Two-Dimensional γ-Graphyne Suspended on Si(111): A Hybrid Device

Abstract

Graphynes (GYs) are a new class of two-dimensional (2D) carbon allotrope materials that are similar to graphene but with C2 units inserted into certain bonds to produce physical properties distinct from those of graphene. In this work, atomic, electronic, and quantum transport properties of γ-GY—a particular type of graphyne—absorbed on the silicon (111) surface are investigated from atomistic first principles. γ-GY possesses an intrinsic direct band gap, and when interacting with the Si(111), interesting subgap electronic structure is induced to mediate charge transport. In particular, the transmission spectra of the γ-GY/Si(111) hybrid device have a high broad peak at the Fermi level due to hybridization. For γ-GY/Si(111) transport junctions having a finite length trench underneath the γ-GY, substantial charge conduction can still occur through the γ-GY bridge. Nonequilibrium calculations suggest that the hybrid 2D γ-GY/Si(111) transport junction is highly controllable by external voltages.