Electronic decoupling by h-BN layer between silicene and Cu(111): A DFT-based analysis

Abstract

Geometric and electronic structures of silicene on Cu(111) covered with a monolayer of hexagonal boron nitride (h-BN) were investigated by ab initio density functional theory calculations. We found that a $\sqrt{3}\times \sqrt{3}R30{}^\circ $ silicene with a regularly buckled configuration is stabilized on $\sqrt{7}\times \sqrt{7}\;R19.1{}^\circ $ h-BN layer stacking commensurately to the Cu(111) substrate. The electronic band structure projected to Si 3p _z orbital clearly shows a band crossing similar to a Dirac cone emerging in the band structure of freestanding buckled silicene. This is in contrast to the silicene on Cu(111), in which the Dirac fermion features disappear entirely due to the strong interactions at the interface. These examples demonstrate that the h-BN monolayer effectively prevents silicene from interacting with the underlying Cu(111) substrate and that the h-BN monolayer on Cu(111) is a promising candidate for use as a substrate on which to realize silicene hosting the Dirac fermion features.

Keywords

• silicene
• DFT calculation
• boron nitride