Simulation of junctionless Si nanowire transistors with 3 nm gate length

Ansari, Lida; Feldman, Baruch; Fagas, Giorgos; Colinge, Jean–Pierre; Greer, James C.

doi:10.1063/1.3478012

Cited by 97 publications

(51 citation statements)

References 13 publications

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“…Finally, the source-drain tunneling currents of the devices for the two doping profiles are around 0. that is, FETs with homogeneous source-channel-drain doping similar channel dimensions and NW orientation. Supporting our previous findings, 25 this suggests that at such scales the distribution of charge carriers around the dopant blurs the boundaries of a junction over a distance comparable to the channel length. Therefore, besides being very difficult to fabricate, junctioned FET designs at this scale will fail to effectively keep carriers out of the channel in the off-state.…”

Section: A Transport Propertiessupporting

confidence: 74%

“…Over the last decade, the description of electronic quantum transport based on computational methods has become one of the core topics in atomic-scale modeling and device simulations, 20 and the explicit electronic structure of materials has been considered from approximate methods that use empirical bulk parameterization 15 to first-principles approaches, [21][22][23] and approximations thereof. 13,[23][24][25] In this paper, we first discuss our own quantum transport implementation (TiMeS-Transport in Mesoscopic Systems). Separating the step that provides the electronic structure description from the transport module, TiMeS offers a crossplatform solution that allows efficient calculations of materials transport properties and realistic device simulations to extract current-voltage and transfer characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Transport properties and electrical device characteristics with the TiMeS computational platform: Application in silicon nanowires

Sharma

Ansari

Feldman

et al. 2013

Journal of Applied Physics

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Nanoelectronics requires the development of a priori technology evaluation for materials and device design that takes into account quantum physical effects and the explicit chemical nature at the atomic scale. Here, we present a cross-platform quantum transport computation tool. Using first-principles electronic structure, it allows for flexible and efficient calculations of materials transport properties and realistic device simulations to extract current-voltage and transfer characteristics. We apply this computational method to the calculation of the mean free path in silicon nanowires with dopant and surface oxygen impurities. The dependence of transport on basis set is established, with the optimized double zeta polarized basis giving a reasonable compromise between converged results and efficiency. The current-voltage characteristics of ultrascaled (3 nm length) nanowire-based transistors with p-i-p and p-n-p doping profiles are also investigated. It is found that charge self-consistency affects the device characteristics more significantly than the choice of the basis set. These devices yield sourced-drain tunneling currents in the range of 0.5 nA (p-n-p junction) to 2 nA (p-i-p junction), implying that junctioned transistor designs at these length scales would likely fail to keep carriers out of the channel in the off-state. (C) 2013 AIP Publishing LLC

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Section: A Transport Propertiessupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Transport properties and electrical device characteristics with the TiMeS computational platform: Application in silicon nanowires

Sharma

Ansari

Feldman

et al. 2013

Journal of Applied Physics

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“…8 Atomic-scale simulations have confirmed the scalability of JNTs down to sub-5 nm dimensions. 9 Several recent publications on the characterization of JNTs and comparison of these devices with conventional IM devices can be found in the literature. [10][11][12][13][14][15][16][17][18] Germanium inversionmode (IM) devices have been previously investigated 19,20 but no quantum mechanical study on the performance comparison of germanium and silicon JNTs has been reported.…”

Section: Introductionmentioning

confidence: 99%

Influence of channel material properties on performance of nanowire transistors

Razavi

Fagas

Ferain

et al. 2012

Journal of Applied Physics

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Access to the full text of the published version may require a subscription. The performance of germanium and silicon inversion-mode and junctionless nanowire field-effect transistors are investigated using three-dimensional quantum mechanical simulations in the ballistic transport regime and within the framework of effective-mass theory for different channel materials and orientations. Our study shows that junctionless nanowire transistors made using n-type Ge or Si nanowires as a channel material are more immune to short-channel effects than conventional inversion-mode nanowire field-effect transistors. As a result, these transistors present smaller subthreshold swing, less drain-induced barrier-lowering, lower source-to-drain tunneling, and higher I on /I off ratio for the same technology node and low standby power technologies. We also show that the short-channel characteristics of Ge and Si junctionless nanowire transistors, unlike the inversion-mode nanowire transistors, are very similar. The results are explained through a detailed analysis on the effect of the channel crystallographic orientation, effective masses, and dielectric constant on electrical characteristics. V C 2012 American Institute of Physics. Rights

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Section: Introductionmentioning

confidence: 99%

“…A substantial amount of theoretical work has been done in studying the performance of trigate FETs and nanowires. This work ranges from semi-classical transport studies [4] to full-band quantum transport analysis [5].Substantial work on the impact of random discrete dopants on the performance of MOSFET transistors has been carried out [6][7][8][9][10]. This work has made use of Drift-diffusion, Monte Carlo and the Non-Equilibrium Green function (NEGF) carrier transport models.…”

mentioning

confidence: 99%

NEGF simulations of a junctionless Si gate-all-around nanowire transistor with discrete dopants

Martı́nez

Aldegunde

Brown

et al. 2012

Solid-State Electronics

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We have carried out 3D Non-Equilibrium Green Function simulations of a junctionless gate-all-around ntype silicon nanowire transistor of 4.2×4.2 nm 2 crosssection. We model the dopants in a fully atomistic way. The dopant distributions are randomly generated following an average doping concentration of 10 20 cm -3 . Elastic and inelastic Phonon scattering is considered in our simulation. Considering the dopants in a discrete way is the first step in the simulation of random dopant variability in junctionless transistors in a fully quantum mechanical way. Our results show that, for devices with an "unlucky" dopant configuration, with a starvation of donors under the gate, the threshold voltage can increase by a few hundred mV relative to devices with a more homogeneous distribution of dopants. IntroductionJunctionless Field Effect Transistors (JLFET) [1-2] have been proposed as an alternative to the standard minority-carrier channel MOSFETs at the end of the road map. As transistor dimensions scale down to tens of nanometres it became increasingly complicated to control the dopants at the source/channel and channel/drain boundaries. Another related problem is the intrinsic discreteness of dopants, which makes these boundaries less well defined at the nanoscale. As the JLFET is doped all the way through from source/channel/drain at the same doping concentration it is argued that it will not suffer of variability coming from fluctuations in the effective channel length, which becomes important at channel lengths of approximately 20 nm for conventional silicon transistors. Recently, a paper from the Tyndall Institute [3] has shown, experimentally and theoretically, the potential of the JLFET. A substantial amount of theoretical work has been done in studying the performance of trigate FETs and nanowires. This work ranges from semi-classical transport studies [4] to full-band quantum transport analysis [5].Substantial work on the impact of random discrete dopants on the performance of MOSFET transistors has been carried out [6][7][8][9][10]. This work has made use of Drift-diffusion, Monte Carlo and the Non-Equilibrium Green function (NEGF) carrier transport models.Gate-all-around (GAA) nanowire transistors have a superior electrostatic integrity compared with the standard planar MOSFET architecture. When the nanowire cross-section becomes smaller than 10 nm, quantum confinement becomes important and a proper description of the sub-bands is necessary in order to properly describe quantum capacitances and the quasi-1D density of states. Furthermore, at channel lengths of less than 20 nm the tunnelling component of the sourcedrain current cannot be neglected [11]. Semi-classical simulation based on a Boltzmann description of the transport cannot capture the source-drain tunnelling.In this work we use the NEGF formalism to carry out simulations of the transfer characteristics of a junctionless Si GAA nanowire transistor. We consider the impact of the random discrete dopants in the active region of the device. Th...

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Simulation of junctionless Si nanowire transistors with 3 nm gate length

Abstract: Access to the full text of the published version may require a subscription. Rights

Cited by 97 publications

References 13 publications

Transport properties and electrical device characteristics with the TiMeS computational platform: Application in silicon nanowires

Transport properties and electrical device characteristics with the TiMeS computational platform: Application in silicon nanowires

Influence of channel material properties on performance of nanowire transistors

NEGF simulations of a junctionless Si gate-all-around nanowire transistor with discrete dopants

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