▎ 摘　　要

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. C(2)Fs) as well as those under biaxial compressive and tensile strains. Our results reveal that both C(2)Fs are semiconductor with large direct band gaps in their unstrained configurations. Under biaxial compressive strains, the band gaps of both C(2)Fs can be reduced. However, by applying biaxial tensile strains, both C(2)Fs undergo a direct-to-indirect band gap transition. Electronic nature of the strain-tuned band gaps has been discussed. (c) 2012 Elsevier B.V. All rights reserved.