AMaSiS 2021 - Abstract

Romano, Vittorio

Simulation of graphene field effect transistors by directly solving the semiclassical Boltzmann equation

Università degli Studi di Catania, Italy

In the last years an increasing interest has been devoted to graphene field effect transistors (GFETs) as potential candidates for high-speed analog electronics, where transistor current gain is more important than ratio current ON/current OFF. Several types of GFETs have been considered in the literature [1]: top-gated graphene based transistors, obtained synthesizing graphene on silicon dioxide wafer, and double gate GFETs. The current-voltage curves present a behaviour different from that of devices made of semiconductors, like Si or GaAs, because of the zero gap in monolayer graphene. The current is no longer a monotone function of the gate voltage but there exists an inversion gate voltage [1]. As a consequence, there is a certain degree of uncertainty in the determination of the current-off regime which requires a rather well tuning of the gate-source voltage.
Lately, some attempts to simulate Graphene Field Effects transistors (GFETs) have been performed (see for example [2, 3, 4, 5]) with simplified models like drift-diffusion. The latter contains several functions to be fitted by experimental data such as mobilities and generation-recombination terms. Often adaptations of the expressions used for standard semiconductors are adopted and a reduced 1D Poisson equation is coupled to the equations for the charge transport. It is therefore warranted to have a confirmation of the obtained results by a direct solution of the semiclassical Boltzmann equation for charge transport in graphene. Here a discontinuous Galerkin method, already developed in ([6, 7]), is used to simulate some challenging geometry for future GFETs by numerically solving the Boltzamnn equations for electrons and holes in graphene.

Acknowledgments: The authors acknowledge the financial support from Universitá degli Studi di Catania, Piano della Ricerca 2020/2022 Linea di intervento 2 “QICT”. G. N. acknowledges the financial support from the National Group of Mathematical Physics (GNFM-INdAM) Progetti Giovani GNFM 2020.

References
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