Density functional study of < 110 >-oriented thin silicon nanowires

The electronic band structure and energetic stability of two types of < 110 > oriented silicon nanowires terminated by hydrogen atoms are studied using the density functional theory. The nanowires truncated from the bulk silicon with [100] and [111] facets and the pentagonal star-shaped nanowires with [111] facets have the lowest cohesive energies, whereas the hexagonal star-shaped ones are the highest in energy. The star-shaped nanowires have the lowest band gaps with direct and indirect transitions for pentagonal and hexagonal types, respectively. Based on the theoretical results, an interpretation of existing experimental data has been provided.