• Title/Summary/Keyword: Double Gate (DG)

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Design on Optimum Control of Subthreshold Current for Double Gate MOSFET (DGMOSFET에서 최적의 서브문턱전류제어를 위한 설계)

  • Jung, Hak-Kee;Na, Young-Il;Lee, Jong-In
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.887-890
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    • 2005
  • The double gate(DG) MOSFET is a promising candidate to further extend the CMOS scaling and provide better control of short channel effect(SCE). DGMOSFETs, having ultra thin updoped Si channel for SCEs control, are being validated for sub-20nm scaling, A channel effects such as the subthreshold swing(SS), and the threshold voltage roll-off(${\Delta}V_{th}$). The propsed model includes the effects of thermionic emission and quantum tunneling of carriers through the source-drain barrier. The proposed model is used to design contours for gate length, channel thickness, and gate oxide thickness.

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Dependence of Channel Doping Concentration on Drain Induced Barrier Lowering for Asymmetric Double Gate MOSFET (비대칭 이중게이트 MOSFET에 대한 DIBL의 채널도핑농도 의존성)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.4
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    • pp.805-810
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    • 2016
  • The dependence of drain induced barrier lowering(DIBL) is analyzed for doping concentration in channel of asymmetric double gate(DG) MOSFET. The DIBL, the important short channel effect, is described as lowering of source barrier height by drain voltage. The analytical potential distribution is derived from Poisson's equation to analyze the DIBL, and the DIBL is observed according to top/bottom gate oxide thickness and bottom gate voltage as well as channel doping concentration. As a results, the DIBL is significantly influenced by channel doping concentration. DIBL is significantly increased by doping concentration if channel length becomes under 25 nm. The deviation of DIBL is increasing with increase of oxide thickness. Top and bottom gate oxide thicknesses have relation of an inverse proportion to sustain constant DIBL regardless channel doping concentration. We also know the deviation of DIBL for doping concentration is changed according to bottom gate voltage.

Analysis of Subthreshold Swing for Channel Doping of Asymmetric Double Gate MOSFET (비대칭 이중게이트 MOSFET의 채널도핑에 따른 문턱전압이하 스윙 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.3
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    • pp.651-656
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    • 2014
  • This paper analyzed the change of subthreshold swing for channel doping of asymmetric double gate(DG) MOSFET. The subthreshold swing is the factor to describe the decreasing rate of off current in the subthreshold region, and plays a very important role in application of digital circuits. Poisson's equation was used to analyze the subthreshold swing for asymmetric DGMOSFET. Asymmetric DGMOSFET could be fabricated with the different top and bottom gate oxide thickness and bias voltage unlike symmetric DGMOSFET. It is investigated in this paper how the doping in channel, gate oxide thickness and gate bias voltages for asymmetric DGMOSFET influenced on subthreshold swing. Gaussian function had been used as doping distribution in solving the Poisson's equation, and the change of subthreshold swing was observed for projected range and standard projected deviation used as parameters of Gaussian distribution. Resultly, the subthreshold swing was greatly changed for doping concentration and profiles, and gate oxide thickness and bias voltage had a big impact on subthreshold swing.

Analysis of Subthreshold Characteristics for Device Parameter of DGMOSFET Using Gaussian Function

  • Jung, Hak-Kee
    • Journal of information and communication convergence engineering
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    • v.9 no.6
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    • pp.733-737
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    • 2011
  • This paper has studied subthreshold characteristics for double gate(DG) MOSFET using Gaussian function in solving Poisson's equation. Typical two dimensional analytical transport models have been presented for symmetrical Double Gate MOSFETs (DGMOSFETs). Subthreshold swing and threshold voltage are very important factors for digital devices because of determination of ON and OFF. In general, subthreshold swings have to be under 100mV/dec, and threshold voltage roll-off small in short channel devices. These models are used to obtain the change of subthreshold swings and threshold voltage for DGMOSFET according to channel doping profiles. Also subthreshold swings and threshold voltages have been analyzed for device parameters such as channel length, channel thickness and channel doping profiles.

Analysis of Subthreshold Swing for Channel Length of Asymmetric Double Gate MOSFET (비대칭 DGMOSFET의 채널길이에 대한 문턱전압이하 스윙 분석)

  • Jung, Hakkee;Lee, Jongin;Cheong, Dongsoo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.745-748
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    • 2014
  • 본 연구에서는 비대칭 이중게이트(double gate; DG) MOSFET의 채널길이에 대한 문턱전압이하 스윙의 변화에 대하여 분석하였다. 문턱전압이하 스윙은 트랜지스터의 디지털특성을 결정하는 중요한 요소로서 채널길이가 감소하면 특성이 저하되는 문제가 나타나고 있다. 이러한 문제를 해결하기 위하여 개발된 DGMOSFET의 문턱전압이하 스윙의 채널길이에 대한 변화를 채널두께, 산화막두께, 상하단 게이트 전압 및 도핑농도 등에 따라 조사하고자 한다. 특히 하단 게이트 구조를 상단과 달리 제작할 수 있는 비대칭 DGMOSFET에 대하여 문턱전압이하 스윙을 분석함으로써 하단 게이트 전압 및 하단 산화막 두께 등에 대하여 자세히 관찰하였다. 문턱전압이하 스윙의 해석학적 모델을 구하기 위하여 포아송방정식에서 해석학적 전위분포모델을 유도하였으며 도핑분포함수는 가우스분포함수를 사용하였다. 결과적으로 문턱전압이하 스윙은 상하단 게이트 전압 및 채널도핑농도 그리고 채널의 크기에 매우 민감하게 변화하고 있다는 것을 알 수 있었다.

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Analysis of Off Current for Conduction Path of Asymmetric Double Gate MOSFET (전도중심에 따른 비대칭 이중게이트 MOSFET의 차단전류 분석)

  • Jung, Hakkee;Kwon, Ohshin
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.759-762
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    • 2014
  • 비대칭 이중게이트(double gate; DG) MOSFET는 단채널 효과를 감소시킬 수 있는 새로운 구조의 트랜지스터이다. 본 연구에서는 비대칭 DGMOSFET의 전도중심에 따른 차단전류를 분석하고자 한다. 전도중심은 채널 내 캐리어의 이동이 발생하는 상단게이트에서의 평균거리로써 상하단 게이트 산화막 두께를 달리 제작할 수 있는 비대칭 DGMOSFET에서 산화막 두께에 따라 변화하는 요소이며 상단 게이트 전압에 따른 차단전류에 영향을 미치고 있다. 전도중심을 구하고 이를 이용하여 상단 게이트 전압에 따른 차단전류를 계산함으로써 전도중심이 차단전류에 미치는 영향을 산화막 두께 및 채널길이 등을 파라미터로 분석할 것이다. 차단전류를 구하기 위하여 포아송방정식으로부터 급수 형태의 해석학적 전위분포를 유도하였다. 결과적으로 전도중심의 위치에 따라 차단전류는 크게 변화하였으며 이에 따라 문턱전압 및 문턱전압이하 스윙이 변화하는 것을 알 수 있었다.

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Threshold Voltage Control through Layer Doping of Double Gate MOSFETs

  • Joseph, Saji;George, James T.;Mathew, Vincent
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.10 no.3
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    • pp.240-250
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    • 2010
  • Double Gate MOSFETs (DG MOSFETs) with doping in one or two thin layers of an otherwise intrinsic channel are simulated to obtain the transport characteristics, threshold voltage and leakage current. Two different device structures- one with doping on two layers near the top and bottom oxide layers and another with doping on a single layer at the centre- are simulated and the variation of device parameters with a change in doping concentration and doping layer thickness is studied. It is observed that an n-doped layer in the channel reduces the threshold voltage and increases the drive current, when compared with a device of undoped channel. The reduction in the threshold voltage and increase in the drain current are found to increase with the thickness and the level of doping of the layer. The leakage current is larger than that of an undoped channel, but less than that of a uniformly doped channel. For a channel with p-doped layer, the threshold voltage increases with the level of doping and the thickness of the layer, accompanied with a reduction in drain current. The devices with doped middle layers and doped gate layers show almost identical behavior, apart from the slight difference in the drive current. The doping level and the thickness of the layers can be used as a tool to adjust the threshold voltage of the device indicating the possibility of easy fabrication of ICs having FETs of different threshold voltages, and the rest of the channel, being intrinsic having high mobility, serves to maintain high drive current in comparison with a fully doped channel.

Analysis of Subthreshold Swing for Oxide Thickness and Doping Distribution in DGMOSFET (산화막두께 및 도핑분포에 대한 DGMOSFET의 문턱전압이하 스윙분석)

  • Jung, Hak-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.10
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    • pp.2217-2222
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    • 2011
  • In this paper, the relationship of potential and charge distribution in channel for double gate(DG) MOSFET has been derived from Poisson's equation using Gaussian function. The relationship of subthreshold swing and oxide thickness has been investigated according to variables of doping distribution using Gaussian function, i.e. projected range and standard projected deviation, The analytical potential distribution model has been derived from Poisson's equation, and subthreshold swing has been obtained from this model for the change of oxide thickness. The subthreshold swing has been defined as the derivative of gate voltage to drain current and is theoretically minimum of 60 mS/dec, and very important factor in digital application. Those results of this potential model are compared with those of numerical simulation to verify this model. As a result, since potential model presented in this paper is good agreement with numerical model, the relationship of subthreshold swing and oxide thickness have been analyzed according to the shape of doping distribution.

Dependence of Drain Induced Barrier Lowering for Ratio of Channel Length vs. Thickness of Asymmetric Double Gate MOSFET (비대칭 DGMOSFET에서 채널길이와 두께 비에 따른 DIBL 의존성 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.6
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    • pp.1399-1404
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    • 2015
  • This paper analyzed the phenomenon of drain induced barrier lowering(DIBL) for the ratio of channel length vs. thickness of asymmetric double gate(DG) MOSFET. DIBL, the important secondary effect, is occurred for short channel MOSFET in which drain voltage influences on potential barrier height of source, and significantly affects on transistor characteristics such as threshold voltage movement. The series potential distribution is derived from Poisson's equation to analyze DIBL, and threshold voltage is defined by top gate voltage of asymmetric DGMOSFET in case the off current is 10-7 A/m. Since asymmetric DGMOSFET has the advantage that channel length and channel thickness can significantly minimize, and short channel effects reduce, DIBL is investigated for the ratio of channel length vs. thickness in this study. As a results, DIBL is greatly influenced by the ratio of channel length vs. thickness. We also know DIBL is greatly changed for bottom gate voltage, top/bottom gate oxide thickness and channel doping concentration.

Analysis for Potentail Distribution of Asymmetric Double Gate MOSFET Using Series Function (급수함수를 이용한 비대칭 이중게이트 MOSFET의 전위분포 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.11
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    • pp.2621-2626
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    • 2013
  • This paper has presented the potential distribution for asymmetric double gate(DG) MOSFET, and sloved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET where both the front and the back gates are tied together is three terminal device and has the same current controllability for front and back gates. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine current controllability for front and back gates. To approximate with experimental values, we have used the Gaussian function as doping distribution in Poisson equation. The potential distribution has been observed for gate bias voltage and gate oxide thickness and channel doping concentration of the asymmetric DGMOSFET. As a results, we know potential distribution is greatly changed for gate bias voltage and gate oxide thickness, especially for gate to increase gate oxide thickness. Also the potential distribution for source is changed greater than one of drain with increasing of channel doping concentration.