On the Impact of Substrate Uniform Mechanical Tension on the Graphene Electronic Structure

Konstantin P Katin,Vadim D Mur,Mikhail M Maslov,Konstantin S Krylov

doi:10.3390/ma13204683

Abstract

Employing density functional theory calculations, we obtain the possibility of fine-tuning the bandgap in graphene deposited on the hexagonal boron nitride and graphitic carbon nitride substrates. We found that the graphene sheet located on these substrates possesses the semiconducting gap, and uniform biaxial mechanical deformation could provide its smooth fitting. Moreover, mechanical tension offers the ability to control the Dirac velocity in deposited graphene. We analyze the resonant scattering of charge carriers in states with zero total angular momentum using the effective two-dimensional radial Dirac equation. In particular, the dependence of the critical impurity charge on the uniform deformation of graphene on the boron nitride substrate is shown. It turned out that, under uniform stretching/compression, the critical charge decreases/increases monotonically. The elastic scattering phases of a hole by a supercritical impurity are calculated. It is found that the model of a uniform charge distribution over the small radius sphere gives sharper resonance when compared to the case of the ball of the same radius. Overall, resonant scattering by the impurity with the nearly critical charge is similar to the scattering by the potential with a low-permeable barrier in nonrelativistic quantum theory.

Highlights

Since its experimental synthesis in 2004 [1], graphene has attracted considerable attention from researchers due to its promising electronic properties
For considered samples, we chose the types of packing, that is, the mutual arrangement of graphene atoms and the substrate, which correspond to the lowest total energy and, are more thermodynamically stable [74,75]
We tried to answer the question of how the choice of the substrate and uniform mechanical stresses can affect the electronic properties in graphene, and, in particular, opens the energy gap and contributes to its fine-tuning

Summary

Introduction

Since its experimental synthesis in 2004 [1], graphene has attracted considerable attention from researchers due to its promising electronic properties. In terms of electronic characteristics, graphene is a gapless semiconductor [2]. The bottom of the conduction band and the ceiling of the valence band converge at one point in graphene, which is called the Dirac point. Ideal free-standing graphene possesses a linear dispersion relation in the vicinity of the Dirac point [3]. Charge carriers in graphene behave like massless relativistic particles that are called Dirac fermions, which determines their extremely high mobility. The mobility of charge carriers in graphene reaches extremely high values, up to ~200,000 cm V−1 s−1 [4]

Methods

Results

Conclusion