Tunable band gap in half-fluorinated bilayer graphene under biaxial strains

Opening and tuning of the band gap of bilayer graphene (BLG) is of particular importance for its utilization in nanoelectronics. We presented here the electronic structures of two types of stoichiometrically half-fluorinated BLGs (i.e. C2Fs) as well as those under biaxial compressive and tensile strains. Our results reveal that both C2Fs are semiconductor with large direct band gaps in their unstrained configurations. Under biaxial compressive strains, the band gaps of both C2Fs can be reduced. However, by applying biaxial tensile strains, both C2Fs undergo a direct-to-indirect band gap transition. Electronic nature of the strain-tuned band gaps has been discussed.

► The biaxial compressive strains reduce the band gap of C2F, and could transform C2F from semiconductor to metal. ► By biaxial tensile strain, C2F is found to undergo a direct to indirect band gap transition. ► We discuss the detailed electronic state characteristics of the biaxial strain tuned band gaps of C2F. ► The band gap tuning by biaxial strains are of particular importance for the applications of C2F.