Enabling direct silicene integration in electronics: First principles study of silicene on NiSi2(111)

Abstract

Silicene on metal silicides poses promise for direct integration of silicene into electronic devices. The details of the metal silicide-silicene interface, however, may have significant effects on the electronic properties. In this work, we investigate the electronic properties of silicene on NiSi2(111) and hydrogenated NiSi2(111) (H:NiSi2) substrates, as well as hydrogenated silicene (H:silicene) on a NiSi2(111) substrate, from first principles. The preferred Si surface termination of NiSi2 was determined through surface energy calculations, and the band structure and density of states (DOS) were calculated for the two-dimensional silicene and H:silicene layers. Hydrogenating NiSi2 lowered the binding energy between silicene and the substrate, resulting in partial decoupling of the electronic properties. Relaxed silicene on H:NiSi2 showed a small band gap opening of 0.14 eV. Silicene on H:NiSi2 also had a calculated electron effective mass of 0.08m0 and a Fermi velocity of 0.39 × 106 m/s, which are similar to the values for freestanding silicene. H:silicene on NiSi2 retained its indirect band structure and DOS compared to freestanding H:silicene. The band gap of H:silicene on NiSi2 was 1.97 eV which is similar to the freestanding H:silicene band gap of 1.99 eV. This results showed that hydrogenation may be a viable method for decoupling a silicene layer from a NiSi2(111) substrate to tune its electronic properties.