• Title/Summary/Keyword: subthreshold swing

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Analysis of Center Potential and Subthreshold Swing in Junctionless Cylindrical Surrounding Gate and Doube Gate MOSFET (무접합 원통형 및 이중게이트 MOSFET에서 중심전위와 문턱전압이하 스윙 분석)

  • Jung, Hakkee
    • Journal of IKEEE
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    • v.22 no.1
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    • pp.74-79
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    • 2018
  • We analyzed the relationship between center potential and subthreshold swing (SS) of Junctionless Cylindrical Surrounding Gate (JLCSG) and Junctionless Double Gate (JLDG) MOSFET. The SS was obtained using the analytical potential distribution and the center potential, and SSs were compared and investigated according to the change of channel dimension. As a result, we observed that the change in central potential distribution directly affects the SS. As the channel thickness and oxide thickness increased, the SS increased more sensitively in JLDG. Therefore, it was found that JLCSG structure is more effective to reduce the short channel effect of the nano MOSFET.

Temperature-dependent DC Characteristics of Homojunction InGaAs vertical Fin TFETs (동종 접합 InGaAs 수직형 Fin TFET의 온도 의존 DC 특성에 대한 연구)

  • Baek, Ji-Min;Kim, Dae-Hyun
    • Journal of Sensor Science and Technology
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    • v.29 no.4
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    • pp.275-278
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    • 2020
  • In this study, we evaluated the temperature-dependent characteristics of homojunction InGaAs vertical Fin-shaped Tunnel Field-Effect Transistors (Fin TFETs), which were fabricated using a novel nano-fin patterning technique in which the Au electroplating and the high-temperature InGaAs dry-etching processes were combined. The fabricated homojunction InGaAs vertical Fin TFETs, with a fin width and gate length of 60 nm and 100 nm, respectively, exhibited excellent device characteristics, such as a minimum subthreshold swing of 80 mV/decade for drain voltage (VDS) = 0.3 V at 300 K. We also analyzed the temperature-dependent characteristics of the fabricated TFETs and confirmed that the on-state characteristics were insensitive to temperature variations. From 77 K to 300 K, the subthreshold swing at gate voltage (VGS) = threshold voltage (VT), and it was constant at 115 mV/decade, thereby indicating that the conduction mechanism through band-to-band tunneling influenced the on-state characteristics of the devices.

Guide Lines for Optimal Structure of Silicon-based Pocket Tunnel Field Effect Transistor Considering Point and Line Tunneling (포인트 터널링과 라인 터널링을 모두 고려한 실리콘 기반의 포켓 터널링 전계효과 트랜지스터의 최적 구조 조건)

  • Ahn, Tae-Jun;Yu, Yun Seop
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.167-169
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    • 2016
  • The structure guide lines of pocket tunnel field effect transistor(TFET) considering Line and Point tunneling are introduced. As the pocket doping concentration or thickness increase, on-current $I_{on}$ increases. As the pocket thickness or gate insulator increase, subthreshold swing(SS) increases. Optimal structure reducing the hump effects should be proposed in order to enhance SS.

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Source-Overlapped Gate Length Effects at Tunneling current of Tunnel Field-Effect Transistor (소스영역으로 오버랩된 게이트 길이 변화에 따른 터널 트랜지스터의 터널링 전류에 대한 연구)

  • Lee, Ju-Chan;Ahn, Tae-Jun;Sim, Un-Sung;Yu, Yun Seop
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.611-613
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    • 2016
  • The characteristics of tunnel field-effect transistor(TFET) structure with source-overlapped gate was investigated using a TCAD simulations. Tunneling is mostly divided into line-tunneling and point-tunneling, and line-tunneling is higher performance than point-tunneling in terms of subthreshold swing(SS) and on-current. In this paper, from the simulation results of source-overlapped gate length effects at silicon(Si), germanium(Ge), Si-Ge hetero TFET structure, the guideline of optimal structure with highest performance are proposed.

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An Analytical Modeling of Threshold Voltage and Subthreshold Swing on Dual Material Surrounding Gate Nanoscale MOSFETs for High Speed Wireless Communication

  • Balamurugan, N.B.;Sankaranarayanan, K.;Amutha, P.;John, M. Fathima
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.8 no.3
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    • pp.221-226
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    • 2008
  • A new two dimensional (2-D) analytical model for the Threshold Voltage on dual material surrounding gate (DMSG) MOSFETs is presented in this paper. The parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions. The simple and accurate analytical expression for the threshold voltage and sub-threshold swing is derived. It is seen that short channel effects (SCEs) in this structure is suppressed because of the perceivable step in the surface potential which screens the drain potential. We demonstrate that the proposed model exhibits significantly reduced SCEs, thus make it a more reliable device configuration for high speed wireless communication than the conventional single material surrounding gate (SMSG) MOSFETs.

Analysis for Gate Oxide Dependent Subthreshold Swing of Asymmetric Double Gate MOSFET (비대칭 DGMOSFET의 문턱전압이하 스윙에 대한 게이트 산화막 의존성 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.4
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    • pp.885-890
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    • 2014
  • This paper has presented the change of subthreshold swings for gate oxide thickness of asymmetric double gate(DG) MOSFET, and solved Poisson equation to obtain the analytical solution of potential distribution. The Gaussian function as doping distribution is used to approch experimental results. The symmetric DGMOSFET is three terminal device. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine the bias voltage and oxide thickness for top and bottom gates. As a result to observe the subthreshold swings for the change of top and bottom gate oxide thickness, we know the subthreshold swings are greatly changed for gate oxide thickness. Especially we know the subthreshold swings are increasing with the increase of top and bottom gate oxide thickness, and top gate oxide thickness greatly influences subthreshold swings.

Analysis for Relation of Oxide Thickness and Subthreshold Swing of Asymmetric Double Gate MOSFET (비대칭 DGMOSFET의 산화막 두께와 문턱전압이하 스윙의 관계 분석)

  • Jung, Hakkee;Cheong, Dongsoo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.698-701
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    • 2013
  • This paper has presented the change of subthreshold swings for gate oxide thickness of asymmetric double gate(DG) MOSFET, and solved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET is three terminal device. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine the bias voltage and oxide thickness for top and bottom gates. As a result to observe the subthreshold swings for the change of top and bottom gate oxide thickness, we know the subthreshold swings are greatly changed for gate oxide thickness. Especially we know the subthreshold swings are increasing with the increase of top and bottom gate oxide thickness, and top gate oxide thickness greatly influences subthreshold swings.

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Subthreshold characteristics of buried-channel pMOSFET device (매몰채널 pMOSFET소자의 서브쓰레쉬홀드 특성 고찰)

  • 서용진;장의구
    • Electrical & Electronic Materials
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    • v.8 no.6
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    • pp.708-714
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    • 1995
  • We have discussed the buried-channel(BC) behavior through the subthreshold characteristics of submicron PMOSFET device fabricated with twin well CMOS process. In this paper, we have guessed the initial conditions of ion implantation using process simulation, obtained the subthreshold characteristics as a function of process parameter variation such as threshold adjusting ion implant dose($D_c$), channel length(L), gate oxide thickness($T_ox$) and junction depth of source/drain($X_j$) using device simulation. The buried channel behavior with these process prarameter variation were showed apparent difference. Also, the fabricated pMOSFET device having different channel length represented good S.S value and low leakage current with increasing drain voltage.

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Analysis of Subthreshold Characteristics for DGMOSFET according to Oxide Thickness Using Nonuniform Doping Distribution (비선형도핑분포를 이용한 DGMOSFET의 산화막두께에 대한 문턱전압이하 특성분석)

  • Jung, Hak-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.7
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    • pp.1537-1542
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    • 2011
  • In this paper, the subthreshold characteristics have been analyzed for various oxide thickness of double gate MOSFET(DGMOSFET) using Poisson's equation with nonuniform doping distribution. The DGMOSFET is extensively been studying since it can shrink the short channel effects(SCEs) in nano device. The degradation of subthreshold swing(SS) known as SCEs has been presented using analytical for, of Poisson's equation with nonuniform doping distribution for DGMOSFET. The SS have been analyzed for, change of gate oxide thickness to be the most important structural parameters of DGMOSFET. To verify this potential and transport models of thus analytical Poisson's equation, the results have been compared with those of the numerical Poisson's equation, and subthreshold swing has been analyzed using this models for DGMOSFET.

Si1-xGex Positive Feedback Field-effect Transistor with Steep Subthreshold Swing for Low-voltage Operation

  • Hwang, Sungmin;Kim, Hyungjin;Kwon, Dae Woong;Lee, Jong-Ho;Park, Byung-Gook
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.17 no.2
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    • pp.216-222
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    • 2017
  • The most prominent challenge for MOSFET scaling is to reduce power consumption; however, the supply voltage ($V_{DD}$) cannot be scaled down because of the carrier injection mechanism. To overcome this limit, a new type of field-effect transistor using positive feedback as a carrier injection mechanism (FBFET) has been proposed. In this study we have investigated the electrical characteristics of a $Si_{1-x}Ge_x$ FBFET with one gate and one-sided $Si_3N_4$ spacer using TCAD simulations. To reduce the drain bias dependency, $Si_{1-x}Ge_x$ was introduced as a low-bandgap material, and the minimum subthreshold swing was obtained as 2.87 mV/dec. This result suggests that a $Si_{1-x}Ge_x$ FBFET is a promising candidate for future low-power devices.