First-principles Simulations of a Graphene Based Field-Effect Transistor

TL;DR

This paper presents a novel first-principles simulation approach for graphene-based vertical field-effect tunneling transistors, incorporating electrostatic boundary conditions and dielectric property calculations within density functional theory.

Contribution

It introduces a new simulation method combining the effective screening medium approach with density functional theory for graphene/h-BN transistors.

Findings

Permittivities of h-BN layers are close to crystalline values.

Interface with graphene weakly affects h-BN dielectric properties.

Self-consistent calculations of carrier distribution and band structure.

Abstract

We improvise a novel approach to carry out first-principles simulations of graphene-based vertical field effect tunneling transistors that consist of a graphene$|${\it h}-BN$|$graphene multilayer structure. Within the density functional theory framework, we exploit the effective screening medium (ESM) method to properly treat boundary conditions for electrostatic potentials and investigate the effect of gate voltage. The distribution of free carriers and the band structure of both top and bottom graphene layers are calculated self-consistently. The dielectric properties of {\it h}-BN thin films sandwiched between graphene layers are computed layer-by-layer following the theory of microscopic permittivity. We find that the permittivities of BN layers are very close to that of crystalline {\it h}-BN. The effect of interface with graphene on the dielectric properties of {\it h}-BN is weak, according to an analysis on the interface charge redistribution.