Asymmetric 3D Elasticâ Plastic Strainâ Modulated Electron Energy Structure in Monolayer Graphene by Laser Shocking

Abstract

Graphene has a great potential to replace silicon in prospective semiconductor industries due to its outstanding electronic and transport properties; nonetheless, its lack of energy bandgap is a substantial limitation for practical applications. To date, straining graphene to break its lattice symmetry is perhaps the most efficient approach toward realizing bandgap tunability in graphene. However, due to the weak lattice deformation induced by uniaxial or inâ plane shear strain, most strained graphene studies have yielded bandgaps <1 eV. In this work, a modulated inhomogeneous local asymmetric elasticâ plastic straining is reported that utilizes GPaâ level laser shocking at a high strain rate (dε/dt) â 106â 107 sâ 1, with excellent formability, inducing tunable bandgaps in graphene of up to 2.1 eV, as determined by scanning tunneling spectroscopy. Highâ resolution imaging and Raman spectroscopy reveal strainâ induced modifications to the atomic and electronic structure in graphene and firstâ principles simulations predict the measured bandgap openings. Laser shock modulation of semimetallic graphene to a semiconducting material with controllable bandgap has the potential to benefit the electronic and optoelectronic industries.Both the bandgap structure and the Fermi level of monolayer graphene are modulated using an easy and effective optomechanical method. Laserâ shockâ induced 3D nanoshaping enables an asymmetric elasticâ plastic straining of graphene, resulting in a wide graphene bandgap of over 2.1 eV and a wide Fermi level adjustment range of 0.6 eV.