Electronic and optical properties of strained graphene and other strained 2D materials: a review

TL;DR

This review comprehensively discusses how strain influences the electronic and optical properties of graphene and other 2D materials, highlighting theoretical approaches, physical consequences, and potential device applications.

Contribution

It provides an extensive overview of recent advances in understanding strain effects on 2D materials, including new theoretical insights and implications for optoelectronic devices.

Findings

Strain induces exotic electronic states like topological insulators.

Optical properties, especially Raman spectra, are significantly affected by strain.

Strain engineering enables tuning of optical conductivity for device applications.

Abstract

This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schr\"odinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.