, Moonsuk
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.7
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    • pp.115-121
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    • 2013
  • We fabricated thin film transistors (TFTs) using TiInZnO(TiIZO) thin films as active channel layer. The thin films of TiIZO were deposited at room temperature by RF-magnetron co-sputtering system from InZnO(IZO) and Ti targets. We examined the effects of titanium addition by X-ray diffraction, X-ray photoelectron spectroscopy and the electrical characteristics of the TFTs. The TiIZO TFTs were investigated according to the radio-frequency power applied to the Ti target. We found that the transistor on-off currents were greatly influenced by the composition of titanium addition, which suppressed the formation of oxygen vacancies, because of the stronger oxidation tendency of Ti relative to that of Zn or In. A optimized TiIZO TFT with rf power 40W of Ti target showed good performance with an on/off current ratio greater than $10^5$, a field-effect mobility of 2.09 [$cm^2/V{\cdot}s$], a threshold voltage of 2.2 [V] and a subthreshold swing of 0.492 [V/dec.].

Advances in Zinc Oxide-Based Devices for Active Matrix Displays

  • Mann, Mark;Li, Flora;Kiani, Ahmed;Paul, Debjani;Flewitt, Andrew;Milne, William;Dutson, James;Wakeham, Steve J.;Thwaites, Mike
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.389-392
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    • 2009
  • Metal oxides have been proposed as an alternative channel material to hydrogenated amorphous silicon in thin film transistors (TFTs) because their higher mobility and stability make them suitable for transistor active layers. Thin films of indium zinc oxide (IZO) were deposited using a High Target Utilization Sputtering (HiTUS) system on various dielectrics, some of which were also deposited with the HiTUS. Investigations into bottom-gated IZO TFTs have found mobilities of 8 $cm^2V\;^1s^{-1}$ and switching ratios of $10^6$. There is a variation in the threshold voltage dependent on both oxygen concentration, and dielectric choice. Silica, alumina and silicon nitride produced stable TFTs, whilst hafnia was found to break down as a result of the IZO.

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