Improved mobility models for charge transport in graphene

Nastasi, Giovanni; Romano, Vittorio

doi:10.1515/caim-2019-0011

Cited by 8 publications

(7 citation statements)

References 14 publications

(31 reference statements)

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“…From the numerical solutions of the semiclassical Boltzmann equation a model for the mobility functions has been deduced, similarly to what already done in [17] and in [18] in the case of suspended monolayer graphene.…”

Section: Introductionmentioning

confidence: 91%

An efficient GFET structure

Nastasi,

Romano

2020

Preprint

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A graphene field effect transistor, where the active area is made of monolayer large-area graphene, is simulated including a full 2D Poisson equation and a driftdiffusion model with mobilities deduced by a direct numerical solution of the semiclassical Boltzmann equations for charge transport by a suitable discontinuous Galerkin approach.The critical issue in a graphene field effect transistor is the difficulty of fixing the off state which requires an accurate calibration of the gate voltages. In the present paper we propose and simulate a graphene field effect transistor structure which has well-behaved characteristic curves similar to those of conventional (with gap) semiconductor materials. The introduced device has a clear off region and can be the prototype of devices suited for post-silicon nanoscale electron technology. The specific geometry overcomes the problems of triggering the minority charge current and gives a viable way for the design of electron devices based on large area monolayer graphene as substitute of standard semiconductors in the active area. The good field effect transistor behavior of the current versus the gate voltage makes the simulated device very promising and a challenging case for experimentalists.

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Section: Introductionmentioning

confidence: 91%

An efficient GFET structure

Nastasi,

Romano

2020

Preprint

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“…As possible further improvements, the authors are investigating the inclusion of thermal effects along the results obtained for suspended monolayer graphene (Coco et al, 2016; and the extraction of mobility models starting from the DG numerical results as in Majorana et al (2016), Nastasi and Romano (2019).…”

Section: Bipolar Charge Transportmentioning

confidence: 99%

Simulation of bipolar charge transport in graphene on h-BN

Coco

Nastasi

2020

COMPEL

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Purpose The purpose of this paper is to simulate charge transport in monolayer graphene on a substrate made of hexagonal boron nitride (h-BN). This choice is motivated by the fact that h-BN is one of the most promising substrates on account of the reduced degradation of the velocity due to the remote impurities. Design/methodology/approach The semiclassical Boltzmann equations for electrons in the monolayer graphene are numerically solved by an approach based on a discontinuous Galerkin (DG) method. Both the conduction and valence bands are included, and the inter-band scatterings are taken into account as well. Findings The importance of the inter-band scatterings is accurately evaluated for several values of the Fermi energy, addressing the issue related to the validity of neglecting the generation-recombination terms. It is found out that the inclusion of the inter-band scatterings produces sizable variations in the average values, like the current density, at zero Fermi energy, whereas, as expected, the effect of the inter-band scattering becomes negligible by increasing the absolute value of the Fermi energy. Research limitations/implications The correct evaluation of the influence of the inter-band scatterings on the electronic performances is deeply important not only from a theoretical point of view but also for the applications. In particular, it will be shown that the time necessary to reach the steady state is greatly affected by the inter-band scatterings, with not negligible consequences on the switching on/off processes of realistic devices. As a limitation of the present work, the proposed approach refers to the spatially homogeneous case. For the simulation of electron devices, non-homogenous numerical solutions are required. This last case will be tackled in a forthcoming paper. Originality/value As observed in Majorana et al. (2019), the use of a Direct Simulation Monte Carlo (DSMC) approach, which properly describes the inter-band scatterings, is computationally very expensive because the valence band is highly populated and a huge number of particles is needed. Even by simulating holes instead of electrons does not overcome the problem because there is a certain degree of ambiguity in the generation and recombination terms of electron-hole pairs. The DG approach, used in this paper, does not suffer from the previous drawbacks and requires a reasonable computing effort.

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“…In the literature an analysis of this approach is missing (it received only a brief comment in [5]); it is the aim of this work to fill this gap and to present a coherent discussion on the inclusion of the Pauli principle in a Monte Carlo procedure. We do so by comparing the numerical results for a suspended monolayer graphene obtained with the Monte Carlo Method presented in [9] with those obtained using the standard EMC in [4] and the updated direct simulation Monte Carlo (DSMC) in [12], which are by now well established in the semiconductor field and have been cross validated with deterministic solutions, for example, those based on the discontinuous Galerkin method [12][13][14][15][16][17][18][19] or on weighted essentially non-oscillatory (WENO) schemes [20].…”

Section: Introductionmentioning

confidence: 99%

Pauli principle and the Monte Carlo method for charge transport in graphene

et al. 2021

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An attempt to include the Pauli principle in the Monte Carlo method by also acting on the free-flight step and not only at the end of each collision is investigated. The charge transport in suspended monolayer graphene is considered as a test case. The results are compared with those obtained with the standard ensemble Monte Carlo technique and with the updated direct simulation Monte Carlo algorithm which is able to correctly handle with Pauli's principle. The physical aspects of the investigated approach are analyzed as well.

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Improved mobility models for charge transport in graphene

Cited by 8 publications

References 14 publications

An efficient GFET structure

An efficient GFET structure

Simulation of bipolar charge transport in graphene on h-BN

Pauli principle and the Monte Carlo method for charge transport in graphene

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