Metal-semiconductor transition in Ψ-graphene

Abstract

The effect of hydrogenation on the density of states (DOS), band structure, Pauli magnetic susceptibility (PMS), and electronic heat capacity (EHC) of Ψ -graphene is investigated within the nearest neighbor tight-binding model. Two different hydrogenation process of Ψ -graphene is examined: half hydrogenation ( Ψ -graphone) and full hydrogenation ( Ψ -graphane). It was observed that Ψ -graphone, like Ψ -graphene, exhibits metallic behavior, but it has sharp peaks in the DOS and corresponding flat bands in the band structure near the Fermi level, due to unpaired and localized electrons in its structure. Whereas, because of the strong σ bonds in the Ψ -graphane structure, a bandgap is created in its energy spectra. It can also be seen that with the hydrogenation of Ψ -graphene, the van-Hove singularities in the DOS and the number of sub-band in the band structures increased due to the greater overlap of the orbitals. These lead to the crossovers in the PMS and the Schottky anomaly peaks in the EHC, which both of these peaks are observed in the Ψ -graphane curve at a higher temperature than the other two structures. These results indicate that the hydrogenation of Ψ -graphene leads to a metal-to-semiconductor transition.