First-principles prediction of silicon nanocones: Stability and electronic properties

Abstract

Despite the advanced stage of studies on carbon and BN nanocones, with important applications in nanotechnology, systematic investigations on nanocones composed of other atom types are still lacking. Here, we combine density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations to study the stability and electronic properties of silicon nanocones with different disclination angles (θ=60∘,120∘, and180∘). These structures exhibit structural deformation at the edge and apex regions, and also present the same puckered form of silicene. We find that the minimum energy structure is the nanocone with a disclination angle of60∘. Moreover, our ab initio molecular dynamics simulations reveal that this nanocone should remain stable at T = 300 K. We find that all investigated nanocones are metallic and exhibit an energy level located exactly at the Fermi energy. Regarding the magnetic properties, all investigated structures present unpaired electrons, which induce a total spin of1/2or 1. Additionally, we demonstrate that the substitutional doping of silicon nanocones with P and N atoms is energetically favorable, and also promotes the opening of the band gap. Our calculations add a new class of nanostructures to the increasing library of silicon materials.