The structural, electronic, and optical properties of hydrofluorinated germanene (GeH1-xFx): a first-principles study.

The structural, electronic, and optical properties of hydrofluorinated germanene have been studied with different occupancy ratios of fluorine and hydrogen. The hybridization of H-1 s and Ge-4p orbitals in hydrogenated germanene and F-2p and Ge-4p orbitals in fluorinated germanene plays a significant role in creating an energy bandgap. The binding energy and phonon calculations confirm the stability of hydrofluorinated germanene decreases with the increase of the F to H ratio. The value of the energy bandgap decreased by increasing the ratio of F and H. The optical properties have been studied in the energy range of 0-25 eV. Six essential parameters such as energy bandgap (Eg), binding energy (Eb), dielectric constant ε(0), refractive index n(0), plasmon energy (ћωp), and heat capacity (Cp) have been calculated for different occupancies of H and F in hydrofluorinated germanene for the first time. The calculated values of structural parameters agree well with the reported values.