First - Principles Study On The Effect Of Phosphorus - Doped Silicon Nanobelts And Dangling Bonds On Silicon - Germanium Nanobelts

During the last few decades, the low-dimensional graphene nanomaterials, such as nanotubes (GNTs), nanoribbons (GNRs) and nanowires (GNWs), have attracted immense research in experiment and theory, owing to their fascinating structural and electro-nic properties as well as promising applications in nanoelectronics and nanoscale devices. Both silicon (Si) and germanium (Ge) reside in the same column IV of the periodic table with carbon and thus have many similar characters to carbon. Someone reported that among group-IV elements not only C but also Si and Ge can form stable honeycomb structures.In this paper, we have performed the first-principle calculations onto the structural, electronic and magnetic properties of P doped silicene nanoribbons with both armchair and zigzag edges as well as the the zigzag edged SiGeNRs (ZSiGeNRs) with different edge modi cations. The following results are obtained.:phosphorus atom preferentially substitute at the edges of both armchair and zigzag silicene nanoribbons.. P-doped armchair nanoribbons are still non-magnetic and have changed into metal as the appearance of a half-filled band for almost every site except to the edge one, which exhibits a ferromagnetic character due to the spin splitting of the impurity band and turns back into semiconductor same to the pristine nanoribbons. When the P atom is substituted in zigzag silicene nanoribbons, the AFM-FM transition is happened due to spin suppression in doped edge.There is a metallic character in zigzag SiGe nanoribbons (ZSiGeNRs) regardless of their width. The partial DOS projected onto the Si and Ge atoms of ZSiGeNR shows that a sharp peak at the Fermi level is derived from the edge Si and Ge atoms. The charge density contours show the Si-Ge bond is covalent bond, while for the Si-H bond and Ge-H bond, the valence charges are strongly accumulated around H atoms due to their stronger1s potential and the higher electronegativity of2.20than that of1.90for Si atom and2.01for Ge atom, so that a signi cant charge transformation from Si or Ge atoms to H atoms and thus an ionic binding feature. Spin-polarization calculations show that the band structures of ZSiGeNR are modi ed by the dangling bonds. Compared with perfect ZSiGeNR which is a ferrimagnetic semiconductor, the bands of the ZSiGeNRs with bare Si edge, bare Ge edge, and bare Si and Ge edges shift up and nearly at extra bands appear at the Fermi level. The ZSiGeNR with bare Si edge or bare Ge edge is a ferrimagnetic metal, while ZSiGeNR with bare Si and Ge edges is a nonmagnetic metal.