Domain boundaries in silicene: Density functional theory calculations on electronic properties

By using density functional theory (DFT)-based first-principles calculations, the structural stability and electronic properties for two kinds of silicene domain boundaries, forming along armchair edge and zigzag edge, have been investigated. The results indicate that a linkage of tetragonal and octagonal rings (4 vertical bar 8) appears along the armchair edge, while a linkage of paired pentagonal and octagonal rings (5 vertical bar 5 vertical bar 8) appears along the zigzag edge. Different from graphene, the buckling properties of silicene lead to two mirror symmetrical edges of silicene line-defect. The formation energies indicate that the 5 vertical bar 5 vertical bar 8 domain boundary is more stable than the 4 vertical bar 8 domain boundary. Similar to graphene, the calculated electronic properties show that the 5 vertical bar 5 vertical bar 8 domain boundaries exhibit metallic properties and the 4 vertical bar 8 domain boundaries are half-metal. Both domain boundaries create the perfect one-dimensional (1D) metallic wires. Due to the metallic properties, these two kinds of nanowires can be used to build the silicene-based devices.