Eur. Phys. J. B (2017) 90: 112
https://doi.org/10.1140/epjb/e2017-80091-x

Regular Article

Mutual influence of uniaxial tensile strain and point defect pattern on electronic states in graphene

¹ Dept. of General Physics, Taras Shevchenko National University of Kyiv, 64 Volodymyrska Street, 03022 Kyiv, Ukraine
² Dept. of Metallic State Theory, G. V. Kurdyumov Institute for Metal Physics of N.A.S. of Ukraine, 36 Academician Vernadsky Boulevard, 03142 Kyiv, Ukraine
³ Dept. of Biophysics, Institute of Biology and Medicine, Taras Shevchenko National University of Kyiv, 64 Volodymyrska Street, UA-03022 Kyiv, Ukraine
⁴ Institute of Physics, Kazimierz Wielki University, Powstańców Wielkopolskich 2, 85-090 Bydgoszcz, Poland

^a e-mail: tarad@imp.kiev.ua

Received: 11 February 2017
Received in final form: 19 April 2017
Published online: 14 June 2017

Abstract

The study deals with electronic properties of uniaxially stressed mono- and multi-layer graphene sheets with various kinds of imperfection: point defects modelled as resonant (neutral) adsorbed atoms or molecules, vacancies, charged impurities, and local distortions. The presence of randomly distributed defects in a strained graphene counteract the band-gap opening and even can suppress the gap occurs when they are absent. However, impurity ordering contributes to the band gap appearance and thereby re-opens the gap being suppressed by random dopants in graphene stretched along zigzag-edge direction. The band gap is found to be non-monotonic with strain in case of mutual action of defect ordering and zigzag deformation. Herewith, the minimal tensile strain required for the band-gap opening (≈12.5%) is smaller than that for defect-free graphene (≈23%), and band gap energy reaches the value predicted for maximal nondestructive strains in the pristine graphene. Effective manipulating the band gap in graphene requires balanced content of ordered dopants: their concentration should be sufficient for a significant sublattice asymmetry effect, but not so much that they may suppress the band gap or transform it into the “quasi- (or pseudo-) gap”.