Non-equilibrium Green’s function analysis of cross section and channel length dependence of phonon scattering and its impact on the performance of Si nanowire field effect transistors

Aldegunde, Manuel; Martı́nez, Antonio; Asenov, A.

doi:10.1063/1.3658856

Cited by 36 publications

(36 citation statements)

References 24 publications

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“…These structures provide a protection against short channel effects and excellent electrostatic integrity [1][2][3][4]. 1 Their theoretical calculated subthreshold slope is almost 60 mV/dec for a well-balanced structure.…”

Section: Introductionmentioning

confidence: 99%

“…However, the masses are extracted from tight-binding calculations. Our model used an anisotropic mass tensor [4] and coupled mode space approach, in order to reduce computational time. The phonons are assumed to be in equilibrium, and the electron phonon scattering parameters are from reference [7], which has been shown to be a good approximation for confined structures.…”

Section: Electron-phonon Scattering In Gaa Si Nanowires (Low and Highmentioning

confidence: 99%

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Impact of phonon scattering in Si/GaAs/InGaAs nanowires and FinFets: a NEGF perspective

et al. 2016

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This paper reviews our previous theoretical studies and gives further insight into phonon scattering in 3D small nanotransistors using non-equilibrium Green function methodology. The focus is on very small gate-all-around nanowires with Si, GaAs or InGaAs cores. We have calculated phonon-limited mobility and transfer characteristics for a variety of cross-sections at low and high drain bias. The nanowire cross-sectional area is shown to have a significant impact on the phonon-limited mobility and on the current reduction. In a study of narrow Si nanowires we have examined the spatially resolved power dissipation and the validity of Joule's law. Our results show that only a fraction of the power is dissipated inside the drain region even for a relatively large simulated length extension (approximately 30 nm). When considering large source regions in the simulation domain, at low gate bias, a slight cooling of the source is observed. We have also studied the impact of College of Science and Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK the real part of phonon scattering self-energy on a narrow nanowire transistor. This real part is usually neglected in nanotransistor simulation, whereas we compute its impact on current-voltage characteristic and mobility. At low gate bias, the imaginary part strongly underestimated the current and the mobility by 50 %. At high gate bias, the two mobilities are similar and the effect on the current is negligible.Keywords Silicon and III-V nanowire field effect transistors · Non-equilibrium Green's functions · Electronphonon scattering self-energies · Phonon-limited mobility · Local power dissipation

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Section: Introductionmentioning

confidence: 99%

Section: Electron-phonon Scattering In Gaa Si Nanowires (Low and Highmentioning

confidence: 99%

Impact of phonon scattering in Si/GaAs/InGaAs nanowires and FinFets: a NEGF perspective

et al. 2016

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“…As a matter of fact, such models are still missing under the spacers, which are very inhomogeneous but critical regions on the resistive path (see sections III and IV). Also, at variance with most previous NEGF calculations, 16,17,22,23,25,39,52,53 the source and drain contacts are wide enough with respect to the channel to act as bulk reservoirs (with a 3D-like density of states). This is essential for a quantitative description of the contact resistances.…”

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confidence: 99%

“…At low field, the resistance of the channel can be characterized by the carrier mobility µ, which has been extensively measured and calculated in a variety of silicon structures (bulk, 3 films 4-12 and wires [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] ). There is much less literature on the contact resistances, [28][29][30][31][32][33][34][35][36][37][38][39] even though they have become a major bottleneck for device performances.…”

Section: Introductionmentioning

confidence: 99%

Contact resistances in trigate and FinFET devices in a non-equilibrium Green's functions approach

Bourdet

Pelloux-Prayer

et al. 2016

Journal of Applied Physics

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We compute the contact resistances R c in trigate and FinFET devices with widths and heights in the 4 to 24 nm range using a Non-Equilibrium Green's Functions approach. Electron-phonon, surface roughness and Coulomb scattering are taken into account. We show that R c represents a significant part of the total resistance of devices with sub-30 nm gate lengths. The analysis of the quasi-Fermi level profile reveals that the spacers between the heavily doped source/drain and the gate are major contributors to the contact resistance. The conductance is indeed limited by the poor electrostatic control over the carrier density under the spacers. We then disentangle the ballistic and diffusive components of R c , and analyze the impact of different design parameters (cross section and doping profile in the contacts) on the electrical performances of the devices. The contact resistance and variability rapidly increase when the cross sectional area of the channel goes below 50 nm 2 . We also highlight the role of the charges trapped at the interface between silicon and the spacer material.

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“…A favourite algorithm for such full 3-D QT calculations is the Non-Equilibrium Green's Function formalism (NEGF) [18], [19]. An additional strength of the 3-D NEGF method is in the potential to include consistently noncoherent scattering [20]- [22], such as phonon interactions, through introduction of appropriate self-energy matrixes. The self-energies allow folding of the entire manybody quantum transport algorithm into the one-particle Green's function equation [23]- [25].…”

Section: Introductionmentioning

confidence: 99%

Impact of Precisely Positioned Dopants on the Performance of an Ultimate Silicon Nanowire Transistor: A Full Three-Dimensional NEGF Simulation Study

Georgiev

Towie

Asenov

2013

IEEE Trans. Electron Devices

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n Georgiev, V.P., Towie, E.A., and Asenov, A. (2013) Impact of precisely positioned dopants on the performance of an ultimate silicon nanowire transistor: a full threedimensional NEGF simulation study. IEEE Transactions on Electron Devices, 60(3), pp. 965-971.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/82165/ Deposited on: 16 February 2016 Enlighten -Research publications by members of the University of Glasgow http://eprints.gla.ac.uk > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 1Abstract-In this paper, we report the first systematic study of quantum transport simulation of the impact of precisely positioned dopants on the performance of ultimately scaled gateall-around silicon nanowire transistors (SNWT) designed for digital circuit applications. Due to strong inhomogeneity of the self-consistent electrostatic potential, a full 3-D real-space NonEquilibrium Green's Function (NEGF) formalism is used. The simulations are carried out for an n-channel NWT with 2.2 x 2.2 nm 2 cross-section and 6 nm channel length, where the locations of the precisely arranged dopants in the source drain extensions and in the channel region have been varied. The individual dopants act as localized scatters and, hence, impact of the electron transport is directly correlated to the position of the single dopants. As a result, a large variation in the ON-current and modest variation of the subthreshold slope are observed in the I D -V G characteristics when comparing devices with microscopically different discrete dopant configuration. The variations of the current-voltage characteristics are analyzed with reference to the behaviour of the transmission coefficients.Index Terms-single-atom transistor, discrete dopants, nanowire transistor, non-equilibrium Green's function (NEGF), 3-D simulations, quantum transport. I. INTRODUCTIONILICON TECHNOLOGY can deliver sub-10 nm devices where 'every atom counts'. Manipulation of atoms with high precision on such a scale, in principle, can lead to technological innovations, such as transistors with extremely short gate length [1], quantum computing components [2] and optoelectronic devices [3]. One possible strategy to create this next generation of devices is to precisely place individual discrete dopants (such as phosphorous atoms) in a nanoscale transistor [4]. The number and the spatial distribution of individual dopants within the transistor of modern silicon chips determine both their characteristics and their unwanted variability [5], [6]. Hence, it is crucial to establish a direct link between the position of individual dopants and the transistors' performance [7], [8]. At the physical limit of transistor scaling a single phosphorous atom embedded within epitaxial silicon environment, in principle, can be used to build a single-atom transistor [9]. Although such an idea looks spectacularly attractive, the side ga...

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Non-equilibrium Green’s function analysis of cross section and channel length dependence of phonon scattering and its impact on the performance of Si nanowire field effect transistors

Cited by 36 publications

References 24 publications

Impact of phonon scattering in Si/GaAs/InGaAs nanowires and FinFets: a NEGF perspective

Impact of phonon scattering in Si/GaAs/InGaAs nanowires and FinFets: a NEGF perspective

Contact resistances in trigate and FinFET devices in a non-equilibrium Green's functions approach

Impact of Precisely Positioned Dopants on the Performance of an Ultimate Silicon Nanowire Transistor: A Full Three-Dimensional NEGF Simulation Study

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