• Title/Summary/Keyword: Drain material

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An Analysis on the Leakage Current of Drain-offset Poly-Si TFT′s (드레인오프셋트 다결정실리콘 박막트랜지스터의 누설전력 해석)

  • 이인찬;김정규;마대영
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.2
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    • pp.111-116
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    • 2001
  • Poly-Si TFT's(Polysilicon thin filmtransistors) have been actively studied due to their applications in active matrix liquid crystal displays and active pull-up devices of CMOS SRAM's. For such applications, the leakage current has to be in the range of sub-picoampere. However, poly-Si TFT's suffer from anomalous high leakage currents, which is attributed to the emission of the traps present at gain boundaries in the drain junction. The leakage current has been analyzed by the field emission via grain-boundary traps and thermionic field emission over potential barrier located at the grain boundary. We found that the models proposed before are not consistent with the experimental results at far as drain-offset poly-Si TFT's we fabricated concern. In this paper, leakage current of drain-offset poly-Si TFT's with different offset lengths was studied. A conduction model based on the thermionic emission of the tunneling electrons is developed to identify the leakage mechanism. It was found that the effective grain size of the drain-offset region is important factor in the leakage current. A good agreement between experimental and simulated results of the leakage current is obtained.

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Performance Improvement of Amorphous In-Ga-Zn-O Thin-film Transistors Using Different Source/drain Electrode Materials (서로 다른 소스/드레인 전극물질을 이용한 비정질 In-Ga-Zn-O 박막트랜지스터 성능향상)

  • Kim, Seung-Tae;Cho, Won-Ju
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.2
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    • pp.69-74
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    • 2016
  • In this study, we proposed an a-IGZO (amorphous In-Ga-Zn-O) TFT (thin-film transistor) with off-planed source/drain structure. Furthermore, two different electrode materials (ITO and Ti) were applied to the source and drain contacts for performance improvement of a-IGZO TFTs. When the ITO with a large work-function and the Ti with a small work-function are applied to drain electrode and source contact, respectively, the electrical performances of a-IGZO TFTs were improved; an increased driving current, a decreased leakage current, a high on-off current ratio, and a reduced subthreshold swing. As a result of gate bias stress test at various temperatures, the off-planed S/D a-IGZO TFTs showed a degradation mechanism due to electron trapping and both devices with ITO-drain or Ti-drain electrode revealed an equivalent instability.

Output Characteristics of Carbon-nanotube Field-effect Transistor Dependent on Nanotube Diameter and Oxide Thickness (나노튜브 직경과 산화막 두께에 따른 탄소나노튜브 전계 효과 트랜지스터의 출력 특성)

  • Park, Jong-Myeon;Hong, Shin-Nam
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.2
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    • pp.87-91
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    • 2013
  • Carbon-nanotube field-effect transistors (CNFETs) have drawn wide attention as one of the potential substitutes for metal-oxide-semiconductor field-effect transistors (MOSFETs) in the sub-10-nm era. Output characteristics of coaxially gated CNFETs were simulated using FETToy simulator to reveal the dependence of drain current on the nanotube diameter and gate oxide thickness. Nanotube diameter and gate oxide thickness employed in the simulation were 1.5, 3, and 6 nm. Simulation results show that drain current becomes large as the diameter of nanotube increases or insulator thickness decreases, and nanotube diameter affects the drain current more than the insulator thickness. An equation relating drain saturation current with nanotube diameter and insulator thickness is also proposed.

Analytical Model of TFT Drain Current based on Effective Area and Average Velocity (유효면적과 평균속도를 고려한 TFT의 해석적 Drain 전류 모델)

  • Jung, Tae-Hee;Won, Chang-Sub;Ryu, Se-Hwan;Han, Deuk-Young;Ahn, Hyung-Keun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.3
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    • pp.197-202
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    • 2008
  • In this paper, we proposed an analytical model for TFT which has series of the polycrystalline structures. An average speed is defined as carrier speed by the electric field. The effective square is suggested as the area of grain without depletion for the changed grain size. First, physical parameters such as grain size, channel lenght and trap density, have been changed to prove the validity of the average speed model and the value of the effective square has been estimated through drain-source current.

Leakage Current Low-Temperature Processed Poly-Si TFT′s (저온제작 Poly-Si TFT′s의 누설전류)

  • 진교원;이진민;김동진;김영호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.90-93
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    • 1996
  • The conduction mechanisms of the off-current in low temperature ($\leq$600$^{\circ}C$) processed polycrystalline silicon thin film transistors (LTP poly-Si TFT's) has been systematically studied. Especially, the temperature and bias dependence of the off-current between unpassivated and passivated poly-Si TFT's was investigated and compared. The off-current of unpassivated poly-Si TFT's is due to a resistive current at low gate and drain voltage, thermal emission current at high gate, low drain voltage, and field enhanced thermal emission current in the depletion region near the drain at high gate and drain voltage. After hydrogenation, it was observed that the off-currents were remarkably reduced by plasma-hydrogenation. It was also observed that the off-currents of the passivated poly-Si TFT's are more critically dependent on temperature rather than electric field.

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The Construction Work Method of Mixed Coal Ash in Ash Pond to Recycle as a Horizontal Drain Material (수평배수재로 재활용하는 회사장 혼합석탄재의 시공 방안)

  • Koh, Yongil
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.4
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    • pp.53-58
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    • 2013
  • The design for horizontal drain layer on soft ground starts from the decision that the material could be used or not, by verifying material condition in permeability of horizontal drain material according to the weight percent of the dry soil retained on #200 sieve. In the next step of the design, we estimate the thickness of horizontal drain layer to confirm trafficability of heavy machinery in construction work. Successively, the long-term functionality for good drainage of horizontal drain layer is checked and if needed, some means are considered. In this study, the system to recycle mixed coal ash in ash pond successfully as a horizontal drain material on soft ground is presented through the process and the result of its practical construction work. Namely, the pact is confirmed that mixed coal ash in ash pond should be sorted out by sieve screen to a certain extent and the remainders of this mixed coal ash on sieve openings be recycled, because the amount of finer particles than $75{\mu}m$ contained in mixed coal ash in ash pond is quite massive and irregular depending on the coal power plant or the location in same ash pond. In order to sort at large scale in situ, the dimension of a sieve squre hole and the sort-out method, etc. should be decided before the sort-out process. And, it is described that we need to manufacture classifier to sort out mixed coal ash in ash pond, too.

The Discharge Capacity Test & Vertical Drain Adoption Considering the Ground Condition (지반특성을 고려한 연직배수재의 통수능 시험 및 선정)

  • Jung, Hun-Chul;Shin, Kyung-Ha;Jung, Ki-Moon;Huh, Jip
    • Proceedings of the Korean Geotechical Society Conference
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    • 2007.09a
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    • pp.373-382
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    • 2007
  • In the vertical drain method, discharge capacity is generally one of the most important factor which affect on the estimation of the drain efficiency. However, adopting the drain considering discharge capacity only is not sufficiently considered method so that systematic criteria for adoption is necessary to choose the most suitable drain. Therefore, this study represents the application method considering behavior of the ground and vertical drain which is coupled together and ground improvement efficiency analyzing various cases of discharge capacity test performed in the recent soft ground improvement projects. According to the analysis, most drains tend to satisfy the required discharge capacity. It presents that deformed shape of the drains and well resistance estimation along the ground settlement, improvement efficiency by water content ratio along the depth and shear strength obtained after ground improvement should be considered altogether with the discharge capacity to select the proper drain. Also, appropriate adoption of drain material considering the ground condition is vital through analyzing the field measured data and comparing the result of the discharge capacity test as various vertical drain materials are being constructed continuously.

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A Study on Utilization of Recycled Aggregates as Lateral Drain for Soft Ground Improvemnet (연약지반 개량을 위한 수평배수층 재료로 순환골재의 적용 방안에 대한 연구)

  • Lee, Jong-Yoon;Chun, Hae-Pyo;Jeong, Woo-Chul;Lim, Hae-Sic
    • Journal of the Korean Geotechnical Society
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    • v.24 no.10
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    • pp.5-15
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    • 2008
  • The purpose of this study is to examine the validity of recycled aggregates (RAs) as a substitute for Sand-Mat material for soft ground improvement in the housing site development. To evaluate the possibility of RAs as a substitute for sand mat material, first of all, the criteria and regulations related with the quality of lateral drain layer were collected and checked. Secondly, both of the properties of RAs were compared with the properties of natural sand for the lateral drain layer. The material properties related to coefficient of permeability, pressure at-rest state and so on satisfied most standards. On the basis of the test results, RAs were used to the construction site as lateral drain layer. Accordingly, if the quality of RAs can be managed well, the application of these RAs as lateral drain layer to replace natural sand was highly effective. Also, based on cost analysis of two materials, RAs are proved to be very competitive.

Study on the Characteristics of Gravity Drainage for Geotextiles by Model Tests (모형실험에 의한 지오텍스타일의 중력배수 특성 연구)

  • 이상호;권무남
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.38 no.4
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    • pp.125-136
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    • 1996
  • In order to investigate the characteristics of gravity drainage for geotextile, small-scale model tests for the geotextile chimney drain of earth dam which is a typical type of gravity drainage were carried out using 15 kinds of nonwoven and composite geotextiles. According to the results of this study, the drainage discharge of geotexgile drain generally increases with exponential function as hydraulic head increases and the increasing rate is greater in the coarser soil of dam material. It has a trend to increase when the construction slope of geotextile drain is steeper and the number of layers of geotextile is more. The relationship between the transmissivity of geotextile and the drainage discharge has positive correlation and the rate of increase is greater in the coarser soil. The geotextile products must be carefully selected in consideration of transmissivity of geotextile when the soil to be drained is coarser and the seepage flow is relatively high. Most of staple fiber nonwoven geotextile used in this study are found to be appropriate for drainage purpose. Among them, the composite geotextile the type of which geotextile is evaluated to be the most excellent material. But the geotextile of low permeability such as filament thermal bonded and filament spunbonded nowovens closely examined their transmissivity especially to be used for drainage function.

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Analysis on Consolidation Behavior of Soft Ground with Reactive Drain Pile (반응성 배수파일이 타설된 지반의 압밀거동 분석)

  • Kim, Beomjun;Oh, Myounghak;Yune, Chanyoung
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.1
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    • pp.13-23
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    • 2014
  • Geotechnical evaluation on the reactive drain pile which can achieve simultaneously both the soft ground improvement and the remediation of contaminated pore water in reclamation site was performed. Applicability of steel-making slag used as a inside reactive material was confirmed. To investigate the consolidation characteristics of the soft ground improved by reactive drain pile, testing devices to form and install the reactive drain pile were developed and laboratory tests were performed according to the existence of outside sand drain and the length of impermeable barrier. Test results showed that the consolidation time was decreased as the shortening of impermeable barrier. However, the effect of outside sand drain on consolidation time was dominant compared with the length of impermeable barrier.