title: Quasi-particle energies and optical excitations of hydrogenated and fluorinated germanene.
abstract: Using density functional theory, the G0W0 method and Bethe-Salpeter equation calculations, we systematically explore the structural, electronic and optical properties of hydrogenated and fluorinated germanene. The hydrogenated/fluorinated germanene tends to form chair and zigzag-line configurations and its electronic and optical properties show close geometry dependence. The chair hydrogenated/fluorinated and zigzag-line fluorinated germanene are direct band-gap semiconductors, while the zigzag-line hydrogenated germanene owns an indirect band-gap. Moreover, the quasi-particle corrections are significant and strong excitonic effects with large exciton binding energies are observed. Moreover, the zigzag-line hydrogenated/fluorinated germanene shows highly anisotropic optical responses, which may be used as a good optical linear polarizer.
authors.affiliation: Department of Physics, Southeast University, Nanjing, 211189, China. jlwang@seu.edu.cn.
authors.forename: Huabing
authors.initials: H
authors.lastname: Shu
authors.forename: Yunhai
authors.initials: Y
authors.lastname: Li
authors.forename: Shudong
authors.initials: S
authors.lastname: Wang
authors.forename: Jinlan
authors.initials: J
authors.lastname: Wang