Efficient and realistic device modeling from atomic detail to the nanoscale

Fonseca, James; Kubis, Tillmann; Povolotskyi, Michael; Novaković, Božidar; Ajoy, Arvind; Hegde, Ganesh; Ilatikhameneh, Hesameddin; Jiang, Zhengping; Sengupta, Parijat; Tan, Yui-Hong Matthias; Klimeck, Gerhard

doi:10.1007/s10825-013-0509-0

Cited by 94 publications

(77 citation statements)

References 39 publications

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“…ETB has established itself as the standard state-of-the-art basis for realistic device simulations. 8 It has been successfully applied to electronic structures of millions of atoms 9 as well as on non-equilibrium transport problems that even involve inelastic scattering. 10 The accuracy of the ETB methods depend critically on the careful calibration of the empirical parameters.…”

Section: Introductionmentioning

confidence: 99%

Tight-binding analysis of Si and GaAs ultrathin bodies with subatomic wave-function resolution

et al. 2015

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Empirical tight binding(ETB) methods are widely used in atomistic device simulations. Traditional ways of generating the ETB parameters rely on direct fitting to bulk experiments or theoretical electronic bands. However, ETB calculations based on existing parameters lead to unphysical results in ultra small structures like the As terminated GaAs ultra thin bodies(UTBs). In this work, it is shown that more transferable ETB parameters with short interaction range can be obtained by a process of mapping ab-initio bands and wave functions to ETB models. This process enables the calibration of not only the ETB energy bands but also the ETB wave functions with corresponding ab-initio calculations. Based on the mapping process, ETB model of Si and GaAs are parameterized with respect to hybrid functional calculations. Highly localized ETB basis functions are obtained. Both the ETB energy bands and wave functions with subatomic resolution of UTBs show good agreement with the corresponding hybrid functional calculations. The ETB methods can then be used to explain realistically extended devices in non-equilibrium that can not be tackled with ab-initio methods.

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Section: Introductionmentioning

confidence: 99%

Tight-binding analysis of Si and GaAs ultrathin bodies with subatomic wave-function resolution

et al. 2015

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“…In this paper, the transport simulations have been performed with the Nanoelectronics Modeling tool NEMO53132.…”

Section: Methodsmentioning

confidence: 99%

Few-layer Phosphorene: An Ideal 2D Material For Tunnel Transistors

Ameen

Ilatikhameneh

Klimeck

et al. 2016

Sci Rep

100

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2D transition metal dichalcogenides (TMDs) have attracted a lot of attention recently for energy-efficient tunneling-field-effect transistor (TFET) applications due to their excellent gate control resulting from their atomically thin dimensions. However, most TMDs have bandgaps (Eg) and effective masses (m*) outside the optimum range needed for high performance. It is shown here that the newly discovered 2D material, few-layer phosphorene, has several properties ideally suited for TFET applications: 1) direct Eg in the optimum range ~1.0–0.4 eV, 2) light transport m* (0.15 m0), 3) anisotropic m* which increases the density of states near the band edges, and 4) a high mobility. These properties combine to provide phosphorene TFET outstanding ION ~ 1 mA/um, ON/OFF ratio ~ 106 for a 15 nm channel and 0.5 V supply voltage, thereby significantly outperforming the best TMD-TFETs and CMOS in many aspects such as ON/OFF current ratio and energy-delay products. Furthermore, phosphorene TFETS can scale down to 6 nm channel length and 0.2 V supply voltage within acceptable range in deterioration of the performance metrics. Full-band atomistic quantum transport simulations establish phosphorene TFETs as serious candidates for energy-efficient and scalable replacements of MOSFETs.

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“…The structure extends infinitely in the z direction (perpendicular to the page). The device is simulated using the atomistic nanoelectronics modeling tool set NEMO5 16,17 by self-consistently solving Poisson's equation and a set of multiscale transport equations. In the multiscale transport approach, the phenomenological scattering model is applied to the source thermalized reservoir, where the carrier energy levels are broadened, and imposed in the drain thermalized reservoir, where carriers dissipate their remaining kinetic energy after ballistic transmission through the central non-equilibrium device.…”

Section: Device Structure and Modeling Methodsmentioning

confidence: 99%

Performance degradation of superlattice MOSFETs due to scattering in the contacts

Long

Huang

Jiang

et al. 2016

Journal of Applied Physics

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Ideal, completely coherent quantum transport calculations had predicted that superlattice MOSFETs may offer steep subthreshold swing performance below 60mV/dec to around 39mV/dec. However, the high carrier density in the superlattice source suggest that scattering may significantly degrade the ideal device performance. Such effects of electron scattering and decoherence in the contacts of superlattice MOSFETs are examined through a multiscale quantum transport model developed in NEMO5. This model couples NEGF-based quantum ballistic transport in the channel to a quantum mechanical density of states dominated reservoir, which is thermalized through strong scattering with local quasi-Fermi levels determined by drift-diffusion transport. The simulations show that scattering increases the electron transmission in the nominally forbidden minigap therefore degrading the subthreshold swing (S.S.) and the ON/OFF DC current ratio. This degradation varies with both the scattering rate and the length of the scattering dominated regions. Different superlattice MOSFET designs are explored to mitigate the effects of such deleterious scattering. Specifically, shortening the spacer region between the superlattice and the channel from 3.5 nm to 0 nm improves the simulated S.S. from 51mV/dec. to 40mV/dec.

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Efficient and realistic device modeling from atomic detail to the nanoscale

Cited by 94 publications

References 39 publications

Tight-binding analysis of Si and GaAs ultrathin bodies with subatomic wave-function resolution

Tight-binding analysis of Si and GaAs ultrathin bodies with subatomic wave-function resolution

Few-layer Phosphorene: An Ideal 2D Material For Tunnel Transistors

Performance degradation of superlattice MOSFETs due to scattering in the contacts

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